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