1 /* 2 * kernel/sched/core.c 3 * 4 * Kernel scheduler and related syscalls 5 * 6 * Copyright (C) 1991-2002 Linus Torvalds 7 * 8 * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and 9 * make semaphores SMP safe 10 * 1998-11-19 Implemented schedule_timeout() and related stuff 11 * by Andrea Arcangeli 12 * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar: 13 * hybrid priority-list and round-robin design with 14 * an array-switch method of distributing timeslices 15 * and per-CPU runqueues. Cleanups and useful suggestions 16 * by Davide Libenzi, preemptible kernel bits by Robert Love. 17 * 2003-09-03 Interactivity tuning by Con Kolivas. 18 * 2004-04-02 Scheduler domains code by Nick Piggin 19 * 2007-04-15 Work begun on replacing all interactivity tuning with a 20 * fair scheduling design by Con Kolivas. 21 * 2007-05-05 Load balancing (smp-nice) and other improvements 22 * by Peter Williams 23 * 2007-05-06 Interactivity improvements to CFS by Mike Galbraith 24 * 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri 25 * 2007-11-29 RT balancing improvements by Steven Rostedt, Gregory Haskins, 26 * Thomas Gleixner, Mike Kravetz 27 */ 28 29 #include <linux/kasan.h> 30 #include <linux/mm.h> 31 #include <linux/module.h> 32 #include <linux/nmi.h> 33 #include <linux/init.h> 34 #include <linux/uaccess.h> 35 #include <linux/highmem.h> 36 #include <linux/mmu_context.h> 37 #include <linux/interrupt.h> 38 #include <linux/capability.h> 39 #include <linux/completion.h> 40 #include <linux/kernel_stat.h> 41 #include <linux/debug_locks.h> 42 #include <linux/perf_event.h> 43 #include <linux/security.h> 44 #include <linux/notifier.h> 45 #include <linux/profile.h> 46 #include <linux/freezer.h> 47 #include <linux/vmalloc.h> 48 #include <linux/blkdev.h> 49 #include <linux/delay.h> 50 #include <linux/pid_namespace.h> 51 #include <linux/smp.h> 52 #include <linux/threads.h> 53 #include <linux/timer.h> 54 #include <linux/rcupdate.h> 55 #include <linux/cpu.h> 56 #include <linux/cpuset.h> 57 #include <linux/percpu.h> 58 #include <linux/proc_fs.h> 59 #include <linux/seq_file.h> 60 #include <linux/sysctl.h> 61 #include <linux/syscalls.h> 62 #include <linux/times.h> 63 #include <linux/tsacct_kern.h> 64 #include <linux/kprobes.h> 65 #include <linux/delayacct.h> 66 #include <linux/unistd.h> 67 #include <linux/pagemap.h> 68 #include <linux/hrtimer.h> 69 #include <linux/tick.h> 70 #include <linux/ctype.h> 71 #include <linux/ftrace.h> 72 #include <linux/slab.h> 73 #include <linux/init_task.h> 74 #include <linux/context_tracking.h> 75 #include <linux/compiler.h> 76 #include <linux/frame.h> 77 #include <linux/prefetch.h> 78 79 #include <asm/switch_to.h> 80 #include <asm/tlb.h> 81 #include <asm/irq_regs.h> 82 #include <asm/mutex.h> 83 #ifdef CONFIG_PARAVIRT 84 #include <asm/paravirt.h> 85 #endif 86 87 #include "sched.h" 88 #include "../workqueue_internal.h" 89 #include "../smpboot.h" 90 91 #define CREATE_TRACE_POINTS 92 #include <trace/events/sched.h> 93 94 DEFINE_MUTEX(sched_domains_mutex); 95 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); 96 97 static void update_rq_clock_task(struct rq *rq, s64 delta); 98 99 void update_rq_clock(struct rq *rq) 100 { 101 s64 delta; 102 103 lockdep_assert_held(&rq->lock); 104 105 if (rq->clock_skip_update & RQCF_ACT_SKIP) 106 return; 107 108 delta = sched_clock_cpu(cpu_of(rq)) - rq->clock; 109 if (delta < 0) 110 return; 111 rq->clock += delta; 112 update_rq_clock_task(rq, delta); 113 } 114 115 /* 116 * Debugging: various feature bits 117 */ 118 119 #define SCHED_FEAT(name, enabled) \ 120 (1UL << __SCHED_FEAT_##name) * enabled | 121 122 const_debug unsigned int sysctl_sched_features = 123 #include "features.h" 124 0; 125 126 #undef SCHED_FEAT 127 128 /* 129 * Number of tasks to iterate in a single balance run. 130 * Limited because this is done with IRQs disabled. 131 */ 132 const_debug unsigned int sysctl_sched_nr_migrate = 32; 133 134 /* 135 * period over which we average the RT time consumption, measured 136 * in ms. 137 * 138 * default: 1s 139 */ 140 const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC; 141 142 /* 143 * period over which we measure -rt task cpu usage in us. 144 * default: 1s 145 */ 146 unsigned int sysctl_sched_rt_period = 1000000; 147 148 __read_mostly int scheduler_running; 149 150 /* 151 * part of the period that we allow rt tasks to run in us. 152 * default: 0.95s 153 */ 154 int sysctl_sched_rt_runtime = 950000; 155 156 /* cpus with isolated domains */ 157 cpumask_var_t cpu_isolated_map; 158 159 /* 160 * this_rq_lock - lock this runqueue and disable interrupts. 161 */ 162 static struct rq *this_rq_lock(void) 163 __acquires(rq->lock) 164 { 165 struct rq *rq; 166 167 local_irq_disable(); 168 rq = this_rq(); 169 raw_spin_lock(&rq->lock); 170 171 return rq; 172 } 173 174 /* 175 * __task_rq_lock - lock the rq @p resides on. 176 */ 177 struct rq *__task_rq_lock(struct task_struct *p, struct rq_flags *rf) 178 __acquires(rq->lock) 179 { 180 struct rq *rq; 181 182 lockdep_assert_held(&p->pi_lock); 183 184 for (;;) { 185 rq = task_rq(p); 186 raw_spin_lock(&rq->lock); 187 if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) { 188 rf->cookie = lockdep_pin_lock(&rq->lock); 189 return rq; 190 } 191 raw_spin_unlock(&rq->lock); 192 193 while (unlikely(task_on_rq_migrating(p))) 194 cpu_relax(); 195 } 196 } 197 198 /* 199 * task_rq_lock - lock p->pi_lock and lock the rq @p resides on. 200 */ 201 struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf) 202 __acquires(p->pi_lock) 203 __acquires(rq->lock) 204 { 205 struct rq *rq; 206 207 for (;;) { 208 raw_spin_lock_irqsave(&p->pi_lock, rf->flags); 209 rq = task_rq(p); 210 raw_spin_lock(&rq->lock); 211 /* 212 * move_queued_task() task_rq_lock() 213 * 214 * ACQUIRE (rq->lock) 215 * [S] ->on_rq = MIGRATING [L] rq = task_rq() 216 * WMB (__set_task_cpu()) ACQUIRE (rq->lock); 217 * [S] ->cpu = new_cpu [L] task_rq() 218 * [L] ->on_rq 219 * RELEASE (rq->lock) 220 * 221 * If we observe the old cpu in task_rq_lock, the acquire of 222 * the old rq->lock will fully serialize against the stores. 223 * 224 * If we observe the new cpu in task_rq_lock, the acquire will 225 * pair with the WMB to ensure we must then also see migrating. 226 */ 227 if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) { 228 rf->cookie = lockdep_pin_lock(&rq->lock); 229 return rq; 230 } 231 raw_spin_unlock(&rq->lock); 232 raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags); 233 234 while (unlikely(task_on_rq_migrating(p))) 235 cpu_relax(); 236 } 237 } 238 239 #ifdef CONFIG_SCHED_HRTICK 240 /* 241 * Use HR-timers to deliver accurate preemption points. 242 */ 243 244 static void hrtick_clear(struct rq *rq) 245 { 246 if (hrtimer_active(&rq->hrtick_timer)) 247 hrtimer_cancel(&rq->hrtick_timer); 248 } 249 250 /* 251 * High-resolution timer tick. 252 * Runs from hardirq context with interrupts disabled. 253 */ 254 static enum hrtimer_restart hrtick(struct hrtimer *timer) 255 { 256 struct rq *rq = container_of(timer, struct rq, hrtick_timer); 257 258 WARN_ON_ONCE(cpu_of(rq) != smp_processor_id()); 259 260 raw_spin_lock(&rq->lock); 261 update_rq_clock(rq); 262 rq->curr->sched_class->task_tick(rq, rq->curr, 1); 263 raw_spin_unlock(&rq->lock); 264 265 return HRTIMER_NORESTART; 266 } 267 268 #ifdef CONFIG_SMP 269 270 static void __hrtick_restart(struct rq *rq) 271 { 272 struct hrtimer *timer = &rq->hrtick_timer; 273 274 hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED); 275 } 276 277 /* 278 * called from hardirq (IPI) context 279 */ 280 static void __hrtick_start(void *arg) 281 { 282 struct rq *rq = arg; 283 284 raw_spin_lock(&rq->lock); 285 __hrtick_restart(rq); 286 rq->hrtick_csd_pending = 0; 287 raw_spin_unlock(&rq->lock); 288 } 289 290 /* 291 * Called to set the hrtick timer state. 292 * 293 * called with rq->lock held and irqs disabled 294 */ 295 void hrtick_start(struct rq *rq, u64 delay) 296 { 297 struct hrtimer *timer = &rq->hrtick_timer; 298 ktime_t time; 299 s64 delta; 300 301 /* 302 * Don't schedule slices shorter than 10000ns, that just 303 * doesn't make sense and can cause timer DoS. 304 */ 305 delta = max_t(s64, delay, 10000LL); 306 time = ktime_add_ns(timer->base->get_time(), delta); 307 308 hrtimer_set_expires(timer, time); 309 310 if (rq == this_rq()) { 311 __hrtick_restart(rq); 312 } else if (!rq->hrtick_csd_pending) { 313 smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd); 314 rq->hrtick_csd_pending = 1; 315 } 316 } 317 318 #else 319 /* 320 * Called to set the hrtick timer state. 321 * 322 * called with rq->lock held and irqs disabled 323 */ 324 void hrtick_start(struct rq *rq, u64 delay) 325 { 326 /* 327 * Don't schedule slices shorter than 10000ns, that just 328 * doesn't make sense. Rely on vruntime for fairness. 329 */ 330 delay = max_t(u64, delay, 10000LL); 331 hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay), 332 HRTIMER_MODE_REL_PINNED); 333 } 334 #endif /* CONFIG_SMP */ 335 336 static void init_rq_hrtick(struct rq *rq) 337 { 338 #ifdef CONFIG_SMP 339 rq->hrtick_csd_pending = 0; 340 341 rq->hrtick_csd.flags = 0; 342 rq->hrtick_csd.func = __hrtick_start; 343 rq->hrtick_csd.info = rq; 344 #endif 345 346 hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 347 rq->hrtick_timer.function = hrtick; 348 } 349 #else /* CONFIG_SCHED_HRTICK */ 350 static inline void hrtick_clear(struct rq *rq) 351 { 352 } 353 354 static inline void init_rq_hrtick(struct rq *rq) 355 { 356 } 357 #endif /* CONFIG_SCHED_HRTICK */ 358 359 /* 360 * cmpxchg based fetch_or, macro so it works for different integer types 361 */ 362 #define fetch_or(ptr, mask) \ 363 ({ \ 364 typeof(ptr) _ptr = (ptr); \ 365 typeof(mask) _mask = (mask); \ 366 typeof(*_ptr) _old, _val = *_ptr; \ 367 \ 368 for (;;) { \ 369 _old = cmpxchg(_ptr, _val, _val | _mask); \ 370 if (_old == _val) \ 371 break; \ 372 _val = _old; \ 373 } \ 374 _old; \ 375 }) 376 377 #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG) 378 /* 379 * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG, 380 * this avoids any races wrt polling state changes and thereby avoids 381 * spurious IPIs. 382 */ 383 static bool set_nr_and_not_polling(struct task_struct *p) 384 { 385 struct thread_info *ti = task_thread_info(p); 386 return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG); 387 } 388 389 /* 390 * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set. 391 * 392 * If this returns true, then the idle task promises to call 393 * sched_ttwu_pending() and reschedule soon. 394 */ 395 static bool set_nr_if_polling(struct task_struct *p) 396 { 397 struct thread_info *ti = task_thread_info(p); 398 typeof(ti->flags) old, val = READ_ONCE(ti->flags); 399 400 for (;;) { 401 if (!(val & _TIF_POLLING_NRFLAG)) 402 return false; 403 if (val & _TIF_NEED_RESCHED) 404 return true; 405 old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED); 406 if (old == val) 407 break; 408 val = old; 409 } 410 return true; 411 } 412 413 #else 414 static bool set_nr_and_not_polling(struct task_struct *p) 415 { 416 set_tsk_need_resched(p); 417 return true; 418 } 419 420 #ifdef CONFIG_SMP 421 static bool set_nr_if_polling(struct task_struct *p) 422 { 423 return false; 424 } 425 #endif 426 #endif 427 428 void wake_q_add(struct wake_q_head *head, struct task_struct *task) 429 { 430 struct wake_q_node *node = &task->wake_q; 431 432 /* 433 * Atomically grab the task, if ->wake_q is !nil already it means 434 * its already queued (either by us or someone else) and will get the 435 * wakeup due to that. 436 * 437 * This cmpxchg() implies a full barrier, which pairs with the write 438 * barrier implied by the wakeup in wake_up_q(). 439 */ 440 if (cmpxchg(&node->next, NULL, WAKE_Q_TAIL)) 441 return; 442 443 get_task_struct(task); 444 445 /* 446 * The head is context local, there can be no concurrency. 447 */ 448 *head->lastp = node; 449 head->lastp = &node->next; 450 } 451 452 void wake_up_q(struct wake_q_head *head) 453 { 454 struct wake_q_node *node = head->first; 455 456 while (node != WAKE_Q_TAIL) { 457 struct task_struct *task; 458 459 task = container_of(node, struct task_struct, wake_q); 460 BUG_ON(!task); 461 /* task can safely be re-inserted now */ 462 node = node->next; 463 task->wake_q.next = NULL; 464 465 /* 466 * wake_up_process() implies a wmb() to pair with the queueing 467 * in wake_q_add() so as not to miss wakeups. 468 */ 469 wake_up_process(task); 470 put_task_struct(task); 471 } 472 } 473 474 /* 475 * resched_curr - mark rq's current task 'to be rescheduled now'. 476 * 477 * On UP this means the setting of the need_resched flag, on SMP it 478 * might also involve a cross-CPU call to trigger the scheduler on 479 * the target CPU. 480 */ 481 void resched_curr(struct rq *rq) 482 { 483 struct task_struct *curr = rq->curr; 484 int cpu; 485 486 lockdep_assert_held(&rq->lock); 487 488 if (test_tsk_need_resched(curr)) 489 return; 490 491 cpu = cpu_of(rq); 492 493 if (cpu == smp_processor_id()) { 494 set_tsk_need_resched(curr); 495 set_preempt_need_resched(); 496 return; 497 } 498 499 if (set_nr_and_not_polling(curr)) 500 smp_send_reschedule(cpu); 501 else 502 trace_sched_wake_idle_without_ipi(cpu); 503 } 504 505 void resched_cpu(int cpu) 506 { 507 struct rq *rq = cpu_rq(cpu); 508 unsigned long flags; 509 510 if (!raw_spin_trylock_irqsave(&rq->lock, flags)) 511 return; 512 resched_curr(rq); 513 raw_spin_unlock_irqrestore(&rq->lock, flags); 514 } 515 516 #ifdef CONFIG_SMP 517 #ifdef CONFIG_NO_HZ_COMMON 518 /* 519 * In the semi idle case, use the nearest busy cpu for migrating timers 520 * from an idle cpu. This is good for power-savings. 521 * 522 * We don't do similar optimization for completely idle system, as 523 * selecting an idle cpu will add more delays to the timers than intended 524 * (as that cpu's timer base may not be uptodate wrt jiffies etc). 525 */ 526 int get_nohz_timer_target(void) 527 { 528 int i, cpu = smp_processor_id(); 529 struct sched_domain *sd; 530 531 if (!idle_cpu(cpu) && is_housekeeping_cpu(cpu)) 532 return cpu; 533 534 rcu_read_lock(); 535 for_each_domain(cpu, sd) { 536 for_each_cpu(i, sched_domain_span(sd)) { 537 if (cpu == i) 538 continue; 539 540 if (!idle_cpu(i) && is_housekeeping_cpu(i)) { 541 cpu = i; 542 goto unlock; 543 } 544 } 545 } 546 547 if (!is_housekeeping_cpu(cpu)) 548 cpu = housekeeping_any_cpu(); 549 unlock: 550 rcu_read_unlock(); 551 return cpu; 552 } 553 /* 554 * When add_timer_on() enqueues a timer into the timer wheel of an 555 * idle CPU then this timer might expire before the next timer event 556 * which is scheduled to wake up that CPU. In case of a completely 557 * idle system the next event might even be infinite time into the 558 * future. wake_up_idle_cpu() ensures that the CPU is woken up and 559 * leaves the inner idle loop so the newly added timer is taken into 560 * account when the CPU goes back to idle and evaluates the timer 561 * wheel for the next timer event. 562 */ 563 static void wake_up_idle_cpu(int cpu) 564 { 565 struct rq *rq = cpu_rq(cpu); 566 567 if (cpu == smp_processor_id()) 568 return; 569 570 if (set_nr_and_not_polling(rq->idle)) 571 smp_send_reschedule(cpu); 572 else 573 trace_sched_wake_idle_without_ipi(cpu); 574 } 575 576 static bool wake_up_full_nohz_cpu(int cpu) 577 { 578 /* 579 * We just need the target to call irq_exit() and re-evaluate 580 * the next tick. The nohz full kick at least implies that. 581 * If needed we can still optimize that later with an 582 * empty IRQ. 583 */ 584 if (tick_nohz_full_cpu(cpu)) { 585 if (cpu != smp_processor_id() || 586 tick_nohz_tick_stopped()) 587 tick_nohz_full_kick_cpu(cpu); 588 return true; 589 } 590 591 return false; 592 } 593 594 void wake_up_nohz_cpu(int cpu) 595 { 596 if (!wake_up_full_nohz_cpu(cpu)) 597 wake_up_idle_cpu(cpu); 598 } 599 600 static inline bool got_nohz_idle_kick(void) 601 { 602 int cpu = smp_processor_id(); 603 604 if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu))) 605 return false; 606 607 if (idle_cpu(cpu) && !need_resched()) 608 return true; 609 610 /* 611 * We can't run Idle Load Balance on this CPU for this time so we 612 * cancel it and clear NOHZ_BALANCE_KICK 613 */ 614 clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)); 615 return false; 616 } 617 618 #else /* CONFIG_NO_HZ_COMMON */ 619 620 static inline bool got_nohz_idle_kick(void) 621 { 622 return false; 623 } 624 625 #endif /* CONFIG_NO_HZ_COMMON */ 626 627 #ifdef CONFIG_NO_HZ_FULL 628 bool sched_can_stop_tick(struct rq *rq) 629 { 630 int fifo_nr_running; 631 632 /* Deadline tasks, even if single, need the tick */ 633 if (rq->dl.dl_nr_running) 634 return false; 635 636 /* 637 * If there are more than one RR tasks, we need the tick to effect the 638 * actual RR behaviour. 639 */ 640 if (rq->rt.rr_nr_running) { 641 if (rq->rt.rr_nr_running == 1) 642 return true; 643 else 644 return false; 645 } 646 647 /* 648 * If there's no RR tasks, but FIFO tasks, we can skip the tick, no 649 * forced preemption between FIFO tasks. 650 */ 651 fifo_nr_running = rq->rt.rt_nr_running - rq->rt.rr_nr_running; 652 if (fifo_nr_running) 653 return true; 654 655 /* 656 * If there are no DL,RR/FIFO tasks, there must only be CFS tasks left; 657 * if there's more than one we need the tick for involuntary 658 * preemption. 659 */ 660 if (rq->nr_running > 1) 661 return false; 662 663 return true; 664 } 665 #endif /* CONFIG_NO_HZ_FULL */ 666 667 void sched_avg_update(struct rq *rq) 668 { 669 s64 period = sched_avg_period(); 670 671 while ((s64)(rq_clock(rq) - rq->age_stamp) > period) { 672 /* 673 * Inline assembly required to prevent the compiler 674 * optimising this loop into a divmod call. 675 * See __iter_div_u64_rem() for another example of this. 676 */ 677 asm("" : "+rm" (rq->age_stamp)); 678 rq->age_stamp += period; 679 rq->rt_avg /= 2; 680 } 681 } 682 683 #endif /* CONFIG_SMP */ 684 685 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \ 686 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH))) 687 /* 688 * Iterate task_group tree rooted at *from, calling @down when first entering a 689 * node and @up when leaving it for the final time. 690 * 691 * Caller must hold rcu_lock or sufficient equivalent. 692 */ 693 int walk_tg_tree_from(struct task_group *from, 694 tg_visitor down, tg_visitor up, void *data) 695 { 696 struct task_group *parent, *child; 697 int ret; 698 699 parent = from; 700 701 down: 702 ret = (*down)(parent, data); 703 if (ret) 704 goto out; 705 list_for_each_entry_rcu(child, &parent->children, siblings) { 706 parent = child; 707 goto down; 708 709 up: 710 continue; 711 } 712 ret = (*up)(parent, data); 713 if (ret || parent == from) 714 goto out; 715 716 child = parent; 717 parent = parent->parent; 718 if (parent) 719 goto up; 720 out: 721 return ret; 722 } 723 724 int tg_nop(struct task_group *tg, void *data) 725 { 726 return 0; 727 } 728 #endif 729 730 static void set_load_weight(struct task_struct *p) 731 { 732 int prio = p->static_prio - MAX_RT_PRIO; 733 struct load_weight *load = &p->se.load; 734 735 /* 736 * SCHED_IDLE tasks get minimal weight: 737 */ 738 if (idle_policy(p->policy)) { 739 load->weight = scale_load(WEIGHT_IDLEPRIO); 740 load->inv_weight = WMULT_IDLEPRIO; 741 return; 742 } 743 744 load->weight = scale_load(sched_prio_to_weight[prio]); 745 load->inv_weight = sched_prio_to_wmult[prio]; 746 } 747 748 static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags) 749 { 750 update_rq_clock(rq); 751 if (!(flags & ENQUEUE_RESTORE)) 752 sched_info_queued(rq, p); 753 p->sched_class->enqueue_task(rq, p, flags); 754 } 755 756 static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags) 757 { 758 update_rq_clock(rq); 759 if (!(flags & DEQUEUE_SAVE)) 760 sched_info_dequeued(rq, p); 761 p->sched_class->dequeue_task(rq, p, flags); 762 } 763 764 void activate_task(struct rq *rq, struct task_struct *p, int flags) 765 { 766 if (task_contributes_to_load(p)) 767 rq->nr_uninterruptible--; 768 769 enqueue_task(rq, p, flags); 770 } 771 772 void deactivate_task(struct rq *rq, struct task_struct *p, int flags) 773 { 774 if (task_contributes_to_load(p)) 775 rq->nr_uninterruptible++; 776 777 dequeue_task(rq, p, flags); 778 } 779 780 static void update_rq_clock_task(struct rq *rq, s64 delta) 781 { 782 /* 783 * In theory, the compile should just see 0 here, and optimize out the call 784 * to sched_rt_avg_update. But I don't trust it... 785 */ 786 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) 787 s64 steal = 0, irq_delta = 0; 788 #endif 789 #ifdef CONFIG_IRQ_TIME_ACCOUNTING 790 irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time; 791 792 /* 793 * Since irq_time is only updated on {soft,}irq_exit, we might run into 794 * this case when a previous update_rq_clock() happened inside a 795 * {soft,}irq region. 796 * 797 * When this happens, we stop ->clock_task and only update the 798 * prev_irq_time stamp to account for the part that fit, so that a next 799 * update will consume the rest. This ensures ->clock_task is 800 * monotonic. 801 * 802 * It does however cause some slight miss-attribution of {soft,}irq 803 * time, a more accurate solution would be to update the irq_time using 804 * the current rq->clock timestamp, except that would require using 805 * atomic ops. 806 */ 807 if (irq_delta > delta) 808 irq_delta = delta; 809 810 rq->prev_irq_time += irq_delta; 811 delta -= irq_delta; 812 #endif 813 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING 814 if (static_key_false((¶virt_steal_rq_enabled))) { 815 steal = paravirt_steal_clock(cpu_of(rq)); 816 steal -= rq->prev_steal_time_rq; 817 818 if (unlikely(steal > delta)) 819 steal = delta; 820 821 rq->prev_steal_time_rq += steal; 822 delta -= steal; 823 } 824 #endif 825 826 rq->clock_task += delta; 827 828 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) 829 if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY)) 830 sched_rt_avg_update(rq, irq_delta + steal); 831 #endif 832 } 833 834 void sched_set_stop_task(int cpu, struct task_struct *stop) 835 { 836 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 }; 837 struct task_struct *old_stop = cpu_rq(cpu)->stop; 838 839 if (stop) { 840 /* 841 * Make it appear like a SCHED_FIFO task, its something 842 * userspace knows about and won't get confused about. 843 * 844 * Also, it will make PI more or less work without too 845 * much confusion -- but then, stop work should not 846 * rely on PI working anyway. 847 */ 848 sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m); 849 850 stop->sched_class = &stop_sched_class; 851 } 852 853 cpu_rq(cpu)->stop = stop; 854 855 if (old_stop) { 856 /* 857 * Reset it back to a normal scheduling class so that 858 * it can die in pieces. 859 */ 860 old_stop->sched_class = &rt_sched_class; 861 } 862 } 863 864 /* 865 * __normal_prio - return the priority that is based on the static prio 866 */ 867 static inline int __normal_prio(struct task_struct *p) 868 { 869 return p->static_prio; 870 } 871 872 /* 873 * Calculate the expected normal priority: i.e. priority 874 * without taking RT-inheritance into account. Might be 875 * boosted by interactivity modifiers. Changes upon fork, 876 * setprio syscalls, and whenever the interactivity 877 * estimator recalculates. 878 */ 879 static inline int normal_prio(struct task_struct *p) 880 { 881 int prio; 882 883 if (task_has_dl_policy(p)) 884 prio = MAX_DL_PRIO-1; 885 else if (task_has_rt_policy(p)) 886 prio = MAX_RT_PRIO-1 - p->rt_priority; 887 else 888 prio = __normal_prio(p); 889 return prio; 890 } 891 892 /* 893 * Calculate the current priority, i.e. the priority 894 * taken into account by the scheduler. This value might 895 * be boosted by RT tasks, or might be boosted by 896 * interactivity modifiers. Will be RT if the task got 897 * RT-boosted. If not then it returns p->normal_prio. 898 */ 899 static int effective_prio(struct task_struct *p) 900 { 901 p->normal_prio = normal_prio(p); 902 /* 903 * If we are RT tasks or we were boosted to RT priority, 904 * keep the priority unchanged. Otherwise, update priority 905 * to the normal priority: 906 */ 907 if (!rt_prio(p->prio)) 908 return p->normal_prio; 909 return p->prio; 910 } 911 912 /** 913 * task_curr - is this task currently executing on a CPU? 914 * @p: the task in question. 915 * 916 * Return: 1 if the task is currently executing. 0 otherwise. 917 */ 918 inline int task_curr(const struct task_struct *p) 919 { 920 return cpu_curr(task_cpu(p)) == p; 921 } 922 923 /* 924 * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock, 925 * use the balance_callback list if you want balancing. 926 * 927 * this means any call to check_class_changed() must be followed by a call to 928 * balance_callback(). 929 */ 930 static inline void check_class_changed(struct rq *rq, struct task_struct *p, 931 const struct sched_class *prev_class, 932 int oldprio) 933 { 934 if (prev_class != p->sched_class) { 935 if (prev_class->switched_from) 936 prev_class->switched_from(rq, p); 937 938 p->sched_class->switched_to(rq, p); 939 } else if (oldprio != p->prio || dl_task(p)) 940 p->sched_class->prio_changed(rq, p, oldprio); 941 } 942 943 void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags) 944 { 945 const struct sched_class *class; 946 947 if (p->sched_class == rq->curr->sched_class) { 948 rq->curr->sched_class->check_preempt_curr(rq, p, flags); 949 } else { 950 for_each_class(class) { 951 if (class == rq->curr->sched_class) 952 break; 953 if (class == p->sched_class) { 954 resched_curr(rq); 955 break; 956 } 957 } 958 } 959 960 /* 961 * A queue event has occurred, and we're going to schedule. In 962 * this case, we can save a useless back to back clock update. 963 */ 964 if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr)) 965 rq_clock_skip_update(rq, true); 966 } 967 968 #ifdef CONFIG_SMP 969 /* 970 * This is how migration works: 971 * 972 * 1) we invoke migration_cpu_stop() on the target CPU using 973 * stop_one_cpu(). 974 * 2) stopper starts to run (implicitly forcing the migrated thread 975 * off the CPU) 976 * 3) it checks whether the migrated task is still in the wrong runqueue. 977 * 4) if it's in the wrong runqueue then the migration thread removes 978 * it and puts it into the right queue. 979 * 5) stopper completes and stop_one_cpu() returns and the migration 980 * is done. 981 */ 982 983 /* 984 * move_queued_task - move a queued task to new rq. 985 * 986 * Returns (locked) new rq. Old rq's lock is released. 987 */ 988 static struct rq *move_queued_task(struct rq *rq, struct task_struct *p, int new_cpu) 989 { 990 lockdep_assert_held(&rq->lock); 991 992 p->on_rq = TASK_ON_RQ_MIGRATING; 993 dequeue_task(rq, p, 0); 994 set_task_cpu(p, new_cpu); 995 raw_spin_unlock(&rq->lock); 996 997 rq = cpu_rq(new_cpu); 998 999 raw_spin_lock(&rq->lock); 1000 BUG_ON(task_cpu(p) != new_cpu); 1001 enqueue_task(rq, p, 0); 1002 p->on_rq = TASK_ON_RQ_QUEUED; 1003 check_preempt_curr(rq, p, 0); 1004 1005 return rq; 1006 } 1007 1008 struct migration_arg { 1009 struct task_struct *task; 1010 int dest_cpu; 1011 }; 1012 1013 /* 1014 * Move (not current) task off this cpu, onto dest cpu. We're doing 1015 * this because either it can't run here any more (set_cpus_allowed() 1016 * away from this CPU, or CPU going down), or because we're 1017 * attempting to rebalance this task on exec (sched_exec). 1018 * 1019 * So we race with normal scheduler movements, but that's OK, as long 1020 * as the task is no longer on this CPU. 1021 */ 1022 static struct rq *__migrate_task(struct rq *rq, struct task_struct *p, int dest_cpu) 1023 { 1024 if (unlikely(!cpu_active(dest_cpu))) 1025 return rq; 1026 1027 /* Affinity changed (again). */ 1028 if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p))) 1029 return rq; 1030 1031 rq = move_queued_task(rq, p, dest_cpu); 1032 1033 return rq; 1034 } 1035 1036 /* 1037 * migration_cpu_stop - this will be executed by a highprio stopper thread 1038 * and performs thread migration by bumping thread off CPU then 1039 * 'pushing' onto another runqueue. 1040 */ 1041 static int migration_cpu_stop(void *data) 1042 { 1043 struct migration_arg *arg = data; 1044 struct task_struct *p = arg->task; 1045 struct rq *rq = this_rq(); 1046 1047 /* 1048 * The original target cpu might have gone down and we might 1049 * be on another cpu but it doesn't matter. 1050 */ 1051 local_irq_disable(); 1052 /* 1053 * We need to explicitly wake pending tasks before running 1054 * __migrate_task() such that we will not miss enforcing cpus_allowed 1055 * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test. 1056 */ 1057 sched_ttwu_pending(); 1058 1059 raw_spin_lock(&p->pi_lock); 1060 raw_spin_lock(&rq->lock); 1061 /* 1062 * If task_rq(p) != rq, it cannot be migrated here, because we're 1063 * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because 1064 * we're holding p->pi_lock. 1065 */ 1066 if (task_rq(p) == rq && task_on_rq_queued(p)) 1067 rq = __migrate_task(rq, p, arg->dest_cpu); 1068 raw_spin_unlock(&rq->lock); 1069 raw_spin_unlock(&p->pi_lock); 1070 1071 local_irq_enable(); 1072 return 0; 1073 } 1074 1075 /* 1076 * sched_class::set_cpus_allowed must do the below, but is not required to 1077 * actually call this function. 1078 */ 1079 void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask) 1080 { 1081 cpumask_copy(&p->cpus_allowed, new_mask); 1082 p->nr_cpus_allowed = cpumask_weight(new_mask); 1083 } 1084 1085 void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) 1086 { 1087 struct rq *rq = task_rq(p); 1088 bool queued, running; 1089 1090 lockdep_assert_held(&p->pi_lock); 1091 1092 queued = task_on_rq_queued(p); 1093 running = task_current(rq, p); 1094 1095 if (queued) { 1096 /* 1097 * Because __kthread_bind() calls this on blocked tasks without 1098 * holding rq->lock. 1099 */ 1100 lockdep_assert_held(&rq->lock); 1101 dequeue_task(rq, p, DEQUEUE_SAVE); 1102 } 1103 if (running) 1104 put_prev_task(rq, p); 1105 1106 p->sched_class->set_cpus_allowed(p, new_mask); 1107 1108 if (running) 1109 p->sched_class->set_curr_task(rq); 1110 if (queued) 1111 enqueue_task(rq, p, ENQUEUE_RESTORE); 1112 } 1113 1114 /* 1115 * Change a given task's CPU affinity. Migrate the thread to a 1116 * proper CPU and schedule it away if the CPU it's executing on 1117 * is removed from the allowed bitmask. 1118 * 1119 * NOTE: the caller must have a valid reference to the task, the 1120 * task must not exit() & deallocate itself prematurely. The 1121 * call is not atomic; no spinlocks may be held. 1122 */ 1123 static int __set_cpus_allowed_ptr(struct task_struct *p, 1124 const struct cpumask *new_mask, bool check) 1125 { 1126 const struct cpumask *cpu_valid_mask = cpu_active_mask; 1127 unsigned int dest_cpu; 1128 struct rq_flags rf; 1129 struct rq *rq; 1130 int ret = 0; 1131 1132 rq = task_rq_lock(p, &rf); 1133 1134 if (p->flags & PF_KTHREAD) { 1135 /* 1136 * Kernel threads are allowed on online && !active CPUs 1137 */ 1138 cpu_valid_mask = cpu_online_mask; 1139 } 1140 1141 /* 1142 * Must re-check here, to close a race against __kthread_bind(), 1143 * sched_setaffinity() is not guaranteed to observe the flag. 1144 */ 1145 if (check && (p->flags & PF_NO_SETAFFINITY)) { 1146 ret = -EINVAL; 1147 goto out; 1148 } 1149 1150 if (cpumask_equal(&p->cpus_allowed, new_mask)) 1151 goto out; 1152 1153 if (!cpumask_intersects(new_mask, cpu_valid_mask)) { 1154 ret = -EINVAL; 1155 goto out; 1156 } 1157 1158 do_set_cpus_allowed(p, new_mask); 1159 1160 if (p->flags & PF_KTHREAD) { 1161 /* 1162 * For kernel threads that do indeed end up on online && 1163 * !active we want to ensure they are strict per-cpu threads. 1164 */ 1165 WARN_ON(cpumask_intersects(new_mask, cpu_online_mask) && 1166 !cpumask_intersects(new_mask, cpu_active_mask) && 1167 p->nr_cpus_allowed != 1); 1168 } 1169 1170 /* Can the task run on the task's current CPU? If so, we're done */ 1171 if (cpumask_test_cpu(task_cpu(p), new_mask)) 1172 goto out; 1173 1174 dest_cpu = cpumask_any_and(cpu_valid_mask, new_mask); 1175 if (task_running(rq, p) || p->state == TASK_WAKING) { 1176 struct migration_arg arg = { p, dest_cpu }; 1177 /* Need help from migration thread: drop lock and wait. */ 1178 task_rq_unlock(rq, p, &rf); 1179 stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg); 1180 tlb_migrate_finish(p->mm); 1181 return 0; 1182 } else if (task_on_rq_queued(p)) { 1183 /* 1184 * OK, since we're going to drop the lock immediately 1185 * afterwards anyway. 1186 */ 1187 lockdep_unpin_lock(&rq->lock, rf.cookie); 1188 rq = move_queued_task(rq, p, dest_cpu); 1189 lockdep_repin_lock(&rq->lock, rf.cookie); 1190 } 1191 out: 1192 task_rq_unlock(rq, p, &rf); 1193 1194 return ret; 1195 } 1196 1197 int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) 1198 { 1199 return __set_cpus_allowed_ptr(p, new_mask, false); 1200 } 1201 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr); 1202 1203 void set_task_cpu(struct task_struct *p, unsigned int new_cpu) 1204 { 1205 #ifdef CONFIG_SCHED_DEBUG 1206 /* 1207 * We should never call set_task_cpu() on a blocked task, 1208 * ttwu() will sort out the placement. 1209 */ 1210 WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING && 1211 !p->on_rq); 1212 1213 /* 1214 * Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING, 1215 * because schedstat_wait_{start,end} rebase migrating task's wait_start 1216 * time relying on p->on_rq. 1217 */ 1218 WARN_ON_ONCE(p->state == TASK_RUNNING && 1219 p->sched_class == &fair_sched_class && 1220 (p->on_rq && !task_on_rq_migrating(p))); 1221 1222 #ifdef CONFIG_LOCKDEP 1223 /* 1224 * The caller should hold either p->pi_lock or rq->lock, when changing 1225 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks. 1226 * 1227 * sched_move_task() holds both and thus holding either pins the cgroup, 1228 * see task_group(). 1229 * 1230 * Furthermore, all task_rq users should acquire both locks, see 1231 * task_rq_lock(). 1232 */ 1233 WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) || 1234 lockdep_is_held(&task_rq(p)->lock))); 1235 #endif 1236 #endif 1237 1238 trace_sched_migrate_task(p, new_cpu); 1239 1240 if (task_cpu(p) != new_cpu) { 1241 if (p->sched_class->migrate_task_rq) 1242 p->sched_class->migrate_task_rq(p); 1243 p->se.nr_migrations++; 1244 perf_event_task_migrate(p); 1245 } 1246 1247 __set_task_cpu(p, new_cpu); 1248 } 1249 1250 static void __migrate_swap_task(struct task_struct *p, int cpu) 1251 { 1252 if (task_on_rq_queued(p)) { 1253 struct rq *src_rq, *dst_rq; 1254 1255 src_rq = task_rq(p); 1256 dst_rq = cpu_rq(cpu); 1257 1258 p->on_rq = TASK_ON_RQ_MIGRATING; 1259 deactivate_task(src_rq, p, 0); 1260 set_task_cpu(p, cpu); 1261 activate_task(dst_rq, p, 0); 1262 p->on_rq = TASK_ON_RQ_QUEUED; 1263 check_preempt_curr(dst_rq, p, 0); 1264 } else { 1265 /* 1266 * Task isn't running anymore; make it appear like we migrated 1267 * it before it went to sleep. This means on wakeup we make the 1268 * previous cpu our targer instead of where it really is. 1269 */ 1270 p->wake_cpu = cpu; 1271 } 1272 } 1273 1274 struct migration_swap_arg { 1275 struct task_struct *src_task, *dst_task; 1276 int src_cpu, dst_cpu; 1277 }; 1278 1279 static int migrate_swap_stop(void *data) 1280 { 1281 struct migration_swap_arg *arg = data; 1282 struct rq *src_rq, *dst_rq; 1283 int ret = -EAGAIN; 1284 1285 if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu)) 1286 return -EAGAIN; 1287 1288 src_rq = cpu_rq(arg->src_cpu); 1289 dst_rq = cpu_rq(arg->dst_cpu); 1290 1291 double_raw_lock(&arg->src_task->pi_lock, 1292 &arg->dst_task->pi_lock); 1293 double_rq_lock(src_rq, dst_rq); 1294 1295 if (task_cpu(arg->dst_task) != arg->dst_cpu) 1296 goto unlock; 1297 1298 if (task_cpu(arg->src_task) != arg->src_cpu) 1299 goto unlock; 1300 1301 if (!cpumask_test_cpu(arg->dst_cpu, tsk_cpus_allowed(arg->src_task))) 1302 goto unlock; 1303 1304 if (!cpumask_test_cpu(arg->src_cpu, tsk_cpus_allowed(arg->dst_task))) 1305 goto unlock; 1306 1307 __migrate_swap_task(arg->src_task, arg->dst_cpu); 1308 __migrate_swap_task(arg->dst_task, arg->src_cpu); 1309 1310 ret = 0; 1311 1312 unlock: 1313 double_rq_unlock(src_rq, dst_rq); 1314 raw_spin_unlock(&arg->dst_task->pi_lock); 1315 raw_spin_unlock(&arg->src_task->pi_lock); 1316 1317 return ret; 1318 } 1319 1320 /* 1321 * Cross migrate two tasks 1322 */ 1323 int migrate_swap(struct task_struct *cur, struct task_struct *p) 1324 { 1325 struct migration_swap_arg arg; 1326 int ret = -EINVAL; 1327 1328 arg = (struct migration_swap_arg){ 1329 .src_task = cur, 1330 .src_cpu = task_cpu(cur), 1331 .dst_task = p, 1332 .dst_cpu = task_cpu(p), 1333 }; 1334 1335 if (arg.src_cpu == arg.dst_cpu) 1336 goto out; 1337 1338 /* 1339 * These three tests are all lockless; this is OK since all of them 1340 * will be re-checked with proper locks held further down the line. 1341 */ 1342 if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu)) 1343 goto out; 1344 1345 if (!cpumask_test_cpu(arg.dst_cpu, tsk_cpus_allowed(arg.src_task))) 1346 goto out; 1347 1348 if (!cpumask_test_cpu(arg.src_cpu, tsk_cpus_allowed(arg.dst_task))) 1349 goto out; 1350 1351 trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu); 1352 ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg); 1353 1354 out: 1355 return ret; 1356 } 1357 1358 /* 1359 * wait_task_inactive - wait for a thread to unschedule. 1360 * 1361 * If @match_state is nonzero, it's the @p->state value just checked and 1362 * not expected to change. If it changes, i.e. @p might have woken up, 1363 * then return zero. When we succeed in waiting for @p to be off its CPU, 1364 * we return a positive number (its total switch count). If a second call 1365 * a short while later returns the same number, the caller can be sure that 1366 * @p has remained unscheduled the whole time. 1367 * 1368 * The caller must ensure that the task *will* unschedule sometime soon, 1369 * else this function might spin for a *long* time. This function can't 1370 * be called with interrupts off, or it may introduce deadlock with 1371 * smp_call_function() if an IPI is sent by the same process we are 1372 * waiting to become inactive. 1373 */ 1374 unsigned long wait_task_inactive(struct task_struct *p, long match_state) 1375 { 1376 int running, queued; 1377 struct rq_flags rf; 1378 unsigned long ncsw; 1379 struct rq *rq; 1380 1381 for (;;) { 1382 /* 1383 * We do the initial early heuristics without holding 1384 * any task-queue locks at all. We'll only try to get 1385 * the runqueue lock when things look like they will 1386 * work out! 1387 */ 1388 rq = task_rq(p); 1389 1390 /* 1391 * If the task is actively running on another CPU 1392 * still, just relax and busy-wait without holding 1393 * any locks. 1394 * 1395 * NOTE! Since we don't hold any locks, it's not 1396 * even sure that "rq" stays as the right runqueue! 1397 * But we don't care, since "task_running()" will 1398 * return false if the runqueue has changed and p 1399 * is actually now running somewhere else! 1400 */ 1401 while (task_running(rq, p)) { 1402 if (match_state && unlikely(p->state != match_state)) 1403 return 0; 1404 cpu_relax(); 1405 } 1406 1407 /* 1408 * Ok, time to look more closely! We need the rq 1409 * lock now, to be *sure*. If we're wrong, we'll 1410 * just go back and repeat. 1411 */ 1412 rq = task_rq_lock(p, &rf); 1413 trace_sched_wait_task(p); 1414 running = task_running(rq, p); 1415 queued = task_on_rq_queued(p); 1416 ncsw = 0; 1417 if (!match_state || p->state == match_state) 1418 ncsw = p->nvcsw | LONG_MIN; /* sets MSB */ 1419 task_rq_unlock(rq, p, &rf); 1420 1421 /* 1422 * If it changed from the expected state, bail out now. 1423 */ 1424 if (unlikely(!ncsw)) 1425 break; 1426 1427 /* 1428 * Was it really running after all now that we 1429 * checked with the proper locks actually held? 1430 * 1431 * Oops. Go back and try again.. 1432 */ 1433 if (unlikely(running)) { 1434 cpu_relax(); 1435 continue; 1436 } 1437 1438 /* 1439 * It's not enough that it's not actively running, 1440 * it must be off the runqueue _entirely_, and not 1441 * preempted! 1442 * 1443 * So if it was still runnable (but just not actively 1444 * running right now), it's preempted, and we should 1445 * yield - it could be a while. 1446 */ 1447 if (unlikely(queued)) { 1448 ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ); 1449 1450 set_current_state(TASK_UNINTERRUPTIBLE); 1451 schedule_hrtimeout(&to, HRTIMER_MODE_REL); 1452 continue; 1453 } 1454 1455 /* 1456 * Ahh, all good. It wasn't running, and it wasn't 1457 * runnable, which means that it will never become 1458 * running in the future either. We're all done! 1459 */ 1460 break; 1461 } 1462 1463 return ncsw; 1464 } 1465 1466 /*** 1467 * kick_process - kick a running thread to enter/exit the kernel 1468 * @p: the to-be-kicked thread 1469 * 1470 * Cause a process which is running on another CPU to enter 1471 * kernel-mode, without any delay. (to get signals handled.) 1472 * 1473 * NOTE: this function doesn't have to take the runqueue lock, 1474 * because all it wants to ensure is that the remote task enters 1475 * the kernel. If the IPI races and the task has been migrated 1476 * to another CPU then no harm is done and the purpose has been 1477 * achieved as well. 1478 */ 1479 void kick_process(struct task_struct *p) 1480 { 1481 int cpu; 1482 1483 preempt_disable(); 1484 cpu = task_cpu(p); 1485 if ((cpu != smp_processor_id()) && task_curr(p)) 1486 smp_send_reschedule(cpu); 1487 preempt_enable(); 1488 } 1489 EXPORT_SYMBOL_GPL(kick_process); 1490 1491 /* 1492 * ->cpus_allowed is protected by both rq->lock and p->pi_lock 1493 * 1494 * A few notes on cpu_active vs cpu_online: 1495 * 1496 * - cpu_active must be a subset of cpu_online 1497 * 1498 * - on cpu-up we allow per-cpu kthreads on the online && !active cpu, 1499 * see __set_cpus_allowed_ptr(). At this point the newly online 1500 * cpu isn't yet part of the sched domains, and balancing will not 1501 * see it. 1502 * 1503 * - on cpu-down we clear cpu_active() to mask the sched domains and 1504 * avoid the load balancer to place new tasks on the to be removed 1505 * cpu. Existing tasks will remain running there and will be taken 1506 * off. 1507 * 1508 * This means that fallback selection must not select !active CPUs. 1509 * And can assume that any active CPU must be online. Conversely 1510 * select_task_rq() below may allow selection of !active CPUs in order 1511 * to satisfy the above rules. 1512 */ 1513 static int select_fallback_rq(int cpu, struct task_struct *p) 1514 { 1515 int nid = cpu_to_node(cpu); 1516 const struct cpumask *nodemask = NULL; 1517 enum { cpuset, possible, fail } state = cpuset; 1518 int dest_cpu; 1519 1520 /* 1521 * If the node that the cpu is on has been offlined, cpu_to_node() 1522 * will return -1. There is no cpu on the node, and we should 1523 * select the cpu on the other node. 1524 */ 1525 if (nid != -1) { 1526 nodemask = cpumask_of_node(nid); 1527 1528 /* Look for allowed, online CPU in same node. */ 1529 for_each_cpu(dest_cpu, nodemask) { 1530 if (!cpu_active(dest_cpu)) 1531 continue; 1532 if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p))) 1533 return dest_cpu; 1534 } 1535 } 1536 1537 for (;;) { 1538 /* Any allowed, online CPU? */ 1539 for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) { 1540 if (!(p->flags & PF_KTHREAD) && !cpu_active(dest_cpu)) 1541 continue; 1542 if (!cpu_online(dest_cpu)) 1543 continue; 1544 goto out; 1545 } 1546 1547 /* No more Mr. Nice Guy. */ 1548 switch (state) { 1549 case cpuset: 1550 if (IS_ENABLED(CONFIG_CPUSETS)) { 1551 cpuset_cpus_allowed_fallback(p); 1552 state = possible; 1553 break; 1554 } 1555 /* fall-through */ 1556 case possible: 1557 do_set_cpus_allowed(p, cpu_possible_mask); 1558 state = fail; 1559 break; 1560 1561 case fail: 1562 BUG(); 1563 break; 1564 } 1565 } 1566 1567 out: 1568 if (state != cpuset) { 1569 /* 1570 * Don't tell them about moving exiting tasks or 1571 * kernel threads (both mm NULL), since they never 1572 * leave kernel. 1573 */ 1574 if (p->mm && printk_ratelimit()) { 1575 printk_deferred("process %d (%s) no longer affine to cpu%d\n", 1576 task_pid_nr(p), p->comm, cpu); 1577 } 1578 } 1579 1580 return dest_cpu; 1581 } 1582 1583 /* 1584 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable. 1585 */ 1586 static inline 1587 int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags) 1588 { 1589 lockdep_assert_held(&p->pi_lock); 1590 1591 if (tsk_nr_cpus_allowed(p) > 1) 1592 cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags); 1593 else 1594 cpu = cpumask_any(tsk_cpus_allowed(p)); 1595 1596 /* 1597 * In order not to call set_task_cpu() on a blocking task we need 1598 * to rely on ttwu() to place the task on a valid ->cpus_allowed 1599 * cpu. 1600 * 1601 * Since this is common to all placement strategies, this lives here. 1602 * 1603 * [ this allows ->select_task() to simply return task_cpu(p) and 1604 * not worry about this generic constraint ] 1605 */ 1606 if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) || 1607 !cpu_online(cpu))) 1608 cpu = select_fallback_rq(task_cpu(p), p); 1609 1610 return cpu; 1611 } 1612 1613 static void update_avg(u64 *avg, u64 sample) 1614 { 1615 s64 diff = sample - *avg; 1616 *avg += diff >> 3; 1617 } 1618 1619 #else 1620 1621 static inline int __set_cpus_allowed_ptr(struct task_struct *p, 1622 const struct cpumask *new_mask, bool check) 1623 { 1624 return set_cpus_allowed_ptr(p, new_mask); 1625 } 1626 1627 #endif /* CONFIG_SMP */ 1628 1629 static void 1630 ttwu_stat(struct task_struct *p, int cpu, int wake_flags) 1631 { 1632 #ifdef CONFIG_SCHEDSTATS 1633 struct rq *rq = this_rq(); 1634 1635 #ifdef CONFIG_SMP 1636 int this_cpu = smp_processor_id(); 1637 1638 if (cpu == this_cpu) { 1639 schedstat_inc(rq, ttwu_local); 1640 schedstat_inc(p, se.statistics.nr_wakeups_local); 1641 } else { 1642 struct sched_domain *sd; 1643 1644 schedstat_inc(p, se.statistics.nr_wakeups_remote); 1645 rcu_read_lock(); 1646 for_each_domain(this_cpu, sd) { 1647 if (cpumask_test_cpu(cpu, sched_domain_span(sd))) { 1648 schedstat_inc(sd, ttwu_wake_remote); 1649 break; 1650 } 1651 } 1652 rcu_read_unlock(); 1653 } 1654 1655 if (wake_flags & WF_MIGRATED) 1656 schedstat_inc(p, se.statistics.nr_wakeups_migrate); 1657 1658 #endif /* CONFIG_SMP */ 1659 1660 schedstat_inc(rq, ttwu_count); 1661 schedstat_inc(p, se.statistics.nr_wakeups); 1662 1663 if (wake_flags & WF_SYNC) 1664 schedstat_inc(p, se.statistics.nr_wakeups_sync); 1665 1666 #endif /* CONFIG_SCHEDSTATS */ 1667 } 1668 1669 static inline void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags) 1670 { 1671 activate_task(rq, p, en_flags); 1672 p->on_rq = TASK_ON_RQ_QUEUED; 1673 1674 /* if a worker is waking up, notify workqueue */ 1675 if (p->flags & PF_WQ_WORKER) 1676 wq_worker_waking_up(p, cpu_of(rq)); 1677 } 1678 1679 /* 1680 * Mark the task runnable and perform wakeup-preemption. 1681 */ 1682 static void ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags, 1683 struct pin_cookie cookie) 1684 { 1685 check_preempt_curr(rq, p, wake_flags); 1686 p->state = TASK_RUNNING; 1687 trace_sched_wakeup(p); 1688 1689 #ifdef CONFIG_SMP 1690 if (p->sched_class->task_woken) { 1691 /* 1692 * Our task @p is fully woken up and running; so its safe to 1693 * drop the rq->lock, hereafter rq is only used for statistics. 1694 */ 1695 lockdep_unpin_lock(&rq->lock, cookie); 1696 p->sched_class->task_woken(rq, p); 1697 lockdep_repin_lock(&rq->lock, cookie); 1698 } 1699 1700 if (rq->idle_stamp) { 1701 u64 delta = rq_clock(rq) - rq->idle_stamp; 1702 u64 max = 2*rq->max_idle_balance_cost; 1703 1704 update_avg(&rq->avg_idle, delta); 1705 1706 if (rq->avg_idle > max) 1707 rq->avg_idle = max; 1708 1709 rq->idle_stamp = 0; 1710 } 1711 #endif 1712 } 1713 1714 static void 1715 ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags, 1716 struct pin_cookie cookie) 1717 { 1718 int en_flags = ENQUEUE_WAKEUP; 1719 1720 lockdep_assert_held(&rq->lock); 1721 1722 #ifdef CONFIG_SMP 1723 if (p->sched_contributes_to_load) 1724 rq->nr_uninterruptible--; 1725 1726 if (wake_flags & WF_MIGRATED) 1727 en_flags |= ENQUEUE_MIGRATED; 1728 #endif 1729 1730 ttwu_activate(rq, p, en_flags); 1731 ttwu_do_wakeup(rq, p, wake_flags, cookie); 1732 } 1733 1734 /* 1735 * Called in case the task @p isn't fully descheduled from its runqueue, 1736 * in this case we must do a remote wakeup. Its a 'light' wakeup though, 1737 * since all we need to do is flip p->state to TASK_RUNNING, since 1738 * the task is still ->on_rq. 1739 */ 1740 static int ttwu_remote(struct task_struct *p, int wake_flags) 1741 { 1742 struct rq_flags rf; 1743 struct rq *rq; 1744 int ret = 0; 1745 1746 rq = __task_rq_lock(p, &rf); 1747 if (task_on_rq_queued(p)) { 1748 /* check_preempt_curr() may use rq clock */ 1749 update_rq_clock(rq); 1750 ttwu_do_wakeup(rq, p, wake_flags, rf.cookie); 1751 ret = 1; 1752 } 1753 __task_rq_unlock(rq, &rf); 1754 1755 return ret; 1756 } 1757 1758 #ifdef CONFIG_SMP 1759 void sched_ttwu_pending(void) 1760 { 1761 struct rq *rq = this_rq(); 1762 struct llist_node *llist = llist_del_all(&rq->wake_list); 1763 struct pin_cookie cookie; 1764 struct task_struct *p; 1765 unsigned long flags; 1766 1767 if (!llist) 1768 return; 1769 1770 raw_spin_lock_irqsave(&rq->lock, flags); 1771 cookie = lockdep_pin_lock(&rq->lock); 1772 1773 while (llist) { 1774 int wake_flags = 0; 1775 1776 p = llist_entry(llist, struct task_struct, wake_entry); 1777 llist = llist_next(llist); 1778 1779 if (p->sched_remote_wakeup) 1780 wake_flags = WF_MIGRATED; 1781 1782 ttwu_do_activate(rq, p, wake_flags, cookie); 1783 } 1784 1785 lockdep_unpin_lock(&rq->lock, cookie); 1786 raw_spin_unlock_irqrestore(&rq->lock, flags); 1787 } 1788 1789 void scheduler_ipi(void) 1790 { 1791 /* 1792 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting 1793 * TIF_NEED_RESCHED remotely (for the first time) will also send 1794 * this IPI. 1795 */ 1796 preempt_fold_need_resched(); 1797 1798 if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick()) 1799 return; 1800 1801 /* 1802 * Not all reschedule IPI handlers call irq_enter/irq_exit, since 1803 * traditionally all their work was done from the interrupt return 1804 * path. Now that we actually do some work, we need to make sure 1805 * we do call them. 1806 * 1807 * Some archs already do call them, luckily irq_enter/exit nest 1808 * properly. 1809 * 1810 * Arguably we should visit all archs and update all handlers, 1811 * however a fair share of IPIs are still resched only so this would 1812 * somewhat pessimize the simple resched case. 1813 */ 1814 irq_enter(); 1815 sched_ttwu_pending(); 1816 1817 /* 1818 * Check if someone kicked us for doing the nohz idle load balance. 1819 */ 1820 if (unlikely(got_nohz_idle_kick())) { 1821 this_rq()->idle_balance = 1; 1822 raise_softirq_irqoff(SCHED_SOFTIRQ); 1823 } 1824 irq_exit(); 1825 } 1826 1827 static void ttwu_queue_remote(struct task_struct *p, int cpu, int wake_flags) 1828 { 1829 struct rq *rq = cpu_rq(cpu); 1830 1831 p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED); 1832 1833 if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) { 1834 if (!set_nr_if_polling(rq->idle)) 1835 smp_send_reschedule(cpu); 1836 else 1837 trace_sched_wake_idle_without_ipi(cpu); 1838 } 1839 } 1840 1841 void wake_up_if_idle(int cpu) 1842 { 1843 struct rq *rq = cpu_rq(cpu); 1844 unsigned long flags; 1845 1846 rcu_read_lock(); 1847 1848 if (!is_idle_task(rcu_dereference(rq->curr))) 1849 goto out; 1850 1851 if (set_nr_if_polling(rq->idle)) { 1852 trace_sched_wake_idle_without_ipi(cpu); 1853 } else { 1854 raw_spin_lock_irqsave(&rq->lock, flags); 1855 if (is_idle_task(rq->curr)) 1856 smp_send_reschedule(cpu); 1857 /* Else cpu is not in idle, do nothing here */ 1858 raw_spin_unlock_irqrestore(&rq->lock, flags); 1859 } 1860 1861 out: 1862 rcu_read_unlock(); 1863 } 1864 1865 bool cpus_share_cache(int this_cpu, int that_cpu) 1866 { 1867 return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu); 1868 } 1869 #endif /* CONFIG_SMP */ 1870 1871 static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags) 1872 { 1873 struct rq *rq = cpu_rq(cpu); 1874 struct pin_cookie cookie; 1875 1876 #if defined(CONFIG_SMP) 1877 if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) { 1878 sched_clock_cpu(cpu); /* sync clocks x-cpu */ 1879 ttwu_queue_remote(p, cpu, wake_flags); 1880 return; 1881 } 1882 #endif 1883 1884 raw_spin_lock(&rq->lock); 1885 cookie = lockdep_pin_lock(&rq->lock); 1886 ttwu_do_activate(rq, p, wake_flags, cookie); 1887 lockdep_unpin_lock(&rq->lock, cookie); 1888 raw_spin_unlock(&rq->lock); 1889 } 1890 1891 /* 1892 * Notes on Program-Order guarantees on SMP systems. 1893 * 1894 * MIGRATION 1895 * 1896 * The basic program-order guarantee on SMP systems is that when a task [t] 1897 * migrates, all its activity on its old cpu [c0] happens-before any subsequent 1898 * execution on its new cpu [c1]. 1899 * 1900 * For migration (of runnable tasks) this is provided by the following means: 1901 * 1902 * A) UNLOCK of the rq(c0)->lock scheduling out task t 1903 * B) migration for t is required to synchronize *both* rq(c0)->lock and 1904 * rq(c1)->lock (if not at the same time, then in that order). 1905 * C) LOCK of the rq(c1)->lock scheduling in task 1906 * 1907 * Transitivity guarantees that B happens after A and C after B. 1908 * Note: we only require RCpc transitivity. 1909 * Note: the cpu doing B need not be c0 or c1 1910 * 1911 * Example: 1912 * 1913 * CPU0 CPU1 CPU2 1914 * 1915 * LOCK rq(0)->lock 1916 * sched-out X 1917 * sched-in Y 1918 * UNLOCK rq(0)->lock 1919 * 1920 * LOCK rq(0)->lock // orders against CPU0 1921 * dequeue X 1922 * UNLOCK rq(0)->lock 1923 * 1924 * LOCK rq(1)->lock 1925 * enqueue X 1926 * UNLOCK rq(1)->lock 1927 * 1928 * LOCK rq(1)->lock // orders against CPU2 1929 * sched-out Z 1930 * sched-in X 1931 * UNLOCK rq(1)->lock 1932 * 1933 * 1934 * BLOCKING -- aka. SLEEP + WAKEUP 1935 * 1936 * For blocking we (obviously) need to provide the same guarantee as for 1937 * migration. However the means are completely different as there is no lock 1938 * chain to provide order. Instead we do: 1939 * 1940 * 1) smp_store_release(X->on_cpu, 0) 1941 * 2) smp_cond_load_acquire(!X->on_cpu) 1942 * 1943 * Example: 1944 * 1945 * CPU0 (schedule) CPU1 (try_to_wake_up) CPU2 (schedule) 1946 * 1947 * LOCK rq(0)->lock LOCK X->pi_lock 1948 * dequeue X 1949 * sched-out X 1950 * smp_store_release(X->on_cpu, 0); 1951 * 1952 * smp_cond_load_acquire(&X->on_cpu, !VAL); 1953 * X->state = WAKING 1954 * set_task_cpu(X,2) 1955 * 1956 * LOCK rq(2)->lock 1957 * enqueue X 1958 * X->state = RUNNING 1959 * UNLOCK rq(2)->lock 1960 * 1961 * LOCK rq(2)->lock // orders against CPU1 1962 * sched-out Z 1963 * sched-in X 1964 * UNLOCK rq(2)->lock 1965 * 1966 * UNLOCK X->pi_lock 1967 * UNLOCK rq(0)->lock 1968 * 1969 * 1970 * However; for wakeups there is a second guarantee we must provide, namely we 1971 * must observe the state that lead to our wakeup. That is, not only must our 1972 * task observe its own prior state, it must also observe the stores prior to 1973 * its wakeup. 1974 * 1975 * This means that any means of doing remote wakeups must order the CPU doing 1976 * the wakeup against the CPU the task is going to end up running on. This, 1977 * however, is already required for the regular Program-Order guarantee above, 1978 * since the waking CPU is the one issueing the ACQUIRE (smp_cond_load_acquire). 1979 * 1980 */ 1981 1982 /** 1983 * try_to_wake_up - wake up a thread 1984 * @p: the thread to be awakened 1985 * @state: the mask of task states that can be woken 1986 * @wake_flags: wake modifier flags (WF_*) 1987 * 1988 * Put it on the run-queue if it's not already there. The "current" 1989 * thread is always on the run-queue (except when the actual 1990 * re-schedule is in progress), and as such you're allowed to do 1991 * the simpler "current->state = TASK_RUNNING" to mark yourself 1992 * runnable without the overhead of this. 1993 * 1994 * Return: %true if @p was woken up, %false if it was already running. 1995 * or @state didn't match @p's state. 1996 */ 1997 static int 1998 try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) 1999 { 2000 unsigned long flags; 2001 int cpu, success = 0; 2002 2003 /* 2004 * If we are going to wake up a thread waiting for CONDITION we 2005 * need to ensure that CONDITION=1 done by the caller can not be 2006 * reordered with p->state check below. This pairs with mb() in 2007 * set_current_state() the waiting thread does. 2008 */ 2009 smp_mb__before_spinlock(); 2010 raw_spin_lock_irqsave(&p->pi_lock, flags); 2011 if (!(p->state & state)) 2012 goto out; 2013 2014 trace_sched_waking(p); 2015 2016 success = 1; /* we're going to change ->state */ 2017 cpu = task_cpu(p); 2018 2019 /* 2020 * Ensure we load p->on_rq _after_ p->state, otherwise it would 2021 * be possible to, falsely, observe p->on_rq == 0 and get stuck 2022 * in smp_cond_load_acquire() below. 2023 * 2024 * sched_ttwu_pending() try_to_wake_up() 2025 * [S] p->on_rq = 1; [L] P->state 2026 * UNLOCK rq->lock -----. 2027 * \ 2028 * +--- RMB 2029 * schedule() / 2030 * LOCK rq->lock -----' 2031 * UNLOCK rq->lock 2032 * 2033 * [task p] 2034 * [S] p->state = UNINTERRUPTIBLE [L] p->on_rq 2035 * 2036 * Pairs with the UNLOCK+LOCK on rq->lock from the 2037 * last wakeup of our task and the schedule that got our task 2038 * current. 2039 */ 2040 smp_rmb(); 2041 if (p->on_rq && ttwu_remote(p, wake_flags)) 2042 goto stat; 2043 2044 #ifdef CONFIG_SMP 2045 /* 2046 * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be 2047 * possible to, falsely, observe p->on_cpu == 0. 2048 * 2049 * One must be running (->on_cpu == 1) in order to remove oneself 2050 * from the runqueue. 2051 * 2052 * [S] ->on_cpu = 1; [L] ->on_rq 2053 * UNLOCK rq->lock 2054 * RMB 2055 * LOCK rq->lock 2056 * [S] ->on_rq = 0; [L] ->on_cpu 2057 * 2058 * Pairs with the full barrier implied in the UNLOCK+LOCK on rq->lock 2059 * from the consecutive calls to schedule(); the first switching to our 2060 * task, the second putting it to sleep. 2061 */ 2062 smp_rmb(); 2063 2064 /* 2065 * If the owning (remote) cpu is still in the middle of schedule() with 2066 * this task as prev, wait until its done referencing the task. 2067 * 2068 * Pairs with the smp_store_release() in finish_lock_switch(). 2069 * 2070 * This ensures that tasks getting woken will be fully ordered against 2071 * their previous state and preserve Program Order. 2072 */ 2073 smp_cond_load_acquire(&p->on_cpu, !VAL); 2074 2075 p->sched_contributes_to_load = !!task_contributes_to_load(p); 2076 p->state = TASK_WAKING; 2077 2078 cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags); 2079 if (task_cpu(p) != cpu) { 2080 wake_flags |= WF_MIGRATED; 2081 set_task_cpu(p, cpu); 2082 } 2083 #endif /* CONFIG_SMP */ 2084 2085 ttwu_queue(p, cpu, wake_flags); 2086 stat: 2087 if (schedstat_enabled()) 2088 ttwu_stat(p, cpu, wake_flags); 2089 out: 2090 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 2091 2092 return success; 2093 } 2094 2095 /** 2096 * try_to_wake_up_local - try to wake up a local task with rq lock held 2097 * @p: the thread to be awakened 2098 * 2099 * Put @p on the run-queue if it's not already there. The caller must 2100 * ensure that this_rq() is locked, @p is bound to this_rq() and not 2101 * the current task. 2102 */ 2103 static void try_to_wake_up_local(struct task_struct *p, struct pin_cookie cookie) 2104 { 2105 struct rq *rq = task_rq(p); 2106 2107 if (WARN_ON_ONCE(rq != this_rq()) || 2108 WARN_ON_ONCE(p == current)) 2109 return; 2110 2111 lockdep_assert_held(&rq->lock); 2112 2113 if (!raw_spin_trylock(&p->pi_lock)) { 2114 /* 2115 * This is OK, because current is on_cpu, which avoids it being 2116 * picked for load-balance and preemption/IRQs are still 2117 * disabled avoiding further scheduler activity on it and we've 2118 * not yet picked a replacement task. 2119 */ 2120 lockdep_unpin_lock(&rq->lock, cookie); 2121 raw_spin_unlock(&rq->lock); 2122 raw_spin_lock(&p->pi_lock); 2123 raw_spin_lock(&rq->lock); 2124 lockdep_repin_lock(&rq->lock, cookie); 2125 } 2126 2127 if (!(p->state & TASK_NORMAL)) 2128 goto out; 2129 2130 trace_sched_waking(p); 2131 2132 if (!task_on_rq_queued(p)) 2133 ttwu_activate(rq, p, ENQUEUE_WAKEUP); 2134 2135 ttwu_do_wakeup(rq, p, 0, cookie); 2136 if (schedstat_enabled()) 2137 ttwu_stat(p, smp_processor_id(), 0); 2138 out: 2139 raw_spin_unlock(&p->pi_lock); 2140 } 2141 2142 /** 2143 * wake_up_process - Wake up a specific process 2144 * @p: The process to be woken up. 2145 * 2146 * Attempt to wake up the nominated process and move it to the set of runnable 2147 * processes. 2148 * 2149 * Return: 1 if the process was woken up, 0 if it was already running. 2150 * 2151 * It may be assumed that this function implies a write memory barrier before 2152 * changing the task state if and only if any tasks are woken up. 2153 */ 2154 int wake_up_process(struct task_struct *p) 2155 { 2156 return try_to_wake_up(p, TASK_NORMAL, 0); 2157 } 2158 EXPORT_SYMBOL(wake_up_process); 2159 2160 int wake_up_state(struct task_struct *p, unsigned int state) 2161 { 2162 return try_to_wake_up(p, state, 0); 2163 } 2164 2165 /* 2166 * This function clears the sched_dl_entity static params. 2167 */ 2168 void __dl_clear_params(struct task_struct *p) 2169 { 2170 struct sched_dl_entity *dl_se = &p->dl; 2171 2172 dl_se->dl_runtime = 0; 2173 dl_se->dl_deadline = 0; 2174 dl_se->dl_period = 0; 2175 dl_se->flags = 0; 2176 dl_se->dl_bw = 0; 2177 2178 dl_se->dl_throttled = 0; 2179 dl_se->dl_yielded = 0; 2180 } 2181 2182 /* 2183 * Perform scheduler related setup for a newly forked process p. 2184 * p is forked by current. 2185 * 2186 * __sched_fork() is basic setup used by init_idle() too: 2187 */ 2188 static void __sched_fork(unsigned long clone_flags, struct task_struct *p) 2189 { 2190 p->on_rq = 0; 2191 2192 p->se.on_rq = 0; 2193 p->se.exec_start = 0; 2194 p->se.sum_exec_runtime = 0; 2195 p->se.prev_sum_exec_runtime = 0; 2196 p->se.nr_migrations = 0; 2197 p->se.vruntime = 0; 2198 INIT_LIST_HEAD(&p->se.group_node); 2199 2200 #ifdef CONFIG_FAIR_GROUP_SCHED 2201 p->se.cfs_rq = NULL; 2202 #endif 2203 2204 #ifdef CONFIG_SCHEDSTATS 2205 /* Even if schedstat is disabled, there should not be garbage */ 2206 memset(&p->se.statistics, 0, sizeof(p->se.statistics)); 2207 #endif 2208 2209 RB_CLEAR_NODE(&p->dl.rb_node); 2210 init_dl_task_timer(&p->dl); 2211 __dl_clear_params(p); 2212 2213 INIT_LIST_HEAD(&p->rt.run_list); 2214 p->rt.timeout = 0; 2215 p->rt.time_slice = sched_rr_timeslice; 2216 p->rt.on_rq = 0; 2217 p->rt.on_list = 0; 2218 2219 #ifdef CONFIG_PREEMPT_NOTIFIERS 2220 INIT_HLIST_HEAD(&p->preempt_notifiers); 2221 #endif 2222 2223 #ifdef CONFIG_NUMA_BALANCING 2224 if (p->mm && atomic_read(&p->mm->mm_users) == 1) { 2225 p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay); 2226 p->mm->numa_scan_seq = 0; 2227 } 2228 2229 if (clone_flags & CLONE_VM) 2230 p->numa_preferred_nid = current->numa_preferred_nid; 2231 else 2232 p->numa_preferred_nid = -1; 2233 2234 p->node_stamp = 0ULL; 2235 p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0; 2236 p->numa_scan_period = sysctl_numa_balancing_scan_delay; 2237 p->numa_work.next = &p->numa_work; 2238 p->numa_faults = NULL; 2239 p->last_task_numa_placement = 0; 2240 p->last_sum_exec_runtime = 0; 2241 2242 p->numa_group = NULL; 2243 #endif /* CONFIG_NUMA_BALANCING */ 2244 } 2245 2246 DEFINE_STATIC_KEY_FALSE(sched_numa_balancing); 2247 2248 #ifdef CONFIG_NUMA_BALANCING 2249 2250 void set_numabalancing_state(bool enabled) 2251 { 2252 if (enabled) 2253 static_branch_enable(&sched_numa_balancing); 2254 else 2255 static_branch_disable(&sched_numa_balancing); 2256 } 2257 2258 #ifdef CONFIG_PROC_SYSCTL 2259 int sysctl_numa_balancing(struct ctl_table *table, int write, 2260 void __user *buffer, size_t *lenp, loff_t *ppos) 2261 { 2262 struct ctl_table t; 2263 int err; 2264 int state = static_branch_likely(&sched_numa_balancing); 2265 2266 if (write && !capable(CAP_SYS_ADMIN)) 2267 return -EPERM; 2268 2269 t = *table; 2270 t.data = &state; 2271 err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); 2272 if (err < 0) 2273 return err; 2274 if (write) 2275 set_numabalancing_state(state); 2276 return err; 2277 } 2278 #endif 2279 #endif 2280 2281 #ifdef CONFIG_SCHEDSTATS 2282 2283 DEFINE_STATIC_KEY_FALSE(sched_schedstats); 2284 static bool __initdata __sched_schedstats = false; 2285 2286 static void set_schedstats(bool enabled) 2287 { 2288 if (enabled) 2289 static_branch_enable(&sched_schedstats); 2290 else 2291 static_branch_disable(&sched_schedstats); 2292 } 2293 2294 void force_schedstat_enabled(void) 2295 { 2296 if (!schedstat_enabled()) { 2297 pr_info("kernel profiling enabled schedstats, disable via kernel.sched_schedstats.\n"); 2298 static_branch_enable(&sched_schedstats); 2299 } 2300 } 2301 2302 static int __init setup_schedstats(char *str) 2303 { 2304 int ret = 0; 2305 if (!str) 2306 goto out; 2307 2308 /* 2309 * This code is called before jump labels have been set up, so we can't 2310 * change the static branch directly just yet. Instead set a temporary 2311 * variable so init_schedstats() can do it later. 2312 */ 2313 if (!strcmp(str, "enable")) { 2314 __sched_schedstats = true; 2315 ret = 1; 2316 } else if (!strcmp(str, "disable")) { 2317 __sched_schedstats = false; 2318 ret = 1; 2319 } 2320 out: 2321 if (!ret) 2322 pr_warn("Unable to parse schedstats=\n"); 2323 2324 return ret; 2325 } 2326 __setup("schedstats=", setup_schedstats); 2327 2328 static void __init init_schedstats(void) 2329 { 2330 set_schedstats(__sched_schedstats); 2331 } 2332 2333 #ifdef CONFIG_PROC_SYSCTL 2334 int sysctl_schedstats(struct ctl_table *table, int write, 2335 void __user *buffer, size_t *lenp, loff_t *ppos) 2336 { 2337 struct ctl_table t; 2338 int err; 2339 int state = static_branch_likely(&sched_schedstats); 2340 2341 if (write && !capable(CAP_SYS_ADMIN)) 2342 return -EPERM; 2343 2344 t = *table; 2345 t.data = &state; 2346 err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); 2347 if (err < 0) 2348 return err; 2349 if (write) 2350 set_schedstats(state); 2351 return err; 2352 } 2353 #endif /* CONFIG_PROC_SYSCTL */ 2354 #else /* !CONFIG_SCHEDSTATS */ 2355 static inline void init_schedstats(void) {} 2356 #endif /* CONFIG_SCHEDSTATS */ 2357 2358 /* 2359 * fork()/clone()-time setup: 2360 */ 2361 int sched_fork(unsigned long clone_flags, struct task_struct *p) 2362 { 2363 unsigned long flags; 2364 int cpu = get_cpu(); 2365 2366 __sched_fork(clone_flags, p); 2367 /* 2368 * We mark the process as NEW here. This guarantees that 2369 * nobody will actually run it, and a signal or other external 2370 * event cannot wake it up and insert it on the runqueue either. 2371 */ 2372 p->state = TASK_NEW; 2373 2374 /* 2375 * Make sure we do not leak PI boosting priority to the child. 2376 */ 2377 p->prio = current->normal_prio; 2378 2379 /* 2380 * Revert to default priority/policy on fork if requested. 2381 */ 2382 if (unlikely(p->sched_reset_on_fork)) { 2383 if (task_has_dl_policy(p) || task_has_rt_policy(p)) { 2384 p->policy = SCHED_NORMAL; 2385 p->static_prio = NICE_TO_PRIO(0); 2386 p->rt_priority = 0; 2387 } else if (PRIO_TO_NICE(p->static_prio) < 0) 2388 p->static_prio = NICE_TO_PRIO(0); 2389 2390 p->prio = p->normal_prio = __normal_prio(p); 2391 set_load_weight(p); 2392 2393 /* 2394 * We don't need the reset flag anymore after the fork. It has 2395 * fulfilled its duty: 2396 */ 2397 p->sched_reset_on_fork = 0; 2398 } 2399 2400 if (dl_prio(p->prio)) { 2401 put_cpu(); 2402 return -EAGAIN; 2403 } else if (rt_prio(p->prio)) { 2404 p->sched_class = &rt_sched_class; 2405 } else { 2406 p->sched_class = &fair_sched_class; 2407 } 2408 2409 init_entity_runnable_average(&p->se); 2410 2411 /* 2412 * The child is not yet in the pid-hash so no cgroup attach races, 2413 * and the cgroup is pinned to this child due to cgroup_fork() 2414 * is ran before sched_fork(). 2415 * 2416 * Silence PROVE_RCU. 2417 */ 2418 raw_spin_lock_irqsave(&p->pi_lock, flags); 2419 /* 2420 * We're setting the cpu for the first time, we don't migrate, 2421 * so use __set_task_cpu(). 2422 */ 2423 __set_task_cpu(p, cpu); 2424 if (p->sched_class->task_fork) 2425 p->sched_class->task_fork(p); 2426 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 2427 2428 #ifdef CONFIG_SCHED_INFO 2429 if (likely(sched_info_on())) 2430 memset(&p->sched_info, 0, sizeof(p->sched_info)); 2431 #endif 2432 #if defined(CONFIG_SMP) 2433 p->on_cpu = 0; 2434 #endif 2435 init_task_preempt_count(p); 2436 #ifdef CONFIG_SMP 2437 plist_node_init(&p->pushable_tasks, MAX_PRIO); 2438 RB_CLEAR_NODE(&p->pushable_dl_tasks); 2439 #endif 2440 2441 put_cpu(); 2442 return 0; 2443 } 2444 2445 unsigned long to_ratio(u64 period, u64 runtime) 2446 { 2447 if (runtime == RUNTIME_INF) 2448 return 1ULL << 20; 2449 2450 /* 2451 * Doing this here saves a lot of checks in all 2452 * the calling paths, and returning zero seems 2453 * safe for them anyway. 2454 */ 2455 if (period == 0) 2456 return 0; 2457 2458 return div64_u64(runtime << 20, period); 2459 } 2460 2461 #ifdef CONFIG_SMP 2462 inline struct dl_bw *dl_bw_of(int i) 2463 { 2464 RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), 2465 "sched RCU must be held"); 2466 return &cpu_rq(i)->rd->dl_bw; 2467 } 2468 2469 static inline int dl_bw_cpus(int i) 2470 { 2471 struct root_domain *rd = cpu_rq(i)->rd; 2472 int cpus = 0; 2473 2474 RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), 2475 "sched RCU must be held"); 2476 for_each_cpu_and(i, rd->span, cpu_active_mask) 2477 cpus++; 2478 2479 return cpus; 2480 } 2481 #else 2482 inline struct dl_bw *dl_bw_of(int i) 2483 { 2484 return &cpu_rq(i)->dl.dl_bw; 2485 } 2486 2487 static inline int dl_bw_cpus(int i) 2488 { 2489 return 1; 2490 } 2491 #endif 2492 2493 /* 2494 * We must be sure that accepting a new task (or allowing changing the 2495 * parameters of an existing one) is consistent with the bandwidth 2496 * constraints. If yes, this function also accordingly updates the currently 2497 * allocated bandwidth to reflect the new situation. 2498 * 2499 * This function is called while holding p's rq->lock. 2500 * 2501 * XXX we should delay bw change until the task's 0-lag point, see 2502 * __setparam_dl(). 2503 */ 2504 static int dl_overflow(struct task_struct *p, int policy, 2505 const struct sched_attr *attr) 2506 { 2507 2508 struct dl_bw *dl_b = dl_bw_of(task_cpu(p)); 2509 u64 period = attr->sched_period ?: attr->sched_deadline; 2510 u64 runtime = attr->sched_runtime; 2511 u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0; 2512 int cpus, err = -1; 2513 2514 /* !deadline task may carry old deadline bandwidth */ 2515 if (new_bw == p->dl.dl_bw && task_has_dl_policy(p)) 2516 return 0; 2517 2518 /* 2519 * Either if a task, enters, leave, or stays -deadline but changes 2520 * its parameters, we may need to update accordingly the total 2521 * allocated bandwidth of the container. 2522 */ 2523 raw_spin_lock(&dl_b->lock); 2524 cpus = dl_bw_cpus(task_cpu(p)); 2525 if (dl_policy(policy) && !task_has_dl_policy(p) && 2526 !__dl_overflow(dl_b, cpus, 0, new_bw)) { 2527 __dl_add(dl_b, new_bw); 2528 err = 0; 2529 } else if (dl_policy(policy) && task_has_dl_policy(p) && 2530 !__dl_overflow(dl_b, cpus, p->dl.dl_bw, new_bw)) { 2531 __dl_clear(dl_b, p->dl.dl_bw); 2532 __dl_add(dl_b, new_bw); 2533 err = 0; 2534 } else if (!dl_policy(policy) && task_has_dl_policy(p)) { 2535 __dl_clear(dl_b, p->dl.dl_bw); 2536 err = 0; 2537 } 2538 raw_spin_unlock(&dl_b->lock); 2539 2540 return err; 2541 } 2542 2543 extern void init_dl_bw(struct dl_bw *dl_b); 2544 2545 /* 2546 * wake_up_new_task - wake up a newly created task for the first time. 2547 * 2548 * This function will do some initial scheduler statistics housekeeping 2549 * that must be done for every newly created context, then puts the task 2550 * on the runqueue and wakes it. 2551 */ 2552 void wake_up_new_task(struct task_struct *p) 2553 { 2554 struct rq_flags rf; 2555 struct rq *rq; 2556 2557 raw_spin_lock_irqsave(&p->pi_lock, rf.flags); 2558 p->state = TASK_RUNNING; 2559 #ifdef CONFIG_SMP 2560 /* 2561 * Fork balancing, do it here and not earlier because: 2562 * - cpus_allowed can change in the fork path 2563 * - any previously selected cpu might disappear through hotplug 2564 * 2565 * Use __set_task_cpu() to avoid calling sched_class::migrate_task_rq, 2566 * as we're not fully set-up yet. 2567 */ 2568 __set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0)); 2569 #endif 2570 rq = __task_rq_lock(p, &rf); 2571 post_init_entity_util_avg(&p->se); 2572 2573 activate_task(rq, p, 0); 2574 p->on_rq = TASK_ON_RQ_QUEUED; 2575 trace_sched_wakeup_new(p); 2576 check_preempt_curr(rq, p, WF_FORK); 2577 #ifdef CONFIG_SMP 2578 if (p->sched_class->task_woken) { 2579 /* 2580 * Nothing relies on rq->lock after this, so its fine to 2581 * drop it. 2582 */ 2583 lockdep_unpin_lock(&rq->lock, rf.cookie); 2584 p->sched_class->task_woken(rq, p); 2585 lockdep_repin_lock(&rq->lock, rf.cookie); 2586 } 2587 #endif 2588 task_rq_unlock(rq, p, &rf); 2589 } 2590 2591 #ifdef CONFIG_PREEMPT_NOTIFIERS 2592 2593 static struct static_key preempt_notifier_key = STATIC_KEY_INIT_FALSE; 2594 2595 void preempt_notifier_inc(void) 2596 { 2597 static_key_slow_inc(&preempt_notifier_key); 2598 } 2599 EXPORT_SYMBOL_GPL(preempt_notifier_inc); 2600 2601 void preempt_notifier_dec(void) 2602 { 2603 static_key_slow_dec(&preempt_notifier_key); 2604 } 2605 EXPORT_SYMBOL_GPL(preempt_notifier_dec); 2606 2607 /** 2608 * preempt_notifier_register - tell me when current is being preempted & rescheduled 2609 * @notifier: notifier struct to register 2610 */ 2611 void preempt_notifier_register(struct preempt_notifier *notifier) 2612 { 2613 if (!static_key_false(&preempt_notifier_key)) 2614 WARN(1, "registering preempt_notifier while notifiers disabled\n"); 2615 2616 hlist_add_head(¬ifier->link, ¤t->preempt_notifiers); 2617 } 2618 EXPORT_SYMBOL_GPL(preempt_notifier_register); 2619 2620 /** 2621 * preempt_notifier_unregister - no longer interested in preemption notifications 2622 * @notifier: notifier struct to unregister 2623 * 2624 * This is *not* safe to call from within a preemption notifier. 2625 */ 2626 void preempt_notifier_unregister(struct preempt_notifier *notifier) 2627 { 2628 hlist_del(¬ifier->link); 2629 } 2630 EXPORT_SYMBOL_GPL(preempt_notifier_unregister); 2631 2632 static void __fire_sched_in_preempt_notifiers(struct task_struct *curr) 2633 { 2634 struct preempt_notifier *notifier; 2635 2636 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link) 2637 notifier->ops->sched_in(notifier, raw_smp_processor_id()); 2638 } 2639 2640 static __always_inline void fire_sched_in_preempt_notifiers(struct task_struct *curr) 2641 { 2642 if (static_key_false(&preempt_notifier_key)) 2643 __fire_sched_in_preempt_notifiers(curr); 2644 } 2645 2646 static void 2647 __fire_sched_out_preempt_notifiers(struct task_struct *curr, 2648 struct task_struct *next) 2649 { 2650 struct preempt_notifier *notifier; 2651 2652 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link) 2653 notifier->ops->sched_out(notifier, next); 2654 } 2655 2656 static __always_inline void 2657 fire_sched_out_preempt_notifiers(struct task_struct *curr, 2658 struct task_struct *next) 2659 { 2660 if (static_key_false(&preempt_notifier_key)) 2661 __fire_sched_out_preempt_notifiers(curr, next); 2662 } 2663 2664 #else /* !CONFIG_PREEMPT_NOTIFIERS */ 2665 2666 static inline void fire_sched_in_preempt_notifiers(struct task_struct *curr) 2667 { 2668 } 2669 2670 static inline void 2671 fire_sched_out_preempt_notifiers(struct task_struct *curr, 2672 struct task_struct *next) 2673 { 2674 } 2675 2676 #endif /* CONFIG_PREEMPT_NOTIFIERS */ 2677 2678 /** 2679 * prepare_task_switch - prepare to switch tasks 2680 * @rq: the runqueue preparing to switch 2681 * @prev: the current task that is being switched out 2682 * @next: the task we are going to switch to. 2683 * 2684 * This is called with the rq lock held and interrupts off. It must 2685 * be paired with a subsequent finish_task_switch after the context 2686 * switch. 2687 * 2688 * prepare_task_switch sets up locking and calls architecture specific 2689 * hooks. 2690 */ 2691 static inline void 2692 prepare_task_switch(struct rq *rq, struct task_struct *prev, 2693 struct task_struct *next) 2694 { 2695 sched_info_switch(rq, prev, next); 2696 perf_event_task_sched_out(prev, next); 2697 fire_sched_out_preempt_notifiers(prev, next); 2698 prepare_lock_switch(rq, next); 2699 prepare_arch_switch(next); 2700 } 2701 2702 /** 2703 * finish_task_switch - clean up after a task-switch 2704 * @prev: the thread we just switched away from. 2705 * 2706 * finish_task_switch must be called after the context switch, paired 2707 * with a prepare_task_switch call before the context switch. 2708 * finish_task_switch will reconcile locking set up by prepare_task_switch, 2709 * and do any other architecture-specific cleanup actions. 2710 * 2711 * Note that we may have delayed dropping an mm in context_switch(). If 2712 * so, we finish that here outside of the runqueue lock. (Doing it 2713 * with the lock held can cause deadlocks; see schedule() for 2714 * details.) 2715 * 2716 * The context switch have flipped the stack from under us and restored the 2717 * local variables which were saved when this task called schedule() in the 2718 * past. prev == current is still correct but we need to recalculate this_rq 2719 * because prev may have moved to another CPU. 2720 */ 2721 static struct rq *finish_task_switch(struct task_struct *prev) 2722 __releases(rq->lock) 2723 { 2724 struct rq *rq = this_rq(); 2725 struct mm_struct *mm = rq->prev_mm; 2726 long prev_state; 2727 2728 /* 2729 * The previous task will have left us with a preempt_count of 2 2730 * because it left us after: 2731 * 2732 * schedule() 2733 * preempt_disable(); // 1 2734 * __schedule() 2735 * raw_spin_lock_irq(&rq->lock) // 2 2736 * 2737 * Also, see FORK_PREEMPT_COUNT. 2738 */ 2739 if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET, 2740 "corrupted preempt_count: %s/%d/0x%x\n", 2741 current->comm, current->pid, preempt_count())) 2742 preempt_count_set(FORK_PREEMPT_COUNT); 2743 2744 rq->prev_mm = NULL; 2745 2746 /* 2747 * A task struct has one reference for the use as "current". 2748 * If a task dies, then it sets TASK_DEAD in tsk->state and calls 2749 * schedule one last time. The schedule call will never return, and 2750 * the scheduled task must drop that reference. 2751 * 2752 * We must observe prev->state before clearing prev->on_cpu (in 2753 * finish_lock_switch), otherwise a concurrent wakeup can get prev 2754 * running on another CPU and we could rave with its RUNNING -> DEAD 2755 * transition, resulting in a double drop. 2756 */ 2757 prev_state = prev->state; 2758 vtime_task_switch(prev); 2759 perf_event_task_sched_in(prev, current); 2760 finish_lock_switch(rq, prev); 2761 finish_arch_post_lock_switch(); 2762 2763 fire_sched_in_preempt_notifiers(current); 2764 if (mm) 2765 mmdrop(mm); 2766 if (unlikely(prev_state == TASK_DEAD)) { 2767 if (prev->sched_class->task_dead) 2768 prev->sched_class->task_dead(prev); 2769 2770 /* 2771 * Remove function-return probe instances associated with this 2772 * task and put them back on the free list. 2773 */ 2774 kprobe_flush_task(prev); 2775 put_task_struct(prev); 2776 } 2777 2778 tick_nohz_task_switch(); 2779 return rq; 2780 } 2781 2782 #ifdef CONFIG_SMP 2783 2784 /* rq->lock is NOT held, but preemption is disabled */ 2785 static void __balance_callback(struct rq *rq) 2786 { 2787 struct callback_head *head, *next; 2788 void (*func)(struct rq *rq); 2789 unsigned long flags; 2790 2791 raw_spin_lock_irqsave(&rq->lock, flags); 2792 head = rq->balance_callback; 2793 rq->balance_callback = NULL; 2794 while (head) { 2795 func = (void (*)(struct rq *))head->func; 2796 next = head->next; 2797 head->next = NULL; 2798 head = next; 2799 2800 func(rq); 2801 } 2802 raw_spin_unlock_irqrestore(&rq->lock, flags); 2803 } 2804 2805 static inline void balance_callback(struct rq *rq) 2806 { 2807 if (unlikely(rq->balance_callback)) 2808 __balance_callback(rq); 2809 } 2810 2811 #else 2812 2813 static inline void balance_callback(struct rq *rq) 2814 { 2815 } 2816 2817 #endif 2818 2819 /** 2820 * schedule_tail - first thing a freshly forked thread must call. 2821 * @prev: the thread we just switched away from. 2822 */ 2823 asmlinkage __visible void schedule_tail(struct task_struct *prev) 2824 __releases(rq->lock) 2825 { 2826 struct rq *rq; 2827 2828 /* 2829 * New tasks start with FORK_PREEMPT_COUNT, see there and 2830 * finish_task_switch() for details. 2831 * 2832 * finish_task_switch() will drop rq->lock() and lower preempt_count 2833 * and the preempt_enable() will end up enabling preemption (on 2834 * PREEMPT_COUNT kernels). 2835 */ 2836 2837 rq = finish_task_switch(prev); 2838 balance_callback(rq); 2839 preempt_enable(); 2840 2841 if (current->set_child_tid) 2842 put_user(task_pid_vnr(current), current->set_child_tid); 2843 } 2844 2845 /* 2846 * context_switch - switch to the new MM and the new thread's register state. 2847 */ 2848 static __always_inline struct rq * 2849 context_switch(struct rq *rq, struct task_struct *prev, 2850 struct task_struct *next, struct pin_cookie cookie) 2851 { 2852 struct mm_struct *mm, *oldmm; 2853 2854 prepare_task_switch(rq, prev, next); 2855 2856 mm = next->mm; 2857 oldmm = prev->active_mm; 2858 /* 2859 * For paravirt, this is coupled with an exit in switch_to to 2860 * combine the page table reload and the switch backend into 2861 * one hypercall. 2862 */ 2863 arch_start_context_switch(prev); 2864 2865 if (!mm) { 2866 next->active_mm = oldmm; 2867 atomic_inc(&oldmm->mm_count); 2868 enter_lazy_tlb(oldmm, next); 2869 } else 2870 switch_mm_irqs_off(oldmm, mm, next); 2871 2872 if (!prev->mm) { 2873 prev->active_mm = NULL; 2874 rq->prev_mm = oldmm; 2875 } 2876 /* 2877 * Since the runqueue lock will be released by the next 2878 * task (which is an invalid locking op but in the case 2879 * of the scheduler it's an obvious special-case), so we 2880 * do an early lockdep release here: 2881 */ 2882 lockdep_unpin_lock(&rq->lock, cookie); 2883 spin_release(&rq->lock.dep_map, 1, _THIS_IP_); 2884 2885 /* Here we just switch the register state and the stack. */ 2886 switch_to(prev, next, prev); 2887 barrier(); 2888 2889 return finish_task_switch(prev); 2890 } 2891 2892 /* 2893 * nr_running and nr_context_switches: 2894 * 2895 * externally visible scheduler statistics: current number of runnable 2896 * threads, total number of context switches performed since bootup. 2897 */ 2898 unsigned long nr_running(void) 2899 { 2900 unsigned long i, sum = 0; 2901 2902 for_each_online_cpu(i) 2903 sum += cpu_rq(i)->nr_running; 2904 2905 return sum; 2906 } 2907 2908 /* 2909 * Check if only the current task is running on the cpu. 2910 * 2911 * Caution: this function does not check that the caller has disabled 2912 * preemption, thus the result might have a time-of-check-to-time-of-use 2913 * race. The caller is responsible to use it correctly, for example: 2914 * 2915 * - from a non-preemptable section (of course) 2916 * 2917 * - from a thread that is bound to a single CPU 2918 * 2919 * - in a loop with very short iterations (e.g. a polling loop) 2920 */ 2921 bool single_task_running(void) 2922 { 2923 return raw_rq()->nr_running == 1; 2924 } 2925 EXPORT_SYMBOL(single_task_running); 2926 2927 unsigned long long nr_context_switches(void) 2928 { 2929 int i; 2930 unsigned long long sum = 0; 2931 2932 for_each_possible_cpu(i) 2933 sum += cpu_rq(i)->nr_switches; 2934 2935 return sum; 2936 } 2937 2938 unsigned long nr_iowait(void) 2939 { 2940 unsigned long i, sum = 0; 2941 2942 for_each_possible_cpu(i) 2943 sum += atomic_read(&cpu_rq(i)->nr_iowait); 2944 2945 return sum; 2946 } 2947 2948 unsigned long nr_iowait_cpu(int cpu) 2949 { 2950 struct rq *this = cpu_rq(cpu); 2951 return atomic_read(&this->nr_iowait); 2952 } 2953 2954 void get_iowait_load(unsigned long *nr_waiters, unsigned long *load) 2955 { 2956 struct rq *rq = this_rq(); 2957 *nr_waiters = atomic_read(&rq->nr_iowait); 2958 *load = rq->load.weight; 2959 } 2960 2961 #ifdef CONFIG_SMP 2962 2963 /* 2964 * sched_exec - execve() is a valuable balancing opportunity, because at 2965 * this point the task has the smallest effective memory and cache footprint. 2966 */ 2967 void sched_exec(void) 2968 { 2969 struct task_struct *p = current; 2970 unsigned long flags; 2971 int dest_cpu; 2972 2973 raw_spin_lock_irqsave(&p->pi_lock, flags); 2974 dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0); 2975 if (dest_cpu == smp_processor_id()) 2976 goto unlock; 2977 2978 if (likely(cpu_active(dest_cpu))) { 2979 struct migration_arg arg = { p, dest_cpu }; 2980 2981 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 2982 stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg); 2983 return; 2984 } 2985 unlock: 2986 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 2987 } 2988 2989 #endif 2990 2991 DEFINE_PER_CPU(struct kernel_stat, kstat); 2992 DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat); 2993 2994 EXPORT_PER_CPU_SYMBOL(kstat); 2995 EXPORT_PER_CPU_SYMBOL(kernel_cpustat); 2996 2997 /* 2998 * The function fair_sched_class.update_curr accesses the struct curr 2999 * and its field curr->exec_start; when called from task_sched_runtime(), 3000 * we observe a high rate of cache misses in practice. 3001 * Prefetching this data results in improved performance. 3002 */ 3003 static inline void prefetch_curr_exec_start(struct task_struct *p) 3004 { 3005 #ifdef CONFIG_FAIR_GROUP_SCHED 3006 struct sched_entity *curr = (&p->se)->cfs_rq->curr; 3007 #else 3008 struct sched_entity *curr = (&task_rq(p)->cfs)->curr; 3009 #endif 3010 prefetch(curr); 3011 prefetch(&curr->exec_start); 3012 } 3013 3014 /* 3015 * Return accounted runtime for the task. 3016 * In case the task is currently running, return the runtime plus current's 3017 * pending runtime that have not been accounted yet. 3018 */ 3019 unsigned long long task_sched_runtime(struct task_struct *p) 3020 { 3021 struct rq_flags rf; 3022 struct rq *rq; 3023 u64 ns; 3024 3025 #if defined(CONFIG_64BIT) && defined(CONFIG_SMP) 3026 /* 3027 * 64-bit doesn't need locks to atomically read a 64bit value. 3028 * So we have a optimization chance when the task's delta_exec is 0. 3029 * Reading ->on_cpu is racy, but this is ok. 3030 * 3031 * If we race with it leaving cpu, we'll take a lock. So we're correct. 3032 * If we race with it entering cpu, unaccounted time is 0. This is 3033 * indistinguishable from the read occurring a few cycles earlier. 3034 * If we see ->on_cpu without ->on_rq, the task is leaving, and has 3035 * been accounted, so we're correct here as well. 3036 */ 3037 if (!p->on_cpu || !task_on_rq_queued(p)) 3038 return p->se.sum_exec_runtime; 3039 #endif 3040 3041 rq = task_rq_lock(p, &rf); 3042 /* 3043 * Must be ->curr _and_ ->on_rq. If dequeued, we would 3044 * project cycles that may never be accounted to this 3045 * thread, breaking clock_gettime(). 3046 */ 3047 if (task_current(rq, p) && task_on_rq_queued(p)) { 3048 prefetch_curr_exec_start(p); 3049 update_rq_clock(rq); 3050 p->sched_class->update_curr(rq); 3051 } 3052 ns = p->se.sum_exec_runtime; 3053 task_rq_unlock(rq, p, &rf); 3054 3055 return ns; 3056 } 3057 3058 /* 3059 * This function gets called by the timer code, with HZ frequency. 3060 * We call it with interrupts disabled. 3061 */ 3062 void scheduler_tick(void) 3063 { 3064 int cpu = smp_processor_id(); 3065 struct rq *rq = cpu_rq(cpu); 3066 struct task_struct *curr = rq->curr; 3067 3068 sched_clock_tick(); 3069 3070 raw_spin_lock(&rq->lock); 3071 update_rq_clock(rq); 3072 curr->sched_class->task_tick(rq, curr, 0); 3073 cpu_load_update_active(rq); 3074 calc_global_load_tick(rq); 3075 raw_spin_unlock(&rq->lock); 3076 3077 perf_event_task_tick(); 3078 3079 #ifdef CONFIG_SMP 3080 rq->idle_balance = idle_cpu(cpu); 3081 trigger_load_balance(rq); 3082 #endif 3083 rq_last_tick_reset(rq); 3084 } 3085 3086 #ifdef CONFIG_NO_HZ_FULL 3087 /** 3088 * scheduler_tick_max_deferment 3089 * 3090 * Keep at least one tick per second when a single 3091 * active task is running because the scheduler doesn't 3092 * yet completely support full dynticks environment. 3093 * 3094 * This makes sure that uptime, CFS vruntime, load 3095 * balancing, etc... continue to move forward, even 3096 * with a very low granularity. 3097 * 3098 * Return: Maximum deferment in nanoseconds. 3099 */ 3100 u64 scheduler_tick_max_deferment(void) 3101 { 3102 struct rq *rq = this_rq(); 3103 unsigned long next, now = READ_ONCE(jiffies); 3104 3105 next = rq->last_sched_tick + HZ; 3106 3107 if (time_before_eq(next, now)) 3108 return 0; 3109 3110 return jiffies_to_nsecs(next - now); 3111 } 3112 #endif 3113 3114 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \ 3115 defined(CONFIG_PREEMPT_TRACER)) 3116 /* 3117 * If the value passed in is equal to the current preempt count 3118 * then we just disabled preemption. Start timing the latency. 3119 */ 3120 static inline void preempt_latency_start(int val) 3121 { 3122 if (preempt_count() == val) { 3123 unsigned long ip = get_lock_parent_ip(); 3124 #ifdef CONFIG_DEBUG_PREEMPT 3125 current->preempt_disable_ip = ip; 3126 #endif 3127 trace_preempt_off(CALLER_ADDR0, ip); 3128 } 3129 } 3130 3131 void preempt_count_add(int val) 3132 { 3133 #ifdef CONFIG_DEBUG_PREEMPT 3134 /* 3135 * Underflow? 3136 */ 3137 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0))) 3138 return; 3139 #endif 3140 __preempt_count_add(val); 3141 #ifdef CONFIG_DEBUG_PREEMPT 3142 /* 3143 * Spinlock count overflowing soon? 3144 */ 3145 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >= 3146 PREEMPT_MASK - 10); 3147 #endif 3148 preempt_latency_start(val); 3149 } 3150 EXPORT_SYMBOL(preempt_count_add); 3151 NOKPROBE_SYMBOL(preempt_count_add); 3152 3153 /* 3154 * If the value passed in equals to the current preempt count 3155 * then we just enabled preemption. Stop timing the latency. 3156 */ 3157 static inline void preempt_latency_stop(int val) 3158 { 3159 if (preempt_count() == val) 3160 trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip()); 3161 } 3162 3163 void preempt_count_sub(int val) 3164 { 3165 #ifdef CONFIG_DEBUG_PREEMPT 3166 /* 3167 * Underflow? 3168 */ 3169 if (DEBUG_LOCKS_WARN_ON(val > preempt_count())) 3170 return; 3171 /* 3172 * Is the spinlock portion underflowing? 3173 */ 3174 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) && 3175 !(preempt_count() & PREEMPT_MASK))) 3176 return; 3177 #endif 3178 3179 preempt_latency_stop(val); 3180 __preempt_count_sub(val); 3181 } 3182 EXPORT_SYMBOL(preempt_count_sub); 3183 NOKPROBE_SYMBOL(preempt_count_sub); 3184 3185 #else 3186 static inline void preempt_latency_start(int val) { } 3187 static inline void preempt_latency_stop(int val) { } 3188 #endif 3189 3190 /* 3191 * Print scheduling while atomic bug: 3192 */ 3193 static noinline void __schedule_bug(struct task_struct *prev) 3194 { 3195 if (oops_in_progress) 3196 return; 3197 3198 printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n", 3199 prev->comm, prev->pid, preempt_count()); 3200 3201 debug_show_held_locks(prev); 3202 print_modules(); 3203 if (irqs_disabled()) 3204 print_irqtrace_events(prev); 3205 #ifdef CONFIG_DEBUG_PREEMPT 3206 if (in_atomic_preempt_off()) { 3207 pr_err("Preemption disabled at:"); 3208 print_ip_sym(current->preempt_disable_ip); 3209 pr_cont("\n"); 3210 } 3211 #endif 3212 if (panic_on_warn) 3213 panic("scheduling while atomic\n"); 3214 3215 dump_stack(); 3216 add_taint(TAINT_WARN, LOCKDEP_STILL_OK); 3217 } 3218 3219 /* 3220 * Various schedule()-time debugging checks and statistics: 3221 */ 3222 static inline void schedule_debug(struct task_struct *prev) 3223 { 3224 #ifdef CONFIG_SCHED_STACK_END_CHECK 3225 if (task_stack_end_corrupted(prev)) 3226 panic("corrupted stack end detected inside scheduler\n"); 3227 #endif 3228 3229 if (unlikely(in_atomic_preempt_off())) { 3230 __schedule_bug(prev); 3231 preempt_count_set(PREEMPT_DISABLED); 3232 } 3233 rcu_sleep_check(); 3234 3235 profile_hit(SCHED_PROFILING, __builtin_return_address(0)); 3236 3237 schedstat_inc(this_rq(), sched_count); 3238 } 3239 3240 /* 3241 * Pick up the highest-prio task: 3242 */ 3243 static inline struct task_struct * 3244 pick_next_task(struct rq *rq, struct task_struct *prev, struct pin_cookie cookie) 3245 { 3246 const struct sched_class *class = &fair_sched_class; 3247 struct task_struct *p; 3248 3249 /* 3250 * Optimization: we know that if all tasks are in 3251 * the fair class we can call that function directly: 3252 */ 3253 if (likely(prev->sched_class == class && 3254 rq->nr_running == rq->cfs.h_nr_running)) { 3255 p = fair_sched_class.pick_next_task(rq, prev, cookie); 3256 if (unlikely(p == RETRY_TASK)) 3257 goto again; 3258 3259 /* assumes fair_sched_class->next == idle_sched_class */ 3260 if (unlikely(!p)) 3261 p = idle_sched_class.pick_next_task(rq, prev, cookie); 3262 3263 return p; 3264 } 3265 3266 again: 3267 for_each_class(class) { 3268 p = class->pick_next_task(rq, prev, cookie); 3269 if (p) { 3270 if (unlikely(p == RETRY_TASK)) 3271 goto again; 3272 return p; 3273 } 3274 } 3275 3276 BUG(); /* the idle class will always have a runnable task */ 3277 } 3278 3279 /* 3280 * __schedule() is the main scheduler function. 3281 * 3282 * The main means of driving the scheduler and thus entering this function are: 3283 * 3284 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc. 3285 * 3286 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return 3287 * paths. For example, see arch/x86/entry_64.S. 3288 * 3289 * To drive preemption between tasks, the scheduler sets the flag in timer 3290 * interrupt handler scheduler_tick(). 3291 * 3292 * 3. Wakeups don't really cause entry into schedule(). They add a 3293 * task to the run-queue and that's it. 3294 * 3295 * Now, if the new task added to the run-queue preempts the current 3296 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets 3297 * called on the nearest possible occasion: 3298 * 3299 * - If the kernel is preemptible (CONFIG_PREEMPT=y): 3300 * 3301 * - in syscall or exception context, at the next outmost 3302 * preempt_enable(). (this might be as soon as the wake_up()'s 3303 * spin_unlock()!) 3304 * 3305 * - in IRQ context, return from interrupt-handler to 3306 * preemptible context 3307 * 3308 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set) 3309 * then at the next: 3310 * 3311 * - cond_resched() call 3312 * - explicit schedule() call 3313 * - return from syscall or exception to user-space 3314 * - return from interrupt-handler to user-space 3315 * 3316 * WARNING: must be called with preemption disabled! 3317 */ 3318 static void __sched notrace __schedule(bool preempt) 3319 { 3320 struct task_struct *prev, *next; 3321 unsigned long *switch_count; 3322 struct pin_cookie cookie; 3323 struct rq *rq; 3324 int cpu; 3325 3326 cpu = smp_processor_id(); 3327 rq = cpu_rq(cpu); 3328 prev = rq->curr; 3329 3330 /* 3331 * do_exit() calls schedule() with preemption disabled as an exception; 3332 * however we must fix that up, otherwise the next task will see an 3333 * inconsistent (higher) preempt count. 3334 * 3335 * It also avoids the below schedule_debug() test from complaining 3336 * about this. 3337 */ 3338 if (unlikely(prev->state == TASK_DEAD)) 3339 preempt_enable_no_resched_notrace(); 3340 3341 schedule_debug(prev); 3342 3343 if (sched_feat(HRTICK)) 3344 hrtick_clear(rq); 3345 3346 local_irq_disable(); 3347 rcu_note_context_switch(); 3348 3349 /* 3350 * Make sure that signal_pending_state()->signal_pending() below 3351 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE) 3352 * done by the caller to avoid the race with signal_wake_up(). 3353 */ 3354 smp_mb__before_spinlock(); 3355 raw_spin_lock(&rq->lock); 3356 cookie = lockdep_pin_lock(&rq->lock); 3357 3358 rq->clock_skip_update <<= 1; /* promote REQ to ACT */ 3359 3360 switch_count = &prev->nivcsw; 3361 if (!preempt && prev->state) { 3362 if (unlikely(signal_pending_state(prev->state, prev))) { 3363 prev->state = TASK_RUNNING; 3364 } else { 3365 deactivate_task(rq, prev, DEQUEUE_SLEEP); 3366 prev->on_rq = 0; 3367 3368 /* 3369 * If a worker went to sleep, notify and ask workqueue 3370 * whether it wants to wake up a task to maintain 3371 * concurrency. 3372 */ 3373 if (prev->flags & PF_WQ_WORKER) { 3374 struct task_struct *to_wakeup; 3375 3376 to_wakeup = wq_worker_sleeping(prev); 3377 if (to_wakeup) 3378 try_to_wake_up_local(to_wakeup, cookie); 3379 } 3380 } 3381 switch_count = &prev->nvcsw; 3382 } 3383 3384 if (task_on_rq_queued(prev)) 3385 update_rq_clock(rq); 3386 3387 next = pick_next_task(rq, prev, cookie); 3388 clear_tsk_need_resched(prev); 3389 clear_preempt_need_resched(); 3390 rq->clock_skip_update = 0; 3391 3392 if (likely(prev != next)) { 3393 rq->nr_switches++; 3394 rq->curr = next; 3395 ++*switch_count; 3396 3397 trace_sched_switch(preempt, prev, next); 3398 rq = context_switch(rq, prev, next, cookie); /* unlocks the rq */ 3399 } else { 3400 lockdep_unpin_lock(&rq->lock, cookie); 3401 raw_spin_unlock_irq(&rq->lock); 3402 } 3403 3404 balance_callback(rq); 3405 } 3406 STACK_FRAME_NON_STANDARD(__schedule); /* switch_to() */ 3407 3408 static inline void sched_submit_work(struct task_struct *tsk) 3409 { 3410 if (!tsk->state || tsk_is_pi_blocked(tsk)) 3411 return; 3412 /* 3413 * If we are going to sleep and we have plugged IO queued, 3414 * make sure to submit it to avoid deadlocks. 3415 */ 3416 if (blk_needs_flush_plug(tsk)) 3417 blk_schedule_flush_plug(tsk); 3418 } 3419 3420 asmlinkage __visible void __sched schedule(void) 3421 { 3422 struct task_struct *tsk = current; 3423 3424 sched_submit_work(tsk); 3425 do { 3426 preempt_disable(); 3427 __schedule(false); 3428 sched_preempt_enable_no_resched(); 3429 } while (need_resched()); 3430 } 3431 EXPORT_SYMBOL(schedule); 3432 3433 #ifdef CONFIG_CONTEXT_TRACKING 3434 asmlinkage __visible void __sched schedule_user(void) 3435 { 3436 /* 3437 * If we come here after a random call to set_need_resched(), 3438 * or we have been woken up remotely but the IPI has not yet arrived, 3439 * we haven't yet exited the RCU idle mode. Do it here manually until 3440 * we find a better solution. 3441 * 3442 * NB: There are buggy callers of this function. Ideally we 3443 * should warn if prev_state != CONTEXT_USER, but that will trigger 3444 * too frequently to make sense yet. 3445 */ 3446 enum ctx_state prev_state = exception_enter(); 3447 schedule(); 3448 exception_exit(prev_state); 3449 } 3450 #endif 3451 3452 /** 3453 * schedule_preempt_disabled - called with preemption disabled 3454 * 3455 * Returns with preemption disabled. Note: preempt_count must be 1 3456 */ 3457 void __sched schedule_preempt_disabled(void) 3458 { 3459 sched_preempt_enable_no_resched(); 3460 schedule(); 3461 preempt_disable(); 3462 } 3463 3464 static void __sched notrace preempt_schedule_common(void) 3465 { 3466 do { 3467 /* 3468 * Because the function tracer can trace preempt_count_sub() 3469 * and it also uses preempt_enable/disable_notrace(), if 3470 * NEED_RESCHED is set, the preempt_enable_notrace() called 3471 * by the function tracer will call this function again and 3472 * cause infinite recursion. 3473 * 3474 * Preemption must be disabled here before the function 3475 * tracer can trace. Break up preempt_disable() into two 3476 * calls. One to disable preemption without fear of being 3477 * traced. The other to still record the preemption latency, 3478 * which can also be traced by the function tracer. 3479 */ 3480 preempt_disable_notrace(); 3481 preempt_latency_start(1); 3482 __schedule(true); 3483 preempt_latency_stop(1); 3484 preempt_enable_no_resched_notrace(); 3485 3486 /* 3487 * Check again in case we missed a preemption opportunity 3488 * between schedule and now. 3489 */ 3490 } while (need_resched()); 3491 } 3492 3493 #ifdef CONFIG_PREEMPT 3494 /* 3495 * this is the entry point to schedule() from in-kernel preemption 3496 * off of preempt_enable. Kernel preemptions off return from interrupt 3497 * occur there and call schedule directly. 3498 */ 3499 asmlinkage __visible void __sched notrace preempt_schedule(void) 3500 { 3501 /* 3502 * If there is a non-zero preempt_count or interrupts are disabled, 3503 * we do not want to preempt the current task. Just return.. 3504 */ 3505 if (likely(!preemptible())) 3506 return; 3507 3508 preempt_schedule_common(); 3509 } 3510 NOKPROBE_SYMBOL(preempt_schedule); 3511 EXPORT_SYMBOL(preempt_schedule); 3512 3513 /** 3514 * preempt_schedule_notrace - preempt_schedule called by tracing 3515 * 3516 * The tracing infrastructure uses preempt_enable_notrace to prevent 3517 * recursion and tracing preempt enabling caused by the tracing 3518 * infrastructure itself. But as tracing can happen in areas coming 3519 * from userspace or just about to enter userspace, a preempt enable 3520 * can occur before user_exit() is called. This will cause the scheduler 3521 * to be called when the system is still in usermode. 3522 * 3523 * To prevent this, the preempt_enable_notrace will use this function 3524 * instead of preempt_schedule() to exit user context if needed before 3525 * calling the scheduler. 3526 */ 3527 asmlinkage __visible void __sched notrace preempt_schedule_notrace(void) 3528 { 3529 enum ctx_state prev_ctx; 3530 3531 if (likely(!preemptible())) 3532 return; 3533 3534 do { 3535 /* 3536 * Because the function tracer can trace preempt_count_sub() 3537 * and it also uses preempt_enable/disable_notrace(), if 3538 * NEED_RESCHED is set, the preempt_enable_notrace() called 3539 * by the function tracer will call this function again and 3540 * cause infinite recursion. 3541 * 3542 * Preemption must be disabled here before the function 3543 * tracer can trace. Break up preempt_disable() into two 3544 * calls. One to disable preemption without fear of being 3545 * traced. The other to still record the preemption latency, 3546 * which can also be traced by the function tracer. 3547 */ 3548 preempt_disable_notrace(); 3549 preempt_latency_start(1); 3550 /* 3551 * Needs preempt disabled in case user_exit() is traced 3552 * and the tracer calls preempt_enable_notrace() causing 3553 * an infinite recursion. 3554 */ 3555 prev_ctx = exception_enter(); 3556 __schedule(true); 3557 exception_exit(prev_ctx); 3558 3559 preempt_latency_stop(1); 3560 preempt_enable_no_resched_notrace(); 3561 } while (need_resched()); 3562 } 3563 EXPORT_SYMBOL_GPL(preempt_schedule_notrace); 3564 3565 #endif /* CONFIG_PREEMPT */ 3566 3567 /* 3568 * this is the entry point to schedule() from kernel preemption 3569 * off of irq context. 3570 * Note, that this is called and return with irqs disabled. This will 3571 * protect us against recursive calling from irq. 3572 */ 3573 asmlinkage __visible void __sched preempt_schedule_irq(void) 3574 { 3575 enum ctx_state prev_state; 3576 3577 /* Catch callers which need to be fixed */ 3578 BUG_ON(preempt_count() || !irqs_disabled()); 3579 3580 prev_state = exception_enter(); 3581 3582 do { 3583 preempt_disable(); 3584 local_irq_enable(); 3585 __schedule(true); 3586 local_irq_disable(); 3587 sched_preempt_enable_no_resched(); 3588 } while (need_resched()); 3589 3590 exception_exit(prev_state); 3591 } 3592 3593 int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags, 3594 void *key) 3595 { 3596 return try_to_wake_up(curr->private, mode, wake_flags); 3597 } 3598 EXPORT_SYMBOL(default_wake_function); 3599 3600 #ifdef CONFIG_RT_MUTEXES 3601 3602 /* 3603 * rt_mutex_setprio - set the current priority of a task 3604 * @p: task 3605 * @prio: prio value (kernel-internal form) 3606 * 3607 * This function changes the 'effective' priority of a task. It does 3608 * not touch ->normal_prio like __setscheduler(). 3609 * 3610 * Used by the rt_mutex code to implement priority inheritance 3611 * logic. Call site only calls if the priority of the task changed. 3612 */ 3613 void rt_mutex_setprio(struct task_struct *p, int prio) 3614 { 3615 int oldprio, queued, running, queue_flag = DEQUEUE_SAVE | DEQUEUE_MOVE; 3616 const struct sched_class *prev_class; 3617 struct rq_flags rf; 3618 struct rq *rq; 3619 3620 BUG_ON(prio > MAX_PRIO); 3621 3622 rq = __task_rq_lock(p, &rf); 3623 3624 /* 3625 * Idle task boosting is a nono in general. There is one 3626 * exception, when PREEMPT_RT and NOHZ is active: 3627 * 3628 * The idle task calls get_next_timer_interrupt() and holds 3629 * the timer wheel base->lock on the CPU and another CPU wants 3630 * to access the timer (probably to cancel it). We can safely 3631 * ignore the boosting request, as the idle CPU runs this code 3632 * with interrupts disabled and will complete the lock 3633 * protected section without being interrupted. So there is no 3634 * real need to boost. 3635 */ 3636 if (unlikely(p == rq->idle)) { 3637 WARN_ON(p != rq->curr); 3638 WARN_ON(p->pi_blocked_on); 3639 goto out_unlock; 3640 } 3641 3642 trace_sched_pi_setprio(p, prio); 3643 oldprio = p->prio; 3644 3645 if (oldprio == prio) 3646 queue_flag &= ~DEQUEUE_MOVE; 3647 3648 prev_class = p->sched_class; 3649 queued = task_on_rq_queued(p); 3650 running = task_current(rq, p); 3651 if (queued) 3652 dequeue_task(rq, p, queue_flag); 3653 if (running) 3654 put_prev_task(rq, p); 3655 3656 /* 3657 * Boosting condition are: 3658 * 1. -rt task is running and holds mutex A 3659 * --> -dl task blocks on mutex A 3660 * 3661 * 2. -dl task is running and holds mutex A 3662 * --> -dl task blocks on mutex A and could preempt the 3663 * running task 3664 */ 3665 if (dl_prio(prio)) { 3666 struct task_struct *pi_task = rt_mutex_get_top_task(p); 3667 if (!dl_prio(p->normal_prio) || 3668 (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) { 3669 p->dl.dl_boosted = 1; 3670 queue_flag |= ENQUEUE_REPLENISH; 3671 } else 3672 p->dl.dl_boosted = 0; 3673 p->sched_class = &dl_sched_class; 3674 } else if (rt_prio(prio)) { 3675 if (dl_prio(oldprio)) 3676 p->dl.dl_boosted = 0; 3677 if (oldprio < prio) 3678 queue_flag |= ENQUEUE_HEAD; 3679 p->sched_class = &rt_sched_class; 3680 } else { 3681 if (dl_prio(oldprio)) 3682 p->dl.dl_boosted = 0; 3683 if (rt_prio(oldprio)) 3684 p->rt.timeout = 0; 3685 p->sched_class = &fair_sched_class; 3686 } 3687 3688 p->prio = prio; 3689 3690 if (running) 3691 p->sched_class->set_curr_task(rq); 3692 if (queued) 3693 enqueue_task(rq, p, queue_flag); 3694 3695 check_class_changed(rq, p, prev_class, oldprio); 3696 out_unlock: 3697 preempt_disable(); /* avoid rq from going away on us */ 3698 __task_rq_unlock(rq, &rf); 3699 3700 balance_callback(rq); 3701 preempt_enable(); 3702 } 3703 #endif 3704 3705 void set_user_nice(struct task_struct *p, long nice) 3706 { 3707 int old_prio, delta, queued; 3708 struct rq_flags rf; 3709 struct rq *rq; 3710 3711 if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE) 3712 return; 3713 /* 3714 * We have to be careful, if called from sys_setpriority(), 3715 * the task might be in the middle of scheduling on another CPU. 3716 */ 3717 rq = task_rq_lock(p, &rf); 3718 /* 3719 * The RT priorities are set via sched_setscheduler(), but we still 3720 * allow the 'normal' nice value to be set - but as expected 3721 * it wont have any effect on scheduling until the task is 3722 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR: 3723 */ 3724 if (task_has_dl_policy(p) || task_has_rt_policy(p)) { 3725 p->static_prio = NICE_TO_PRIO(nice); 3726 goto out_unlock; 3727 } 3728 queued = task_on_rq_queued(p); 3729 if (queued) 3730 dequeue_task(rq, p, DEQUEUE_SAVE); 3731 3732 p->static_prio = NICE_TO_PRIO(nice); 3733 set_load_weight(p); 3734 old_prio = p->prio; 3735 p->prio = effective_prio(p); 3736 delta = p->prio - old_prio; 3737 3738 if (queued) { 3739 enqueue_task(rq, p, ENQUEUE_RESTORE); 3740 /* 3741 * If the task increased its priority or is running and 3742 * lowered its priority, then reschedule its CPU: 3743 */ 3744 if (delta < 0 || (delta > 0 && task_running(rq, p))) 3745 resched_curr(rq); 3746 } 3747 out_unlock: 3748 task_rq_unlock(rq, p, &rf); 3749 } 3750 EXPORT_SYMBOL(set_user_nice); 3751 3752 /* 3753 * can_nice - check if a task can reduce its nice value 3754 * @p: task 3755 * @nice: nice value 3756 */ 3757 int can_nice(const struct task_struct *p, const int nice) 3758 { 3759 /* convert nice value [19,-20] to rlimit style value [1,40] */ 3760 int nice_rlim = nice_to_rlimit(nice); 3761 3762 return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) || 3763 capable(CAP_SYS_NICE)); 3764 } 3765 3766 #ifdef __ARCH_WANT_SYS_NICE 3767 3768 /* 3769 * sys_nice - change the priority of the current process. 3770 * @increment: priority increment 3771 * 3772 * sys_setpriority is a more generic, but much slower function that 3773 * does similar things. 3774 */ 3775 SYSCALL_DEFINE1(nice, int, increment) 3776 { 3777 long nice, retval; 3778 3779 /* 3780 * Setpriority might change our priority at the same moment. 3781 * We don't have to worry. Conceptually one call occurs first 3782 * and we have a single winner. 3783 */ 3784 increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH); 3785 nice = task_nice(current) + increment; 3786 3787 nice = clamp_val(nice, MIN_NICE, MAX_NICE); 3788 if (increment < 0 && !can_nice(current, nice)) 3789 return -EPERM; 3790 3791 retval = security_task_setnice(current, nice); 3792 if (retval) 3793 return retval; 3794 3795 set_user_nice(current, nice); 3796 return 0; 3797 } 3798 3799 #endif 3800 3801 /** 3802 * task_prio - return the priority value of a given task. 3803 * @p: the task in question. 3804 * 3805 * Return: The priority value as seen by users in /proc. 3806 * RT tasks are offset by -200. Normal tasks are centered 3807 * around 0, value goes from -16 to +15. 3808 */ 3809 int task_prio(const struct task_struct *p) 3810 { 3811 return p->prio - MAX_RT_PRIO; 3812 } 3813 3814 /** 3815 * idle_cpu - is a given cpu idle currently? 3816 * @cpu: the processor in question. 3817 * 3818 * Return: 1 if the CPU is currently idle. 0 otherwise. 3819 */ 3820 int idle_cpu(int cpu) 3821 { 3822 struct rq *rq = cpu_rq(cpu); 3823 3824 if (rq->curr != rq->idle) 3825 return 0; 3826 3827 if (rq->nr_running) 3828 return 0; 3829 3830 #ifdef CONFIG_SMP 3831 if (!llist_empty(&rq->wake_list)) 3832 return 0; 3833 #endif 3834 3835 return 1; 3836 } 3837 3838 /** 3839 * idle_task - return the idle task for a given cpu. 3840 * @cpu: the processor in question. 3841 * 3842 * Return: The idle task for the cpu @cpu. 3843 */ 3844 struct task_struct *idle_task(int cpu) 3845 { 3846 return cpu_rq(cpu)->idle; 3847 } 3848 3849 /** 3850 * find_process_by_pid - find a process with a matching PID value. 3851 * @pid: the pid in question. 3852 * 3853 * The task of @pid, if found. %NULL otherwise. 3854 */ 3855 static struct task_struct *find_process_by_pid(pid_t pid) 3856 { 3857 return pid ? find_task_by_vpid(pid) : current; 3858 } 3859 3860 /* 3861 * This function initializes the sched_dl_entity of a newly becoming 3862 * SCHED_DEADLINE task. 3863 * 3864 * Only the static values are considered here, the actual runtime and the 3865 * absolute deadline will be properly calculated when the task is enqueued 3866 * for the first time with its new policy. 3867 */ 3868 static void 3869 __setparam_dl(struct task_struct *p, const struct sched_attr *attr) 3870 { 3871 struct sched_dl_entity *dl_se = &p->dl; 3872 3873 dl_se->dl_runtime = attr->sched_runtime; 3874 dl_se->dl_deadline = attr->sched_deadline; 3875 dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline; 3876 dl_se->flags = attr->sched_flags; 3877 dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime); 3878 3879 /* 3880 * Changing the parameters of a task is 'tricky' and we're not doing 3881 * the correct thing -- also see task_dead_dl() and switched_from_dl(). 3882 * 3883 * What we SHOULD do is delay the bandwidth release until the 0-lag 3884 * point. This would include retaining the task_struct until that time 3885 * and change dl_overflow() to not immediately decrement the current 3886 * amount. 3887 * 3888 * Instead we retain the current runtime/deadline and let the new 3889 * parameters take effect after the current reservation period lapses. 3890 * This is safe (albeit pessimistic) because the 0-lag point is always 3891 * before the current scheduling deadline. 3892 * 3893 * We can still have temporary overloads because we do not delay the 3894 * change in bandwidth until that time; so admission control is 3895 * not on the safe side. It does however guarantee tasks will never 3896 * consume more than promised. 3897 */ 3898 } 3899 3900 /* 3901 * sched_setparam() passes in -1 for its policy, to let the functions 3902 * it calls know not to change it. 3903 */ 3904 #define SETPARAM_POLICY -1 3905 3906 static void __setscheduler_params(struct task_struct *p, 3907 const struct sched_attr *attr) 3908 { 3909 int policy = attr->sched_policy; 3910 3911 if (policy == SETPARAM_POLICY) 3912 policy = p->policy; 3913 3914 p->policy = policy; 3915 3916 if (dl_policy(policy)) 3917 __setparam_dl(p, attr); 3918 else if (fair_policy(policy)) 3919 p->static_prio = NICE_TO_PRIO(attr->sched_nice); 3920 3921 /* 3922 * __sched_setscheduler() ensures attr->sched_priority == 0 when 3923 * !rt_policy. Always setting this ensures that things like 3924 * getparam()/getattr() don't report silly values for !rt tasks. 3925 */ 3926 p->rt_priority = attr->sched_priority; 3927 p->normal_prio = normal_prio(p); 3928 set_load_weight(p); 3929 } 3930 3931 /* Actually do priority change: must hold pi & rq lock. */ 3932 static void __setscheduler(struct rq *rq, struct task_struct *p, 3933 const struct sched_attr *attr, bool keep_boost) 3934 { 3935 __setscheduler_params(p, attr); 3936 3937 /* 3938 * Keep a potential priority boosting if called from 3939 * sched_setscheduler(). 3940 */ 3941 if (keep_boost) 3942 p->prio = rt_mutex_get_effective_prio(p, normal_prio(p)); 3943 else 3944 p->prio = normal_prio(p); 3945 3946 if (dl_prio(p->prio)) 3947 p->sched_class = &dl_sched_class; 3948 else if (rt_prio(p->prio)) 3949 p->sched_class = &rt_sched_class; 3950 else 3951 p->sched_class = &fair_sched_class; 3952 } 3953 3954 static void 3955 __getparam_dl(struct task_struct *p, struct sched_attr *attr) 3956 { 3957 struct sched_dl_entity *dl_se = &p->dl; 3958 3959 attr->sched_priority = p->rt_priority; 3960 attr->sched_runtime = dl_se->dl_runtime; 3961 attr->sched_deadline = dl_se->dl_deadline; 3962 attr->sched_period = dl_se->dl_period; 3963 attr->sched_flags = dl_se->flags; 3964 } 3965 3966 /* 3967 * This function validates the new parameters of a -deadline task. 3968 * We ask for the deadline not being zero, and greater or equal 3969 * than the runtime, as well as the period of being zero or 3970 * greater than deadline. Furthermore, we have to be sure that 3971 * user parameters are above the internal resolution of 1us (we 3972 * check sched_runtime only since it is always the smaller one) and 3973 * below 2^63 ns (we have to check both sched_deadline and 3974 * sched_period, as the latter can be zero). 3975 */ 3976 static bool 3977 __checkparam_dl(const struct sched_attr *attr) 3978 { 3979 /* deadline != 0 */ 3980 if (attr->sched_deadline == 0) 3981 return false; 3982 3983 /* 3984 * Since we truncate DL_SCALE bits, make sure we're at least 3985 * that big. 3986 */ 3987 if (attr->sched_runtime < (1ULL << DL_SCALE)) 3988 return false; 3989 3990 /* 3991 * Since we use the MSB for wrap-around and sign issues, make 3992 * sure it's not set (mind that period can be equal to zero). 3993 */ 3994 if (attr->sched_deadline & (1ULL << 63) || 3995 attr->sched_period & (1ULL << 63)) 3996 return false; 3997 3998 /* runtime <= deadline <= period (if period != 0) */ 3999 if ((attr->sched_period != 0 && 4000 attr->sched_period < attr->sched_deadline) || 4001 attr->sched_deadline < attr->sched_runtime) 4002 return false; 4003 4004 return true; 4005 } 4006 4007 /* 4008 * check the target process has a UID that matches the current process's 4009 */ 4010 static bool check_same_owner(struct task_struct *p) 4011 { 4012 const struct cred *cred = current_cred(), *pcred; 4013 bool match; 4014 4015 rcu_read_lock(); 4016 pcred = __task_cred(p); 4017 match = (uid_eq(cred->euid, pcred->euid) || 4018 uid_eq(cred->euid, pcred->uid)); 4019 rcu_read_unlock(); 4020 return match; 4021 } 4022 4023 static bool dl_param_changed(struct task_struct *p, 4024 const struct sched_attr *attr) 4025 { 4026 struct sched_dl_entity *dl_se = &p->dl; 4027 4028 if (dl_se->dl_runtime != attr->sched_runtime || 4029 dl_se->dl_deadline != attr->sched_deadline || 4030 dl_se->dl_period != attr->sched_period || 4031 dl_se->flags != attr->sched_flags) 4032 return true; 4033 4034 return false; 4035 } 4036 4037 static int __sched_setscheduler(struct task_struct *p, 4038 const struct sched_attr *attr, 4039 bool user, bool pi) 4040 { 4041 int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 : 4042 MAX_RT_PRIO - 1 - attr->sched_priority; 4043 int retval, oldprio, oldpolicy = -1, queued, running; 4044 int new_effective_prio, policy = attr->sched_policy; 4045 const struct sched_class *prev_class; 4046 struct rq_flags rf; 4047 int reset_on_fork; 4048 int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE; 4049 struct rq *rq; 4050 4051 /* may grab non-irq protected spin_locks */ 4052 BUG_ON(in_interrupt()); 4053 recheck: 4054 /* double check policy once rq lock held */ 4055 if (policy < 0) { 4056 reset_on_fork = p->sched_reset_on_fork; 4057 policy = oldpolicy = p->policy; 4058 } else { 4059 reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK); 4060 4061 if (!valid_policy(policy)) 4062 return -EINVAL; 4063 } 4064 4065 if (attr->sched_flags & ~(SCHED_FLAG_RESET_ON_FORK)) 4066 return -EINVAL; 4067 4068 /* 4069 * Valid priorities for SCHED_FIFO and SCHED_RR are 4070 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL, 4071 * SCHED_BATCH and SCHED_IDLE is 0. 4072 */ 4073 if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) || 4074 (!p->mm && attr->sched_priority > MAX_RT_PRIO-1)) 4075 return -EINVAL; 4076 if ((dl_policy(policy) && !__checkparam_dl(attr)) || 4077 (rt_policy(policy) != (attr->sched_priority != 0))) 4078 return -EINVAL; 4079 4080 /* 4081 * Allow unprivileged RT tasks to decrease priority: 4082 */ 4083 if (user && !capable(CAP_SYS_NICE)) { 4084 if (fair_policy(policy)) { 4085 if (attr->sched_nice < task_nice(p) && 4086 !can_nice(p, attr->sched_nice)) 4087 return -EPERM; 4088 } 4089 4090 if (rt_policy(policy)) { 4091 unsigned long rlim_rtprio = 4092 task_rlimit(p, RLIMIT_RTPRIO); 4093 4094 /* can't set/change the rt policy */ 4095 if (policy != p->policy && !rlim_rtprio) 4096 return -EPERM; 4097 4098 /* can't increase priority */ 4099 if (attr->sched_priority > p->rt_priority && 4100 attr->sched_priority > rlim_rtprio) 4101 return -EPERM; 4102 } 4103 4104 /* 4105 * Can't set/change SCHED_DEADLINE policy at all for now 4106 * (safest behavior); in the future we would like to allow 4107 * unprivileged DL tasks to increase their relative deadline 4108 * or reduce their runtime (both ways reducing utilization) 4109 */ 4110 if (dl_policy(policy)) 4111 return -EPERM; 4112 4113 /* 4114 * Treat SCHED_IDLE as nice 20. Only allow a switch to 4115 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it. 4116 */ 4117 if (idle_policy(p->policy) && !idle_policy(policy)) { 4118 if (!can_nice(p, task_nice(p))) 4119 return -EPERM; 4120 } 4121 4122 /* can't change other user's priorities */ 4123 if (!check_same_owner(p)) 4124 return -EPERM; 4125 4126 /* Normal users shall not reset the sched_reset_on_fork flag */ 4127 if (p->sched_reset_on_fork && !reset_on_fork) 4128 return -EPERM; 4129 } 4130 4131 if (user) { 4132 retval = security_task_setscheduler(p); 4133 if (retval) 4134 return retval; 4135 } 4136 4137 /* 4138 * make sure no PI-waiters arrive (or leave) while we are 4139 * changing the priority of the task: 4140 * 4141 * To be able to change p->policy safely, the appropriate 4142 * runqueue lock must be held. 4143 */ 4144 rq = task_rq_lock(p, &rf); 4145 4146 /* 4147 * Changing the policy of the stop threads its a very bad idea 4148 */ 4149 if (p == rq->stop) { 4150 task_rq_unlock(rq, p, &rf); 4151 return -EINVAL; 4152 } 4153 4154 /* 4155 * If not changing anything there's no need to proceed further, 4156 * but store a possible modification of reset_on_fork. 4157 */ 4158 if (unlikely(policy == p->policy)) { 4159 if (fair_policy(policy) && attr->sched_nice != task_nice(p)) 4160 goto change; 4161 if (rt_policy(policy) && attr->sched_priority != p->rt_priority) 4162 goto change; 4163 if (dl_policy(policy) && dl_param_changed(p, attr)) 4164 goto change; 4165 4166 p->sched_reset_on_fork = reset_on_fork; 4167 task_rq_unlock(rq, p, &rf); 4168 return 0; 4169 } 4170 change: 4171 4172 if (user) { 4173 #ifdef CONFIG_RT_GROUP_SCHED 4174 /* 4175 * Do not allow realtime tasks into groups that have no runtime 4176 * assigned. 4177 */ 4178 if (rt_bandwidth_enabled() && rt_policy(policy) && 4179 task_group(p)->rt_bandwidth.rt_runtime == 0 && 4180 !task_group_is_autogroup(task_group(p))) { 4181 task_rq_unlock(rq, p, &rf); 4182 return -EPERM; 4183 } 4184 #endif 4185 #ifdef CONFIG_SMP 4186 if (dl_bandwidth_enabled() && dl_policy(policy)) { 4187 cpumask_t *span = rq->rd->span; 4188 4189 /* 4190 * Don't allow tasks with an affinity mask smaller than 4191 * the entire root_domain to become SCHED_DEADLINE. We 4192 * will also fail if there's no bandwidth available. 4193 */ 4194 if (!cpumask_subset(span, &p->cpus_allowed) || 4195 rq->rd->dl_bw.bw == 0) { 4196 task_rq_unlock(rq, p, &rf); 4197 return -EPERM; 4198 } 4199 } 4200 #endif 4201 } 4202 4203 /* recheck policy now with rq lock held */ 4204 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) { 4205 policy = oldpolicy = -1; 4206 task_rq_unlock(rq, p, &rf); 4207 goto recheck; 4208 } 4209 4210 /* 4211 * If setscheduling to SCHED_DEADLINE (or changing the parameters 4212 * of a SCHED_DEADLINE task) we need to check if enough bandwidth 4213 * is available. 4214 */ 4215 if ((dl_policy(policy) || dl_task(p)) && dl_overflow(p, policy, attr)) { 4216 task_rq_unlock(rq, p, &rf); 4217 return -EBUSY; 4218 } 4219 4220 p->sched_reset_on_fork = reset_on_fork; 4221 oldprio = p->prio; 4222 4223 if (pi) { 4224 /* 4225 * Take priority boosted tasks into account. If the new 4226 * effective priority is unchanged, we just store the new 4227 * normal parameters and do not touch the scheduler class and 4228 * the runqueue. This will be done when the task deboost 4229 * itself. 4230 */ 4231 new_effective_prio = rt_mutex_get_effective_prio(p, newprio); 4232 if (new_effective_prio == oldprio) 4233 queue_flags &= ~DEQUEUE_MOVE; 4234 } 4235 4236 queued = task_on_rq_queued(p); 4237 running = task_current(rq, p); 4238 if (queued) 4239 dequeue_task(rq, p, queue_flags); 4240 if (running) 4241 put_prev_task(rq, p); 4242 4243 prev_class = p->sched_class; 4244 __setscheduler(rq, p, attr, pi); 4245 4246 if (running) 4247 p->sched_class->set_curr_task(rq); 4248 if (queued) { 4249 /* 4250 * We enqueue to tail when the priority of a task is 4251 * increased (user space view). 4252 */ 4253 if (oldprio < p->prio) 4254 queue_flags |= ENQUEUE_HEAD; 4255 4256 enqueue_task(rq, p, queue_flags); 4257 } 4258 4259 check_class_changed(rq, p, prev_class, oldprio); 4260 preempt_disable(); /* avoid rq from going away on us */ 4261 task_rq_unlock(rq, p, &rf); 4262 4263 if (pi) 4264 rt_mutex_adjust_pi(p); 4265 4266 /* 4267 * Run balance callbacks after we've adjusted the PI chain. 4268 */ 4269 balance_callback(rq); 4270 preempt_enable(); 4271 4272 return 0; 4273 } 4274 4275 static int _sched_setscheduler(struct task_struct *p, int policy, 4276 const struct sched_param *param, bool check) 4277 { 4278 struct sched_attr attr = { 4279 .sched_policy = policy, 4280 .sched_priority = param->sched_priority, 4281 .sched_nice = PRIO_TO_NICE(p->static_prio), 4282 }; 4283 4284 /* Fixup the legacy SCHED_RESET_ON_FORK hack. */ 4285 if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) { 4286 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK; 4287 policy &= ~SCHED_RESET_ON_FORK; 4288 attr.sched_policy = policy; 4289 } 4290 4291 return __sched_setscheduler(p, &attr, check, true); 4292 } 4293 /** 4294 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread. 4295 * @p: the task in question. 4296 * @policy: new policy. 4297 * @param: structure containing the new RT priority. 4298 * 4299 * Return: 0 on success. An error code otherwise. 4300 * 4301 * NOTE that the task may be already dead. 4302 */ 4303 int sched_setscheduler(struct task_struct *p, int policy, 4304 const struct sched_param *param) 4305 { 4306 return _sched_setscheduler(p, policy, param, true); 4307 } 4308 EXPORT_SYMBOL_GPL(sched_setscheduler); 4309 4310 int sched_setattr(struct task_struct *p, const struct sched_attr *attr) 4311 { 4312 return __sched_setscheduler(p, attr, true, true); 4313 } 4314 EXPORT_SYMBOL_GPL(sched_setattr); 4315 4316 /** 4317 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace. 4318 * @p: the task in question. 4319 * @policy: new policy. 4320 * @param: structure containing the new RT priority. 4321 * 4322 * Just like sched_setscheduler, only don't bother checking if the 4323 * current context has permission. For example, this is needed in 4324 * stop_machine(): we create temporary high priority worker threads, 4325 * but our caller might not have that capability. 4326 * 4327 * Return: 0 on success. An error code otherwise. 4328 */ 4329 int sched_setscheduler_nocheck(struct task_struct *p, int policy, 4330 const struct sched_param *param) 4331 { 4332 return _sched_setscheduler(p, policy, param, false); 4333 } 4334 EXPORT_SYMBOL_GPL(sched_setscheduler_nocheck); 4335 4336 static int 4337 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) 4338 { 4339 struct sched_param lparam; 4340 struct task_struct *p; 4341 int retval; 4342 4343 if (!param || pid < 0) 4344 return -EINVAL; 4345 if (copy_from_user(&lparam, param, sizeof(struct sched_param))) 4346 return -EFAULT; 4347 4348 rcu_read_lock(); 4349 retval = -ESRCH; 4350 p = find_process_by_pid(pid); 4351 if (p != NULL) 4352 retval = sched_setscheduler(p, policy, &lparam); 4353 rcu_read_unlock(); 4354 4355 return retval; 4356 } 4357 4358 /* 4359 * Mimics kernel/events/core.c perf_copy_attr(). 4360 */ 4361 static int sched_copy_attr(struct sched_attr __user *uattr, 4362 struct sched_attr *attr) 4363 { 4364 u32 size; 4365 int ret; 4366 4367 if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0)) 4368 return -EFAULT; 4369 4370 /* 4371 * zero the full structure, so that a short copy will be nice. 4372 */ 4373 memset(attr, 0, sizeof(*attr)); 4374 4375 ret = get_user(size, &uattr->size); 4376 if (ret) 4377 return ret; 4378 4379 if (size > PAGE_SIZE) /* silly large */ 4380 goto err_size; 4381 4382 if (!size) /* abi compat */ 4383 size = SCHED_ATTR_SIZE_VER0; 4384 4385 if (size < SCHED_ATTR_SIZE_VER0) 4386 goto err_size; 4387 4388 /* 4389 * If we're handed a bigger struct than we know of, 4390 * ensure all the unknown bits are 0 - i.e. new 4391 * user-space does not rely on any kernel feature 4392 * extensions we dont know about yet. 4393 */ 4394 if (size > sizeof(*attr)) { 4395 unsigned char __user *addr; 4396 unsigned char __user *end; 4397 unsigned char val; 4398 4399 addr = (void __user *)uattr + sizeof(*attr); 4400 end = (void __user *)uattr + size; 4401 4402 for (; addr < end; addr++) { 4403 ret = get_user(val, addr); 4404 if (ret) 4405 return ret; 4406 if (val) 4407 goto err_size; 4408 } 4409 size = sizeof(*attr); 4410 } 4411 4412 ret = copy_from_user(attr, uattr, size); 4413 if (ret) 4414 return -EFAULT; 4415 4416 /* 4417 * XXX: do we want to be lenient like existing syscalls; or do we want 4418 * to be strict and return an error on out-of-bounds values? 4419 */ 4420 attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE); 4421 4422 return 0; 4423 4424 err_size: 4425 put_user(sizeof(*attr), &uattr->size); 4426 return -E2BIG; 4427 } 4428 4429 /** 4430 * sys_sched_setscheduler - set/change the scheduler policy and RT priority 4431 * @pid: the pid in question. 4432 * @policy: new policy. 4433 * @param: structure containing the new RT priority. 4434 * 4435 * Return: 0 on success. An error code otherwise. 4436 */ 4437 SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy, 4438 struct sched_param __user *, param) 4439 { 4440 /* negative values for policy are not valid */ 4441 if (policy < 0) 4442 return -EINVAL; 4443 4444 return do_sched_setscheduler(pid, policy, param); 4445 } 4446 4447 /** 4448 * sys_sched_setparam - set/change the RT priority of a thread 4449 * @pid: the pid in question. 4450 * @param: structure containing the new RT priority. 4451 * 4452 * Return: 0 on success. An error code otherwise. 4453 */ 4454 SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param) 4455 { 4456 return do_sched_setscheduler(pid, SETPARAM_POLICY, param); 4457 } 4458 4459 /** 4460 * sys_sched_setattr - same as above, but with extended sched_attr 4461 * @pid: the pid in question. 4462 * @uattr: structure containing the extended parameters. 4463 * @flags: for future extension. 4464 */ 4465 SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr, 4466 unsigned int, flags) 4467 { 4468 struct sched_attr attr; 4469 struct task_struct *p; 4470 int retval; 4471 4472 if (!uattr || pid < 0 || flags) 4473 return -EINVAL; 4474 4475 retval = sched_copy_attr(uattr, &attr); 4476 if (retval) 4477 return retval; 4478 4479 if ((int)attr.sched_policy < 0) 4480 return -EINVAL; 4481 4482 rcu_read_lock(); 4483 retval = -ESRCH; 4484 p = find_process_by_pid(pid); 4485 if (p != NULL) 4486 retval = sched_setattr(p, &attr); 4487 rcu_read_unlock(); 4488 4489 return retval; 4490 } 4491 4492 /** 4493 * sys_sched_getscheduler - get the policy (scheduling class) of a thread 4494 * @pid: the pid in question. 4495 * 4496 * Return: On success, the policy of the thread. Otherwise, a negative error 4497 * code. 4498 */ 4499 SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid) 4500 { 4501 struct task_struct *p; 4502 int retval; 4503 4504 if (pid < 0) 4505 return -EINVAL; 4506 4507 retval = -ESRCH; 4508 rcu_read_lock(); 4509 p = find_process_by_pid(pid); 4510 if (p) { 4511 retval = security_task_getscheduler(p); 4512 if (!retval) 4513 retval = p->policy 4514 | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0); 4515 } 4516 rcu_read_unlock(); 4517 return retval; 4518 } 4519 4520 /** 4521 * sys_sched_getparam - get the RT priority of a thread 4522 * @pid: the pid in question. 4523 * @param: structure containing the RT priority. 4524 * 4525 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error 4526 * code. 4527 */ 4528 SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param) 4529 { 4530 struct sched_param lp = { .sched_priority = 0 }; 4531 struct task_struct *p; 4532 int retval; 4533 4534 if (!param || pid < 0) 4535 return -EINVAL; 4536 4537 rcu_read_lock(); 4538 p = find_process_by_pid(pid); 4539 retval = -ESRCH; 4540 if (!p) 4541 goto out_unlock; 4542 4543 retval = security_task_getscheduler(p); 4544 if (retval) 4545 goto out_unlock; 4546 4547 if (task_has_rt_policy(p)) 4548 lp.sched_priority = p->rt_priority; 4549 rcu_read_unlock(); 4550 4551 /* 4552 * This one might sleep, we cannot do it with a spinlock held ... 4553 */ 4554 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0; 4555 4556 return retval; 4557 4558 out_unlock: 4559 rcu_read_unlock(); 4560 return retval; 4561 } 4562 4563 static int sched_read_attr(struct sched_attr __user *uattr, 4564 struct sched_attr *attr, 4565 unsigned int usize) 4566 { 4567 int ret; 4568 4569 if (!access_ok(VERIFY_WRITE, uattr, usize)) 4570 return -EFAULT; 4571 4572 /* 4573 * If we're handed a smaller struct than we know of, 4574 * ensure all the unknown bits are 0 - i.e. old 4575 * user-space does not get uncomplete information. 4576 */ 4577 if (usize < sizeof(*attr)) { 4578 unsigned char *addr; 4579 unsigned char *end; 4580 4581 addr = (void *)attr + usize; 4582 end = (void *)attr + sizeof(*attr); 4583 4584 for (; addr < end; addr++) { 4585 if (*addr) 4586 return -EFBIG; 4587 } 4588 4589 attr->size = usize; 4590 } 4591 4592 ret = copy_to_user(uattr, attr, attr->size); 4593 if (ret) 4594 return -EFAULT; 4595 4596 return 0; 4597 } 4598 4599 /** 4600 * sys_sched_getattr - similar to sched_getparam, but with sched_attr 4601 * @pid: the pid in question. 4602 * @uattr: structure containing the extended parameters. 4603 * @size: sizeof(attr) for fwd/bwd comp. 4604 * @flags: for future extension. 4605 */ 4606 SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr, 4607 unsigned int, size, unsigned int, flags) 4608 { 4609 struct sched_attr attr = { 4610 .size = sizeof(struct sched_attr), 4611 }; 4612 struct task_struct *p; 4613 int retval; 4614 4615 if (!uattr || pid < 0 || size > PAGE_SIZE || 4616 size < SCHED_ATTR_SIZE_VER0 || flags) 4617 return -EINVAL; 4618 4619 rcu_read_lock(); 4620 p = find_process_by_pid(pid); 4621 retval = -ESRCH; 4622 if (!p) 4623 goto out_unlock; 4624 4625 retval = security_task_getscheduler(p); 4626 if (retval) 4627 goto out_unlock; 4628 4629 attr.sched_policy = p->policy; 4630 if (p->sched_reset_on_fork) 4631 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK; 4632 if (task_has_dl_policy(p)) 4633 __getparam_dl(p, &attr); 4634 else if (task_has_rt_policy(p)) 4635 attr.sched_priority = p->rt_priority; 4636 else 4637 attr.sched_nice = task_nice(p); 4638 4639 rcu_read_unlock(); 4640 4641 retval = sched_read_attr(uattr, &attr, size); 4642 return retval; 4643 4644 out_unlock: 4645 rcu_read_unlock(); 4646 return retval; 4647 } 4648 4649 long sched_setaffinity(pid_t pid, const struct cpumask *in_mask) 4650 { 4651 cpumask_var_t cpus_allowed, new_mask; 4652 struct task_struct *p; 4653 int retval; 4654 4655 rcu_read_lock(); 4656 4657 p = find_process_by_pid(pid); 4658 if (!p) { 4659 rcu_read_unlock(); 4660 return -ESRCH; 4661 } 4662 4663 /* Prevent p going away */ 4664 get_task_struct(p); 4665 rcu_read_unlock(); 4666 4667 if (p->flags & PF_NO_SETAFFINITY) { 4668 retval = -EINVAL; 4669 goto out_put_task; 4670 } 4671 if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) { 4672 retval = -ENOMEM; 4673 goto out_put_task; 4674 } 4675 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) { 4676 retval = -ENOMEM; 4677 goto out_free_cpus_allowed; 4678 } 4679 retval = -EPERM; 4680 if (!check_same_owner(p)) { 4681 rcu_read_lock(); 4682 if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) { 4683 rcu_read_unlock(); 4684 goto out_free_new_mask; 4685 } 4686 rcu_read_unlock(); 4687 } 4688 4689 retval = security_task_setscheduler(p); 4690 if (retval) 4691 goto out_free_new_mask; 4692 4693 4694 cpuset_cpus_allowed(p, cpus_allowed); 4695 cpumask_and(new_mask, in_mask, cpus_allowed); 4696 4697 /* 4698 * Since bandwidth control happens on root_domain basis, 4699 * if admission test is enabled, we only admit -deadline 4700 * tasks allowed to run on all the CPUs in the task's 4701 * root_domain. 4702 */ 4703 #ifdef CONFIG_SMP 4704 if (task_has_dl_policy(p) && dl_bandwidth_enabled()) { 4705 rcu_read_lock(); 4706 if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) { 4707 retval = -EBUSY; 4708 rcu_read_unlock(); 4709 goto out_free_new_mask; 4710 } 4711 rcu_read_unlock(); 4712 } 4713 #endif 4714 again: 4715 retval = __set_cpus_allowed_ptr(p, new_mask, true); 4716 4717 if (!retval) { 4718 cpuset_cpus_allowed(p, cpus_allowed); 4719 if (!cpumask_subset(new_mask, cpus_allowed)) { 4720 /* 4721 * We must have raced with a concurrent cpuset 4722 * update. Just reset the cpus_allowed to the 4723 * cpuset's cpus_allowed 4724 */ 4725 cpumask_copy(new_mask, cpus_allowed); 4726 goto again; 4727 } 4728 } 4729 out_free_new_mask: 4730 free_cpumask_var(new_mask); 4731 out_free_cpus_allowed: 4732 free_cpumask_var(cpus_allowed); 4733 out_put_task: 4734 put_task_struct(p); 4735 return retval; 4736 } 4737 4738 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len, 4739 struct cpumask *new_mask) 4740 { 4741 if (len < cpumask_size()) 4742 cpumask_clear(new_mask); 4743 else if (len > cpumask_size()) 4744 len = cpumask_size(); 4745 4746 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0; 4747 } 4748 4749 /** 4750 * sys_sched_setaffinity - set the cpu affinity of a process 4751 * @pid: pid of the process 4752 * @len: length in bytes of the bitmask pointed to by user_mask_ptr 4753 * @user_mask_ptr: user-space pointer to the new cpu mask 4754 * 4755 * Return: 0 on success. An error code otherwise. 4756 */ 4757 SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len, 4758 unsigned long __user *, user_mask_ptr) 4759 { 4760 cpumask_var_t new_mask; 4761 int retval; 4762 4763 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) 4764 return -ENOMEM; 4765 4766 retval = get_user_cpu_mask(user_mask_ptr, len, new_mask); 4767 if (retval == 0) 4768 retval = sched_setaffinity(pid, new_mask); 4769 free_cpumask_var(new_mask); 4770 return retval; 4771 } 4772 4773 long sched_getaffinity(pid_t pid, struct cpumask *mask) 4774 { 4775 struct task_struct *p; 4776 unsigned long flags; 4777 int retval; 4778 4779 rcu_read_lock(); 4780 4781 retval = -ESRCH; 4782 p = find_process_by_pid(pid); 4783 if (!p) 4784 goto out_unlock; 4785 4786 retval = security_task_getscheduler(p); 4787 if (retval) 4788 goto out_unlock; 4789 4790 raw_spin_lock_irqsave(&p->pi_lock, flags); 4791 cpumask_and(mask, &p->cpus_allowed, cpu_active_mask); 4792 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 4793 4794 out_unlock: 4795 rcu_read_unlock(); 4796 4797 return retval; 4798 } 4799 4800 /** 4801 * sys_sched_getaffinity - get the cpu affinity of a process 4802 * @pid: pid of the process 4803 * @len: length in bytes of the bitmask pointed to by user_mask_ptr 4804 * @user_mask_ptr: user-space pointer to hold the current cpu mask 4805 * 4806 * Return: size of CPU mask copied to user_mask_ptr on success. An 4807 * error code otherwise. 4808 */ 4809 SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len, 4810 unsigned long __user *, user_mask_ptr) 4811 { 4812 int ret; 4813 cpumask_var_t mask; 4814 4815 if ((len * BITS_PER_BYTE) < nr_cpu_ids) 4816 return -EINVAL; 4817 if (len & (sizeof(unsigned long)-1)) 4818 return -EINVAL; 4819 4820 if (!alloc_cpumask_var(&mask, GFP_KERNEL)) 4821 return -ENOMEM; 4822 4823 ret = sched_getaffinity(pid, mask); 4824 if (ret == 0) { 4825 size_t retlen = min_t(size_t, len, cpumask_size()); 4826 4827 if (copy_to_user(user_mask_ptr, mask, retlen)) 4828 ret = -EFAULT; 4829 else 4830 ret = retlen; 4831 } 4832 free_cpumask_var(mask); 4833 4834 return ret; 4835 } 4836 4837 /** 4838 * sys_sched_yield - yield the current processor to other threads. 4839 * 4840 * This function yields the current CPU to other tasks. If there are no 4841 * other threads running on this CPU then this function will return. 4842 * 4843 * Return: 0. 4844 */ 4845 SYSCALL_DEFINE0(sched_yield) 4846 { 4847 struct rq *rq = this_rq_lock(); 4848 4849 schedstat_inc(rq, yld_count); 4850 current->sched_class->yield_task(rq); 4851 4852 /* 4853 * Since we are going to call schedule() anyway, there's 4854 * no need to preempt or enable interrupts: 4855 */ 4856 __release(rq->lock); 4857 spin_release(&rq->lock.dep_map, 1, _THIS_IP_); 4858 do_raw_spin_unlock(&rq->lock); 4859 sched_preempt_enable_no_resched(); 4860 4861 schedule(); 4862 4863 return 0; 4864 } 4865 4866 int __sched _cond_resched(void) 4867 { 4868 if (should_resched(0)) { 4869 preempt_schedule_common(); 4870 return 1; 4871 } 4872 return 0; 4873 } 4874 EXPORT_SYMBOL(_cond_resched); 4875 4876 /* 4877 * __cond_resched_lock() - if a reschedule is pending, drop the given lock, 4878 * call schedule, and on return reacquire the lock. 4879 * 4880 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level 4881 * operations here to prevent schedule() from being called twice (once via 4882 * spin_unlock(), once by hand). 4883 */ 4884 int __cond_resched_lock(spinlock_t *lock) 4885 { 4886 int resched = should_resched(PREEMPT_LOCK_OFFSET); 4887 int ret = 0; 4888 4889 lockdep_assert_held(lock); 4890 4891 if (spin_needbreak(lock) || resched) { 4892 spin_unlock(lock); 4893 if (resched) 4894 preempt_schedule_common(); 4895 else 4896 cpu_relax(); 4897 ret = 1; 4898 spin_lock(lock); 4899 } 4900 return ret; 4901 } 4902 EXPORT_SYMBOL(__cond_resched_lock); 4903 4904 int __sched __cond_resched_softirq(void) 4905 { 4906 BUG_ON(!in_softirq()); 4907 4908 if (should_resched(SOFTIRQ_DISABLE_OFFSET)) { 4909 local_bh_enable(); 4910 preempt_schedule_common(); 4911 local_bh_disable(); 4912 return 1; 4913 } 4914 return 0; 4915 } 4916 EXPORT_SYMBOL(__cond_resched_softirq); 4917 4918 /** 4919 * yield - yield the current processor to other threads. 4920 * 4921 * Do not ever use this function, there's a 99% chance you're doing it wrong. 4922 * 4923 * The scheduler is at all times free to pick the calling task as the most 4924 * eligible task to run, if removing the yield() call from your code breaks 4925 * it, its already broken. 4926 * 4927 * Typical broken usage is: 4928 * 4929 * while (!event) 4930 * yield(); 4931 * 4932 * where one assumes that yield() will let 'the other' process run that will 4933 * make event true. If the current task is a SCHED_FIFO task that will never 4934 * happen. Never use yield() as a progress guarantee!! 4935 * 4936 * If you want to use yield() to wait for something, use wait_event(). 4937 * If you want to use yield() to be 'nice' for others, use cond_resched(). 4938 * If you still want to use yield(), do not! 4939 */ 4940 void __sched yield(void) 4941 { 4942 set_current_state(TASK_RUNNING); 4943 sys_sched_yield(); 4944 } 4945 EXPORT_SYMBOL(yield); 4946 4947 /** 4948 * yield_to - yield the current processor to another thread in 4949 * your thread group, or accelerate that thread toward the 4950 * processor it's on. 4951 * @p: target task 4952 * @preempt: whether task preemption is allowed or not 4953 * 4954 * It's the caller's job to ensure that the target task struct 4955 * can't go away on us before we can do any checks. 4956 * 4957 * Return: 4958 * true (>0) if we indeed boosted the target task. 4959 * false (0) if we failed to boost the target. 4960 * -ESRCH if there's no task to yield to. 4961 */ 4962 int __sched yield_to(struct task_struct *p, bool preempt) 4963 { 4964 struct task_struct *curr = current; 4965 struct rq *rq, *p_rq; 4966 unsigned long flags; 4967 int yielded = 0; 4968 4969 local_irq_save(flags); 4970 rq = this_rq(); 4971 4972 again: 4973 p_rq = task_rq(p); 4974 /* 4975 * If we're the only runnable task on the rq and target rq also 4976 * has only one task, there's absolutely no point in yielding. 4977 */ 4978 if (rq->nr_running == 1 && p_rq->nr_running == 1) { 4979 yielded = -ESRCH; 4980 goto out_irq; 4981 } 4982 4983 double_rq_lock(rq, p_rq); 4984 if (task_rq(p) != p_rq) { 4985 double_rq_unlock(rq, p_rq); 4986 goto again; 4987 } 4988 4989 if (!curr->sched_class->yield_to_task) 4990 goto out_unlock; 4991 4992 if (curr->sched_class != p->sched_class) 4993 goto out_unlock; 4994 4995 if (task_running(p_rq, p) || p->state) 4996 goto out_unlock; 4997 4998 yielded = curr->sched_class->yield_to_task(rq, p, preempt); 4999 if (yielded) { 5000 schedstat_inc(rq, yld_count); 5001 /* 5002 * Make p's CPU reschedule; pick_next_entity takes care of 5003 * fairness. 5004 */ 5005 if (preempt && rq != p_rq) 5006 resched_curr(p_rq); 5007 } 5008 5009 out_unlock: 5010 double_rq_unlock(rq, p_rq); 5011 out_irq: 5012 local_irq_restore(flags); 5013 5014 if (yielded > 0) 5015 schedule(); 5016 5017 return yielded; 5018 } 5019 EXPORT_SYMBOL_GPL(yield_to); 5020 5021 /* 5022 * This task is about to go to sleep on IO. Increment rq->nr_iowait so 5023 * that process accounting knows that this is a task in IO wait state. 5024 */ 5025 long __sched io_schedule_timeout(long timeout) 5026 { 5027 int old_iowait = current->in_iowait; 5028 struct rq *rq; 5029 long ret; 5030 5031 current->in_iowait = 1; 5032 blk_schedule_flush_plug(current); 5033 5034 delayacct_blkio_start(); 5035 rq = raw_rq(); 5036 atomic_inc(&rq->nr_iowait); 5037 ret = schedule_timeout(timeout); 5038 current->in_iowait = old_iowait; 5039 atomic_dec(&rq->nr_iowait); 5040 delayacct_blkio_end(); 5041 5042 return ret; 5043 } 5044 EXPORT_SYMBOL(io_schedule_timeout); 5045 5046 /** 5047 * sys_sched_get_priority_max - return maximum RT priority. 5048 * @policy: scheduling class. 5049 * 5050 * Return: On success, this syscall returns the maximum 5051 * rt_priority that can be used by a given scheduling class. 5052 * On failure, a negative error code is returned. 5053 */ 5054 SYSCALL_DEFINE1(sched_get_priority_max, int, policy) 5055 { 5056 int ret = -EINVAL; 5057 5058 switch (policy) { 5059 case SCHED_FIFO: 5060 case SCHED_RR: 5061 ret = MAX_USER_RT_PRIO-1; 5062 break; 5063 case SCHED_DEADLINE: 5064 case SCHED_NORMAL: 5065 case SCHED_BATCH: 5066 case SCHED_IDLE: 5067 ret = 0; 5068 break; 5069 } 5070 return ret; 5071 } 5072 5073 /** 5074 * sys_sched_get_priority_min - return minimum RT priority. 5075 * @policy: scheduling class. 5076 * 5077 * Return: On success, this syscall returns the minimum 5078 * rt_priority that can be used by a given scheduling class. 5079 * On failure, a negative error code is returned. 5080 */ 5081 SYSCALL_DEFINE1(sched_get_priority_min, int, policy) 5082 { 5083 int ret = -EINVAL; 5084 5085 switch (policy) { 5086 case SCHED_FIFO: 5087 case SCHED_RR: 5088 ret = 1; 5089 break; 5090 case SCHED_DEADLINE: 5091 case SCHED_NORMAL: 5092 case SCHED_BATCH: 5093 case SCHED_IDLE: 5094 ret = 0; 5095 } 5096 return ret; 5097 } 5098 5099 /** 5100 * sys_sched_rr_get_interval - return the default timeslice of a process. 5101 * @pid: pid of the process. 5102 * @interval: userspace pointer to the timeslice value. 5103 * 5104 * this syscall writes the default timeslice value of a given process 5105 * into the user-space timespec buffer. A value of '0' means infinity. 5106 * 5107 * Return: On success, 0 and the timeslice is in @interval. Otherwise, 5108 * an error code. 5109 */ 5110 SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid, 5111 struct timespec __user *, interval) 5112 { 5113 struct task_struct *p; 5114 unsigned int time_slice; 5115 struct rq_flags rf; 5116 struct timespec t; 5117 struct rq *rq; 5118 int retval; 5119 5120 if (pid < 0) 5121 return -EINVAL; 5122 5123 retval = -ESRCH; 5124 rcu_read_lock(); 5125 p = find_process_by_pid(pid); 5126 if (!p) 5127 goto out_unlock; 5128 5129 retval = security_task_getscheduler(p); 5130 if (retval) 5131 goto out_unlock; 5132 5133 rq = task_rq_lock(p, &rf); 5134 time_slice = 0; 5135 if (p->sched_class->get_rr_interval) 5136 time_slice = p->sched_class->get_rr_interval(rq, p); 5137 task_rq_unlock(rq, p, &rf); 5138 5139 rcu_read_unlock(); 5140 jiffies_to_timespec(time_slice, &t); 5141 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0; 5142 return retval; 5143 5144 out_unlock: 5145 rcu_read_unlock(); 5146 return retval; 5147 } 5148 5149 static const char stat_nam[] = TASK_STATE_TO_CHAR_STR; 5150 5151 void sched_show_task(struct task_struct *p) 5152 { 5153 unsigned long free = 0; 5154 int ppid; 5155 unsigned long state = p->state; 5156 5157 if (state) 5158 state = __ffs(state) + 1; 5159 printk(KERN_INFO "%-15.15s %c", p->comm, 5160 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?'); 5161 #if BITS_PER_LONG == 32 5162 if (state == TASK_RUNNING) 5163 printk(KERN_CONT " running "); 5164 else 5165 printk(KERN_CONT " %08lx ", thread_saved_pc(p)); 5166 #else 5167 if (state == TASK_RUNNING) 5168 printk(KERN_CONT " running task "); 5169 else 5170 printk(KERN_CONT " %016lx ", thread_saved_pc(p)); 5171 #endif 5172 #ifdef CONFIG_DEBUG_STACK_USAGE 5173 free = stack_not_used(p); 5174 #endif 5175 ppid = 0; 5176 rcu_read_lock(); 5177 if (pid_alive(p)) 5178 ppid = task_pid_nr(rcu_dereference(p->real_parent)); 5179 rcu_read_unlock(); 5180 printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free, 5181 task_pid_nr(p), ppid, 5182 (unsigned long)task_thread_info(p)->flags); 5183 5184 print_worker_info(KERN_INFO, p); 5185 show_stack(p, NULL); 5186 } 5187 5188 void show_state_filter(unsigned long state_filter) 5189 { 5190 struct task_struct *g, *p; 5191 5192 #if BITS_PER_LONG == 32 5193 printk(KERN_INFO 5194 " task PC stack pid father\n"); 5195 #else 5196 printk(KERN_INFO 5197 " task PC stack pid father\n"); 5198 #endif 5199 rcu_read_lock(); 5200 for_each_process_thread(g, p) { 5201 /* 5202 * reset the NMI-timeout, listing all files on a slow 5203 * console might take a lot of time: 5204 * Also, reset softlockup watchdogs on all CPUs, because 5205 * another CPU might be blocked waiting for us to process 5206 * an IPI. 5207 */ 5208 touch_nmi_watchdog(); 5209 touch_all_softlockup_watchdogs(); 5210 if (!state_filter || (p->state & state_filter)) 5211 sched_show_task(p); 5212 } 5213 5214 #ifdef CONFIG_SCHED_DEBUG 5215 if (!state_filter) 5216 sysrq_sched_debug_show(); 5217 #endif 5218 rcu_read_unlock(); 5219 /* 5220 * Only show locks if all tasks are dumped: 5221 */ 5222 if (!state_filter) 5223 debug_show_all_locks(); 5224 } 5225 5226 void init_idle_bootup_task(struct task_struct *idle) 5227 { 5228 idle->sched_class = &idle_sched_class; 5229 } 5230 5231 /** 5232 * init_idle - set up an idle thread for a given CPU 5233 * @idle: task in question 5234 * @cpu: cpu the idle task belongs to 5235 * 5236 * NOTE: this function does not set the idle thread's NEED_RESCHED 5237 * flag, to make booting more robust. 5238 */ 5239 void init_idle(struct task_struct *idle, int cpu) 5240 { 5241 struct rq *rq = cpu_rq(cpu); 5242 unsigned long flags; 5243 5244 raw_spin_lock_irqsave(&idle->pi_lock, flags); 5245 raw_spin_lock(&rq->lock); 5246 5247 __sched_fork(0, idle); 5248 idle->state = TASK_RUNNING; 5249 idle->se.exec_start = sched_clock(); 5250 5251 kasan_unpoison_task_stack(idle); 5252 5253 #ifdef CONFIG_SMP 5254 /* 5255 * Its possible that init_idle() gets called multiple times on a task, 5256 * in that case do_set_cpus_allowed() will not do the right thing. 5257 * 5258 * And since this is boot we can forgo the serialization. 5259 */ 5260 set_cpus_allowed_common(idle, cpumask_of(cpu)); 5261 #endif 5262 /* 5263 * We're having a chicken and egg problem, even though we are 5264 * holding rq->lock, the cpu isn't yet set to this cpu so the 5265 * lockdep check in task_group() will fail. 5266 * 5267 * Similar case to sched_fork(). / Alternatively we could 5268 * use task_rq_lock() here and obtain the other rq->lock. 5269 * 5270 * Silence PROVE_RCU 5271 */ 5272 rcu_read_lock(); 5273 __set_task_cpu(idle, cpu); 5274 rcu_read_unlock(); 5275 5276 rq->curr = rq->idle = idle; 5277 idle->on_rq = TASK_ON_RQ_QUEUED; 5278 #ifdef CONFIG_SMP 5279 idle->on_cpu = 1; 5280 #endif 5281 raw_spin_unlock(&rq->lock); 5282 raw_spin_unlock_irqrestore(&idle->pi_lock, flags); 5283 5284 /* Set the preempt count _outside_ the spinlocks! */ 5285 init_idle_preempt_count(idle, cpu); 5286 5287 /* 5288 * The idle tasks have their own, simple scheduling class: 5289 */ 5290 idle->sched_class = &idle_sched_class; 5291 ftrace_graph_init_idle_task(idle, cpu); 5292 vtime_init_idle(idle, cpu); 5293 #ifdef CONFIG_SMP 5294 sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu); 5295 #endif 5296 } 5297 5298 int cpuset_cpumask_can_shrink(const struct cpumask *cur, 5299 const struct cpumask *trial) 5300 { 5301 int ret = 1, trial_cpus; 5302 struct dl_bw *cur_dl_b; 5303 unsigned long flags; 5304 5305 if (!cpumask_weight(cur)) 5306 return ret; 5307 5308 rcu_read_lock_sched(); 5309 cur_dl_b = dl_bw_of(cpumask_any(cur)); 5310 trial_cpus = cpumask_weight(trial); 5311 5312 raw_spin_lock_irqsave(&cur_dl_b->lock, flags); 5313 if (cur_dl_b->bw != -1 && 5314 cur_dl_b->bw * trial_cpus < cur_dl_b->total_bw) 5315 ret = 0; 5316 raw_spin_unlock_irqrestore(&cur_dl_b->lock, flags); 5317 rcu_read_unlock_sched(); 5318 5319 return ret; 5320 } 5321 5322 int task_can_attach(struct task_struct *p, 5323 const struct cpumask *cs_cpus_allowed) 5324 { 5325 int ret = 0; 5326 5327 /* 5328 * Kthreads which disallow setaffinity shouldn't be moved 5329 * to a new cpuset; we don't want to change their cpu 5330 * affinity and isolating such threads by their set of 5331 * allowed nodes is unnecessary. Thus, cpusets are not 5332 * applicable for such threads. This prevents checking for 5333 * success of set_cpus_allowed_ptr() on all attached tasks 5334 * before cpus_allowed may be changed. 5335 */ 5336 if (p->flags & PF_NO_SETAFFINITY) { 5337 ret = -EINVAL; 5338 goto out; 5339 } 5340 5341 #ifdef CONFIG_SMP 5342 if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span, 5343 cs_cpus_allowed)) { 5344 unsigned int dest_cpu = cpumask_any_and(cpu_active_mask, 5345 cs_cpus_allowed); 5346 struct dl_bw *dl_b; 5347 bool overflow; 5348 int cpus; 5349 unsigned long flags; 5350 5351 rcu_read_lock_sched(); 5352 dl_b = dl_bw_of(dest_cpu); 5353 raw_spin_lock_irqsave(&dl_b->lock, flags); 5354 cpus = dl_bw_cpus(dest_cpu); 5355 overflow = __dl_overflow(dl_b, cpus, 0, p->dl.dl_bw); 5356 if (overflow) 5357 ret = -EBUSY; 5358 else { 5359 /* 5360 * We reserve space for this task in the destination 5361 * root_domain, as we can't fail after this point. 5362 * We will free resources in the source root_domain 5363 * later on (see set_cpus_allowed_dl()). 5364 */ 5365 __dl_add(dl_b, p->dl.dl_bw); 5366 } 5367 raw_spin_unlock_irqrestore(&dl_b->lock, flags); 5368 rcu_read_unlock_sched(); 5369 5370 } 5371 #endif 5372 out: 5373 return ret; 5374 } 5375 5376 #ifdef CONFIG_SMP 5377 5378 static bool sched_smp_initialized __read_mostly; 5379 5380 #ifdef CONFIG_NUMA_BALANCING 5381 /* Migrate current task p to target_cpu */ 5382 int migrate_task_to(struct task_struct *p, int target_cpu) 5383 { 5384 struct migration_arg arg = { p, target_cpu }; 5385 int curr_cpu = task_cpu(p); 5386 5387 if (curr_cpu == target_cpu) 5388 return 0; 5389 5390 if (!cpumask_test_cpu(target_cpu, tsk_cpus_allowed(p))) 5391 return -EINVAL; 5392 5393 /* TODO: This is not properly updating schedstats */ 5394 5395 trace_sched_move_numa(p, curr_cpu, target_cpu); 5396 return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg); 5397 } 5398 5399 /* 5400 * Requeue a task on a given node and accurately track the number of NUMA 5401 * tasks on the runqueues 5402 */ 5403 void sched_setnuma(struct task_struct *p, int nid) 5404 { 5405 bool queued, running; 5406 struct rq_flags rf; 5407 struct rq *rq; 5408 5409 rq = task_rq_lock(p, &rf); 5410 queued = task_on_rq_queued(p); 5411 running = task_current(rq, p); 5412 5413 if (queued) 5414 dequeue_task(rq, p, DEQUEUE_SAVE); 5415 if (running) 5416 put_prev_task(rq, p); 5417 5418 p->numa_preferred_nid = nid; 5419 5420 if (running) 5421 p->sched_class->set_curr_task(rq); 5422 if (queued) 5423 enqueue_task(rq, p, ENQUEUE_RESTORE); 5424 task_rq_unlock(rq, p, &rf); 5425 } 5426 #endif /* CONFIG_NUMA_BALANCING */ 5427 5428 #ifdef CONFIG_HOTPLUG_CPU 5429 /* 5430 * Ensures that the idle task is using init_mm right before its cpu goes 5431 * offline. 5432 */ 5433 void idle_task_exit(void) 5434 { 5435 struct mm_struct *mm = current->active_mm; 5436 5437 BUG_ON(cpu_online(smp_processor_id())); 5438 5439 if (mm != &init_mm) { 5440 switch_mm_irqs_off(mm, &init_mm, current); 5441 finish_arch_post_lock_switch(); 5442 } 5443 mmdrop(mm); 5444 } 5445 5446 /* 5447 * Since this CPU is going 'away' for a while, fold any nr_active delta 5448 * we might have. Assumes we're called after migrate_tasks() so that the 5449 * nr_active count is stable. We need to take the teardown thread which 5450 * is calling this into account, so we hand in adjust = 1 to the load 5451 * calculation. 5452 * 5453 * Also see the comment "Global load-average calculations". 5454 */ 5455 static void calc_load_migrate(struct rq *rq) 5456 { 5457 long delta = calc_load_fold_active(rq, 1); 5458 if (delta) 5459 atomic_long_add(delta, &calc_load_tasks); 5460 } 5461 5462 static void put_prev_task_fake(struct rq *rq, struct task_struct *prev) 5463 { 5464 } 5465 5466 static const struct sched_class fake_sched_class = { 5467 .put_prev_task = put_prev_task_fake, 5468 }; 5469 5470 static struct task_struct fake_task = { 5471 /* 5472 * Avoid pull_{rt,dl}_task() 5473 */ 5474 .prio = MAX_PRIO + 1, 5475 .sched_class = &fake_sched_class, 5476 }; 5477 5478 /* 5479 * Migrate all tasks from the rq, sleeping tasks will be migrated by 5480 * try_to_wake_up()->select_task_rq(). 5481 * 5482 * Called with rq->lock held even though we'er in stop_machine() and 5483 * there's no concurrency possible, we hold the required locks anyway 5484 * because of lock validation efforts. 5485 */ 5486 static void migrate_tasks(struct rq *dead_rq) 5487 { 5488 struct rq *rq = dead_rq; 5489 struct task_struct *next, *stop = rq->stop; 5490 struct pin_cookie cookie; 5491 int dest_cpu; 5492 5493 /* 5494 * Fudge the rq selection such that the below task selection loop 5495 * doesn't get stuck on the currently eligible stop task. 5496 * 5497 * We're currently inside stop_machine() and the rq is either stuck 5498 * in the stop_machine_cpu_stop() loop, or we're executing this code, 5499 * either way we should never end up calling schedule() until we're 5500 * done here. 5501 */ 5502 rq->stop = NULL; 5503 5504 /* 5505 * put_prev_task() and pick_next_task() sched 5506 * class method both need to have an up-to-date 5507 * value of rq->clock[_task] 5508 */ 5509 update_rq_clock(rq); 5510 5511 for (;;) { 5512 /* 5513 * There's this thread running, bail when that's the only 5514 * remaining thread. 5515 */ 5516 if (rq->nr_running == 1) 5517 break; 5518 5519 /* 5520 * pick_next_task assumes pinned rq->lock. 5521 */ 5522 cookie = lockdep_pin_lock(&rq->lock); 5523 next = pick_next_task(rq, &fake_task, cookie); 5524 BUG_ON(!next); 5525 next->sched_class->put_prev_task(rq, next); 5526 5527 /* 5528 * Rules for changing task_struct::cpus_allowed are holding 5529 * both pi_lock and rq->lock, such that holding either 5530 * stabilizes the mask. 5531 * 5532 * Drop rq->lock is not quite as disastrous as it usually is 5533 * because !cpu_active at this point, which means load-balance 5534 * will not interfere. Also, stop-machine. 5535 */ 5536 lockdep_unpin_lock(&rq->lock, cookie); 5537 raw_spin_unlock(&rq->lock); 5538 raw_spin_lock(&next->pi_lock); 5539 raw_spin_lock(&rq->lock); 5540 5541 /* 5542 * Since we're inside stop-machine, _nothing_ should have 5543 * changed the task, WARN if weird stuff happened, because in 5544 * that case the above rq->lock drop is a fail too. 5545 */ 5546 if (WARN_ON(task_rq(next) != rq || !task_on_rq_queued(next))) { 5547 raw_spin_unlock(&next->pi_lock); 5548 continue; 5549 } 5550 5551 /* Find suitable destination for @next, with force if needed. */ 5552 dest_cpu = select_fallback_rq(dead_rq->cpu, next); 5553 5554 rq = __migrate_task(rq, next, dest_cpu); 5555 if (rq != dead_rq) { 5556 raw_spin_unlock(&rq->lock); 5557 rq = dead_rq; 5558 raw_spin_lock(&rq->lock); 5559 } 5560 raw_spin_unlock(&next->pi_lock); 5561 } 5562 5563 rq->stop = stop; 5564 } 5565 #endif /* CONFIG_HOTPLUG_CPU */ 5566 5567 static void set_rq_online(struct rq *rq) 5568 { 5569 if (!rq->online) { 5570 const struct sched_class *class; 5571 5572 cpumask_set_cpu(rq->cpu, rq->rd->online); 5573 rq->online = 1; 5574 5575 for_each_class(class) { 5576 if (class->rq_online) 5577 class->rq_online(rq); 5578 } 5579 } 5580 } 5581 5582 static void set_rq_offline(struct rq *rq) 5583 { 5584 if (rq->online) { 5585 const struct sched_class *class; 5586 5587 for_each_class(class) { 5588 if (class->rq_offline) 5589 class->rq_offline(rq); 5590 } 5591 5592 cpumask_clear_cpu(rq->cpu, rq->rd->online); 5593 rq->online = 0; 5594 } 5595 } 5596 5597 static void set_cpu_rq_start_time(unsigned int cpu) 5598 { 5599 struct rq *rq = cpu_rq(cpu); 5600 5601 rq->age_stamp = sched_clock_cpu(cpu); 5602 } 5603 5604 static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */ 5605 5606 #ifdef CONFIG_SCHED_DEBUG 5607 5608 static __read_mostly int sched_debug_enabled; 5609 5610 static int __init sched_debug_setup(char *str) 5611 { 5612 sched_debug_enabled = 1; 5613 5614 return 0; 5615 } 5616 early_param("sched_debug", sched_debug_setup); 5617 5618 static inline bool sched_debug(void) 5619 { 5620 return sched_debug_enabled; 5621 } 5622 5623 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level, 5624 struct cpumask *groupmask) 5625 { 5626 struct sched_group *group = sd->groups; 5627 5628 cpumask_clear(groupmask); 5629 5630 printk(KERN_DEBUG "%*s domain %d: ", level, "", level); 5631 5632 if (!(sd->flags & SD_LOAD_BALANCE)) { 5633 printk("does not load-balance\n"); 5634 if (sd->parent) 5635 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain" 5636 " has parent"); 5637 return -1; 5638 } 5639 5640 printk(KERN_CONT "span %*pbl level %s\n", 5641 cpumask_pr_args(sched_domain_span(sd)), sd->name); 5642 5643 if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) { 5644 printk(KERN_ERR "ERROR: domain->span does not contain " 5645 "CPU%d\n", cpu); 5646 } 5647 if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) { 5648 printk(KERN_ERR "ERROR: domain->groups does not contain" 5649 " CPU%d\n", cpu); 5650 } 5651 5652 printk(KERN_DEBUG "%*s groups:", level + 1, ""); 5653 do { 5654 if (!group) { 5655 printk("\n"); 5656 printk(KERN_ERR "ERROR: group is NULL\n"); 5657 break; 5658 } 5659 5660 if (!cpumask_weight(sched_group_cpus(group))) { 5661 printk(KERN_CONT "\n"); 5662 printk(KERN_ERR "ERROR: empty group\n"); 5663 break; 5664 } 5665 5666 if (!(sd->flags & SD_OVERLAP) && 5667 cpumask_intersects(groupmask, sched_group_cpus(group))) { 5668 printk(KERN_CONT "\n"); 5669 printk(KERN_ERR "ERROR: repeated CPUs\n"); 5670 break; 5671 } 5672 5673 cpumask_or(groupmask, groupmask, sched_group_cpus(group)); 5674 5675 printk(KERN_CONT " %*pbl", 5676 cpumask_pr_args(sched_group_cpus(group))); 5677 if (group->sgc->capacity != SCHED_CAPACITY_SCALE) { 5678 printk(KERN_CONT " (cpu_capacity = %d)", 5679 group->sgc->capacity); 5680 } 5681 5682 group = group->next; 5683 } while (group != sd->groups); 5684 printk(KERN_CONT "\n"); 5685 5686 if (!cpumask_equal(sched_domain_span(sd), groupmask)) 5687 printk(KERN_ERR "ERROR: groups don't span domain->span\n"); 5688 5689 if (sd->parent && 5690 !cpumask_subset(groupmask, sched_domain_span(sd->parent))) 5691 printk(KERN_ERR "ERROR: parent span is not a superset " 5692 "of domain->span\n"); 5693 return 0; 5694 } 5695 5696 static void sched_domain_debug(struct sched_domain *sd, int cpu) 5697 { 5698 int level = 0; 5699 5700 if (!sched_debug_enabled) 5701 return; 5702 5703 if (!sd) { 5704 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu); 5705 return; 5706 } 5707 5708 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu); 5709 5710 for (;;) { 5711 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask)) 5712 break; 5713 level++; 5714 sd = sd->parent; 5715 if (!sd) 5716 break; 5717 } 5718 } 5719 #else /* !CONFIG_SCHED_DEBUG */ 5720 # define sched_domain_debug(sd, cpu) do { } while (0) 5721 static inline bool sched_debug(void) 5722 { 5723 return false; 5724 } 5725 #endif /* CONFIG_SCHED_DEBUG */ 5726 5727 static int sd_degenerate(struct sched_domain *sd) 5728 { 5729 if (cpumask_weight(sched_domain_span(sd)) == 1) 5730 return 1; 5731 5732 /* Following flags need at least 2 groups */ 5733 if (sd->flags & (SD_LOAD_BALANCE | 5734 SD_BALANCE_NEWIDLE | 5735 SD_BALANCE_FORK | 5736 SD_BALANCE_EXEC | 5737 SD_SHARE_CPUCAPACITY | 5738 SD_SHARE_PKG_RESOURCES | 5739 SD_SHARE_POWERDOMAIN)) { 5740 if (sd->groups != sd->groups->next) 5741 return 0; 5742 } 5743 5744 /* Following flags don't use groups */ 5745 if (sd->flags & (SD_WAKE_AFFINE)) 5746 return 0; 5747 5748 return 1; 5749 } 5750 5751 static int 5752 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) 5753 { 5754 unsigned long cflags = sd->flags, pflags = parent->flags; 5755 5756 if (sd_degenerate(parent)) 5757 return 1; 5758 5759 if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent))) 5760 return 0; 5761 5762 /* Flags needing groups don't count if only 1 group in parent */ 5763 if (parent->groups == parent->groups->next) { 5764 pflags &= ~(SD_LOAD_BALANCE | 5765 SD_BALANCE_NEWIDLE | 5766 SD_BALANCE_FORK | 5767 SD_BALANCE_EXEC | 5768 SD_SHARE_CPUCAPACITY | 5769 SD_SHARE_PKG_RESOURCES | 5770 SD_PREFER_SIBLING | 5771 SD_SHARE_POWERDOMAIN); 5772 if (nr_node_ids == 1) 5773 pflags &= ~SD_SERIALIZE; 5774 } 5775 if (~cflags & pflags) 5776 return 0; 5777 5778 return 1; 5779 } 5780 5781 static void free_rootdomain(struct rcu_head *rcu) 5782 { 5783 struct root_domain *rd = container_of(rcu, struct root_domain, rcu); 5784 5785 cpupri_cleanup(&rd->cpupri); 5786 cpudl_cleanup(&rd->cpudl); 5787 free_cpumask_var(rd->dlo_mask); 5788 free_cpumask_var(rd->rto_mask); 5789 free_cpumask_var(rd->online); 5790 free_cpumask_var(rd->span); 5791 kfree(rd); 5792 } 5793 5794 static void rq_attach_root(struct rq *rq, struct root_domain *rd) 5795 { 5796 struct root_domain *old_rd = NULL; 5797 unsigned long flags; 5798 5799 raw_spin_lock_irqsave(&rq->lock, flags); 5800 5801 if (rq->rd) { 5802 old_rd = rq->rd; 5803 5804 if (cpumask_test_cpu(rq->cpu, old_rd->online)) 5805 set_rq_offline(rq); 5806 5807 cpumask_clear_cpu(rq->cpu, old_rd->span); 5808 5809 /* 5810 * If we dont want to free the old_rd yet then 5811 * set old_rd to NULL to skip the freeing later 5812 * in this function: 5813 */ 5814 if (!atomic_dec_and_test(&old_rd->refcount)) 5815 old_rd = NULL; 5816 } 5817 5818 atomic_inc(&rd->refcount); 5819 rq->rd = rd; 5820 5821 cpumask_set_cpu(rq->cpu, rd->span); 5822 if (cpumask_test_cpu(rq->cpu, cpu_active_mask)) 5823 set_rq_online(rq); 5824 5825 raw_spin_unlock_irqrestore(&rq->lock, flags); 5826 5827 if (old_rd) 5828 call_rcu_sched(&old_rd->rcu, free_rootdomain); 5829 } 5830 5831 static int init_rootdomain(struct root_domain *rd) 5832 { 5833 memset(rd, 0, sizeof(*rd)); 5834 5835 if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL)) 5836 goto out; 5837 if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL)) 5838 goto free_span; 5839 if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL)) 5840 goto free_online; 5841 if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL)) 5842 goto free_dlo_mask; 5843 5844 init_dl_bw(&rd->dl_bw); 5845 if (cpudl_init(&rd->cpudl) != 0) 5846 goto free_dlo_mask; 5847 5848 if (cpupri_init(&rd->cpupri) != 0) 5849 goto free_rto_mask; 5850 return 0; 5851 5852 free_rto_mask: 5853 free_cpumask_var(rd->rto_mask); 5854 free_dlo_mask: 5855 free_cpumask_var(rd->dlo_mask); 5856 free_online: 5857 free_cpumask_var(rd->online); 5858 free_span: 5859 free_cpumask_var(rd->span); 5860 out: 5861 return -ENOMEM; 5862 } 5863 5864 /* 5865 * By default the system creates a single root-domain with all cpus as 5866 * members (mimicking the global state we have today). 5867 */ 5868 struct root_domain def_root_domain; 5869 5870 static void init_defrootdomain(void) 5871 { 5872 init_rootdomain(&def_root_domain); 5873 5874 atomic_set(&def_root_domain.refcount, 1); 5875 } 5876 5877 static struct root_domain *alloc_rootdomain(void) 5878 { 5879 struct root_domain *rd; 5880 5881 rd = kmalloc(sizeof(*rd), GFP_KERNEL); 5882 if (!rd) 5883 return NULL; 5884 5885 if (init_rootdomain(rd) != 0) { 5886 kfree(rd); 5887 return NULL; 5888 } 5889 5890 return rd; 5891 } 5892 5893 static void free_sched_groups(struct sched_group *sg, int free_sgc) 5894 { 5895 struct sched_group *tmp, *first; 5896 5897 if (!sg) 5898 return; 5899 5900 first = sg; 5901 do { 5902 tmp = sg->next; 5903 5904 if (free_sgc && atomic_dec_and_test(&sg->sgc->ref)) 5905 kfree(sg->sgc); 5906 5907 kfree(sg); 5908 sg = tmp; 5909 } while (sg != first); 5910 } 5911 5912 static void free_sched_domain(struct rcu_head *rcu) 5913 { 5914 struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu); 5915 5916 /* 5917 * If its an overlapping domain it has private groups, iterate and 5918 * nuke them all. 5919 */ 5920 if (sd->flags & SD_OVERLAP) { 5921 free_sched_groups(sd->groups, 1); 5922 } else if (atomic_dec_and_test(&sd->groups->ref)) { 5923 kfree(sd->groups->sgc); 5924 kfree(sd->groups); 5925 } 5926 kfree(sd); 5927 } 5928 5929 static void destroy_sched_domain(struct sched_domain *sd, int cpu) 5930 { 5931 call_rcu(&sd->rcu, free_sched_domain); 5932 } 5933 5934 static void destroy_sched_domains(struct sched_domain *sd, int cpu) 5935 { 5936 for (; sd; sd = sd->parent) 5937 destroy_sched_domain(sd, cpu); 5938 } 5939 5940 /* 5941 * Keep a special pointer to the highest sched_domain that has 5942 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this 5943 * allows us to avoid some pointer chasing select_idle_sibling(). 5944 * 5945 * Also keep a unique ID per domain (we use the first cpu number in 5946 * the cpumask of the domain), this allows us to quickly tell if 5947 * two cpus are in the same cache domain, see cpus_share_cache(). 5948 */ 5949 DEFINE_PER_CPU(struct sched_domain *, sd_llc); 5950 DEFINE_PER_CPU(int, sd_llc_size); 5951 DEFINE_PER_CPU(int, sd_llc_id); 5952 DEFINE_PER_CPU(struct sched_domain *, sd_numa); 5953 DEFINE_PER_CPU(struct sched_domain *, sd_busy); 5954 DEFINE_PER_CPU(struct sched_domain *, sd_asym); 5955 5956 static void update_top_cache_domain(int cpu) 5957 { 5958 struct sched_domain *sd; 5959 struct sched_domain *busy_sd = NULL; 5960 int id = cpu; 5961 int size = 1; 5962 5963 sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES); 5964 if (sd) { 5965 id = cpumask_first(sched_domain_span(sd)); 5966 size = cpumask_weight(sched_domain_span(sd)); 5967 busy_sd = sd->parent; /* sd_busy */ 5968 } 5969 rcu_assign_pointer(per_cpu(sd_busy, cpu), busy_sd); 5970 5971 rcu_assign_pointer(per_cpu(sd_llc, cpu), sd); 5972 per_cpu(sd_llc_size, cpu) = size; 5973 per_cpu(sd_llc_id, cpu) = id; 5974 5975 sd = lowest_flag_domain(cpu, SD_NUMA); 5976 rcu_assign_pointer(per_cpu(sd_numa, cpu), sd); 5977 5978 sd = highest_flag_domain(cpu, SD_ASYM_PACKING); 5979 rcu_assign_pointer(per_cpu(sd_asym, cpu), sd); 5980 } 5981 5982 /* 5983 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must 5984 * hold the hotplug lock. 5985 */ 5986 static void 5987 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu) 5988 { 5989 struct rq *rq = cpu_rq(cpu); 5990 struct sched_domain *tmp; 5991 5992 /* Remove the sched domains which do not contribute to scheduling. */ 5993 for (tmp = sd; tmp; ) { 5994 struct sched_domain *parent = tmp->parent; 5995 if (!parent) 5996 break; 5997 5998 if (sd_parent_degenerate(tmp, parent)) { 5999 tmp->parent = parent->parent; 6000 if (parent->parent) 6001 parent->parent->child = tmp; 6002 /* 6003 * Transfer SD_PREFER_SIBLING down in case of a 6004 * degenerate parent; the spans match for this 6005 * so the property transfers. 6006 */ 6007 if (parent->flags & SD_PREFER_SIBLING) 6008 tmp->flags |= SD_PREFER_SIBLING; 6009 destroy_sched_domain(parent, cpu); 6010 } else 6011 tmp = tmp->parent; 6012 } 6013 6014 if (sd && sd_degenerate(sd)) { 6015 tmp = sd; 6016 sd = sd->parent; 6017 destroy_sched_domain(tmp, cpu); 6018 if (sd) 6019 sd->child = NULL; 6020 } 6021 6022 sched_domain_debug(sd, cpu); 6023 6024 rq_attach_root(rq, rd); 6025 tmp = rq->sd; 6026 rcu_assign_pointer(rq->sd, sd); 6027 destroy_sched_domains(tmp, cpu); 6028 6029 update_top_cache_domain(cpu); 6030 } 6031 6032 /* Setup the mask of cpus configured for isolated domains */ 6033 static int __init isolated_cpu_setup(char *str) 6034 { 6035 int ret; 6036 6037 alloc_bootmem_cpumask_var(&cpu_isolated_map); 6038 ret = cpulist_parse(str, cpu_isolated_map); 6039 if (ret) { 6040 pr_err("sched: Error, all isolcpus= values must be between 0 and %d\n", nr_cpu_ids); 6041 return 0; 6042 } 6043 return 1; 6044 } 6045 __setup("isolcpus=", isolated_cpu_setup); 6046 6047 struct s_data { 6048 struct sched_domain ** __percpu sd; 6049 struct root_domain *rd; 6050 }; 6051 6052 enum s_alloc { 6053 sa_rootdomain, 6054 sa_sd, 6055 sa_sd_storage, 6056 sa_none, 6057 }; 6058 6059 /* 6060 * Build an iteration mask that can exclude certain CPUs from the upwards 6061 * domain traversal. 6062 * 6063 * Asymmetric node setups can result in situations where the domain tree is of 6064 * unequal depth, make sure to skip domains that already cover the entire 6065 * range. 6066 * 6067 * In that case build_sched_domains() will have terminated the iteration early 6068 * and our sibling sd spans will be empty. Domains should always include the 6069 * cpu they're built on, so check that. 6070 * 6071 */ 6072 static void build_group_mask(struct sched_domain *sd, struct sched_group *sg) 6073 { 6074 const struct cpumask *span = sched_domain_span(sd); 6075 struct sd_data *sdd = sd->private; 6076 struct sched_domain *sibling; 6077 int i; 6078 6079 for_each_cpu(i, span) { 6080 sibling = *per_cpu_ptr(sdd->sd, i); 6081 if (!cpumask_test_cpu(i, sched_domain_span(sibling))) 6082 continue; 6083 6084 cpumask_set_cpu(i, sched_group_mask(sg)); 6085 } 6086 } 6087 6088 /* 6089 * Return the canonical balance cpu for this group, this is the first cpu 6090 * of this group that's also in the iteration mask. 6091 */ 6092 int group_balance_cpu(struct sched_group *sg) 6093 { 6094 return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg)); 6095 } 6096 6097 static int 6098 build_overlap_sched_groups(struct sched_domain *sd, int cpu) 6099 { 6100 struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg; 6101 const struct cpumask *span = sched_domain_span(sd); 6102 struct cpumask *covered = sched_domains_tmpmask; 6103 struct sd_data *sdd = sd->private; 6104 struct sched_domain *sibling; 6105 int i; 6106 6107 cpumask_clear(covered); 6108 6109 for_each_cpu(i, span) { 6110 struct cpumask *sg_span; 6111 6112 if (cpumask_test_cpu(i, covered)) 6113 continue; 6114 6115 sibling = *per_cpu_ptr(sdd->sd, i); 6116 6117 /* See the comment near build_group_mask(). */ 6118 if (!cpumask_test_cpu(i, sched_domain_span(sibling))) 6119 continue; 6120 6121 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), 6122 GFP_KERNEL, cpu_to_node(cpu)); 6123 6124 if (!sg) 6125 goto fail; 6126 6127 sg_span = sched_group_cpus(sg); 6128 if (sibling->child) 6129 cpumask_copy(sg_span, sched_domain_span(sibling->child)); 6130 else 6131 cpumask_set_cpu(i, sg_span); 6132 6133 cpumask_or(covered, covered, sg_span); 6134 6135 sg->sgc = *per_cpu_ptr(sdd->sgc, i); 6136 if (atomic_inc_return(&sg->sgc->ref) == 1) 6137 build_group_mask(sd, sg); 6138 6139 /* 6140 * Initialize sgc->capacity such that even if we mess up the 6141 * domains and no possible iteration will get us here, we won't 6142 * die on a /0 trap. 6143 */ 6144 sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span); 6145 6146 /* 6147 * Make sure the first group of this domain contains the 6148 * canonical balance cpu. Otherwise the sched_domain iteration 6149 * breaks. See update_sg_lb_stats(). 6150 */ 6151 if ((!groups && cpumask_test_cpu(cpu, sg_span)) || 6152 group_balance_cpu(sg) == cpu) 6153 groups = sg; 6154 6155 if (!first) 6156 first = sg; 6157 if (last) 6158 last->next = sg; 6159 last = sg; 6160 last->next = first; 6161 } 6162 sd->groups = groups; 6163 6164 return 0; 6165 6166 fail: 6167 free_sched_groups(first, 0); 6168 6169 return -ENOMEM; 6170 } 6171 6172 static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg) 6173 { 6174 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu); 6175 struct sched_domain *child = sd->child; 6176 6177 if (child) 6178 cpu = cpumask_first(sched_domain_span(child)); 6179 6180 if (sg) { 6181 *sg = *per_cpu_ptr(sdd->sg, cpu); 6182 (*sg)->sgc = *per_cpu_ptr(sdd->sgc, cpu); 6183 atomic_set(&(*sg)->sgc->ref, 1); /* for claim_allocations */ 6184 } 6185 6186 return cpu; 6187 } 6188 6189 /* 6190 * build_sched_groups will build a circular linked list of the groups 6191 * covered by the given span, and will set each group's ->cpumask correctly, 6192 * and ->cpu_capacity to 0. 6193 * 6194 * Assumes the sched_domain tree is fully constructed 6195 */ 6196 static int 6197 build_sched_groups(struct sched_domain *sd, int cpu) 6198 { 6199 struct sched_group *first = NULL, *last = NULL; 6200 struct sd_data *sdd = sd->private; 6201 const struct cpumask *span = sched_domain_span(sd); 6202 struct cpumask *covered; 6203 int i; 6204 6205 get_group(cpu, sdd, &sd->groups); 6206 atomic_inc(&sd->groups->ref); 6207 6208 if (cpu != cpumask_first(span)) 6209 return 0; 6210 6211 lockdep_assert_held(&sched_domains_mutex); 6212 covered = sched_domains_tmpmask; 6213 6214 cpumask_clear(covered); 6215 6216 for_each_cpu(i, span) { 6217 struct sched_group *sg; 6218 int group, j; 6219 6220 if (cpumask_test_cpu(i, covered)) 6221 continue; 6222 6223 group = get_group(i, sdd, &sg); 6224 cpumask_setall(sched_group_mask(sg)); 6225 6226 for_each_cpu(j, span) { 6227 if (get_group(j, sdd, NULL) != group) 6228 continue; 6229 6230 cpumask_set_cpu(j, covered); 6231 cpumask_set_cpu(j, sched_group_cpus(sg)); 6232 } 6233 6234 if (!first) 6235 first = sg; 6236 if (last) 6237 last->next = sg; 6238 last = sg; 6239 } 6240 last->next = first; 6241 6242 return 0; 6243 } 6244 6245 /* 6246 * Initialize sched groups cpu_capacity. 6247 * 6248 * cpu_capacity indicates the capacity of sched group, which is used while 6249 * distributing the load between different sched groups in a sched domain. 6250 * Typically cpu_capacity for all the groups in a sched domain will be same 6251 * unless there are asymmetries in the topology. If there are asymmetries, 6252 * group having more cpu_capacity will pickup more load compared to the 6253 * group having less cpu_capacity. 6254 */ 6255 static void init_sched_groups_capacity(int cpu, struct sched_domain *sd) 6256 { 6257 struct sched_group *sg = sd->groups; 6258 6259 WARN_ON(!sg); 6260 6261 do { 6262 sg->group_weight = cpumask_weight(sched_group_cpus(sg)); 6263 sg = sg->next; 6264 } while (sg != sd->groups); 6265 6266 if (cpu != group_balance_cpu(sg)) 6267 return; 6268 6269 update_group_capacity(sd, cpu); 6270 atomic_set(&sg->sgc->nr_busy_cpus, sg->group_weight); 6271 } 6272 6273 /* 6274 * Initializers for schedule domains 6275 * Non-inlined to reduce accumulated stack pressure in build_sched_domains() 6276 */ 6277 6278 static int default_relax_domain_level = -1; 6279 int sched_domain_level_max; 6280 6281 static int __init setup_relax_domain_level(char *str) 6282 { 6283 if (kstrtoint(str, 0, &default_relax_domain_level)) 6284 pr_warn("Unable to set relax_domain_level\n"); 6285 6286 return 1; 6287 } 6288 __setup("relax_domain_level=", setup_relax_domain_level); 6289 6290 static void set_domain_attribute(struct sched_domain *sd, 6291 struct sched_domain_attr *attr) 6292 { 6293 int request; 6294 6295 if (!attr || attr->relax_domain_level < 0) { 6296 if (default_relax_domain_level < 0) 6297 return; 6298 else 6299 request = default_relax_domain_level; 6300 } else 6301 request = attr->relax_domain_level; 6302 if (request < sd->level) { 6303 /* turn off idle balance on this domain */ 6304 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); 6305 } else { 6306 /* turn on idle balance on this domain */ 6307 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); 6308 } 6309 } 6310 6311 static void __sdt_free(const struct cpumask *cpu_map); 6312 static int __sdt_alloc(const struct cpumask *cpu_map); 6313 6314 static void __free_domain_allocs(struct s_data *d, enum s_alloc what, 6315 const struct cpumask *cpu_map) 6316 { 6317 switch (what) { 6318 case sa_rootdomain: 6319 if (!atomic_read(&d->rd->refcount)) 6320 free_rootdomain(&d->rd->rcu); /* fall through */ 6321 case sa_sd: 6322 free_percpu(d->sd); /* fall through */ 6323 case sa_sd_storage: 6324 __sdt_free(cpu_map); /* fall through */ 6325 case sa_none: 6326 break; 6327 } 6328 } 6329 6330 static enum s_alloc __visit_domain_allocation_hell(struct s_data *d, 6331 const struct cpumask *cpu_map) 6332 { 6333 memset(d, 0, sizeof(*d)); 6334 6335 if (__sdt_alloc(cpu_map)) 6336 return sa_sd_storage; 6337 d->sd = alloc_percpu(struct sched_domain *); 6338 if (!d->sd) 6339 return sa_sd_storage; 6340 d->rd = alloc_rootdomain(); 6341 if (!d->rd) 6342 return sa_sd; 6343 return sa_rootdomain; 6344 } 6345 6346 /* 6347 * NULL the sd_data elements we've used to build the sched_domain and 6348 * sched_group structure so that the subsequent __free_domain_allocs() 6349 * will not free the data we're using. 6350 */ 6351 static void claim_allocations(int cpu, struct sched_domain *sd) 6352 { 6353 struct sd_data *sdd = sd->private; 6354 6355 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd); 6356 *per_cpu_ptr(sdd->sd, cpu) = NULL; 6357 6358 if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref)) 6359 *per_cpu_ptr(sdd->sg, cpu) = NULL; 6360 6361 if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref)) 6362 *per_cpu_ptr(sdd->sgc, cpu) = NULL; 6363 } 6364 6365 #ifdef CONFIG_NUMA 6366 static int sched_domains_numa_levels; 6367 enum numa_topology_type sched_numa_topology_type; 6368 static int *sched_domains_numa_distance; 6369 int sched_max_numa_distance; 6370 static struct cpumask ***sched_domains_numa_masks; 6371 static int sched_domains_curr_level; 6372 #endif 6373 6374 /* 6375 * SD_flags allowed in topology descriptions. 6376 * 6377 * SD_SHARE_CPUCAPACITY - describes SMT topologies 6378 * SD_SHARE_PKG_RESOURCES - describes shared caches 6379 * SD_NUMA - describes NUMA topologies 6380 * SD_SHARE_POWERDOMAIN - describes shared power domain 6381 * 6382 * Odd one out: 6383 * SD_ASYM_PACKING - describes SMT quirks 6384 */ 6385 #define TOPOLOGY_SD_FLAGS \ 6386 (SD_SHARE_CPUCAPACITY | \ 6387 SD_SHARE_PKG_RESOURCES | \ 6388 SD_NUMA | \ 6389 SD_ASYM_PACKING | \ 6390 SD_SHARE_POWERDOMAIN) 6391 6392 static struct sched_domain * 6393 sd_init(struct sched_domain_topology_level *tl, int cpu) 6394 { 6395 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); 6396 int sd_weight, sd_flags = 0; 6397 6398 #ifdef CONFIG_NUMA 6399 /* 6400 * Ugly hack to pass state to sd_numa_mask()... 6401 */ 6402 sched_domains_curr_level = tl->numa_level; 6403 #endif 6404 6405 sd_weight = cpumask_weight(tl->mask(cpu)); 6406 6407 if (tl->sd_flags) 6408 sd_flags = (*tl->sd_flags)(); 6409 if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS, 6410 "wrong sd_flags in topology description\n")) 6411 sd_flags &= ~TOPOLOGY_SD_FLAGS; 6412 6413 *sd = (struct sched_domain){ 6414 .min_interval = sd_weight, 6415 .max_interval = 2*sd_weight, 6416 .busy_factor = 32, 6417 .imbalance_pct = 125, 6418 6419 .cache_nice_tries = 0, 6420 .busy_idx = 0, 6421 .idle_idx = 0, 6422 .newidle_idx = 0, 6423 .wake_idx = 0, 6424 .forkexec_idx = 0, 6425 6426 .flags = 1*SD_LOAD_BALANCE 6427 | 1*SD_BALANCE_NEWIDLE 6428 | 1*SD_BALANCE_EXEC 6429 | 1*SD_BALANCE_FORK 6430 | 0*SD_BALANCE_WAKE 6431 | 1*SD_WAKE_AFFINE 6432 | 0*SD_SHARE_CPUCAPACITY 6433 | 0*SD_SHARE_PKG_RESOURCES 6434 | 0*SD_SERIALIZE 6435 | 0*SD_PREFER_SIBLING 6436 | 0*SD_NUMA 6437 | sd_flags 6438 , 6439 6440 .last_balance = jiffies, 6441 .balance_interval = sd_weight, 6442 .smt_gain = 0, 6443 .max_newidle_lb_cost = 0, 6444 .next_decay_max_lb_cost = jiffies, 6445 #ifdef CONFIG_SCHED_DEBUG 6446 .name = tl->name, 6447 #endif 6448 }; 6449 6450 /* 6451 * Convert topological properties into behaviour. 6452 */ 6453 6454 if (sd->flags & SD_SHARE_CPUCAPACITY) { 6455 sd->flags |= SD_PREFER_SIBLING; 6456 sd->imbalance_pct = 110; 6457 sd->smt_gain = 1178; /* ~15% */ 6458 6459 } else if (sd->flags & SD_SHARE_PKG_RESOURCES) { 6460 sd->imbalance_pct = 117; 6461 sd->cache_nice_tries = 1; 6462 sd->busy_idx = 2; 6463 6464 #ifdef CONFIG_NUMA 6465 } else if (sd->flags & SD_NUMA) { 6466 sd->cache_nice_tries = 2; 6467 sd->busy_idx = 3; 6468 sd->idle_idx = 2; 6469 6470 sd->flags |= SD_SERIALIZE; 6471 if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) { 6472 sd->flags &= ~(SD_BALANCE_EXEC | 6473 SD_BALANCE_FORK | 6474 SD_WAKE_AFFINE); 6475 } 6476 6477 #endif 6478 } else { 6479 sd->flags |= SD_PREFER_SIBLING; 6480 sd->cache_nice_tries = 1; 6481 sd->busy_idx = 2; 6482 sd->idle_idx = 1; 6483 } 6484 6485 sd->private = &tl->data; 6486 6487 return sd; 6488 } 6489 6490 /* 6491 * Topology list, bottom-up. 6492 */ 6493 static struct sched_domain_topology_level default_topology[] = { 6494 #ifdef CONFIG_SCHED_SMT 6495 { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) }, 6496 #endif 6497 #ifdef CONFIG_SCHED_MC 6498 { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) }, 6499 #endif 6500 { cpu_cpu_mask, SD_INIT_NAME(DIE) }, 6501 { NULL, }, 6502 }; 6503 6504 static struct sched_domain_topology_level *sched_domain_topology = 6505 default_topology; 6506 6507 #define for_each_sd_topology(tl) \ 6508 for (tl = sched_domain_topology; tl->mask; tl++) 6509 6510 void set_sched_topology(struct sched_domain_topology_level *tl) 6511 { 6512 sched_domain_topology = tl; 6513 } 6514 6515 #ifdef CONFIG_NUMA 6516 6517 static const struct cpumask *sd_numa_mask(int cpu) 6518 { 6519 return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)]; 6520 } 6521 6522 static void sched_numa_warn(const char *str) 6523 { 6524 static int done = false; 6525 int i,j; 6526 6527 if (done) 6528 return; 6529 6530 done = true; 6531 6532 printk(KERN_WARNING "ERROR: %s\n\n", str); 6533 6534 for (i = 0; i < nr_node_ids; i++) { 6535 printk(KERN_WARNING " "); 6536 for (j = 0; j < nr_node_ids; j++) 6537 printk(KERN_CONT "%02d ", node_distance(i,j)); 6538 printk(KERN_CONT "\n"); 6539 } 6540 printk(KERN_WARNING "\n"); 6541 } 6542 6543 bool find_numa_distance(int distance) 6544 { 6545 int i; 6546 6547 if (distance == node_distance(0, 0)) 6548 return true; 6549 6550 for (i = 0; i < sched_domains_numa_levels; i++) { 6551 if (sched_domains_numa_distance[i] == distance) 6552 return true; 6553 } 6554 6555 return false; 6556 } 6557 6558 /* 6559 * A system can have three types of NUMA topology: 6560 * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system 6561 * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes 6562 * NUMA_BACKPLANE: nodes can reach other nodes through a backplane 6563 * 6564 * The difference between a glueless mesh topology and a backplane 6565 * topology lies in whether communication between not directly 6566 * connected nodes goes through intermediary nodes (where programs 6567 * could run), or through backplane controllers. This affects 6568 * placement of programs. 6569 * 6570 * The type of topology can be discerned with the following tests: 6571 * - If the maximum distance between any nodes is 1 hop, the system 6572 * is directly connected. 6573 * - If for two nodes A and B, located N > 1 hops away from each other, 6574 * there is an intermediary node C, which is < N hops away from both 6575 * nodes A and B, the system is a glueless mesh. 6576 */ 6577 static void init_numa_topology_type(void) 6578 { 6579 int a, b, c, n; 6580 6581 n = sched_max_numa_distance; 6582 6583 if (sched_domains_numa_levels <= 1) { 6584 sched_numa_topology_type = NUMA_DIRECT; 6585 return; 6586 } 6587 6588 for_each_online_node(a) { 6589 for_each_online_node(b) { 6590 /* Find two nodes furthest removed from each other. */ 6591 if (node_distance(a, b) < n) 6592 continue; 6593 6594 /* Is there an intermediary node between a and b? */ 6595 for_each_online_node(c) { 6596 if (node_distance(a, c) < n && 6597 node_distance(b, c) < n) { 6598 sched_numa_topology_type = 6599 NUMA_GLUELESS_MESH; 6600 return; 6601 } 6602 } 6603 6604 sched_numa_topology_type = NUMA_BACKPLANE; 6605 return; 6606 } 6607 } 6608 } 6609 6610 static void sched_init_numa(void) 6611 { 6612 int next_distance, curr_distance = node_distance(0, 0); 6613 struct sched_domain_topology_level *tl; 6614 int level = 0; 6615 int i, j, k; 6616 6617 sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL); 6618 if (!sched_domains_numa_distance) 6619 return; 6620 6621 /* 6622 * O(nr_nodes^2) deduplicating selection sort -- in order to find the 6623 * unique distances in the node_distance() table. 6624 * 6625 * Assumes node_distance(0,j) includes all distances in 6626 * node_distance(i,j) in order to avoid cubic time. 6627 */ 6628 next_distance = curr_distance; 6629 for (i = 0; i < nr_node_ids; i++) { 6630 for (j = 0; j < nr_node_ids; j++) { 6631 for (k = 0; k < nr_node_ids; k++) { 6632 int distance = node_distance(i, k); 6633 6634 if (distance > curr_distance && 6635 (distance < next_distance || 6636 next_distance == curr_distance)) 6637 next_distance = distance; 6638 6639 /* 6640 * While not a strong assumption it would be nice to know 6641 * about cases where if node A is connected to B, B is not 6642 * equally connected to A. 6643 */ 6644 if (sched_debug() && node_distance(k, i) != distance) 6645 sched_numa_warn("Node-distance not symmetric"); 6646 6647 if (sched_debug() && i && !find_numa_distance(distance)) 6648 sched_numa_warn("Node-0 not representative"); 6649 } 6650 if (next_distance != curr_distance) { 6651 sched_domains_numa_distance[level++] = next_distance; 6652 sched_domains_numa_levels = level; 6653 curr_distance = next_distance; 6654 } else break; 6655 } 6656 6657 /* 6658 * In case of sched_debug() we verify the above assumption. 6659 */ 6660 if (!sched_debug()) 6661 break; 6662 } 6663 6664 if (!level) 6665 return; 6666 6667 /* 6668 * 'level' contains the number of unique distances, excluding the 6669 * identity distance node_distance(i,i). 6670 * 6671 * The sched_domains_numa_distance[] array includes the actual distance 6672 * numbers. 6673 */ 6674 6675 /* 6676 * Here, we should temporarily reset sched_domains_numa_levels to 0. 6677 * If it fails to allocate memory for array sched_domains_numa_masks[][], 6678 * the array will contain less then 'level' members. This could be 6679 * dangerous when we use it to iterate array sched_domains_numa_masks[][] 6680 * in other functions. 6681 * 6682 * We reset it to 'level' at the end of this function. 6683 */ 6684 sched_domains_numa_levels = 0; 6685 6686 sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL); 6687 if (!sched_domains_numa_masks) 6688 return; 6689 6690 /* 6691 * Now for each level, construct a mask per node which contains all 6692 * cpus of nodes that are that many hops away from us. 6693 */ 6694 for (i = 0; i < level; i++) { 6695 sched_domains_numa_masks[i] = 6696 kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL); 6697 if (!sched_domains_numa_masks[i]) 6698 return; 6699 6700 for (j = 0; j < nr_node_ids; j++) { 6701 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL); 6702 if (!mask) 6703 return; 6704 6705 sched_domains_numa_masks[i][j] = mask; 6706 6707 for_each_node(k) { 6708 if (node_distance(j, k) > sched_domains_numa_distance[i]) 6709 continue; 6710 6711 cpumask_or(mask, mask, cpumask_of_node(k)); 6712 } 6713 } 6714 } 6715 6716 /* Compute default topology size */ 6717 for (i = 0; sched_domain_topology[i].mask; i++); 6718 6719 tl = kzalloc((i + level + 1) * 6720 sizeof(struct sched_domain_topology_level), GFP_KERNEL); 6721 if (!tl) 6722 return; 6723 6724 /* 6725 * Copy the default topology bits.. 6726 */ 6727 for (i = 0; sched_domain_topology[i].mask; i++) 6728 tl[i] = sched_domain_topology[i]; 6729 6730 /* 6731 * .. and append 'j' levels of NUMA goodness. 6732 */ 6733 for (j = 0; j < level; i++, j++) { 6734 tl[i] = (struct sched_domain_topology_level){ 6735 .mask = sd_numa_mask, 6736 .sd_flags = cpu_numa_flags, 6737 .flags = SDTL_OVERLAP, 6738 .numa_level = j, 6739 SD_INIT_NAME(NUMA) 6740 }; 6741 } 6742 6743 sched_domain_topology = tl; 6744 6745 sched_domains_numa_levels = level; 6746 sched_max_numa_distance = sched_domains_numa_distance[level - 1]; 6747 6748 init_numa_topology_type(); 6749 } 6750 6751 static void sched_domains_numa_masks_set(unsigned int cpu) 6752 { 6753 int node = cpu_to_node(cpu); 6754 int i, j; 6755 6756 for (i = 0; i < sched_domains_numa_levels; i++) { 6757 for (j = 0; j < nr_node_ids; j++) { 6758 if (node_distance(j, node) <= sched_domains_numa_distance[i]) 6759 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]); 6760 } 6761 } 6762 } 6763 6764 static void sched_domains_numa_masks_clear(unsigned int cpu) 6765 { 6766 int i, j; 6767 6768 for (i = 0; i < sched_domains_numa_levels; i++) { 6769 for (j = 0; j < nr_node_ids; j++) 6770 cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]); 6771 } 6772 } 6773 6774 #else 6775 static inline void sched_init_numa(void) { } 6776 static void sched_domains_numa_masks_set(unsigned int cpu) { } 6777 static void sched_domains_numa_masks_clear(unsigned int cpu) { } 6778 #endif /* CONFIG_NUMA */ 6779 6780 static int __sdt_alloc(const struct cpumask *cpu_map) 6781 { 6782 struct sched_domain_topology_level *tl; 6783 int j; 6784 6785 for_each_sd_topology(tl) { 6786 struct sd_data *sdd = &tl->data; 6787 6788 sdd->sd = alloc_percpu(struct sched_domain *); 6789 if (!sdd->sd) 6790 return -ENOMEM; 6791 6792 sdd->sg = alloc_percpu(struct sched_group *); 6793 if (!sdd->sg) 6794 return -ENOMEM; 6795 6796 sdd->sgc = alloc_percpu(struct sched_group_capacity *); 6797 if (!sdd->sgc) 6798 return -ENOMEM; 6799 6800 for_each_cpu(j, cpu_map) { 6801 struct sched_domain *sd; 6802 struct sched_group *sg; 6803 struct sched_group_capacity *sgc; 6804 6805 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(), 6806 GFP_KERNEL, cpu_to_node(j)); 6807 if (!sd) 6808 return -ENOMEM; 6809 6810 *per_cpu_ptr(sdd->sd, j) = sd; 6811 6812 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), 6813 GFP_KERNEL, cpu_to_node(j)); 6814 if (!sg) 6815 return -ENOMEM; 6816 6817 sg->next = sg; 6818 6819 *per_cpu_ptr(sdd->sg, j) = sg; 6820 6821 sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(), 6822 GFP_KERNEL, cpu_to_node(j)); 6823 if (!sgc) 6824 return -ENOMEM; 6825 6826 *per_cpu_ptr(sdd->sgc, j) = sgc; 6827 } 6828 } 6829 6830 return 0; 6831 } 6832 6833 static void __sdt_free(const struct cpumask *cpu_map) 6834 { 6835 struct sched_domain_topology_level *tl; 6836 int j; 6837 6838 for_each_sd_topology(tl) { 6839 struct sd_data *sdd = &tl->data; 6840 6841 for_each_cpu(j, cpu_map) { 6842 struct sched_domain *sd; 6843 6844 if (sdd->sd) { 6845 sd = *per_cpu_ptr(sdd->sd, j); 6846 if (sd && (sd->flags & SD_OVERLAP)) 6847 free_sched_groups(sd->groups, 0); 6848 kfree(*per_cpu_ptr(sdd->sd, j)); 6849 } 6850 6851 if (sdd->sg) 6852 kfree(*per_cpu_ptr(sdd->sg, j)); 6853 if (sdd->sgc) 6854 kfree(*per_cpu_ptr(sdd->sgc, j)); 6855 } 6856 free_percpu(sdd->sd); 6857 sdd->sd = NULL; 6858 free_percpu(sdd->sg); 6859 sdd->sg = NULL; 6860 free_percpu(sdd->sgc); 6861 sdd->sgc = NULL; 6862 } 6863 } 6864 6865 struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl, 6866 const struct cpumask *cpu_map, struct sched_domain_attr *attr, 6867 struct sched_domain *child, int cpu) 6868 { 6869 struct sched_domain *sd = sd_init(tl, cpu); 6870 if (!sd) 6871 return child; 6872 6873 cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu)); 6874 if (child) { 6875 sd->level = child->level + 1; 6876 sched_domain_level_max = max(sched_domain_level_max, sd->level); 6877 child->parent = sd; 6878 sd->child = child; 6879 6880 if (!cpumask_subset(sched_domain_span(child), 6881 sched_domain_span(sd))) { 6882 pr_err("BUG: arch topology borken\n"); 6883 #ifdef CONFIG_SCHED_DEBUG 6884 pr_err(" the %s domain not a subset of the %s domain\n", 6885 child->name, sd->name); 6886 #endif 6887 /* Fixup, ensure @sd has at least @child cpus. */ 6888 cpumask_or(sched_domain_span(sd), 6889 sched_domain_span(sd), 6890 sched_domain_span(child)); 6891 } 6892 6893 } 6894 set_domain_attribute(sd, attr); 6895 6896 return sd; 6897 } 6898 6899 /* 6900 * Build sched domains for a given set of cpus and attach the sched domains 6901 * to the individual cpus 6902 */ 6903 static int build_sched_domains(const struct cpumask *cpu_map, 6904 struct sched_domain_attr *attr) 6905 { 6906 enum s_alloc alloc_state; 6907 struct sched_domain *sd; 6908 struct s_data d; 6909 int i, ret = -ENOMEM; 6910 6911 alloc_state = __visit_domain_allocation_hell(&d, cpu_map); 6912 if (alloc_state != sa_rootdomain) 6913 goto error; 6914 6915 /* Set up domains for cpus specified by the cpu_map. */ 6916 for_each_cpu(i, cpu_map) { 6917 struct sched_domain_topology_level *tl; 6918 6919 sd = NULL; 6920 for_each_sd_topology(tl) { 6921 sd = build_sched_domain(tl, cpu_map, attr, sd, i); 6922 if (tl == sched_domain_topology) 6923 *per_cpu_ptr(d.sd, i) = sd; 6924 if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP)) 6925 sd->flags |= SD_OVERLAP; 6926 if (cpumask_equal(cpu_map, sched_domain_span(sd))) 6927 break; 6928 } 6929 } 6930 6931 /* Build the groups for the domains */ 6932 for_each_cpu(i, cpu_map) { 6933 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { 6934 sd->span_weight = cpumask_weight(sched_domain_span(sd)); 6935 if (sd->flags & SD_OVERLAP) { 6936 if (build_overlap_sched_groups(sd, i)) 6937 goto error; 6938 } else { 6939 if (build_sched_groups(sd, i)) 6940 goto error; 6941 } 6942 } 6943 } 6944 6945 /* Calculate CPU capacity for physical packages and nodes */ 6946 for (i = nr_cpumask_bits-1; i >= 0; i--) { 6947 if (!cpumask_test_cpu(i, cpu_map)) 6948 continue; 6949 6950 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { 6951 claim_allocations(i, sd); 6952 init_sched_groups_capacity(i, sd); 6953 } 6954 } 6955 6956 /* Attach the domains */ 6957 rcu_read_lock(); 6958 for_each_cpu(i, cpu_map) { 6959 sd = *per_cpu_ptr(d.sd, i); 6960 cpu_attach_domain(sd, d.rd, i); 6961 } 6962 rcu_read_unlock(); 6963 6964 ret = 0; 6965 error: 6966 __free_domain_allocs(&d, alloc_state, cpu_map); 6967 return ret; 6968 } 6969 6970 static cpumask_var_t *doms_cur; /* current sched domains */ 6971 static int ndoms_cur; /* number of sched domains in 'doms_cur' */ 6972 static struct sched_domain_attr *dattr_cur; 6973 /* attribues of custom domains in 'doms_cur' */ 6974 6975 /* 6976 * Special case: If a kmalloc of a doms_cur partition (array of 6977 * cpumask) fails, then fallback to a single sched domain, 6978 * as determined by the single cpumask fallback_doms. 6979 */ 6980 static cpumask_var_t fallback_doms; 6981 6982 /* 6983 * arch_update_cpu_topology lets virtualized architectures update the 6984 * cpu core maps. It is supposed to return 1 if the topology changed 6985 * or 0 if it stayed the same. 6986 */ 6987 int __weak arch_update_cpu_topology(void) 6988 { 6989 return 0; 6990 } 6991 6992 cpumask_var_t *alloc_sched_domains(unsigned int ndoms) 6993 { 6994 int i; 6995 cpumask_var_t *doms; 6996 6997 doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL); 6998 if (!doms) 6999 return NULL; 7000 for (i = 0; i < ndoms; i++) { 7001 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) { 7002 free_sched_domains(doms, i); 7003 return NULL; 7004 } 7005 } 7006 return doms; 7007 } 7008 7009 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms) 7010 { 7011 unsigned int i; 7012 for (i = 0; i < ndoms; i++) 7013 free_cpumask_var(doms[i]); 7014 kfree(doms); 7015 } 7016 7017 /* 7018 * Set up scheduler domains and groups. Callers must hold the hotplug lock. 7019 * For now this just excludes isolated cpus, but could be used to 7020 * exclude other special cases in the future. 7021 */ 7022 static int init_sched_domains(const struct cpumask *cpu_map) 7023 { 7024 int err; 7025 7026 arch_update_cpu_topology(); 7027 ndoms_cur = 1; 7028 doms_cur = alloc_sched_domains(ndoms_cur); 7029 if (!doms_cur) 7030 doms_cur = &fallback_doms; 7031 cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map); 7032 err = build_sched_domains(doms_cur[0], NULL); 7033 register_sched_domain_sysctl(); 7034 7035 return err; 7036 } 7037 7038 /* 7039 * Detach sched domains from a group of cpus specified in cpu_map 7040 * These cpus will now be attached to the NULL domain 7041 */ 7042 static void detach_destroy_domains(const struct cpumask *cpu_map) 7043 { 7044 int i; 7045 7046 rcu_read_lock(); 7047 for_each_cpu(i, cpu_map) 7048 cpu_attach_domain(NULL, &def_root_domain, i); 7049 rcu_read_unlock(); 7050 } 7051 7052 /* handle null as "default" */ 7053 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur, 7054 struct sched_domain_attr *new, int idx_new) 7055 { 7056 struct sched_domain_attr tmp; 7057 7058 /* fast path */ 7059 if (!new && !cur) 7060 return 1; 7061 7062 tmp = SD_ATTR_INIT; 7063 return !memcmp(cur ? (cur + idx_cur) : &tmp, 7064 new ? (new + idx_new) : &tmp, 7065 sizeof(struct sched_domain_attr)); 7066 } 7067 7068 /* 7069 * Partition sched domains as specified by the 'ndoms_new' 7070 * cpumasks in the array doms_new[] of cpumasks. This compares 7071 * doms_new[] to the current sched domain partitioning, doms_cur[]. 7072 * It destroys each deleted domain and builds each new domain. 7073 * 7074 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'. 7075 * The masks don't intersect (don't overlap.) We should setup one 7076 * sched domain for each mask. CPUs not in any of the cpumasks will 7077 * not be load balanced. If the same cpumask appears both in the 7078 * current 'doms_cur' domains and in the new 'doms_new', we can leave 7079 * it as it is. 7080 * 7081 * The passed in 'doms_new' should be allocated using 7082 * alloc_sched_domains. This routine takes ownership of it and will 7083 * free_sched_domains it when done with it. If the caller failed the 7084 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1, 7085 * and partition_sched_domains() will fallback to the single partition 7086 * 'fallback_doms', it also forces the domains to be rebuilt. 7087 * 7088 * If doms_new == NULL it will be replaced with cpu_online_mask. 7089 * ndoms_new == 0 is a special case for destroying existing domains, 7090 * and it will not create the default domain. 7091 * 7092 * Call with hotplug lock held 7093 */ 7094 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[], 7095 struct sched_domain_attr *dattr_new) 7096 { 7097 int i, j, n; 7098 int new_topology; 7099 7100 mutex_lock(&sched_domains_mutex); 7101 7102 /* always unregister in case we don't destroy any domains */ 7103 unregister_sched_domain_sysctl(); 7104 7105 /* Let architecture update cpu core mappings. */ 7106 new_topology = arch_update_cpu_topology(); 7107 7108 n = doms_new ? ndoms_new : 0; 7109 7110 /* Destroy deleted domains */ 7111 for (i = 0; i < ndoms_cur; i++) { 7112 for (j = 0; j < n && !new_topology; j++) { 7113 if (cpumask_equal(doms_cur[i], doms_new[j]) 7114 && dattrs_equal(dattr_cur, i, dattr_new, j)) 7115 goto match1; 7116 } 7117 /* no match - a current sched domain not in new doms_new[] */ 7118 detach_destroy_domains(doms_cur[i]); 7119 match1: 7120 ; 7121 } 7122 7123 n = ndoms_cur; 7124 if (doms_new == NULL) { 7125 n = 0; 7126 doms_new = &fallback_doms; 7127 cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map); 7128 WARN_ON_ONCE(dattr_new); 7129 } 7130 7131 /* Build new domains */ 7132 for (i = 0; i < ndoms_new; i++) { 7133 for (j = 0; j < n && !new_topology; j++) { 7134 if (cpumask_equal(doms_new[i], doms_cur[j]) 7135 && dattrs_equal(dattr_new, i, dattr_cur, j)) 7136 goto match2; 7137 } 7138 /* no match - add a new doms_new */ 7139 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL); 7140 match2: 7141 ; 7142 } 7143 7144 /* Remember the new sched domains */ 7145 if (doms_cur != &fallback_doms) 7146 free_sched_domains(doms_cur, ndoms_cur); 7147 kfree(dattr_cur); /* kfree(NULL) is safe */ 7148 doms_cur = doms_new; 7149 dattr_cur = dattr_new; 7150 ndoms_cur = ndoms_new; 7151 7152 register_sched_domain_sysctl(); 7153 7154 mutex_unlock(&sched_domains_mutex); 7155 } 7156 7157 static int num_cpus_frozen; /* used to mark begin/end of suspend/resume */ 7158 7159 /* 7160 * Update cpusets according to cpu_active mask. If cpusets are 7161 * disabled, cpuset_update_active_cpus() becomes a simple wrapper 7162 * around partition_sched_domains(). 7163 * 7164 * If we come here as part of a suspend/resume, don't touch cpusets because we 7165 * want to restore it back to its original state upon resume anyway. 7166 */ 7167 static void cpuset_cpu_active(void) 7168 { 7169 if (cpuhp_tasks_frozen) { 7170 /* 7171 * num_cpus_frozen tracks how many CPUs are involved in suspend 7172 * resume sequence. As long as this is not the last online 7173 * operation in the resume sequence, just build a single sched 7174 * domain, ignoring cpusets. 7175 */ 7176 num_cpus_frozen--; 7177 if (likely(num_cpus_frozen)) { 7178 partition_sched_domains(1, NULL, NULL); 7179 return; 7180 } 7181 /* 7182 * This is the last CPU online operation. So fall through and 7183 * restore the original sched domains by considering the 7184 * cpuset configurations. 7185 */ 7186 } 7187 cpuset_update_active_cpus(true); 7188 } 7189 7190 static int cpuset_cpu_inactive(unsigned int cpu) 7191 { 7192 unsigned long flags; 7193 struct dl_bw *dl_b; 7194 bool overflow; 7195 int cpus; 7196 7197 if (!cpuhp_tasks_frozen) { 7198 rcu_read_lock_sched(); 7199 dl_b = dl_bw_of(cpu); 7200 7201 raw_spin_lock_irqsave(&dl_b->lock, flags); 7202 cpus = dl_bw_cpus(cpu); 7203 overflow = __dl_overflow(dl_b, cpus, 0, 0); 7204 raw_spin_unlock_irqrestore(&dl_b->lock, flags); 7205 7206 rcu_read_unlock_sched(); 7207 7208 if (overflow) 7209 return -EBUSY; 7210 cpuset_update_active_cpus(false); 7211 } else { 7212 num_cpus_frozen++; 7213 partition_sched_domains(1, NULL, NULL); 7214 } 7215 return 0; 7216 } 7217 7218 int sched_cpu_activate(unsigned int cpu) 7219 { 7220 struct rq *rq = cpu_rq(cpu); 7221 unsigned long flags; 7222 7223 set_cpu_active(cpu, true); 7224 7225 if (sched_smp_initialized) { 7226 sched_domains_numa_masks_set(cpu); 7227 cpuset_cpu_active(); 7228 } 7229 7230 /* 7231 * Put the rq online, if not already. This happens: 7232 * 7233 * 1) In the early boot process, because we build the real domains 7234 * after all cpus have been brought up. 7235 * 7236 * 2) At runtime, if cpuset_cpu_active() fails to rebuild the 7237 * domains. 7238 */ 7239 raw_spin_lock_irqsave(&rq->lock, flags); 7240 if (rq->rd) { 7241 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); 7242 set_rq_online(rq); 7243 } 7244 raw_spin_unlock_irqrestore(&rq->lock, flags); 7245 7246 update_max_interval(); 7247 7248 return 0; 7249 } 7250 7251 int sched_cpu_deactivate(unsigned int cpu) 7252 { 7253 int ret; 7254 7255 set_cpu_active(cpu, false); 7256 /* 7257 * We've cleared cpu_active_mask, wait for all preempt-disabled and RCU 7258 * users of this state to go away such that all new such users will 7259 * observe it. 7260 * 7261 * For CONFIG_PREEMPT we have preemptible RCU and its sync_rcu() might 7262 * not imply sync_sched(), so wait for both. 7263 * 7264 * Do sync before park smpboot threads to take care the rcu boost case. 7265 */ 7266 if (IS_ENABLED(CONFIG_PREEMPT)) 7267 synchronize_rcu_mult(call_rcu, call_rcu_sched); 7268 else 7269 synchronize_rcu(); 7270 7271 if (!sched_smp_initialized) 7272 return 0; 7273 7274 ret = cpuset_cpu_inactive(cpu); 7275 if (ret) { 7276 set_cpu_active(cpu, true); 7277 return ret; 7278 } 7279 sched_domains_numa_masks_clear(cpu); 7280 return 0; 7281 } 7282 7283 static void sched_rq_cpu_starting(unsigned int cpu) 7284 { 7285 struct rq *rq = cpu_rq(cpu); 7286 7287 rq->calc_load_update = calc_load_update; 7288 update_max_interval(); 7289 } 7290 7291 int sched_cpu_starting(unsigned int cpu) 7292 { 7293 set_cpu_rq_start_time(cpu); 7294 sched_rq_cpu_starting(cpu); 7295 return 0; 7296 } 7297 7298 #ifdef CONFIG_HOTPLUG_CPU 7299 int sched_cpu_dying(unsigned int cpu) 7300 { 7301 struct rq *rq = cpu_rq(cpu); 7302 unsigned long flags; 7303 7304 /* Handle pending wakeups and then migrate everything off */ 7305 sched_ttwu_pending(); 7306 raw_spin_lock_irqsave(&rq->lock, flags); 7307 if (rq->rd) { 7308 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); 7309 set_rq_offline(rq); 7310 } 7311 migrate_tasks(rq); 7312 BUG_ON(rq->nr_running != 1); 7313 raw_spin_unlock_irqrestore(&rq->lock, flags); 7314 calc_load_migrate(rq); 7315 update_max_interval(); 7316 nohz_balance_exit_idle(cpu); 7317 hrtick_clear(rq); 7318 return 0; 7319 } 7320 #endif 7321 7322 void __init sched_init_smp(void) 7323 { 7324 cpumask_var_t non_isolated_cpus; 7325 7326 alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL); 7327 alloc_cpumask_var(&fallback_doms, GFP_KERNEL); 7328 7329 sched_init_numa(); 7330 7331 /* 7332 * There's no userspace yet to cause hotplug operations; hence all the 7333 * cpu masks are stable and all blatant races in the below code cannot 7334 * happen. 7335 */ 7336 mutex_lock(&sched_domains_mutex); 7337 init_sched_domains(cpu_active_mask); 7338 cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map); 7339 if (cpumask_empty(non_isolated_cpus)) 7340 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus); 7341 mutex_unlock(&sched_domains_mutex); 7342 7343 /* Move init over to a non-isolated CPU */ 7344 if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0) 7345 BUG(); 7346 sched_init_granularity(); 7347 free_cpumask_var(non_isolated_cpus); 7348 7349 init_sched_rt_class(); 7350 init_sched_dl_class(); 7351 sched_smp_initialized = true; 7352 } 7353 7354 static int __init migration_init(void) 7355 { 7356 sched_rq_cpu_starting(smp_processor_id()); 7357 return 0; 7358 } 7359 early_initcall(migration_init); 7360 7361 #else 7362 void __init sched_init_smp(void) 7363 { 7364 sched_init_granularity(); 7365 } 7366 #endif /* CONFIG_SMP */ 7367 7368 int in_sched_functions(unsigned long addr) 7369 { 7370 return in_lock_functions(addr) || 7371 (addr >= (unsigned long)__sched_text_start 7372 && addr < (unsigned long)__sched_text_end); 7373 } 7374 7375 #ifdef CONFIG_CGROUP_SCHED 7376 /* 7377 * Default task group. 7378 * Every task in system belongs to this group at bootup. 7379 */ 7380 struct task_group root_task_group; 7381 LIST_HEAD(task_groups); 7382 7383 /* Cacheline aligned slab cache for task_group */ 7384 static struct kmem_cache *task_group_cache __read_mostly; 7385 #endif 7386 7387 DECLARE_PER_CPU(cpumask_var_t, load_balance_mask); 7388 7389 void __init sched_init(void) 7390 { 7391 int i, j; 7392 unsigned long alloc_size = 0, ptr; 7393 7394 #ifdef CONFIG_FAIR_GROUP_SCHED 7395 alloc_size += 2 * nr_cpu_ids * sizeof(void **); 7396 #endif 7397 #ifdef CONFIG_RT_GROUP_SCHED 7398 alloc_size += 2 * nr_cpu_ids * sizeof(void **); 7399 #endif 7400 if (alloc_size) { 7401 ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT); 7402 7403 #ifdef CONFIG_FAIR_GROUP_SCHED 7404 root_task_group.se = (struct sched_entity **)ptr; 7405 ptr += nr_cpu_ids * sizeof(void **); 7406 7407 root_task_group.cfs_rq = (struct cfs_rq **)ptr; 7408 ptr += nr_cpu_ids * sizeof(void **); 7409 7410 #endif /* CONFIG_FAIR_GROUP_SCHED */ 7411 #ifdef CONFIG_RT_GROUP_SCHED 7412 root_task_group.rt_se = (struct sched_rt_entity **)ptr; 7413 ptr += nr_cpu_ids * sizeof(void **); 7414 7415 root_task_group.rt_rq = (struct rt_rq **)ptr; 7416 ptr += nr_cpu_ids * sizeof(void **); 7417 7418 #endif /* CONFIG_RT_GROUP_SCHED */ 7419 } 7420 #ifdef CONFIG_CPUMASK_OFFSTACK 7421 for_each_possible_cpu(i) { 7422 per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node( 7423 cpumask_size(), GFP_KERNEL, cpu_to_node(i)); 7424 } 7425 #endif /* CONFIG_CPUMASK_OFFSTACK */ 7426 7427 init_rt_bandwidth(&def_rt_bandwidth, 7428 global_rt_period(), global_rt_runtime()); 7429 init_dl_bandwidth(&def_dl_bandwidth, 7430 global_rt_period(), global_rt_runtime()); 7431 7432 #ifdef CONFIG_SMP 7433 init_defrootdomain(); 7434 #endif 7435 7436 #ifdef CONFIG_RT_GROUP_SCHED 7437 init_rt_bandwidth(&root_task_group.rt_bandwidth, 7438 global_rt_period(), global_rt_runtime()); 7439 #endif /* CONFIG_RT_GROUP_SCHED */ 7440 7441 #ifdef CONFIG_CGROUP_SCHED 7442 task_group_cache = KMEM_CACHE(task_group, 0); 7443 7444 list_add(&root_task_group.list, &task_groups); 7445 INIT_LIST_HEAD(&root_task_group.children); 7446 INIT_LIST_HEAD(&root_task_group.siblings); 7447 autogroup_init(&init_task); 7448 #endif /* CONFIG_CGROUP_SCHED */ 7449 7450 for_each_possible_cpu(i) { 7451 struct rq *rq; 7452 7453 rq = cpu_rq(i); 7454 raw_spin_lock_init(&rq->lock); 7455 rq->nr_running = 0; 7456 rq->calc_load_active = 0; 7457 rq->calc_load_update = jiffies + LOAD_FREQ; 7458 init_cfs_rq(&rq->cfs); 7459 init_rt_rq(&rq->rt); 7460 init_dl_rq(&rq->dl); 7461 #ifdef CONFIG_FAIR_GROUP_SCHED 7462 root_task_group.shares = ROOT_TASK_GROUP_LOAD; 7463 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list); 7464 /* 7465 * How much cpu bandwidth does root_task_group get? 7466 * 7467 * In case of task-groups formed thr' the cgroup filesystem, it 7468 * gets 100% of the cpu resources in the system. This overall 7469 * system cpu resource is divided among the tasks of 7470 * root_task_group and its child task-groups in a fair manner, 7471 * based on each entity's (task or task-group's) weight 7472 * (se->load.weight). 7473 * 7474 * In other words, if root_task_group has 10 tasks of weight 7475 * 1024) and two child groups A0 and A1 (of weight 1024 each), 7476 * then A0's share of the cpu resource is: 7477 * 7478 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33% 7479 * 7480 * We achieve this by letting root_task_group's tasks sit 7481 * directly in rq->cfs (i.e root_task_group->se[] = NULL). 7482 */ 7483 init_cfs_bandwidth(&root_task_group.cfs_bandwidth); 7484 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL); 7485 #endif /* CONFIG_FAIR_GROUP_SCHED */ 7486 7487 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime; 7488 #ifdef CONFIG_RT_GROUP_SCHED 7489 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL); 7490 #endif 7491 7492 for (j = 0; j < CPU_LOAD_IDX_MAX; j++) 7493 rq->cpu_load[j] = 0; 7494 7495 #ifdef CONFIG_SMP 7496 rq->sd = NULL; 7497 rq->rd = NULL; 7498 rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE; 7499 rq->balance_callback = NULL; 7500 rq->active_balance = 0; 7501 rq->next_balance = jiffies; 7502 rq->push_cpu = 0; 7503 rq->cpu = i; 7504 rq->online = 0; 7505 rq->idle_stamp = 0; 7506 rq->avg_idle = 2*sysctl_sched_migration_cost; 7507 rq->max_idle_balance_cost = sysctl_sched_migration_cost; 7508 7509 INIT_LIST_HEAD(&rq->cfs_tasks); 7510 7511 rq_attach_root(rq, &def_root_domain); 7512 #ifdef CONFIG_NO_HZ_COMMON 7513 rq->last_load_update_tick = jiffies; 7514 rq->nohz_flags = 0; 7515 #endif 7516 #ifdef CONFIG_NO_HZ_FULL 7517 rq->last_sched_tick = 0; 7518 #endif 7519 #endif /* CONFIG_SMP */ 7520 init_rq_hrtick(rq); 7521 atomic_set(&rq->nr_iowait, 0); 7522 } 7523 7524 set_load_weight(&init_task); 7525 7526 #ifdef CONFIG_PREEMPT_NOTIFIERS 7527 INIT_HLIST_HEAD(&init_task.preempt_notifiers); 7528 #endif 7529 7530 /* 7531 * The boot idle thread does lazy MMU switching as well: 7532 */ 7533 atomic_inc(&init_mm.mm_count); 7534 enter_lazy_tlb(&init_mm, current); 7535 7536 /* 7537 * During early bootup we pretend to be a normal task: 7538 */ 7539 current->sched_class = &fair_sched_class; 7540 7541 /* 7542 * Make us the idle thread. Technically, schedule() should not be 7543 * called from this thread, however somewhere below it might be, 7544 * but because we are the idle thread, we just pick up running again 7545 * when this runqueue becomes "idle". 7546 */ 7547 init_idle(current, smp_processor_id()); 7548 7549 calc_load_update = jiffies + LOAD_FREQ; 7550 7551 #ifdef CONFIG_SMP 7552 zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT); 7553 /* May be allocated at isolcpus cmdline parse time */ 7554 if (cpu_isolated_map == NULL) 7555 zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT); 7556 idle_thread_set_boot_cpu(); 7557 set_cpu_rq_start_time(smp_processor_id()); 7558 #endif 7559 init_sched_fair_class(); 7560 7561 init_schedstats(); 7562 7563 scheduler_running = 1; 7564 } 7565 7566 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP 7567 static inline int preempt_count_equals(int preempt_offset) 7568 { 7569 int nested = preempt_count() + rcu_preempt_depth(); 7570 7571 return (nested == preempt_offset); 7572 } 7573 7574 void __might_sleep(const char *file, int line, int preempt_offset) 7575 { 7576 /* 7577 * Blocking primitives will set (and therefore destroy) current->state, 7578 * since we will exit with TASK_RUNNING make sure we enter with it, 7579 * otherwise we will destroy state. 7580 */ 7581 WARN_ONCE(current->state != TASK_RUNNING && current->task_state_change, 7582 "do not call blocking ops when !TASK_RUNNING; " 7583 "state=%lx set at [<%p>] %pS\n", 7584 current->state, 7585 (void *)current->task_state_change, 7586 (void *)current->task_state_change); 7587 7588 ___might_sleep(file, line, preempt_offset); 7589 } 7590 EXPORT_SYMBOL(__might_sleep); 7591 7592 void ___might_sleep(const char *file, int line, int preempt_offset) 7593 { 7594 static unsigned long prev_jiffy; /* ratelimiting */ 7595 7596 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */ 7597 if ((preempt_count_equals(preempt_offset) && !irqs_disabled() && 7598 !is_idle_task(current)) || 7599 system_state != SYSTEM_RUNNING || oops_in_progress) 7600 return; 7601 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) 7602 return; 7603 prev_jiffy = jiffies; 7604 7605 printk(KERN_ERR 7606 "BUG: sleeping function called from invalid context at %s:%d\n", 7607 file, line); 7608 printk(KERN_ERR 7609 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n", 7610 in_atomic(), irqs_disabled(), 7611 current->pid, current->comm); 7612 7613 if (task_stack_end_corrupted(current)) 7614 printk(KERN_EMERG "Thread overran stack, or stack corrupted\n"); 7615 7616 debug_show_held_locks(current); 7617 if (irqs_disabled()) 7618 print_irqtrace_events(current); 7619 #ifdef CONFIG_DEBUG_PREEMPT 7620 if (!preempt_count_equals(preempt_offset)) { 7621 pr_err("Preemption disabled at:"); 7622 print_ip_sym(current->preempt_disable_ip); 7623 pr_cont("\n"); 7624 } 7625 #endif 7626 dump_stack(); 7627 } 7628 EXPORT_SYMBOL(___might_sleep); 7629 #endif 7630 7631 #ifdef CONFIG_MAGIC_SYSRQ 7632 void normalize_rt_tasks(void) 7633 { 7634 struct task_struct *g, *p; 7635 struct sched_attr attr = { 7636 .sched_policy = SCHED_NORMAL, 7637 }; 7638 7639 read_lock(&tasklist_lock); 7640 for_each_process_thread(g, p) { 7641 /* 7642 * Only normalize user tasks: 7643 */ 7644 if (p->flags & PF_KTHREAD) 7645 continue; 7646 7647 p->se.exec_start = 0; 7648 #ifdef CONFIG_SCHEDSTATS 7649 p->se.statistics.wait_start = 0; 7650 p->se.statistics.sleep_start = 0; 7651 p->se.statistics.block_start = 0; 7652 #endif 7653 7654 if (!dl_task(p) && !rt_task(p)) { 7655 /* 7656 * Renice negative nice level userspace 7657 * tasks back to 0: 7658 */ 7659 if (task_nice(p) < 0) 7660 set_user_nice(p, 0); 7661 continue; 7662 } 7663 7664 __sched_setscheduler(p, &attr, false, false); 7665 } 7666 read_unlock(&tasklist_lock); 7667 } 7668 7669 #endif /* CONFIG_MAGIC_SYSRQ */ 7670 7671 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) 7672 /* 7673 * These functions are only useful for the IA64 MCA handling, or kdb. 7674 * 7675 * They can only be called when the whole system has been 7676 * stopped - every CPU needs to be quiescent, and no scheduling 7677 * activity can take place. Using them for anything else would 7678 * be a serious bug, and as a result, they aren't even visible 7679 * under any other configuration. 7680 */ 7681 7682 /** 7683 * curr_task - return the current task for a given cpu. 7684 * @cpu: the processor in question. 7685 * 7686 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! 7687 * 7688 * Return: The current task for @cpu. 7689 */ 7690 struct task_struct *curr_task(int cpu) 7691 { 7692 return cpu_curr(cpu); 7693 } 7694 7695 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */ 7696 7697 #ifdef CONFIG_IA64 7698 /** 7699 * set_curr_task - set the current task for a given cpu. 7700 * @cpu: the processor in question. 7701 * @p: the task pointer to set. 7702 * 7703 * Description: This function must only be used when non-maskable interrupts 7704 * are serviced on a separate stack. It allows the architecture to switch the 7705 * notion of the current task on a cpu in a non-blocking manner. This function 7706 * must be called with all CPU's synchronized, and interrupts disabled, the 7707 * and caller must save the original value of the current task (see 7708 * curr_task() above) and restore that value before reenabling interrupts and 7709 * re-starting the system. 7710 * 7711 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! 7712 */ 7713 void set_curr_task(int cpu, struct task_struct *p) 7714 { 7715 cpu_curr(cpu) = p; 7716 } 7717 7718 #endif 7719 7720 #ifdef CONFIG_CGROUP_SCHED 7721 /* task_group_lock serializes the addition/removal of task groups */ 7722 static DEFINE_SPINLOCK(task_group_lock); 7723 7724 static void sched_free_group(struct task_group *tg) 7725 { 7726 free_fair_sched_group(tg); 7727 free_rt_sched_group(tg); 7728 autogroup_free(tg); 7729 kmem_cache_free(task_group_cache, tg); 7730 } 7731 7732 /* allocate runqueue etc for a new task group */ 7733 struct task_group *sched_create_group(struct task_group *parent) 7734 { 7735 struct task_group *tg; 7736 7737 tg = kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO); 7738 if (!tg) 7739 return ERR_PTR(-ENOMEM); 7740 7741 if (!alloc_fair_sched_group(tg, parent)) 7742 goto err; 7743 7744 if (!alloc_rt_sched_group(tg, parent)) 7745 goto err; 7746 7747 return tg; 7748 7749 err: 7750 sched_free_group(tg); 7751 return ERR_PTR(-ENOMEM); 7752 } 7753 7754 void sched_online_group(struct task_group *tg, struct task_group *parent) 7755 { 7756 unsigned long flags; 7757 7758 spin_lock_irqsave(&task_group_lock, flags); 7759 list_add_rcu(&tg->list, &task_groups); 7760 7761 WARN_ON(!parent); /* root should already exist */ 7762 7763 tg->parent = parent; 7764 INIT_LIST_HEAD(&tg->children); 7765 list_add_rcu(&tg->siblings, &parent->children); 7766 spin_unlock_irqrestore(&task_group_lock, flags); 7767 7768 online_fair_sched_group(tg); 7769 } 7770 7771 /* rcu callback to free various structures associated with a task group */ 7772 static void sched_free_group_rcu(struct rcu_head *rhp) 7773 { 7774 /* now it should be safe to free those cfs_rqs */ 7775 sched_free_group(container_of(rhp, struct task_group, rcu)); 7776 } 7777 7778 void sched_destroy_group(struct task_group *tg) 7779 { 7780 /* wait for possible concurrent references to cfs_rqs complete */ 7781 call_rcu(&tg->rcu, sched_free_group_rcu); 7782 } 7783 7784 void sched_offline_group(struct task_group *tg) 7785 { 7786 unsigned long flags; 7787 7788 /* end participation in shares distribution */ 7789 unregister_fair_sched_group(tg); 7790 7791 spin_lock_irqsave(&task_group_lock, flags); 7792 list_del_rcu(&tg->list); 7793 list_del_rcu(&tg->siblings); 7794 spin_unlock_irqrestore(&task_group_lock, flags); 7795 } 7796 7797 static void sched_change_group(struct task_struct *tsk, int type) 7798 { 7799 struct task_group *tg; 7800 7801 /* 7802 * All callers are synchronized by task_rq_lock(); we do not use RCU 7803 * which is pointless here. Thus, we pass "true" to task_css_check() 7804 * to prevent lockdep warnings. 7805 */ 7806 tg = container_of(task_css_check(tsk, cpu_cgrp_id, true), 7807 struct task_group, css); 7808 tg = autogroup_task_group(tsk, tg); 7809 tsk->sched_task_group = tg; 7810 7811 #ifdef CONFIG_FAIR_GROUP_SCHED 7812 if (tsk->sched_class->task_change_group) 7813 tsk->sched_class->task_change_group(tsk, type); 7814 else 7815 #endif 7816 set_task_rq(tsk, task_cpu(tsk)); 7817 } 7818 7819 /* 7820 * Change task's runqueue when it moves between groups. 7821 * 7822 * The caller of this function should have put the task in its new group by 7823 * now. This function just updates tsk->se.cfs_rq and tsk->se.parent to reflect 7824 * its new group. 7825 */ 7826 void sched_move_task(struct task_struct *tsk) 7827 { 7828 int queued, running; 7829 struct rq_flags rf; 7830 struct rq *rq; 7831 7832 rq = task_rq_lock(tsk, &rf); 7833 7834 running = task_current(rq, tsk); 7835 queued = task_on_rq_queued(tsk); 7836 7837 if (queued) 7838 dequeue_task(rq, tsk, DEQUEUE_SAVE | DEQUEUE_MOVE); 7839 if (unlikely(running)) 7840 put_prev_task(rq, tsk); 7841 7842 sched_change_group(tsk, TASK_MOVE_GROUP); 7843 7844 if (unlikely(running)) 7845 tsk->sched_class->set_curr_task(rq); 7846 if (queued) 7847 enqueue_task(rq, tsk, ENQUEUE_RESTORE | ENQUEUE_MOVE); 7848 7849 task_rq_unlock(rq, tsk, &rf); 7850 } 7851 #endif /* CONFIG_CGROUP_SCHED */ 7852 7853 #ifdef CONFIG_RT_GROUP_SCHED 7854 /* 7855 * Ensure that the real time constraints are schedulable. 7856 */ 7857 static DEFINE_MUTEX(rt_constraints_mutex); 7858 7859 /* Must be called with tasklist_lock held */ 7860 static inline int tg_has_rt_tasks(struct task_group *tg) 7861 { 7862 struct task_struct *g, *p; 7863 7864 /* 7865 * Autogroups do not have RT tasks; see autogroup_create(). 7866 */ 7867 if (task_group_is_autogroup(tg)) 7868 return 0; 7869 7870 for_each_process_thread(g, p) { 7871 if (rt_task(p) && task_group(p) == tg) 7872 return 1; 7873 } 7874 7875 return 0; 7876 } 7877 7878 struct rt_schedulable_data { 7879 struct task_group *tg; 7880 u64 rt_period; 7881 u64 rt_runtime; 7882 }; 7883 7884 static int tg_rt_schedulable(struct task_group *tg, void *data) 7885 { 7886 struct rt_schedulable_data *d = data; 7887 struct task_group *child; 7888 unsigned long total, sum = 0; 7889 u64 period, runtime; 7890 7891 period = ktime_to_ns(tg->rt_bandwidth.rt_period); 7892 runtime = tg->rt_bandwidth.rt_runtime; 7893 7894 if (tg == d->tg) { 7895 period = d->rt_period; 7896 runtime = d->rt_runtime; 7897 } 7898 7899 /* 7900 * Cannot have more runtime than the period. 7901 */ 7902 if (runtime > period && runtime != RUNTIME_INF) 7903 return -EINVAL; 7904 7905 /* 7906 * Ensure we don't starve existing RT tasks. 7907 */ 7908 if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg)) 7909 return -EBUSY; 7910 7911 total = to_ratio(period, runtime); 7912 7913 /* 7914 * Nobody can have more than the global setting allows. 7915 */ 7916 if (total > to_ratio(global_rt_period(), global_rt_runtime())) 7917 return -EINVAL; 7918 7919 /* 7920 * The sum of our children's runtime should not exceed our own. 7921 */ 7922 list_for_each_entry_rcu(child, &tg->children, siblings) { 7923 period = ktime_to_ns(child->rt_bandwidth.rt_period); 7924 runtime = child->rt_bandwidth.rt_runtime; 7925 7926 if (child == d->tg) { 7927 period = d->rt_period; 7928 runtime = d->rt_runtime; 7929 } 7930 7931 sum += to_ratio(period, runtime); 7932 } 7933 7934 if (sum > total) 7935 return -EINVAL; 7936 7937 return 0; 7938 } 7939 7940 static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime) 7941 { 7942 int ret; 7943 7944 struct rt_schedulable_data data = { 7945 .tg = tg, 7946 .rt_period = period, 7947 .rt_runtime = runtime, 7948 }; 7949 7950 rcu_read_lock(); 7951 ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data); 7952 rcu_read_unlock(); 7953 7954 return ret; 7955 } 7956 7957 static int tg_set_rt_bandwidth(struct task_group *tg, 7958 u64 rt_period, u64 rt_runtime) 7959 { 7960 int i, err = 0; 7961 7962 /* 7963 * Disallowing the root group RT runtime is BAD, it would disallow the 7964 * kernel creating (and or operating) RT threads. 7965 */ 7966 if (tg == &root_task_group && rt_runtime == 0) 7967 return -EINVAL; 7968 7969 /* No period doesn't make any sense. */ 7970 if (rt_period == 0) 7971 return -EINVAL; 7972 7973 mutex_lock(&rt_constraints_mutex); 7974 read_lock(&tasklist_lock); 7975 err = __rt_schedulable(tg, rt_period, rt_runtime); 7976 if (err) 7977 goto unlock; 7978 7979 raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock); 7980 tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period); 7981 tg->rt_bandwidth.rt_runtime = rt_runtime; 7982 7983 for_each_possible_cpu(i) { 7984 struct rt_rq *rt_rq = tg->rt_rq[i]; 7985 7986 raw_spin_lock(&rt_rq->rt_runtime_lock); 7987 rt_rq->rt_runtime = rt_runtime; 7988 raw_spin_unlock(&rt_rq->rt_runtime_lock); 7989 } 7990 raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock); 7991 unlock: 7992 read_unlock(&tasklist_lock); 7993 mutex_unlock(&rt_constraints_mutex); 7994 7995 return err; 7996 } 7997 7998 static int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us) 7999 { 8000 u64 rt_runtime, rt_period; 8001 8002 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period); 8003 rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC; 8004 if (rt_runtime_us < 0) 8005 rt_runtime = RUNTIME_INF; 8006 8007 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime); 8008 } 8009 8010 static long sched_group_rt_runtime(struct task_group *tg) 8011 { 8012 u64 rt_runtime_us; 8013 8014 if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF) 8015 return -1; 8016 8017 rt_runtime_us = tg->rt_bandwidth.rt_runtime; 8018 do_div(rt_runtime_us, NSEC_PER_USEC); 8019 return rt_runtime_us; 8020 } 8021 8022 static int sched_group_set_rt_period(struct task_group *tg, u64 rt_period_us) 8023 { 8024 u64 rt_runtime, rt_period; 8025 8026 rt_period = rt_period_us * NSEC_PER_USEC; 8027 rt_runtime = tg->rt_bandwidth.rt_runtime; 8028 8029 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime); 8030 } 8031 8032 static long sched_group_rt_period(struct task_group *tg) 8033 { 8034 u64 rt_period_us; 8035 8036 rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period); 8037 do_div(rt_period_us, NSEC_PER_USEC); 8038 return rt_period_us; 8039 } 8040 #endif /* CONFIG_RT_GROUP_SCHED */ 8041 8042 #ifdef CONFIG_RT_GROUP_SCHED 8043 static int sched_rt_global_constraints(void) 8044 { 8045 int ret = 0; 8046 8047 mutex_lock(&rt_constraints_mutex); 8048 read_lock(&tasklist_lock); 8049 ret = __rt_schedulable(NULL, 0, 0); 8050 read_unlock(&tasklist_lock); 8051 mutex_unlock(&rt_constraints_mutex); 8052 8053 return ret; 8054 } 8055 8056 static int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk) 8057 { 8058 /* Don't accept realtime tasks when there is no way for them to run */ 8059 if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0) 8060 return 0; 8061 8062 return 1; 8063 } 8064 8065 #else /* !CONFIG_RT_GROUP_SCHED */ 8066 static int sched_rt_global_constraints(void) 8067 { 8068 unsigned long flags; 8069 int i; 8070 8071 raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags); 8072 for_each_possible_cpu(i) { 8073 struct rt_rq *rt_rq = &cpu_rq(i)->rt; 8074 8075 raw_spin_lock(&rt_rq->rt_runtime_lock); 8076 rt_rq->rt_runtime = global_rt_runtime(); 8077 raw_spin_unlock(&rt_rq->rt_runtime_lock); 8078 } 8079 raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags); 8080 8081 return 0; 8082 } 8083 #endif /* CONFIG_RT_GROUP_SCHED */ 8084 8085 static int sched_dl_global_validate(void) 8086 { 8087 u64 runtime = global_rt_runtime(); 8088 u64 period = global_rt_period(); 8089 u64 new_bw = to_ratio(period, runtime); 8090 struct dl_bw *dl_b; 8091 int cpu, ret = 0; 8092 unsigned long flags; 8093 8094 /* 8095 * Here we want to check the bandwidth not being set to some 8096 * value smaller than the currently allocated bandwidth in 8097 * any of the root_domains. 8098 * 8099 * FIXME: Cycling on all the CPUs is overdoing, but simpler than 8100 * cycling on root_domains... Discussion on different/better 8101 * solutions is welcome! 8102 */ 8103 for_each_possible_cpu(cpu) { 8104 rcu_read_lock_sched(); 8105 dl_b = dl_bw_of(cpu); 8106 8107 raw_spin_lock_irqsave(&dl_b->lock, flags); 8108 if (new_bw < dl_b->total_bw) 8109 ret = -EBUSY; 8110 raw_spin_unlock_irqrestore(&dl_b->lock, flags); 8111 8112 rcu_read_unlock_sched(); 8113 8114 if (ret) 8115 break; 8116 } 8117 8118 return ret; 8119 } 8120 8121 static void sched_dl_do_global(void) 8122 { 8123 u64 new_bw = -1; 8124 struct dl_bw *dl_b; 8125 int cpu; 8126 unsigned long flags; 8127 8128 def_dl_bandwidth.dl_period = global_rt_period(); 8129 def_dl_bandwidth.dl_runtime = global_rt_runtime(); 8130 8131 if (global_rt_runtime() != RUNTIME_INF) 8132 new_bw = to_ratio(global_rt_period(), global_rt_runtime()); 8133 8134 /* 8135 * FIXME: As above... 8136 */ 8137 for_each_possible_cpu(cpu) { 8138 rcu_read_lock_sched(); 8139 dl_b = dl_bw_of(cpu); 8140 8141 raw_spin_lock_irqsave(&dl_b->lock, flags); 8142 dl_b->bw = new_bw; 8143 raw_spin_unlock_irqrestore(&dl_b->lock, flags); 8144 8145 rcu_read_unlock_sched(); 8146 } 8147 } 8148 8149 static int sched_rt_global_validate(void) 8150 { 8151 if (sysctl_sched_rt_period <= 0) 8152 return -EINVAL; 8153 8154 if ((sysctl_sched_rt_runtime != RUNTIME_INF) && 8155 (sysctl_sched_rt_runtime > sysctl_sched_rt_period)) 8156 return -EINVAL; 8157 8158 return 0; 8159 } 8160 8161 static void sched_rt_do_global(void) 8162 { 8163 def_rt_bandwidth.rt_runtime = global_rt_runtime(); 8164 def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period()); 8165 } 8166 8167 int sched_rt_handler(struct ctl_table *table, int write, 8168 void __user *buffer, size_t *lenp, 8169 loff_t *ppos) 8170 { 8171 int old_period, old_runtime; 8172 static DEFINE_MUTEX(mutex); 8173 int ret; 8174 8175 mutex_lock(&mutex); 8176 old_period = sysctl_sched_rt_period; 8177 old_runtime = sysctl_sched_rt_runtime; 8178 8179 ret = proc_dointvec(table, write, buffer, lenp, ppos); 8180 8181 if (!ret && write) { 8182 ret = sched_rt_global_validate(); 8183 if (ret) 8184 goto undo; 8185 8186 ret = sched_dl_global_validate(); 8187 if (ret) 8188 goto undo; 8189 8190 ret = sched_rt_global_constraints(); 8191 if (ret) 8192 goto undo; 8193 8194 sched_rt_do_global(); 8195 sched_dl_do_global(); 8196 } 8197 if (0) { 8198 undo: 8199 sysctl_sched_rt_period = old_period; 8200 sysctl_sched_rt_runtime = old_runtime; 8201 } 8202 mutex_unlock(&mutex); 8203 8204 return ret; 8205 } 8206 8207 int sched_rr_handler(struct ctl_table *table, int write, 8208 void __user *buffer, size_t *lenp, 8209 loff_t *ppos) 8210 { 8211 int ret; 8212 static DEFINE_MUTEX(mutex); 8213 8214 mutex_lock(&mutex); 8215 ret = proc_dointvec(table, write, buffer, lenp, ppos); 8216 /* make sure that internally we keep jiffies */ 8217 /* also, writing zero resets timeslice to default */ 8218 if (!ret && write) { 8219 sched_rr_timeslice = sched_rr_timeslice <= 0 ? 8220 RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice); 8221 } 8222 mutex_unlock(&mutex); 8223 return ret; 8224 } 8225 8226 #ifdef CONFIG_CGROUP_SCHED 8227 8228 static inline struct task_group *css_tg(struct cgroup_subsys_state *css) 8229 { 8230 return css ? container_of(css, struct task_group, css) : NULL; 8231 } 8232 8233 static struct cgroup_subsys_state * 8234 cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) 8235 { 8236 struct task_group *parent = css_tg(parent_css); 8237 struct task_group *tg; 8238 8239 if (!parent) { 8240 /* This is early initialization for the top cgroup */ 8241 return &root_task_group.css; 8242 } 8243 8244 tg = sched_create_group(parent); 8245 if (IS_ERR(tg)) 8246 return ERR_PTR(-ENOMEM); 8247 8248 sched_online_group(tg, parent); 8249 8250 return &tg->css; 8251 } 8252 8253 static void cpu_cgroup_css_released(struct cgroup_subsys_state *css) 8254 { 8255 struct task_group *tg = css_tg(css); 8256 8257 sched_offline_group(tg); 8258 } 8259 8260 static void cpu_cgroup_css_free(struct cgroup_subsys_state *css) 8261 { 8262 struct task_group *tg = css_tg(css); 8263 8264 /* 8265 * Relies on the RCU grace period between css_released() and this. 8266 */ 8267 sched_free_group(tg); 8268 } 8269 8270 /* 8271 * This is called before wake_up_new_task(), therefore we really only 8272 * have to set its group bits, all the other stuff does not apply. 8273 */ 8274 static void cpu_cgroup_fork(struct task_struct *task) 8275 { 8276 struct rq_flags rf; 8277 struct rq *rq; 8278 8279 rq = task_rq_lock(task, &rf); 8280 8281 sched_change_group(task, TASK_SET_GROUP); 8282 8283 task_rq_unlock(rq, task, &rf); 8284 } 8285 8286 static int cpu_cgroup_can_attach(struct cgroup_taskset *tset) 8287 { 8288 struct task_struct *task; 8289 struct cgroup_subsys_state *css; 8290 int ret = 0; 8291 8292 cgroup_taskset_for_each(task, css, tset) { 8293 #ifdef CONFIG_RT_GROUP_SCHED 8294 if (!sched_rt_can_attach(css_tg(css), task)) 8295 return -EINVAL; 8296 #else 8297 /* We don't support RT-tasks being in separate groups */ 8298 if (task->sched_class != &fair_sched_class) 8299 return -EINVAL; 8300 #endif 8301 /* 8302 * Serialize against wake_up_new_task() such that if its 8303 * running, we're sure to observe its full state. 8304 */ 8305 raw_spin_lock_irq(&task->pi_lock); 8306 /* 8307 * Avoid calling sched_move_task() before wake_up_new_task() 8308 * has happened. This would lead to problems with PELT, due to 8309 * move wanting to detach+attach while we're not attached yet. 8310 */ 8311 if (task->state == TASK_NEW) 8312 ret = -EINVAL; 8313 raw_spin_unlock_irq(&task->pi_lock); 8314 8315 if (ret) 8316 break; 8317 } 8318 return ret; 8319 } 8320 8321 static void cpu_cgroup_attach(struct cgroup_taskset *tset) 8322 { 8323 struct task_struct *task; 8324 struct cgroup_subsys_state *css; 8325 8326 cgroup_taskset_for_each(task, css, tset) 8327 sched_move_task(task); 8328 } 8329 8330 #ifdef CONFIG_FAIR_GROUP_SCHED 8331 static int cpu_shares_write_u64(struct cgroup_subsys_state *css, 8332 struct cftype *cftype, u64 shareval) 8333 { 8334 return sched_group_set_shares(css_tg(css), scale_load(shareval)); 8335 } 8336 8337 static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css, 8338 struct cftype *cft) 8339 { 8340 struct task_group *tg = css_tg(css); 8341 8342 return (u64) scale_load_down(tg->shares); 8343 } 8344 8345 #ifdef CONFIG_CFS_BANDWIDTH 8346 static DEFINE_MUTEX(cfs_constraints_mutex); 8347 8348 const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */ 8349 const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */ 8350 8351 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime); 8352 8353 static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota) 8354 { 8355 int i, ret = 0, runtime_enabled, runtime_was_enabled; 8356 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 8357 8358 if (tg == &root_task_group) 8359 return -EINVAL; 8360 8361 /* 8362 * Ensure we have at some amount of bandwidth every period. This is 8363 * to prevent reaching a state of large arrears when throttled via 8364 * entity_tick() resulting in prolonged exit starvation. 8365 */ 8366 if (quota < min_cfs_quota_period || period < min_cfs_quota_period) 8367 return -EINVAL; 8368 8369 /* 8370 * Likewise, bound things on the otherside by preventing insane quota 8371 * periods. This also allows us to normalize in computing quota 8372 * feasibility. 8373 */ 8374 if (period > max_cfs_quota_period) 8375 return -EINVAL; 8376 8377 /* 8378 * Prevent race between setting of cfs_rq->runtime_enabled and 8379 * unthrottle_offline_cfs_rqs(). 8380 */ 8381 get_online_cpus(); 8382 mutex_lock(&cfs_constraints_mutex); 8383 ret = __cfs_schedulable(tg, period, quota); 8384 if (ret) 8385 goto out_unlock; 8386 8387 runtime_enabled = quota != RUNTIME_INF; 8388 runtime_was_enabled = cfs_b->quota != RUNTIME_INF; 8389 /* 8390 * If we need to toggle cfs_bandwidth_used, off->on must occur 8391 * before making related changes, and on->off must occur afterwards 8392 */ 8393 if (runtime_enabled && !runtime_was_enabled) 8394 cfs_bandwidth_usage_inc(); 8395 raw_spin_lock_irq(&cfs_b->lock); 8396 cfs_b->period = ns_to_ktime(period); 8397 cfs_b->quota = quota; 8398 8399 __refill_cfs_bandwidth_runtime(cfs_b); 8400 /* restart the period timer (if active) to handle new period expiry */ 8401 if (runtime_enabled) 8402 start_cfs_bandwidth(cfs_b); 8403 raw_spin_unlock_irq(&cfs_b->lock); 8404 8405 for_each_online_cpu(i) { 8406 struct cfs_rq *cfs_rq = tg->cfs_rq[i]; 8407 struct rq *rq = cfs_rq->rq; 8408 8409 raw_spin_lock_irq(&rq->lock); 8410 cfs_rq->runtime_enabled = runtime_enabled; 8411 cfs_rq->runtime_remaining = 0; 8412 8413 if (cfs_rq->throttled) 8414 unthrottle_cfs_rq(cfs_rq); 8415 raw_spin_unlock_irq(&rq->lock); 8416 } 8417 if (runtime_was_enabled && !runtime_enabled) 8418 cfs_bandwidth_usage_dec(); 8419 out_unlock: 8420 mutex_unlock(&cfs_constraints_mutex); 8421 put_online_cpus(); 8422 8423 return ret; 8424 } 8425 8426 int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us) 8427 { 8428 u64 quota, period; 8429 8430 period = ktime_to_ns(tg->cfs_bandwidth.period); 8431 if (cfs_quota_us < 0) 8432 quota = RUNTIME_INF; 8433 else 8434 quota = (u64)cfs_quota_us * NSEC_PER_USEC; 8435 8436 return tg_set_cfs_bandwidth(tg, period, quota); 8437 } 8438 8439 long tg_get_cfs_quota(struct task_group *tg) 8440 { 8441 u64 quota_us; 8442 8443 if (tg->cfs_bandwidth.quota == RUNTIME_INF) 8444 return -1; 8445 8446 quota_us = tg->cfs_bandwidth.quota; 8447 do_div(quota_us, NSEC_PER_USEC); 8448 8449 return quota_us; 8450 } 8451 8452 int tg_set_cfs_period(struct task_group *tg, long cfs_period_us) 8453 { 8454 u64 quota, period; 8455 8456 period = (u64)cfs_period_us * NSEC_PER_USEC; 8457 quota = tg->cfs_bandwidth.quota; 8458 8459 return tg_set_cfs_bandwidth(tg, period, quota); 8460 } 8461 8462 long tg_get_cfs_period(struct task_group *tg) 8463 { 8464 u64 cfs_period_us; 8465 8466 cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period); 8467 do_div(cfs_period_us, NSEC_PER_USEC); 8468 8469 return cfs_period_us; 8470 } 8471 8472 static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css, 8473 struct cftype *cft) 8474 { 8475 return tg_get_cfs_quota(css_tg(css)); 8476 } 8477 8478 static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css, 8479 struct cftype *cftype, s64 cfs_quota_us) 8480 { 8481 return tg_set_cfs_quota(css_tg(css), cfs_quota_us); 8482 } 8483 8484 static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css, 8485 struct cftype *cft) 8486 { 8487 return tg_get_cfs_period(css_tg(css)); 8488 } 8489 8490 static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css, 8491 struct cftype *cftype, u64 cfs_period_us) 8492 { 8493 return tg_set_cfs_period(css_tg(css), cfs_period_us); 8494 } 8495 8496 struct cfs_schedulable_data { 8497 struct task_group *tg; 8498 u64 period, quota; 8499 }; 8500 8501 /* 8502 * normalize group quota/period to be quota/max_period 8503 * note: units are usecs 8504 */ 8505 static u64 normalize_cfs_quota(struct task_group *tg, 8506 struct cfs_schedulable_data *d) 8507 { 8508 u64 quota, period; 8509 8510 if (tg == d->tg) { 8511 period = d->period; 8512 quota = d->quota; 8513 } else { 8514 period = tg_get_cfs_period(tg); 8515 quota = tg_get_cfs_quota(tg); 8516 } 8517 8518 /* note: these should typically be equivalent */ 8519 if (quota == RUNTIME_INF || quota == -1) 8520 return RUNTIME_INF; 8521 8522 return to_ratio(period, quota); 8523 } 8524 8525 static int tg_cfs_schedulable_down(struct task_group *tg, void *data) 8526 { 8527 struct cfs_schedulable_data *d = data; 8528 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 8529 s64 quota = 0, parent_quota = -1; 8530 8531 if (!tg->parent) { 8532 quota = RUNTIME_INF; 8533 } else { 8534 struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth; 8535 8536 quota = normalize_cfs_quota(tg, d); 8537 parent_quota = parent_b->hierarchical_quota; 8538 8539 /* 8540 * ensure max(child_quota) <= parent_quota, inherit when no 8541 * limit is set 8542 */ 8543 if (quota == RUNTIME_INF) 8544 quota = parent_quota; 8545 else if (parent_quota != RUNTIME_INF && quota > parent_quota) 8546 return -EINVAL; 8547 } 8548 cfs_b->hierarchical_quota = quota; 8549 8550 return 0; 8551 } 8552 8553 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota) 8554 { 8555 int ret; 8556 struct cfs_schedulable_data data = { 8557 .tg = tg, 8558 .period = period, 8559 .quota = quota, 8560 }; 8561 8562 if (quota != RUNTIME_INF) { 8563 do_div(data.period, NSEC_PER_USEC); 8564 do_div(data.quota, NSEC_PER_USEC); 8565 } 8566 8567 rcu_read_lock(); 8568 ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data); 8569 rcu_read_unlock(); 8570 8571 return ret; 8572 } 8573 8574 static int cpu_stats_show(struct seq_file *sf, void *v) 8575 { 8576 struct task_group *tg = css_tg(seq_css(sf)); 8577 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 8578 8579 seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods); 8580 seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled); 8581 seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time); 8582 8583 return 0; 8584 } 8585 #endif /* CONFIG_CFS_BANDWIDTH */ 8586 #endif /* CONFIG_FAIR_GROUP_SCHED */ 8587 8588 #ifdef CONFIG_RT_GROUP_SCHED 8589 static int cpu_rt_runtime_write(struct cgroup_subsys_state *css, 8590 struct cftype *cft, s64 val) 8591 { 8592 return sched_group_set_rt_runtime(css_tg(css), val); 8593 } 8594 8595 static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css, 8596 struct cftype *cft) 8597 { 8598 return sched_group_rt_runtime(css_tg(css)); 8599 } 8600 8601 static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css, 8602 struct cftype *cftype, u64 rt_period_us) 8603 { 8604 return sched_group_set_rt_period(css_tg(css), rt_period_us); 8605 } 8606 8607 static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css, 8608 struct cftype *cft) 8609 { 8610 return sched_group_rt_period(css_tg(css)); 8611 } 8612 #endif /* CONFIG_RT_GROUP_SCHED */ 8613 8614 static struct cftype cpu_files[] = { 8615 #ifdef CONFIG_FAIR_GROUP_SCHED 8616 { 8617 .name = "shares", 8618 .read_u64 = cpu_shares_read_u64, 8619 .write_u64 = cpu_shares_write_u64, 8620 }, 8621 #endif 8622 #ifdef CONFIG_CFS_BANDWIDTH 8623 { 8624 .name = "cfs_quota_us", 8625 .read_s64 = cpu_cfs_quota_read_s64, 8626 .write_s64 = cpu_cfs_quota_write_s64, 8627 }, 8628 { 8629 .name = "cfs_period_us", 8630 .read_u64 = cpu_cfs_period_read_u64, 8631 .write_u64 = cpu_cfs_period_write_u64, 8632 }, 8633 { 8634 .name = "stat", 8635 .seq_show = cpu_stats_show, 8636 }, 8637 #endif 8638 #ifdef CONFIG_RT_GROUP_SCHED 8639 { 8640 .name = "rt_runtime_us", 8641 .read_s64 = cpu_rt_runtime_read, 8642 .write_s64 = cpu_rt_runtime_write, 8643 }, 8644 { 8645 .name = "rt_period_us", 8646 .read_u64 = cpu_rt_period_read_uint, 8647 .write_u64 = cpu_rt_period_write_uint, 8648 }, 8649 #endif 8650 { } /* terminate */ 8651 }; 8652 8653 struct cgroup_subsys cpu_cgrp_subsys = { 8654 .css_alloc = cpu_cgroup_css_alloc, 8655 .css_released = cpu_cgroup_css_released, 8656 .css_free = cpu_cgroup_css_free, 8657 .fork = cpu_cgroup_fork, 8658 .can_attach = cpu_cgroup_can_attach, 8659 .attach = cpu_cgroup_attach, 8660 .legacy_cftypes = cpu_files, 8661 .early_init = true, 8662 }; 8663 8664 #endif /* CONFIG_CGROUP_SCHED */ 8665 8666 void dump_cpu_task(int cpu) 8667 { 8668 pr_info("Task dump for CPU %d:\n", cpu); 8669 sched_show_task(cpu_curr(cpu)); 8670 } 8671 8672 /* 8673 * Nice levels are multiplicative, with a gentle 10% change for every 8674 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to 8675 * nice 1, it will get ~10% less CPU time than another CPU-bound task 8676 * that remained on nice 0. 8677 * 8678 * The "10% effect" is relative and cumulative: from _any_ nice level, 8679 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level 8680 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25. 8681 * If a task goes up by ~10% and another task goes down by ~10% then 8682 * the relative distance between them is ~25%.) 8683 */ 8684 const int sched_prio_to_weight[40] = { 8685 /* -20 */ 88761, 71755, 56483, 46273, 36291, 8686 /* -15 */ 29154, 23254, 18705, 14949, 11916, 8687 /* -10 */ 9548, 7620, 6100, 4904, 3906, 8688 /* -5 */ 3121, 2501, 1991, 1586, 1277, 8689 /* 0 */ 1024, 820, 655, 526, 423, 8690 /* 5 */ 335, 272, 215, 172, 137, 8691 /* 10 */ 110, 87, 70, 56, 45, 8692 /* 15 */ 36, 29, 23, 18, 15, 8693 }; 8694 8695 /* 8696 * Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated. 8697 * 8698 * In cases where the weight does not change often, we can use the 8699 * precalculated inverse to speed up arithmetics by turning divisions 8700 * into multiplications: 8701 */ 8702 const u32 sched_prio_to_wmult[40] = { 8703 /* -20 */ 48388, 59856, 76040, 92818, 118348, 8704 /* -15 */ 147320, 184698, 229616, 287308, 360437, 8705 /* -10 */ 449829, 563644, 704093, 875809, 1099582, 8706 /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326, 8707 /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587, 8708 /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126, 8709 /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717, 8710 /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153, 8711 }; 8712