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/mm.h> 30 #include <linux/module.h> 31 #include <linux/nmi.h> 32 #include <linux/init.h> 33 #include <linux/uaccess.h> 34 #include <linux/highmem.h> 35 #include <asm/mmu_context.h> 36 #include <linux/interrupt.h> 37 #include <linux/capability.h> 38 #include <linux/completion.h> 39 #include <linux/kernel_stat.h> 40 #include <linux/debug_locks.h> 41 #include <linux/perf_event.h> 42 #include <linux/security.h> 43 #include <linux/notifier.h> 44 #include <linux/profile.h> 45 #include <linux/freezer.h> 46 #include <linux/vmalloc.h> 47 #include <linux/blkdev.h> 48 #include <linux/delay.h> 49 #include <linux/pid_namespace.h> 50 #include <linux/smp.h> 51 #include <linux/threads.h> 52 #include <linux/timer.h> 53 #include <linux/rcupdate.h> 54 #include <linux/cpu.h> 55 #include <linux/cpuset.h> 56 #include <linux/percpu.h> 57 #include <linux/proc_fs.h> 58 #include <linux/seq_file.h> 59 #include <linux/sysctl.h> 60 #include <linux/syscalls.h> 61 #include <linux/times.h> 62 #include <linux/tsacct_kern.h> 63 #include <linux/kprobes.h> 64 #include <linux/delayacct.h> 65 #include <linux/unistd.h> 66 #include <linux/pagemap.h> 67 #include <linux/hrtimer.h> 68 #include <linux/tick.h> 69 #include <linux/debugfs.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/binfmts.h> 75 #include <linux/context_tracking.h> 76 #include <linux/compiler.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 void start_bandwidth_timer(struct hrtimer *period_timer, ktime_t period) 94 { 95 unsigned long delta; 96 ktime_t soft, hard, now; 97 98 for (;;) { 99 if (hrtimer_active(period_timer)) 100 break; 101 102 now = hrtimer_cb_get_time(period_timer); 103 hrtimer_forward(period_timer, now, period); 104 105 soft = hrtimer_get_softexpires(period_timer); 106 hard = hrtimer_get_expires(period_timer); 107 delta = ktime_to_ns(ktime_sub(hard, soft)); 108 __hrtimer_start_range_ns(period_timer, soft, delta, 109 HRTIMER_MODE_ABS_PINNED, 0); 110 } 111 } 112 113 DEFINE_MUTEX(sched_domains_mutex); 114 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); 115 116 static void update_rq_clock_task(struct rq *rq, s64 delta); 117 118 void update_rq_clock(struct rq *rq) 119 { 120 s64 delta; 121 122 lockdep_assert_held(&rq->lock); 123 124 if (rq->clock_skip_update & RQCF_ACT_SKIP) 125 return; 126 127 delta = sched_clock_cpu(cpu_of(rq)) - rq->clock; 128 if (delta < 0) 129 return; 130 rq->clock += delta; 131 update_rq_clock_task(rq, delta); 132 } 133 134 /* 135 * Debugging: various feature bits 136 */ 137 138 #define SCHED_FEAT(name, enabled) \ 139 (1UL << __SCHED_FEAT_##name) * enabled | 140 141 const_debug unsigned int sysctl_sched_features = 142 #include "features.h" 143 0; 144 145 #undef SCHED_FEAT 146 147 #ifdef CONFIG_SCHED_DEBUG 148 #define SCHED_FEAT(name, enabled) \ 149 #name , 150 151 static const char * const sched_feat_names[] = { 152 #include "features.h" 153 }; 154 155 #undef SCHED_FEAT 156 157 static int sched_feat_show(struct seq_file *m, void *v) 158 { 159 int i; 160 161 for (i = 0; i < __SCHED_FEAT_NR; i++) { 162 if (!(sysctl_sched_features & (1UL << i))) 163 seq_puts(m, "NO_"); 164 seq_printf(m, "%s ", sched_feat_names[i]); 165 } 166 seq_puts(m, "\n"); 167 168 return 0; 169 } 170 171 #ifdef HAVE_JUMP_LABEL 172 173 #define jump_label_key__true STATIC_KEY_INIT_TRUE 174 #define jump_label_key__false STATIC_KEY_INIT_FALSE 175 176 #define SCHED_FEAT(name, enabled) \ 177 jump_label_key__##enabled , 178 179 struct static_key sched_feat_keys[__SCHED_FEAT_NR] = { 180 #include "features.h" 181 }; 182 183 #undef SCHED_FEAT 184 185 static void sched_feat_disable(int i) 186 { 187 if (static_key_enabled(&sched_feat_keys[i])) 188 static_key_slow_dec(&sched_feat_keys[i]); 189 } 190 191 static void sched_feat_enable(int i) 192 { 193 if (!static_key_enabled(&sched_feat_keys[i])) 194 static_key_slow_inc(&sched_feat_keys[i]); 195 } 196 #else 197 static void sched_feat_disable(int i) { }; 198 static void sched_feat_enable(int i) { }; 199 #endif /* HAVE_JUMP_LABEL */ 200 201 static int sched_feat_set(char *cmp) 202 { 203 int i; 204 int neg = 0; 205 206 if (strncmp(cmp, "NO_", 3) == 0) { 207 neg = 1; 208 cmp += 3; 209 } 210 211 for (i = 0; i < __SCHED_FEAT_NR; i++) { 212 if (strcmp(cmp, sched_feat_names[i]) == 0) { 213 if (neg) { 214 sysctl_sched_features &= ~(1UL << i); 215 sched_feat_disable(i); 216 } else { 217 sysctl_sched_features |= (1UL << i); 218 sched_feat_enable(i); 219 } 220 break; 221 } 222 } 223 224 return i; 225 } 226 227 static ssize_t 228 sched_feat_write(struct file *filp, const char __user *ubuf, 229 size_t cnt, loff_t *ppos) 230 { 231 char buf[64]; 232 char *cmp; 233 int i; 234 struct inode *inode; 235 236 if (cnt > 63) 237 cnt = 63; 238 239 if (copy_from_user(&buf, ubuf, cnt)) 240 return -EFAULT; 241 242 buf[cnt] = 0; 243 cmp = strstrip(buf); 244 245 /* Ensure the static_key remains in a consistent state */ 246 inode = file_inode(filp); 247 mutex_lock(&inode->i_mutex); 248 i = sched_feat_set(cmp); 249 mutex_unlock(&inode->i_mutex); 250 if (i == __SCHED_FEAT_NR) 251 return -EINVAL; 252 253 *ppos += cnt; 254 255 return cnt; 256 } 257 258 static int sched_feat_open(struct inode *inode, struct file *filp) 259 { 260 return single_open(filp, sched_feat_show, NULL); 261 } 262 263 static const struct file_operations sched_feat_fops = { 264 .open = sched_feat_open, 265 .write = sched_feat_write, 266 .read = seq_read, 267 .llseek = seq_lseek, 268 .release = single_release, 269 }; 270 271 static __init int sched_init_debug(void) 272 { 273 debugfs_create_file("sched_features", 0644, NULL, NULL, 274 &sched_feat_fops); 275 276 return 0; 277 } 278 late_initcall(sched_init_debug); 279 #endif /* CONFIG_SCHED_DEBUG */ 280 281 /* 282 * Number of tasks to iterate in a single balance run. 283 * Limited because this is done with IRQs disabled. 284 */ 285 const_debug unsigned int sysctl_sched_nr_migrate = 32; 286 287 /* 288 * period over which we average the RT time consumption, measured 289 * in ms. 290 * 291 * default: 1s 292 */ 293 const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC; 294 295 /* 296 * period over which we measure -rt task cpu usage in us. 297 * default: 1s 298 */ 299 unsigned int sysctl_sched_rt_period = 1000000; 300 301 __read_mostly int scheduler_running; 302 303 /* 304 * part of the period that we allow rt tasks to run in us. 305 * default: 0.95s 306 */ 307 int sysctl_sched_rt_runtime = 950000; 308 309 /* cpus with isolated domains */ 310 cpumask_var_t cpu_isolated_map; 311 312 /* 313 * this_rq_lock - lock this runqueue and disable interrupts. 314 */ 315 static struct rq *this_rq_lock(void) 316 __acquires(rq->lock) 317 { 318 struct rq *rq; 319 320 local_irq_disable(); 321 rq = this_rq(); 322 raw_spin_lock(&rq->lock); 323 324 return rq; 325 } 326 327 #ifdef CONFIG_SCHED_HRTICK 328 /* 329 * Use HR-timers to deliver accurate preemption points. 330 */ 331 332 static void hrtick_clear(struct rq *rq) 333 { 334 if (hrtimer_active(&rq->hrtick_timer)) 335 hrtimer_cancel(&rq->hrtick_timer); 336 } 337 338 /* 339 * High-resolution timer tick. 340 * Runs from hardirq context with interrupts disabled. 341 */ 342 static enum hrtimer_restart hrtick(struct hrtimer *timer) 343 { 344 struct rq *rq = container_of(timer, struct rq, hrtick_timer); 345 346 WARN_ON_ONCE(cpu_of(rq) != smp_processor_id()); 347 348 raw_spin_lock(&rq->lock); 349 update_rq_clock(rq); 350 rq->curr->sched_class->task_tick(rq, rq->curr, 1); 351 raw_spin_unlock(&rq->lock); 352 353 return HRTIMER_NORESTART; 354 } 355 356 #ifdef CONFIG_SMP 357 358 static int __hrtick_restart(struct rq *rq) 359 { 360 struct hrtimer *timer = &rq->hrtick_timer; 361 ktime_t time = hrtimer_get_softexpires(timer); 362 363 return __hrtimer_start_range_ns(timer, time, 0, HRTIMER_MODE_ABS_PINNED, 0); 364 } 365 366 /* 367 * called from hardirq (IPI) context 368 */ 369 static void __hrtick_start(void *arg) 370 { 371 struct rq *rq = arg; 372 373 raw_spin_lock(&rq->lock); 374 __hrtick_restart(rq); 375 rq->hrtick_csd_pending = 0; 376 raw_spin_unlock(&rq->lock); 377 } 378 379 /* 380 * Called to set the hrtick timer state. 381 * 382 * called with rq->lock held and irqs disabled 383 */ 384 void hrtick_start(struct rq *rq, u64 delay) 385 { 386 struct hrtimer *timer = &rq->hrtick_timer; 387 ktime_t time; 388 s64 delta; 389 390 /* 391 * Don't schedule slices shorter than 10000ns, that just 392 * doesn't make sense and can cause timer DoS. 393 */ 394 delta = max_t(s64, delay, 10000LL); 395 time = ktime_add_ns(timer->base->get_time(), delta); 396 397 hrtimer_set_expires(timer, time); 398 399 if (rq == this_rq()) { 400 __hrtick_restart(rq); 401 } else if (!rq->hrtick_csd_pending) { 402 smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd); 403 rq->hrtick_csd_pending = 1; 404 } 405 } 406 407 static int 408 hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu) 409 { 410 int cpu = (int)(long)hcpu; 411 412 switch (action) { 413 case CPU_UP_CANCELED: 414 case CPU_UP_CANCELED_FROZEN: 415 case CPU_DOWN_PREPARE: 416 case CPU_DOWN_PREPARE_FROZEN: 417 case CPU_DEAD: 418 case CPU_DEAD_FROZEN: 419 hrtick_clear(cpu_rq(cpu)); 420 return NOTIFY_OK; 421 } 422 423 return NOTIFY_DONE; 424 } 425 426 static __init void init_hrtick(void) 427 { 428 hotcpu_notifier(hotplug_hrtick, 0); 429 } 430 #else 431 /* 432 * Called to set the hrtick timer state. 433 * 434 * called with rq->lock held and irqs disabled 435 */ 436 void hrtick_start(struct rq *rq, u64 delay) 437 { 438 /* 439 * Don't schedule slices shorter than 10000ns, that just 440 * doesn't make sense. Rely on vruntime for fairness. 441 */ 442 delay = max_t(u64, delay, 10000LL); 443 __hrtimer_start_range_ns(&rq->hrtick_timer, ns_to_ktime(delay), 0, 444 HRTIMER_MODE_REL_PINNED, 0); 445 } 446 447 static inline void init_hrtick(void) 448 { 449 } 450 #endif /* CONFIG_SMP */ 451 452 static void init_rq_hrtick(struct rq *rq) 453 { 454 #ifdef CONFIG_SMP 455 rq->hrtick_csd_pending = 0; 456 457 rq->hrtick_csd.flags = 0; 458 rq->hrtick_csd.func = __hrtick_start; 459 rq->hrtick_csd.info = rq; 460 #endif 461 462 hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 463 rq->hrtick_timer.function = hrtick; 464 } 465 #else /* CONFIG_SCHED_HRTICK */ 466 static inline void hrtick_clear(struct rq *rq) 467 { 468 } 469 470 static inline void init_rq_hrtick(struct rq *rq) 471 { 472 } 473 474 static inline void init_hrtick(void) 475 { 476 } 477 #endif /* CONFIG_SCHED_HRTICK */ 478 479 /* 480 * cmpxchg based fetch_or, macro so it works for different integer types 481 */ 482 #define fetch_or(ptr, val) \ 483 ({ typeof(*(ptr)) __old, __val = *(ptr); \ 484 for (;;) { \ 485 __old = cmpxchg((ptr), __val, __val | (val)); \ 486 if (__old == __val) \ 487 break; \ 488 __val = __old; \ 489 } \ 490 __old; \ 491 }) 492 493 #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG) 494 /* 495 * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG, 496 * this avoids any races wrt polling state changes and thereby avoids 497 * spurious IPIs. 498 */ 499 static bool set_nr_and_not_polling(struct task_struct *p) 500 { 501 struct thread_info *ti = task_thread_info(p); 502 return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG); 503 } 504 505 /* 506 * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set. 507 * 508 * If this returns true, then the idle task promises to call 509 * sched_ttwu_pending() and reschedule soon. 510 */ 511 static bool set_nr_if_polling(struct task_struct *p) 512 { 513 struct thread_info *ti = task_thread_info(p); 514 typeof(ti->flags) old, val = ACCESS_ONCE(ti->flags); 515 516 for (;;) { 517 if (!(val & _TIF_POLLING_NRFLAG)) 518 return false; 519 if (val & _TIF_NEED_RESCHED) 520 return true; 521 old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED); 522 if (old == val) 523 break; 524 val = old; 525 } 526 return true; 527 } 528 529 #else 530 static bool set_nr_and_not_polling(struct task_struct *p) 531 { 532 set_tsk_need_resched(p); 533 return true; 534 } 535 536 #ifdef CONFIG_SMP 537 static bool set_nr_if_polling(struct task_struct *p) 538 { 539 return false; 540 } 541 #endif 542 #endif 543 544 /* 545 * resched_curr - mark rq's current task 'to be rescheduled now'. 546 * 547 * On UP this means the setting of the need_resched flag, on SMP it 548 * might also involve a cross-CPU call to trigger the scheduler on 549 * the target CPU. 550 */ 551 void resched_curr(struct rq *rq) 552 { 553 struct task_struct *curr = rq->curr; 554 int cpu; 555 556 lockdep_assert_held(&rq->lock); 557 558 if (test_tsk_need_resched(curr)) 559 return; 560 561 cpu = cpu_of(rq); 562 563 if (cpu == smp_processor_id()) { 564 set_tsk_need_resched(curr); 565 set_preempt_need_resched(); 566 return; 567 } 568 569 if (set_nr_and_not_polling(curr)) 570 smp_send_reschedule(cpu); 571 else 572 trace_sched_wake_idle_without_ipi(cpu); 573 } 574 575 void resched_cpu(int cpu) 576 { 577 struct rq *rq = cpu_rq(cpu); 578 unsigned long flags; 579 580 if (!raw_spin_trylock_irqsave(&rq->lock, flags)) 581 return; 582 resched_curr(rq); 583 raw_spin_unlock_irqrestore(&rq->lock, flags); 584 } 585 586 #ifdef CONFIG_SMP 587 #ifdef CONFIG_NO_HZ_COMMON 588 /* 589 * In the semi idle case, use the nearest busy cpu for migrating timers 590 * from an idle cpu. This is good for power-savings. 591 * 592 * We don't do similar optimization for completely idle system, as 593 * selecting an idle cpu will add more delays to the timers than intended 594 * (as that cpu's timer base may not be uptodate wrt jiffies etc). 595 */ 596 int get_nohz_timer_target(int pinned) 597 { 598 int cpu = smp_processor_id(); 599 int i; 600 struct sched_domain *sd; 601 602 if (pinned || !get_sysctl_timer_migration() || !idle_cpu(cpu)) 603 return cpu; 604 605 rcu_read_lock(); 606 for_each_domain(cpu, sd) { 607 for_each_cpu(i, sched_domain_span(sd)) { 608 if (!idle_cpu(i)) { 609 cpu = i; 610 goto unlock; 611 } 612 } 613 } 614 unlock: 615 rcu_read_unlock(); 616 return cpu; 617 } 618 /* 619 * When add_timer_on() enqueues a timer into the timer wheel of an 620 * idle CPU then this timer might expire before the next timer event 621 * which is scheduled to wake up that CPU. In case of a completely 622 * idle system the next event might even be infinite time into the 623 * future. wake_up_idle_cpu() ensures that the CPU is woken up and 624 * leaves the inner idle loop so the newly added timer is taken into 625 * account when the CPU goes back to idle and evaluates the timer 626 * wheel for the next timer event. 627 */ 628 static void wake_up_idle_cpu(int cpu) 629 { 630 struct rq *rq = cpu_rq(cpu); 631 632 if (cpu == smp_processor_id()) 633 return; 634 635 if (set_nr_and_not_polling(rq->idle)) 636 smp_send_reschedule(cpu); 637 else 638 trace_sched_wake_idle_without_ipi(cpu); 639 } 640 641 static bool wake_up_full_nohz_cpu(int cpu) 642 { 643 /* 644 * We just need the target to call irq_exit() and re-evaluate 645 * the next tick. The nohz full kick at least implies that. 646 * If needed we can still optimize that later with an 647 * empty IRQ. 648 */ 649 if (tick_nohz_full_cpu(cpu)) { 650 if (cpu != smp_processor_id() || 651 tick_nohz_tick_stopped()) 652 tick_nohz_full_kick_cpu(cpu); 653 return true; 654 } 655 656 return false; 657 } 658 659 void wake_up_nohz_cpu(int cpu) 660 { 661 if (!wake_up_full_nohz_cpu(cpu)) 662 wake_up_idle_cpu(cpu); 663 } 664 665 static inline bool got_nohz_idle_kick(void) 666 { 667 int cpu = smp_processor_id(); 668 669 if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu))) 670 return false; 671 672 if (idle_cpu(cpu) && !need_resched()) 673 return true; 674 675 /* 676 * We can't run Idle Load Balance on this CPU for this time so we 677 * cancel it and clear NOHZ_BALANCE_KICK 678 */ 679 clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)); 680 return false; 681 } 682 683 #else /* CONFIG_NO_HZ_COMMON */ 684 685 static inline bool got_nohz_idle_kick(void) 686 { 687 return false; 688 } 689 690 #endif /* CONFIG_NO_HZ_COMMON */ 691 692 #ifdef CONFIG_NO_HZ_FULL 693 bool sched_can_stop_tick(void) 694 { 695 /* 696 * FIFO realtime policy runs the highest priority task. Other runnable 697 * tasks are of a lower priority. The scheduler tick does nothing. 698 */ 699 if (current->policy == SCHED_FIFO) 700 return true; 701 702 /* 703 * Round-robin realtime tasks time slice with other tasks at the same 704 * realtime priority. Is this task the only one at this priority? 705 */ 706 if (current->policy == SCHED_RR) { 707 struct sched_rt_entity *rt_se = ¤t->rt; 708 709 return rt_se->run_list.prev == rt_se->run_list.next; 710 } 711 712 /* 713 * More than one running task need preemption. 714 * nr_running update is assumed to be visible 715 * after IPI is sent from wakers. 716 */ 717 if (this_rq()->nr_running > 1) 718 return false; 719 720 return true; 721 } 722 #endif /* CONFIG_NO_HZ_FULL */ 723 724 void sched_avg_update(struct rq *rq) 725 { 726 s64 period = sched_avg_period(); 727 728 while ((s64)(rq_clock(rq) - rq->age_stamp) > period) { 729 /* 730 * Inline assembly required to prevent the compiler 731 * optimising this loop into a divmod call. 732 * See __iter_div_u64_rem() for another example of this. 733 */ 734 asm("" : "+rm" (rq->age_stamp)); 735 rq->age_stamp += period; 736 rq->rt_avg /= 2; 737 } 738 } 739 740 #endif /* CONFIG_SMP */ 741 742 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \ 743 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH))) 744 /* 745 * Iterate task_group tree rooted at *from, calling @down when first entering a 746 * node and @up when leaving it for the final time. 747 * 748 * Caller must hold rcu_lock or sufficient equivalent. 749 */ 750 int walk_tg_tree_from(struct task_group *from, 751 tg_visitor down, tg_visitor up, void *data) 752 { 753 struct task_group *parent, *child; 754 int ret; 755 756 parent = from; 757 758 down: 759 ret = (*down)(parent, data); 760 if (ret) 761 goto out; 762 list_for_each_entry_rcu(child, &parent->children, siblings) { 763 parent = child; 764 goto down; 765 766 up: 767 continue; 768 } 769 ret = (*up)(parent, data); 770 if (ret || parent == from) 771 goto out; 772 773 child = parent; 774 parent = parent->parent; 775 if (parent) 776 goto up; 777 out: 778 return ret; 779 } 780 781 int tg_nop(struct task_group *tg, void *data) 782 { 783 return 0; 784 } 785 #endif 786 787 static void set_load_weight(struct task_struct *p) 788 { 789 int prio = p->static_prio - MAX_RT_PRIO; 790 struct load_weight *load = &p->se.load; 791 792 /* 793 * SCHED_IDLE tasks get minimal weight: 794 */ 795 if (p->policy == SCHED_IDLE) { 796 load->weight = scale_load(WEIGHT_IDLEPRIO); 797 load->inv_weight = WMULT_IDLEPRIO; 798 return; 799 } 800 801 load->weight = scale_load(prio_to_weight[prio]); 802 load->inv_weight = prio_to_wmult[prio]; 803 } 804 805 static void enqueue_task(struct rq *rq, struct task_struct *p, int flags) 806 { 807 update_rq_clock(rq); 808 sched_info_queued(rq, p); 809 p->sched_class->enqueue_task(rq, p, flags); 810 } 811 812 static void dequeue_task(struct rq *rq, struct task_struct *p, int flags) 813 { 814 update_rq_clock(rq); 815 sched_info_dequeued(rq, p); 816 p->sched_class->dequeue_task(rq, p, flags); 817 } 818 819 void activate_task(struct rq *rq, struct task_struct *p, int flags) 820 { 821 if (task_contributes_to_load(p)) 822 rq->nr_uninterruptible--; 823 824 enqueue_task(rq, p, flags); 825 } 826 827 void deactivate_task(struct rq *rq, struct task_struct *p, int flags) 828 { 829 if (task_contributes_to_load(p)) 830 rq->nr_uninterruptible++; 831 832 dequeue_task(rq, p, flags); 833 } 834 835 static void update_rq_clock_task(struct rq *rq, s64 delta) 836 { 837 /* 838 * In theory, the compile should just see 0 here, and optimize out the call 839 * to sched_rt_avg_update. But I don't trust it... 840 */ 841 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) 842 s64 steal = 0, irq_delta = 0; 843 #endif 844 #ifdef CONFIG_IRQ_TIME_ACCOUNTING 845 irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time; 846 847 /* 848 * Since irq_time is only updated on {soft,}irq_exit, we might run into 849 * this case when a previous update_rq_clock() happened inside a 850 * {soft,}irq region. 851 * 852 * When this happens, we stop ->clock_task and only update the 853 * prev_irq_time stamp to account for the part that fit, so that a next 854 * update will consume the rest. This ensures ->clock_task is 855 * monotonic. 856 * 857 * It does however cause some slight miss-attribution of {soft,}irq 858 * time, a more accurate solution would be to update the irq_time using 859 * the current rq->clock timestamp, except that would require using 860 * atomic ops. 861 */ 862 if (irq_delta > delta) 863 irq_delta = delta; 864 865 rq->prev_irq_time += irq_delta; 866 delta -= irq_delta; 867 #endif 868 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING 869 if (static_key_false((¶virt_steal_rq_enabled))) { 870 steal = paravirt_steal_clock(cpu_of(rq)); 871 steal -= rq->prev_steal_time_rq; 872 873 if (unlikely(steal > delta)) 874 steal = delta; 875 876 rq->prev_steal_time_rq += steal; 877 delta -= steal; 878 } 879 #endif 880 881 rq->clock_task += delta; 882 883 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) 884 if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY)) 885 sched_rt_avg_update(rq, irq_delta + steal); 886 #endif 887 } 888 889 void sched_set_stop_task(int cpu, struct task_struct *stop) 890 { 891 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 }; 892 struct task_struct *old_stop = cpu_rq(cpu)->stop; 893 894 if (stop) { 895 /* 896 * Make it appear like a SCHED_FIFO task, its something 897 * userspace knows about and won't get confused about. 898 * 899 * Also, it will make PI more or less work without too 900 * much confusion -- but then, stop work should not 901 * rely on PI working anyway. 902 */ 903 sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m); 904 905 stop->sched_class = &stop_sched_class; 906 } 907 908 cpu_rq(cpu)->stop = stop; 909 910 if (old_stop) { 911 /* 912 * Reset it back to a normal scheduling class so that 913 * it can die in pieces. 914 */ 915 old_stop->sched_class = &rt_sched_class; 916 } 917 } 918 919 /* 920 * __normal_prio - return the priority that is based on the static prio 921 */ 922 static inline int __normal_prio(struct task_struct *p) 923 { 924 return p->static_prio; 925 } 926 927 /* 928 * Calculate the expected normal priority: i.e. priority 929 * without taking RT-inheritance into account. Might be 930 * boosted by interactivity modifiers. Changes upon fork, 931 * setprio syscalls, and whenever the interactivity 932 * estimator recalculates. 933 */ 934 static inline int normal_prio(struct task_struct *p) 935 { 936 int prio; 937 938 if (task_has_dl_policy(p)) 939 prio = MAX_DL_PRIO-1; 940 else if (task_has_rt_policy(p)) 941 prio = MAX_RT_PRIO-1 - p->rt_priority; 942 else 943 prio = __normal_prio(p); 944 return prio; 945 } 946 947 /* 948 * Calculate the current priority, i.e. the priority 949 * taken into account by the scheduler. This value might 950 * be boosted by RT tasks, or might be boosted by 951 * interactivity modifiers. Will be RT if the task got 952 * RT-boosted. If not then it returns p->normal_prio. 953 */ 954 static int effective_prio(struct task_struct *p) 955 { 956 p->normal_prio = normal_prio(p); 957 /* 958 * If we are RT tasks or we were boosted to RT priority, 959 * keep the priority unchanged. Otherwise, update priority 960 * to the normal priority: 961 */ 962 if (!rt_prio(p->prio)) 963 return p->normal_prio; 964 return p->prio; 965 } 966 967 /** 968 * task_curr - is this task currently executing on a CPU? 969 * @p: the task in question. 970 * 971 * Return: 1 if the task is currently executing. 0 otherwise. 972 */ 973 inline int task_curr(const struct task_struct *p) 974 { 975 return cpu_curr(task_cpu(p)) == p; 976 } 977 978 /* 979 * Can drop rq->lock because from sched_class::switched_from() methods drop it. 980 */ 981 static inline void check_class_changed(struct rq *rq, struct task_struct *p, 982 const struct sched_class *prev_class, 983 int oldprio) 984 { 985 if (prev_class != p->sched_class) { 986 if (prev_class->switched_from) 987 prev_class->switched_from(rq, p); 988 /* Possble rq->lock 'hole'. */ 989 p->sched_class->switched_to(rq, p); 990 } else if (oldprio != p->prio || dl_task(p)) 991 p->sched_class->prio_changed(rq, p, oldprio); 992 } 993 994 void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags) 995 { 996 const struct sched_class *class; 997 998 if (p->sched_class == rq->curr->sched_class) { 999 rq->curr->sched_class->check_preempt_curr(rq, p, flags); 1000 } else { 1001 for_each_class(class) { 1002 if (class == rq->curr->sched_class) 1003 break; 1004 if (class == p->sched_class) { 1005 resched_curr(rq); 1006 break; 1007 } 1008 } 1009 } 1010 1011 /* 1012 * A queue event has occurred, and we're going to schedule. In 1013 * this case, we can save a useless back to back clock update. 1014 */ 1015 if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr)) 1016 rq_clock_skip_update(rq, true); 1017 } 1018 1019 #ifdef CONFIG_SMP 1020 void set_task_cpu(struct task_struct *p, unsigned int new_cpu) 1021 { 1022 #ifdef CONFIG_SCHED_DEBUG 1023 /* 1024 * We should never call set_task_cpu() on a blocked task, 1025 * ttwu() will sort out the placement. 1026 */ 1027 WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING && 1028 !p->on_rq); 1029 1030 #ifdef CONFIG_LOCKDEP 1031 /* 1032 * The caller should hold either p->pi_lock or rq->lock, when changing 1033 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks. 1034 * 1035 * sched_move_task() holds both and thus holding either pins the cgroup, 1036 * see task_group(). 1037 * 1038 * Furthermore, all task_rq users should acquire both locks, see 1039 * task_rq_lock(). 1040 */ 1041 WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) || 1042 lockdep_is_held(&task_rq(p)->lock))); 1043 #endif 1044 #endif 1045 1046 trace_sched_migrate_task(p, new_cpu); 1047 1048 if (task_cpu(p) != new_cpu) { 1049 if (p->sched_class->migrate_task_rq) 1050 p->sched_class->migrate_task_rq(p, new_cpu); 1051 p->se.nr_migrations++; 1052 perf_sw_event_sched(PERF_COUNT_SW_CPU_MIGRATIONS, 1, 0); 1053 } 1054 1055 __set_task_cpu(p, new_cpu); 1056 } 1057 1058 static void __migrate_swap_task(struct task_struct *p, int cpu) 1059 { 1060 if (task_on_rq_queued(p)) { 1061 struct rq *src_rq, *dst_rq; 1062 1063 src_rq = task_rq(p); 1064 dst_rq = cpu_rq(cpu); 1065 1066 deactivate_task(src_rq, p, 0); 1067 set_task_cpu(p, cpu); 1068 activate_task(dst_rq, p, 0); 1069 check_preempt_curr(dst_rq, p, 0); 1070 } else { 1071 /* 1072 * Task isn't running anymore; make it appear like we migrated 1073 * it before it went to sleep. This means on wakeup we make the 1074 * previous cpu our targer instead of where it really is. 1075 */ 1076 p->wake_cpu = cpu; 1077 } 1078 } 1079 1080 struct migration_swap_arg { 1081 struct task_struct *src_task, *dst_task; 1082 int src_cpu, dst_cpu; 1083 }; 1084 1085 static int migrate_swap_stop(void *data) 1086 { 1087 struct migration_swap_arg *arg = data; 1088 struct rq *src_rq, *dst_rq; 1089 int ret = -EAGAIN; 1090 1091 src_rq = cpu_rq(arg->src_cpu); 1092 dst_rq = cpu_rq(arg->dst_cpu); 1093 1094 double_raw_lock(&arg->src_task->pi_lock, 1095 &arg->dst_task->pi_lock); 1096 double_rq_lock(src_rq, dst_rq); 1097 if (task_cpu(arg->dst_task) != arg->dst_cpu) 1098 goto unlock; 1099 1100 if (task_cpu(arg->src_task) != arg->src_cpu) 1101 goto unlock; 1102 1103 if (!cpumask_test_cpu(arg->dst_cpu, tsk_cpus_allowed(arg->src_task))) 1104 goto unlock; 1105 1106 if (!cpumask_test_cpu(arg->src_cpu, tsk_cpus_allowed(arg->dst_task))) 1107 goto unlock; 1108 1109 __migrate_swap_task(arg->src_task, arg->dst_cpu); 1110 __migrate_swap_task(arg->dst_task, arg->src_cpu); 1111 1112 ret = 0; 1113 1114 unlock: 1115 double_rq_unlock(src_rq, dst_rq); 1116 raw_spin_unlock(&arg->dst_task->pi_lock); 1117 raw_spin_unlock(&arg->src_task->pi_lock); 1118 1119 return ret; 1120 } 1121 1122 /* 1123 * Cross migrate two tasks 1124 */ 1125 int migrate_swap(struct task_struct *cur, struct task_struct *p) 1126 { 1127 struct migration_swap_arg arg; 1128 int ret = -EINVAL; 1129 1130 arg = (struct migration_swap_arg){ 1131 .src_task = cur, 1132 .src_cpu = task_cpu(cur), 1133 .dst_task = p, 1134 .dst_cpu = task_cpu(p), 1135 }; 1136 1137 if (arg.src_cpu == arg.dst_cpu) 1138 goto out; 1139 1140 /* 1141 * These three tests are all lockless; this is OK since all of them 1142 * will be re-checked with proper locks held further down the line. 1143 */ 1144 if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu)) 1145 goto out; 1146 1147 if (!cpumask_test_cpu(arg.dst_cpu, tsk_cpus_allowed(arg.src_task))) 1148 goto out; 1149 1150 if (!cpumask_test_cpu(arg.src_cpu, tsk_cpus_allowed(arg.dst_task))) 1151 goto out; 1152 1153 trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu); 1154 ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg); 1155 1156 out: 1157 return ret; 1158 } 1159 1160 struct migration_arg { 1161 struct task_struct *task; 1162 int dest_cpu; 1163 }; 1164 1165 static int migration_cpu_stop(void *data); 1166 1167 /* 1168 * wait_task_inactive - wait for a thread to unschedule. 1169 * 1170 * If @match_state is nonzero, it's the @p->state value just checked and 1171 * not expected to change. If it changes, i.e. @p might have woken up, 1172 * then return zero. When we succeed in waiting for @p to be off its CPU, 1173 * we return a positive number (its total switch count). If a second call 1174 * a short while later returns the same number, the caller can be sure that 1175 * @p has remained unscheduled the whole time. 1176 * 1177 * The caller must ensure that the task *will* unschedule sometime soon, 1178 * else this function might spin for a *long* time. This function can't 1179 * be called with interrupts off, or it may introduce deadlock with 1180 * smp_call_function() if an IPI is sent by the same process we are 1181 * waiting to become inactive. 1182 */ 1183 unsigned long wait_task_inactive(struct task_struct *p, long match_state) 1184 { 1185 unsigned long flags; 1186 int running, queued; 1187 unsigned long ncsw; 1188 struct rq *rq; 1189 1190 for (;;) { 1191 /* 1192 * We do the initial early heuristics without holding 1193 * any task-queue locks at all. We'll only try to get 1194 * the runqueue lock when things look like they will 1195 * work out! 1196 */ 1197 rq = task_rq(p); 1198 1199 /* 1200 * If the task is actively running on another CPU 1201 * still, just relax and busy-wait without holding 1202 * any locks. 1203 * 1204 * NOTE! Since we don't hold any locks, it's not 1205 * even sure that "rq" stays as the right runqueue! 1206 * But we don't care, since "task_running()" will 1207 * return false if the runqueue has changed and p 1208 * is actually now running somewhere else! 1209 */ 1210 while (task_running(rq, p)) { 1211 if (match_state && unlikely(p->state != match_state)) 1212 return 0; 1213 cpu_relax(); 1214 } 1215 1216 /* 1217 * Ok, time to look more closely! We need the rq 1218 * lock now, to be *sure*. If we're wrong, we'll 1219 * just go back and repeat. 1220 */ 1221 rq = task_rq_lock(p, &flags); 1222 trace_sched_wait_task(p); 1223 running = task_running(rq, p); 1224 queued = task_on_rq_queued(p); 1225 ncsw = 0; 1226 if (!match_state || p->state == match_state) 1227 ncsw = p->nvcsw | LONG_MIN; /* sets MSB */ 1228 task_rq_unlock(rq, p, &flags); 1229 1230 /* 1231 * If it changed from the expected state, bail out now. 1232 */ 1233 if (unlikely(!ncsw)) 1234 break; 1235 1236 /* 1237 * Was it really running after all now that we 1238 * checked with the proper locks actually held? 1239 * 1240 * Oops. Go back and try again.. 1241 */ 1242 if (unlikely(running)) { 1243 cpu_relax(); 1244 continue; 1245 } 1246 1247 /* 1248 * It's not enough that it's not actively running, 1249 * it must be off the runqueue _entirely_, and not 1250 * preempted! 1251 * 1252 * So if it was still runnable (but just not actively 1253 * running right now), it's preempted, and we should 1254 * yield - it could be a while. 1255 */ 1256 if (unlikely(queued)) { 1257 ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ); 1258 1259 set_current_state(TASK_UNINTERRUPTIBLE); 1260 schedule_hrtimeout(&to, HRTIMER_MODE_REL); 1261 continue; 1262 } 1263 1264 /* 1265 * Ahh, all good. It wasn't running, and it wasn't 1266 * runnable, which means that it will never become 1267 * running in the future either. We're all done! 1268 */ 1269 break; 1270 } 1271 1272 return ncsw; 1273 } 1274 1275 /*** 1276 * kick_process - kick a running thread to enter/exit the kernel 1277 * @p: the to-be-kicked thread 1278 * 1279 * Cause a process which is running on another CPU to enter 1280 * kernel-mode, without any delay. (to get signals handled.) 1281 * 1282 * NOTE: this function doesn't have to take the runqueue lock, 1283 * because all it wants to ensure is that the remote task enters 1284 * the kernel. If the IPI races and the task has been migrated 1285 * to another CPU then no harm is done and the purpose has been 1286 * achieved as well. 1287 */ 1288 void kick_process(struct task_struct *p) 1289 { 1290 int cpu; 1291 1292 preempt_disable(); 1293 cpu = task_cpu(p); 1294 if ((cpu != smp_processor_id()) && task_curr(p)) 1295 smp_send_reschedule(cpu); 1296 preempt_enable(); 1297 } 1298 EXPORT_SYMBOL_GPL(kick_process); 1299 #endif /* CONFIG_SMP */ 1300 1301 #ifdef CONFIG_SMP 1302 /* 1303 * ->cpus_allowed is protected by both rq->lock and p->pi_lock 1304 */ 1305 static int select_fallback_rq(int cpu, struct task_struct *p) 1306 { 1307 int nid = cpu_to_node(cpu); 1308 const struct cpumask *nodemask = NULL; 1309 enum { cpuset, possible, fail } state = cpuset; 1310 int dest_cpu; 1311 1312 /* 1313 * If the node that the cpu is on has been offlined, cpu_to_node() 1314 * will return -1. There is no cpu on the node, and we should 1315 * select the cpu on the other node. 1316 */ 1317 if (nid != -1) { 1318 nodemask = cpumask_of_node(nid); 1319 1320 /* Look for allowed, online CPU in same node. */ 1321 for_each_cpu(dest_cpu, nodemask) { 1322 if (!cpu_online(dest_cpu)) 1323 continue; 1324 if (!cpu_active(dest_cpu)) 1325 continue; 1326 if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p))) 1327 return dest_cpu; 1328 } 1329 } 1330 1331 for (;;) { 1332 /* Any allowed, online CPU? */ 1333 for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) { 1334 if (!cpu_online(dest_cpu)) 1335 continue; 1336 if (!cpu_active(dest_cpu)) 1337 continue; 1338 goto out; 1339 } 1340 1341 switch (state) { 1342 case cpuset: 1343 /* No more Mr. Nice Guy. */ 1344 cpuset_cpus_allowed_fallback(p); 1345 state = possible; 1346 break; 1347 1348 case possible: 1349 do_set_cpus_allowed(p, cpu_possible_mask); 1350 state = fail; 1351 break; 1352 1353 case fail: 1354 BUG(); 1355 break; 1356 } 1357 } 1358 1359 out: 1360 if (state != cpuset) { 1361 /* 1362 * Don't tell them about moving exiting tasks or 1363 * kernel threads (both mm NULL), since they never 1364 * leave kernel. 1365 */ 1366 if (p->mm && printk_ratelimit()) { 1367 printk_deferred("process %d (%s) no longer affine to cpu%d\n", 1368 task_pid_nr(p), p->comm, cpu); 1369 } 1370 } 1371 1372 return dest_cpu; 1373 } 1374 1375 /* 1376 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable. 1377 */ 1378 static inline 1379 int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags) 1380 { 1381 if (p->nr_cpus_allowed > 1) 1382 cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags); 1383 1384 /* 1385 * In order not to call set_task_cpu() on a blocking task we need 1386 * to rely on ttwu() to place the task on a valid ->cpus_allowed 1387 * cpu. 1388 * 1389 * Since this is common to all placement strategies, this lives here. 1390 * 1391 * [ this allows ->select_task() to simply return task_cpu(p) and 1392 * not worry about this generic constraint ] 1393 */ 1394 if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) || 1395 !cpu_online(cpu))) 1396 cpu = select_fallback_rq(task_cpu(p), p); 1397 1398 return cpu; 1399 } 1400 1401 static void update_avg(u64 *avg, u64 sample) 1402 { 1403 s64 diff = sample - *avg; 1404 *avg += diff >> 3; 1405 } 1406 #endif 1407 1408 static void 1409 ttwu_stat(struct task_struct *p, int cpu, int wake_flags) 1410 { 1411 #ifdef CONFIG_SCHEDSTATS 1412 struct rq *rq = this_rq(); 1413 1414 #ifdef CONFIG_SMP 1415 int this_cpu = smp_processor_id(); 1416 1417 if (cpu == this_cpu) { 1418 schedstat_inc(rq, ttwu_local); 1419 schedstat_inc(p, se.statistics.nr_wakeups_local); 1420 } else { 1421 struct sched_domain *sd; 1422 1423 schedstat_inc(p, se.statistics.nr_wakeups_remote); 1424 rcu_read_lock(); 1425 for_each_domain(this_cpu, sd) { 1426 if (cpumask_test_cpu(cpu, sched_domain_span(sd))) { 1427 schedstat_inc(sd, ttwu_wake_remote); 1428 break; 1429 } 1430 } 1431 rcu_read_unlock(); 1432 } 1433 1434 if (wake_flags & WF_MIGRATED) 1435 schedstat_inc(p, se.statistics.nr_wakeups_migrate); 1436 1437 #endif /* CONFIG_SMP */ 1438 1439 schedstat_inc(rq, ttwu_count); 1440 schedstat_inc(p, se.statistics.nr_wakeups); 1441 1442 if (wake_flags & WF_SYNC) 1443 schedstat_inc(p, se.statistics.nr_wakeups_sync); 1444 1445 #endif /* CONFIG_SCHEDSTATS */ 1446 } 1447 1448 static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags) 1449 { 1450 activate_task(rq, p, en_flags); 1451 p->on_rq = TASK_ON_RQ_QUEUED; 1452 1453 /* if a worker is waking up, notify workqueue */ 1454 if (p->flags & PF_WQ_WORKER) 1455 wq_worker_waking_up(p, cpu_of(rq)); 1456 } 1457 1458 /* 1459 * Mark the task runnable and perform wakeup-preemption. 1460 */ 1461 static void 1462 ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags) 1463 { 1464 check_preempt_curr(rq, p, wake_flags); 1465 trace_sched_wakeup(p, true); 1466 1467 p->state = TASK_RUNNING; 1468 #ifdef CONFIG_SMP 1469 if (p->sched_class->task_woken) 1470 p->sched_class->task_woken(rq, p); 1471 1472 if (rq->idle_stamp) { 1473 u64 delta = rq_clock(rq) - rq->idle_stamp; 1474 u64 max = 2*rq->max_idle_balance_cost; 1475 1476 update_avg(&rq->avg_idle, delta); 1477 1478 if (rq->avg_idle > max) 1479 rq->avg_idle = max; 1480 1481 rq->idle_stamp = 0; 1482 } 1483 #endif 1484 } 1485 1486 static void 1487 ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags) 1488 { 1489 #ifdef CONFIG_SMP 1490 if (p->sched_contributes_to_load) 1491 rq->nr_uninterruptible--; 1492 #endif 1493 1494 ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING); 1495 ttwu_do_wakeup(rq, p, wake_flags); 1496 } 1497 1498 /* 1499 * Called in case the task @p isn't fully descheduled from its runqueue, 1500 * in this case we must do a remote wakeup. Its a 'light' wakeup though, 1501 * since all we need to do is flip p->state to TASK_RUNNING, since 1502 * the task is still ->on_rq. 1503 */ 1504 static int ttwu_remote(struct task_struct *p, int wake_flags) 1505 { 1506 struct rq *rq; 1507 int ret = 0; 1508 1509 rq = __task_rq_lock(p); 1510 if (task_on_rq_queued(p)) { 1511 /* check_preempt_curr() may use rq clock */ 1512 update_rq_clock(rq); 1513 ttwu_do_wakeup(rq, p, wake_flags); 1514 ret = 1; 1515 } 1516 __task_rq_unlock(rq); 1517 1518 return ret; 1519 } 1520 1521 #ifdef CONFIG_SMP 1522 void sched_ttwu_pending(void) 1523 { 1524 struct rq *rq = this_rq(); 1525 struct llist_node *llist = llist_del_all(&rq->wake_list); 1526 struct task_struct *p; 1527 unsigned long flags; 1528 1529 if (!llist) 1530 return; 1531 1532 raw_spin_lock_irqsave(&rq->lock, flags); 1533 1534 while (llist) { 1535 p = llist_entry(llist, struct task_struct, wake_entry); 1536 llist = llist_next(llist); 1537 ttwu_do_activate(rq, p, 0); 1538 } 1539 1540 raw_spin_unlock_irqrestore(&rq->lock, flags); 1541 } 1542 1543 void scheduler_ipi(void) 1544 { 1545 /* 1546 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting 1547 * TIF_NEED_RESCHED remotely (for the first time) will also send 1548 * this IPI. 1549 */ 1550 preempt_fold_need_resched(); 1551 1552 if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick()) 1553 return; 1554 1555 /* 1556 * Not all reschedule IPI handlers call irq_enter/irq_exit, since 1557 * traditionally all their work was done from the interrupt return 1558 * path. Now that we actually do some work, we need to make sure 1559 * we do call them. 1560 * 1561 * Some archs already do call them, luckily irq_enter/exit nest 1562 * properly. 1563 * 1564 * Arguably we should visit all archs and update all handlers, 1565 * however a fair share of IPIs are still resched only so this would 1566 * somewhat pessimize the simple resched case. 1567 */ 1568 irq_enter(); 1569 sched_ttwu_pending(); 1570 1571 /* 1572 * Check if someone kicked us for doing the nohz idle load balance. 1573 */ 1574 if (unlikely(got_nohz_idle_kick())) { 1575 this_rq()->idle_balance = 1; 1576 raise_softirq_irqoff(SCHED_SOFTIRQ); 1577 } 1578 irq_exit(); 1579 } 1580 1581 static void ttwu_queue_remote(struct task_struct *p, int cpu) 1582 { 1583 struct rq *rq = cpu_rq(cpu); 1584 1585 if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) { 1586 if (!set_nr_if_polling(rq->idle)) 1587 smp_send_reschedule(cpu); 1588 else 1589 trace_sched_wake_idle_without_ipi(cpu); 1590 } 1591 } 1592 1593 void wake_up_if_idle(int cpu) 1594 { 1595 struct rq *rq = cpu_rq(cpu); 1596 unsigned long flags; 1597 1598 rcu_read_lock(); 1599 1600 if (!is_idle_task(rcu_dereference(rq->curr))) 1601 goto out; 1602 1603 if (set_nr_if_polling(rq->idle)) { 1604 trace_sched_wake_idle_without_ipi(cpu); 1605 } else { 1606 raw_spin_lock_irqsave(&rq->lock, flags); 1607 if (is_idle_task(rq->curr)) 1608 smp_send_reschedule(cpu); 1609 /* Else cpu is not in idle, do nothing here */ 1610 raw_spin_unlock_irqrestore(&rq->lock, flags); 1611 } 1612 1613 out: 1614 rcu_read_unlock(); 1615 } 1616 1617 bool cpus_share_cache(int this_cpu, int that_cpu) 1618 { 1619 return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu); 1620 } 1621 #endif /* CONFIG_SMP */ 1622 1623 static void ttwu_queue(struct task_struct *p, int cpu) 1624 { 1625 struct rq *rq = cpu_rq(cpu); 1626 1627 #if defined(CONFIG_SMP) 1628 if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) { 1629 sched_clock_cpu(cpu); /* sync clocks x-cpu */ 1630 ttwu_queue_remote(p, cpu); 1631 return; 1632 } 1633 #endif 1634 1635 raw_spin_lock(&rq->lock); 1636 ttwu_do_activate(rq, p, 0); 1637 raw_spin_unlock(&rq->lock); 1638 } 1639 1640 /** 1641 * try_to_wake_up - wake up a thread 1642 * @p: the thread to be awakened 1643 * @state: the mask of task states that can be woken 1644 * @wake_flags: wake modifier flags (WF_*) 1645 * 1646 * Put it on the run-queue if it's not already there. The "current" 1647 * thread is always on the run-queue (except when the actual 1648 * re-schedule is in progress), and as such you're allowed to do 1649 * the simpler "current->state = TASK_RUNNING" to mark yourself 1650 * runnable without the overhead of this. 1651 * 1652 * Return: %true if @p was woken up, %false if it was already running. 1653 * or @state didn't match @p's state. 1654 */ 1655 static int 1656 try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) 1657 { 1658 unsigned long flags; 1659 int cpu, success = 0; 1660 1661 /* 1662 * If we are going to wake up a thread waiting for CONDITION we 1663 * need to ensure that CONDITION=1 done by the caller can not be 1664 * reordered with p->state check below. This pairs with mb() in 1665 * set_current_state() the waiting thread does. 1666 */ 1667 smp_mb__before_spinlock(); 1668 raw_spin_lock_irqsave(&p->pi_lock, flags); 1669 if (!(p->state & state)) 1670 goto out; 1671 1672 success = 1; /* we're going to change ->state */ 1673 cpu = task_cpu(p); 1674 1675 if (p->on_rq && ttwu_remote(p, wake_flags)) 1676 goto stat; 1677 1678 #ifdef CONFIG_SMP 1679 /* 1680 * If the owning (remote) cpu is still in the middle of schedule() with 1681 * this task as prev, wait until its done referencing the task. 1682 */ 1683 while (p->on_cpu) 1684 cpu_relax(); 1685 /* 1686 * Pairs with the smp_wmb() in finish_lock_switch(). 1687 */ 1688 smp_rmb(); 1689 1690 p->sched_contributes_to_load = !!task_contributes_to_load(p); 1691 p->state = TASK_WAKING; 1692 1693 if (p->sched_class->task_waking) 1694 p->sched_class->task_waking(p); 1695 1696 cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags); 1697 if (task_cpu(p) != cpu) { 1698 wake_flags |= WF_MIGRATED; 1699 set_task_cpu(p, cpu); 1700 } 1701 #endif /* CONFIG_SMP */ 1702 1703 ttwu_queue(p, cpu); 1704 stat: 1705 ttwu_stat(p, cpu, wake_flags); 1706 out: 1707 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 1708 1709 return success; 1710 } 1711 1712 /** 1713 * try_to_wake_up_local - try to wake up a local task with rq lock held 1714 * @p: the thread to be awakened 1715 * 1716 * Put @p on the run-queue if it's not already there. The caller must 1717 * ensure that this_rq() is locked, @p is bound to this_rq() and not 1718 * the current task. 1719 */ 1720 static void try_to_wake_up_local(struct task_struct *p) 1721 { 1722 struct rq *rq = task_rq(p); 1723 1724 if (WARN_ON_ONCE(rq != this_rq()) || 1725 WARN_ON_ONCE(p == current)) 1726 return; 1727 1728 lockdep_assert_held(&rq->lock); 1729 1730 if (!raw_spin_trylock(&p->pi_lock)) { 1731 raw_spin_unlock(&rq->lock); 1732 raw_spin_lock(&p->pi_lock); 1733 raw_spin_lock(&rq->lock); 1734 } 1735 1736 if (!(p->state & TASK_NORMAL)) 1737 goto out; 1738 1739 if (!task_on_rq_queued(p)) 1740 ttwu_activate(rq, p, ENQUEUE_WAKEUP); 1741 1742 ttwu_do_wakeup(rq, p, 0); 1743 ttwu_stat(p, smp_processor_id(), 0); 1744 out: 1745 raw_spin_unlock(&p->pi_lock); 1746 } 1747 1748 /** 1749 * wake_up_process - Wake up a specific process 1750 * @p: The process to be woken up. 1751 * 1752 * Attempt to wake up the nominated process and move it to the set of runnable 1753 * processes. 1754 * 1755 * Return: 1 if the process was woken up, 0 if it was already running. 1756 * 1757 * It may be assumed that this function implies a write memory barrier before 1758 * changing the task state if and only if any tasks are woken up. 1759 */ 1760 int wake_up_process(struct task_struct *p) 1761 { 1762 WARN_ON(task_is_stopped_or_traced(p)); 1763 return try_to_wake_up(p, TASK_NORMAL, 0); 1764 } 1765 EXPORT_SYMBOL(wake_up_process); 1766 1767 int wake_up_state(struct task_struct *p, unsigned int state) 1768 { 1769 return try_to_wake_up(p, state, 0); 1770 } 1771 1772 /* 1773 * This function clears the sched_dl_entity static params. 1774 */ 1775 void __dl_clear_params(struct task_struct *p) 1776 { 1777 struct sched_dl_entity *dl_se = &p->dl; 1778 1779 dl_se->dl_runtime = 0; 1780 dl_se->dl_deadline = 0; 1781 dl_se->dl_period = 0; 1782 dl_se->flags = 0; 1783 dl_se->dl_bw = 0; 1784 1785 dl_se->dl_throttled = 0; 1786 dl_se->dl_new = 1; 1787 dl_se->dl_yielded = 0; 1788 } 1789 1790 /* 1791 * Perform scheduler related setup for a newly forked process p. 1792 * p is forked by current. 1793 * 1794 * __sched_fork() is basic setup used by init_idle() too: 1795 */ 1796 static void __sched_fork(unsigned long clone_flags, struct task_struct *p) 1797 { 1798 p->on_rq = 0; 1799 1800 p->se.on_rq = 0; 1801 p->se.exec_start = 0; 1802 p->se.sum_exec_runtime = 0; 1803 p->se.prev_sum_exec_runtime = 0; 1804 p->se.nr_migrations = 0; 1805 p->se.vruntime = 0; 1806 #ifdef CONFIG_SMP 1807 p->se.avg.decay_count = 0; 1808 #endif 1809 INIT_LIST_HEAD(&p->se.group_node); 1810 1811 #ifdef CONFIG_SCHEDSTATS 1812 memset(&p->se.statistics, 0, sizeof(p->se.statistics)); 1813 #endif 1814 1815 RB_CLEAR_NODE(&p->dl.rb_node); 1816 init_dl_task_timer(&p->dl); 1817 __dl_clear_params(p); 1818 1819 INIT_LIST_HEAD(&p->rt.run_list); 1820 1821 #ifdef CONFIG_PREEMPT_NOTIFIERS 1822 INIT_HLIST_HEAD(&p->preempt_notifiers); 1823 #endif 1824 1825 #ifdef CONFIG_NUMA_BALANCING 1826 if (p->mm && atomic_read(&p->mm->mm_users) == 1) { 1827 p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay); 1828 p->mm->numa_scan_seq = 0; 1829 } 1830 1831 if (clone_flags & CLONE_VM) 1832 p->numa_preferred_nid = current->numa_preferred_nid; 1833 else 1834 p->numa_preferred_nid = -1; 1835 1836 p->node_stamp = 0ULL; 1837 p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0; 1838 p->numa_scan_period = sysctl_numa_balancing_scan_delay; 1839 p->numa_work.next = &p->numa_work; 1840 p->numa_faults = NULL; 1841 p->last_task_numa_placement = 0; 1842 p->last_sum_exec_runtime = 0; 1843 1844 p->numa_group = NULL; 1845 #endif /* CONFIG_NUMA_BALANCING */ 1846 } 1847 1848 #ifdef CONFIG_NUMA_BALANCING 1849 #ifdef CONFIG_SCHED_DEBUG 1850 void set_numabalancing_state(bool enabled) 1851 { 1852 if (enabled) 1853 sched_feat_set("NUMA"); 1854 else 1855 sched_feat_set("NO_NUMA"); 1856 } 1857 #else 1858 __read_mostly bool numabalancing_enabled; 1859 1860 void set_numabalancing_state(bool enabled) 1861 { 1862 numabalancing_enabled = enabled; 1863 } 1864 #endif /* CONFIG_SCHED_DEBUG */ 1865 1866 #ifdef CONFIG_PROC_SYSCTL 1867 int sysctl_numa_balancing(struct ctl_table *table, int write, 1868 void __user *buffer, size_t *lenp, loff_t *ppos) 1869 { 1870 struct ctl_table t; 1871 int err; 1872 int state = numabalancing_enabled; 1873 1874 if (write && !capable(CAP_SYS_ADMIN)) 1875 return -EPERM; 1876 1877 t = *table; 1878 t.data = &state; 1879 err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); 1880 if (err < 0) 1881 return err; 1882 if (write) 1883 set_numabalancing_state(state); 1884 return err; 1885 } 1886 #endif 1887 #endif 1888 1889 /* 1890 * fork()/clone()-time setup: 1891 */ 1892 int sched_fork(unsigned long clone_flags, struct task_struct *p) 1893 { 1894 unsigned long flags; 1895 int cpu = get_cpu(); 1896 1897 __sched_fork(clone_flags, p); 1898 /* 1899 * We mark the process as running here. This guarantees that 1900 * nobody will actually run it, and a signal or other external 1901 * event cannot wake it up and insert it on the runqueue either. 1902 */ 1903 p->state = TASK_RUNNING; 1904 1905 /* 1906 * Make sure we do not leak PI boosting priority to the child. 1907 */ 1908 p->prio = current->normal_prio; 1909 1910 /* 1911 * Revert to default priority/policy on fork if requested. 1912 */ 1913 if (unlikely(p->sched_reset_on_fork)) { 1914 if (task_has_dl_policy(p) || task_has_rt_policy(p)) { 1915 p->policy = SCHED_NORMAL; 1916 p->static_prio = NICE_TO_PRIO(0); 1917 p->rt_priority = 0; 1918 } else if (PRIO_TO_NICE(p->static_prio) < 0) 1919 p->static_prio = NICE_TO_PRIO(0); 1920 1921 p->prio = p->normal_prio = __normal_prio(p); 1922 set_load_weight(p); 1923 1924 /* 1925 * We don't need the reset flag anymore after the fork. It has 1926 * fulfilled its duty: 1927 */ 1928 p->sched_reset_on_fork = 0; 1929 } 1930 1931 if (dl_prio(p->prio)) { 1932 put_cpu(); 1933 return -EAGAIN; 1934 } else if (rt_prio(p->prio)) { 1935 p->sched_class = &rt_sched_class; 1936 } else { 1937 p->sched_class = &fair_sched_class; 1938 } 1939 1940 if (p->sched_class->task_fork) 1941 p->sched_class->task_fork(p); 1942 1943 /* 1944 * The child is not yet in the pid-hash so no cgroup attach races, 1945 * and the cgroup is pinned to this child due to cgroup_fork() 1946 * is ran before sched_fork(). 1947 * 1948 * Silence PROVE_RCU. 1949 */ 1950 raw_spin_lock_irqsave(&p->pi_lock, flags); 1951 set_task_cpu(p, cpu); 1952 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 1953 1954 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) 1955 if (likely(sched_info_on())) 1956 memset(&p->sched_info, 0, sizeof(p->sched_info)); 1957 #endif 1958 #if defined(CONFIG_SMP) 1959 p->on_cpu = 0; 1960 #endif 1961 init_task_preempt_count(p); 1962 #ifdef CONFIG_SMP 1963 plist_node_init(&p->pushable_tasks, MAX_PRIO); 1964 RB_CLEAR_NODE(&p->pushable_dl_tasks); 1965 #endif 1966 1967 put_cpu(); 1968 return 0; 1969 } 1970 1971 unsigned long to_ratio(u64 period, u64 runtime) 1972 { 1973 if (runtime == RUNTIME_INF) 1974 return 1ULL << 20; 1975 1976 /* 1977 * Doing this here saves a lot of checks in all 1978 * the calling paths, and returning zero seems 1979 * safe for them anyway. 1980 */ 1981 if (period == 0) 1982 return 0; 1983 1984 return div64_u64(runtime << 20, period); 1985 } 1986 1987 #ifdef CONFIG_SMP 1988 inline struct dl_bw *dl_bw_of(int i) 1989 { 1990 rcu_lockdep_assert(rcu_read_lock_sched_held(), 1991 "sched RCU must be held"); 1992 return &cpu_rq(i)->rd->dl_bw; 1993 } 1994 1995 static inline int dl_bw_cpus(int i) 1996 { 1997 struct root_domain *rd = cpu_rq(i)->rd; 1998 int cpus = 0; 1999 2000 rcu_lockdep_assert(rcu_read_lock_sched_held(), 2001 "sched RCU must be held"); 2002 for_each_cpu_and(i, rd->span, cpu_active_mask) 2003 cpus++; 2004 2005 return cpus; 2006 } 2007 #else 2008 inline struct dl_bw *dl_bw_of(int i) 2009 { 2010 return &cpu_rq(i)->dl.dl_bw; 2011 } 2012 2013 static inline int dl_bw_cpus(int i) 2014 { 2015 return 1; 2016 } 2017 #endif 2018 2019 /* 2020 * We must be sure that accepting a new task (or allowing changing the 2021 * parameters of an existing one) is consistent with the bandwidth 2022 * constraints. If yes, this function also accordingly updates the currently 2023 * allocated bandwidth to reflect the new situation. 2024 * 2025 * This function is called while holding p's rq->lock. 2026 * 2027 * XXX we should delay bw change until the task's 0-lag point, see 2028 * __setparam_dl(). 2029 */ 2030 static int dl_overflow(struct task_struct *p, int policy, 2031 const struct sched_attr *attr) 2032 { 2033 2034 struct dl_bw *dl_b = dl_bw_of(task_cpu(p)); 2035 u64 period = attr->sched_period ?: attr->sched_deadline; 2036 u64 runtime = attr->sched_runtime; 2037 u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0; 2038 int cpus, err = -1; 2039 2040 if (new_bw == p->dl.dl_bw) 2041 return 0; 2042 2043 /* 2044 * Either if a task, enters, leave, or stays -deadline but changes 2045 * its parameters, we may need to update accordingly the total 2046 * allocated bandwidth of the container. 2047 */ 2048 raw_spin_lock(&dl_b->lock); 2049 cpus = dl_bw_cpus(task_cpu(p)); 2050 if (dl_policy(policy) && !task_has_dl_policy(p) && 2051 !__dl_overflow(dl_b, cpus, 0, new_bw)) { 2052 __dl_add(dl_b, new_bw); 2053 err = 0; 2054 } else if (dl_policy(policy) && task_has_dl_policy(p) && 2055 !__dl_overflow(dl_b, cpus, p->dl.dl_bw, new_bw)) { 2056 __dl_clear(dl_b, p->dl.dl_bw); 2057 __dl_add(dl_b, new_bw); 2058 err = 0; 2059 } else if (!dl_policy(policy) && task_has_dl_policy(p)) { 2060 __dl_clear(dl_b, p->dl.dl_bw); 2061 err = 0; 2062 } 2063 raw_spin_unlock(&dl_b->lock); 2064 2065 return err; 2066 } 2067 2068 extern void init_dl_bw(struct dl_bw *dl_b); 2069 2070 /* 2071 * wake_up_new_task - wake up a newly created task for the first time. 2072 * 2073 * This function will do some initial scheduler statistics housekeeping 2074 * that must be done for every newly created context, then puts the task 2075 * on the runqueue and wakes it. 2076 */ 2077 void wake_up_new_task(struct task_struct *p) 2078 { 2079 unsigned long flags; 2080 struct rq *rq; 2081 2082 raw_spin_lock_irqsave(&p->pi_lock, flags); 2083 #ifdef CONFIG_SMP 2084 /* 2085 * Fork balancing, do it here and not earlier because: 2086 * - cpus_allowed can change in the fork path 2087 * - any previously selected cpu might disappear through hotplug 2088 */ 2089 set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0)); 2090 #endif 2091 2092 /* Initialize new task's runnable average */ 2093 init_task_runnable_average(p); 2094 rq = __task_rq_lock(p); 2095 activate_task(rq, p, 0); 2096 p->on_rq = TASK_ON_RQ_QUEUED; 2097 trace_sched_wakeup_new(p, true); 2098 check_preempt_curr(rq, p, WF_FORK); 2099 #ifdef CONFIG_SMP 2100 if (p->sched_class->task_woken) 2101 p->sched_class->task_woken(rq, p); 2102 #endif 2103 task_rq_unlock(rq, p, &flags); 2104 } 2105 2106 #ifdef CONFIG_PREEMPT_NOTIFIERS 2107 2108 /** 2109 * preempt_notifier_register - tell me when current is being preempted & rescheduled 2110 * @notifier: notifier struct to register 2111 */ 2112 void preempt_notifier_register(struct preempt_notifier *notifier) 2113 { 2114 hlist_add_head(¬ifier->link, ¤t->preempt_notifiers); 2115 } 2116 EXPORT_SYMBOL_GPL(preempt_notifier_register); 2117 2118 /** 2119 * preempt_notifier_unregister - no longer interested in preemption notifications 2120 * @notifier: notifier struct to unregister 2121 * 2122 * This is safe to call from within a preemption notifier. 2123 */ 2124 void preempt_notifier_unregister(struct preempt_notifier *notifier) 2125 { 2126 hlist_del(¬ifier->link); 2127 } 2128 EXPORT_SYMBOL_GPL(preempt_notifier_unregister); 2129 2130 static void fire_sched_in_preempt_notifiers(struct task_struct *curr) 2131 { 2132 struct preempt_notifier *notifier; 2133 2134 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link) 2135 notifier->ops->sched_in(notifier, raw_smp_processor_id()); 2136 } 2137 2138 static void 2139 fire_sched_out_preempt_notifiers(struct task_struct *curr, 2140 struct task_struct *next) 2141 { 2142 struct preempt_notifier *notifier; 2143 2144 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link) 2145 notifier->ops->sched_out(notifier, next); 2146 } 2147 2148 #else /* !CONFIG_PREEMPT_NOTIFIERS */ 2149 2150 static void fire_sched_in_preempt_notifiers(struct task_struct *curr) 2151 { 2152 } 2153 2154 static void 2155 fire_sched_out_preempt_notifiers(struct task_struct *curr, 2156 struct task_struct *next) 2157 { 2158 } 2159 2160 #endif /* CONFIG_PREEMPT_NOTIFIERS */ 2161 2162 /** 2163 * prepare_task_switch - prepare to switch tasks 2164 * @rq: the runqueue preparing to switch 2165 * @prev: the current task that is being switched out 2166 * @next: the task we are going to switch to. 2167 * 2168 * This is called with the rq lock held and interrupts off. It must 2169 * be paired with a subsequent finish_task_switch after the context 2170 * switch. 2171 * 2172 * prepare_task_switch sets up locking and calls architecture specific 2173 * hooks. 2174 */ 2175 static inline void 2176 prepare_task_switch(struct rq *rq, struct task_struct *prev, 2177 struct task_struct *next) 2178 { 2179 trace_sched_switch(prev, next); 2180 sched_info_switch(rq, prev, next); 2181 perf_event_task_sched_out(prev, next); 2182 fire_sched_out_preempt_notifiers(prev, next); 2183 prepare_lock_switch(rq, next); 2184 prepare_arch_switch(next); 2185 } 2186 2187 /** 2188 * finish_task_switch - clean up after a task-switch 2189 * @prev: the thread we just switched away from. 2190 * 2191 * finish_task_switch must be called after the context switch, paired 2192 * with a prepare_task_switch call before the context switch. 2193 * finish_task_switch will reconcile locking set up by prepare_task_switch, 2194 * and do any other architecture-specific cleanup actions. 2195 * 2196 * Note that we may have delayed dropping an mm in context_switch(). If 2197 * so, we finish that here outside of the runqueue lock. (Doing it 2198 * with the lock held can cause deadlocks; see schedule() for 2199 * details.) 2200 * 2201 * The context switch have flipped the stack from under us and restored the 2202 * local variables which were saved when this task called schedule() in the 2203 * past. prev == current is still correct but we need to recalculate this_rq 2204 * because prev may have moved to another CPU. 2205 */ 2206 static struct rq *finish_task_switch(struct task_struct *prev) 2207 __releases(rq->lock) 2208 { 2209 struct rq *rq = this_rq(); 2210 struct mm_struct *mm = rq->prev_mm; 2211 long prev_state; 2212 2213 rq->prev_mm = NULL; 2214 2215 /* 2216 * A task struct has one reference for the use as "current". 2217 * If a task dies, then it sets TASK_DEAD in tsk->state and calls 2218 * schedule one last time. The schedule call will never return, and 2219 * the scheduled task must drop that reference. 2220 * The test for TASK_DEAD must occur while the runqueue locks are 2221 * still held, otherwise prev could be scheduled on another cpu, die 2222 * there before we look at prev->state, and then the reference would 2223 * be dropped twice. 2224 * Manfred Spraul <manfred@colorfullife.com> 2225 */ 2226 prev_state = prev->state; 2227 vtime_task_switch(prev); 2228 finish_arch_switch(prev); 2229 perf_event_task_sched_in(prev, current); 2230 finish_lock_switch(rq, prev); 2231 finish_arch_post_lock_switch(); 2232 2233 fire_sched_in_preempt_notifiers(current); 2234 if (mm) 2235 mmdrop(mm); 2236 if (unlikely(prev_state == TASK_DEAD)) { 2237 if (prev->sched_class->task_dead) 2238 prev->sched_class->task_dead(prev); 2239 2240 /* 2241 * Remove function-return probe instances associated with this 2242 * task and put them back on the free list. 2243 */ 2244 kprobe_flush_task(prev); 2245 put_task_struct(prev); 2246 } 2247 2248 tick_nohz_task_switch(current); 2249 return rq; 2250 } 2251 2252 #ifdef CONFIG_SMP 2253 2254 /* rq->lock is NOT held, but preemption is disabled */ 2255 static inline void post_schedule(struct rq *rq) 2256 { 2257 if (rq->post_schedule) { 2258 unsigned long flags; 2259 2260 raw_spin_lock_irqsave(&rq->lock, flags); 2261 if (rq->curr->sched_class->post_schedule) 2262 rq->curr->sched_class->post_schedule(rq); 2263 raw_spin_unlock_irqrestore(&rq->lock, flags); 2264 2265 rq->post_schedule = 0; 2266 } 2267 } 2268 2269 #else 2270 2271 static inline void post_schedule(struct rq *rq) 2272 { 2273 } 2274 2275 #endif 2276 2277 /** 2278 * schedule_tail - first thing a freshly forked thread must call. 2279 * @prev: the thread we just switched away from. 2280 */ 2281 asmlinkage __visible void schedule_tail(struct task_struct *prev) 2282 __releases(rq->lock) 2283 { 2284 struct rq *rq; 2285 2286 /* finish_task_switch() drops rq->lock and enables preemtion */ 2287 preempt_disable(); 2288 rq = finish_task_switch(prev); 2289 post_schedule(rq); 2290 preempt_enable(); 2291 2292 if (current->set_child_tid) 2293 put_user(task_pid_vnr(current), current->set_child_tid); 2294 } 2295 2296 /* 2297 * context_switch - switch to the new MM and the new thread's register state. 2298 */ 2299 static inline struct rq * 2300 context_switch(struct rq *rq, struct task_struct *prev, 2301 struct task_struct *next) 2302 { 2303 struct mm_struct *mm, *oldmm; 2304 2305 prepare_task_switch(rq, prev, next); 2306 2307 mm = next->mm; 2308 oldmm = prev->active_mm; 2309 /* 2310 * For paravirt, this is coupled with an exit in switch_to to 2311 * combine the page table reload and the switch backend into 2312 * one hypercall. 2313 */ 2314 arch_start_context_switch(prev); 2315 2316 if (!mm) { 2317 next->active_mm = oldmm; 2318 atomic_inc(&oldmm->mm_count); 2319 enter_lazy_tlb(oldmm, next); 2320 } else 2321 switch_mm(oldmm, mm, next); 2322 2323 if (!prev->mm) { 2324 prev->active_mm = NULL; 2325 rq->prev_mm = oldmm; 2326 } 2327 /* 2328 * Since the runqueue lock will be released by the next 2329 * task (which is an invalid locking op but in the case 2330 * of the scheduler it's an obvious special-case), so we 2331 * do an early lockdep release here: 2332 */ 2333 spin_release(&rq->lock.dep_map, 1, _THIS_IP_); 2334 2335 context_tracking_task_switch(prev, next); 2336 /* Here we just switch the register state and the stack. */ 2337 switch_to(prev, next, prev); 2338 barrier(); 2339 2340 return finish_task_switch(prev); 2341 } 2342 2343 /* 2344 * nr_running and nr_context_switches: 2345 * 2346 * externally visible scheduler statistics: current number of runnable 2347 * threads, total number of context switches performed since bootup. 2348 */ 2349 unsigned long nr_running(void) 2350 { 2351 unsigned long i, sum = 0; 2352 2353 for_each_online_cpu(i) 2354 sum += cpu_rq(i)->nr_running; 2355 2356 return sum; 2357 } 2358 2359 /* 2360 * Check if only the current task is running on the cpu. 2361 */ 2362 bool single_task_running(void) 2363 { 2364 if (cpu_rq(smp_processor_id())->nr_running == 1) 2365 return true; 2366 else 2367 return false; 2368 } 2369 EXPORT_SYMBOL(single_task_running); 2370 2371 unsigned long long nr_context_switches(void) 2372 { 2373 int i; 2374 unsigned long long sum = 0; 2375 2376 for_each_possible_cpu(i) 2377 sum += cpu_rq(i)->nr_switches; 2378 2379 return sum; 2380 } 2381 2382 unsigned long nr_iowait(void) 2383 { 2384 unsigned long i, sum = 0; 2385 2386 for_each_possible_cpu(i) 2387 sum += atomic_read(&cpu_rq(i)->nr_iowait); 2388 2389 return sum; 2390 } 2391 2392 unsigned long nr_iowait_cpu(int cpu) 2393 { 2394 struct rq *this = cpu_rq(cpu); 2395 return atomic_read(&this->nr_iowait); 2396 } 2397 2398 void get_iowait_load(unsigned long *nr_waiters, unsigned long *load) 2399 { 2400 struct rq *this = this_rq(); 2401 *nr_waiters = atomic_read(&this->nr_iowait); 2402 *load = this->cpu_load[0]; 2403 } 2404 2405 #ifdef CONFIG_SMP 2406 2407 /* 2408 * sched_exec - execve() is a valuable balancing opportunity, because at 2409 * this point the task has the smallest effective memory and cache footprint. 2410 */ 2411 void sched_exec(void) 2412 { 2413 struct task_struct *p = current; 2414 unsigned long flags; 2415 int dest_cpu; 2416 2417 raw_spin_lock_irqsave(&p->pi_lock, flags); 2418 dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0); 2419 if (dest_cpu == smp_processor_id()) 2420 goto unlock; 2421 2422 if (likely(cpu_active(dest_cpu))) { 2423 struct migration_arg arg = { p, dest_cpu }; 2424 2425 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 2426 stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg); 2427 return; 2428 } 2429 unlock: 2430 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 2431 } 2432 2433 #endif 2434 2435 DEFINE_PER_CPU(struct kernel_stat, kstat); 2436 DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat); 2437 2438 EXPORT_PER_CPU_SYMBOL(kstat); 2439 EXPORT_PER_CPU_SYMBOL(kernel_cpustat); 2440 2441 /* 2442 * Return accounted runtime for the task. 2443 * In case the task is currently running, return the runtime plus current's 2444 * pending runtime that have not been accounted yet. 2445 */ 2446 unsigned long long task_sched_runtime(struct task_struct *p) 2447 { 2448 unsigned long flags; 2449 struct rq *rq; 2450 u64 ns; 2451 2452 #if defined(CONFIG_64BIT) && defined(CONFIG_SMP) 2453 /* 2454 * 64-bit doesn't need locks to atomically read a 64bit value. 2455 * So we have a optimization chance when the task's delta_exec is 0. 2456 * Reading ->on_cpu is racy, but this is ok. 2457 * 2458 * If we race with it leaving cpu, we'll take a lock. So we're correct. 2459 * If we race with it entering cpu, unaccounted time is 0. This is 2460 * indistinguishable from the read occurring a few cycles earlier. 2461 * If we see ->on_cpu without ->on_rq, the task is leaving, and has 2462 * been accounted, so we're correct here as well. 2463 */ 2464 if (!p->on_cpu || !task_on_rq_queued(p)) 2465 return p->se.sum_exec_runtime; 2466 #endif 2467 2468 rq = task_rq_lock(p, &flags); 2469 /* 2470 * Must be ->curr _and_ ->on_rq. If dequeued, we would 2471 * project cycles that may never be accounted to this 2472 * thread, breaking clock_gettime(). 2473 */ 2474 if (task_current(rq, p) && task_on_rq_queued(p)) { 2475 update_rq_clock(rq); 2476 p->sched_class->update_curr(rq); 2477 } 2478 ns = p->se.sum_exec_runtime; 2479 task_rq_unlock(rq, p, &flags); 2480 2481 return ns; 2482 } 2483 2484 /* 2485 * This function gets called by the timer code, with HZ frequency. 2486 * We call it with interrupts disabled. 2487 */ 2488 void scheduler_tick(void) 2489 { 2490 int cpu = smp_processor_id(); 2491 struct rq *rq = cpu_rq(cpu); 2492 struct task_struct *curr = rq->curr; 2493 2494 sched_clock_tick(); 2495 2496 raw_spin_lock(&rq->lock); 2497 update_rq_clock(rq); 2498 curr->sched_class->task_tick(rq, curr, 0); 2499 update_cpu_load_active(rq); 2500 raw_spin_unlock(&rq->lock); 2501 2502 perf_event_task_tick(); 2503 2504 #ifdef CONFIG_SMP 2505 rq->idle_balance = idle_cpu(cpu); 2506 trigger_load_balance(rq); 2507 #endif 2508 rq_last_tick_reset(rq); 2509 } 2510 2511 #ifdef CONFIG_NO_HZ_FULL 2512 /** 2513 * scheduler_tick_max_deferment 2514 * 2515 * Keep at least one tick per second when a single 2516 * active task is running because the scheduler doesn't 2517 * yet completely support full dynticks environment. 2518 * 2519 * This makes sure that uptime, CFS vruntime, load 2520 * balancing, etc... continue to move forward, even 2521 * with a very low granularity. 2522 * 2523 * Return: Maximum deferment in nanoseconds. 2524 */ 2525 u64 scheduler_tick_max_deferment(void) 2526 { 2527 struct rq *rq = this_rq(); 2528 unsigned long next, now = ACCESS_ONCE(jiffies); 2529 2530 next = rq->last_sched_tick + HZ; 2531 2532 if (time_before_eq(next, now)) 2533 return 0; 2534 2535 return jiffies_to_nsecs(next - now); 2536 } 2537 #endif 2538 2539 notrace unsigned long get_parent_ip(unsigned long addr) 2540 { 2541 if (in_lock_functions(addr)) { 2542 addr = CALLER_ADDR2; 2543 if (in_lock_functions(addr)) 2544 addr = CALLER_ADDR3; 2545 } 2546 return addr; 2547 } 2548 2549 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \ 2550 defined(CONFIG_PREEMPT_TRACER)) 2551 2552 void preempt_count_add(int val) 2553 { 2554 #ifdef CONFIG_DEBUG_PREEMPT 2555 /* 2556 * Underflow? 2557 */ 2558 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0))) 2559 return; 2560 #endif 2561 __preempt_count_add(val); 2562 #ifdef CONFIG_DEBUG_PREEMPT 2563 /* 2564 * Spinlock count overflowing soon? 2565 */ 2566 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >= 2567 PREEMPT_MASK - 10); 2568 #endif 2569 if (preempt_count() == val) { 2570 unsigned long ip = get_parent_ip(CALLER_ADDR1); 2571 #ifdef CONFIG_DEBUG_PREEMPT 2572 current->preempt_disable_ip = ip; 2573 #endif 2574 trace_preempt_off(CALLER_ADDR0, ip); 2575 } 2576 } 2577 EXPORT_SYMBOL(preempt_count_add); 2578 NOKPROBE_SYMBOL(preempt_count_add); 2579 2580 void preempt_count_sub(int val) 2581 { 2582 #ifdef CONFIG_DEBUG_PREEMPT 2583 /* 2584 * Underflow? 2585 */ 2586 if (DEBUG_LOCKS_WARN_ON(val > preempt_count())) 2587 return; 2588 /* 2589 * Is the spinlock portion underflowing? 2590 */ 2591 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) && 2592 !(preempt_count() & PREEMPT_MASK))) 2593 return; 2594 #endif 2595 2596 if (preempt_count() == val) 2597 trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); 2598 __preempt_count_sub(val); 2599 } 2600 EXPORT_SYMBOL(preempt_count_sub); 2601 NOKPROBE_SYMBOL(preempt_count_sub); 2602 2603 #endif 2604 2605 /* 2606 * Print scheduling while atomic bug: 2607 */ 2608 static noinline void __schedule_bug(struct task_struct *prev) 2609 { 2610 if (oops_in_progress) 2611 return; 2612 2613 printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n", 2614 prev->comm, prev->pid, preempt_count()); 2615 2616 debug_show_held_locks(prev); 2617 print_modules(); 2618 if (irqs_disabled()) 2619 print_irqtrace_events(prev); 2620 #ifdef CONFIG_DEBUG_PREEMPT 2621 if (in_atomic_preempt_off()) { 2622 pr_err("Preemption disabled at:"); 2623 print_ip_sym(current->preempt_disable_ip); 2624 pr_cont("\n"); 2625 } 2626 #endif 2627 dump_stack(); 2628 add_taint(TAINT_WARN, LOCKDEP_STILL_OK); 2629 } 2630 2631 /* 2632 * Various schedule()-time debugging checks and statistics: 2633 */ 2634 static inline void schedule_debug(struct task_struct *prev) 2635 { 2636 #ifdef CONFIG_SCHED_STACK_END_CHECK 2637 BUG_ON(unlikely(task_stack_end_corrupted(prev))); 2638 #endif 2639 /* 2640 * Test if we are atomic. Since do_exit() needs to call into 2641 * schedule() atomically, we ignore that path. Otherwise whine 2642 * if we are scheduling when we should not. 2643 */ 2644 if (unlikely(in_atomic_preempt_off() && prev->state != TASK_DEAD)) 2645 __schedule_bug(prev); 2646 rcu_sleep_check(); 2647 2648 profile_hit(SCHED_PROFILING, __builtin_return_address(0)); 2649 2650 schedstat_inc(this_rq(), sched_count); 2651 } 2652 2653 /* 2654 * Pick up the highest-prio task: 2655 */ 2656 static inline struct task_struct * 2657 pick_next_task(struct rq *rq, struct task_struct *prev) 2658 { 2659 const struct sched_class *class = &fair_sched_class; 2660 struct task_struct *p; 2661 2662 /* 2663 * Optimization: we know that if all tasks are in 2664 * the fair class we can call that function directly: 2665 */ 2666 if (likely(prev->sched_class == class && 2667 rq->nr_running == rq->cfs.h_nr_running)) { 2668 p = fair_sched_class.pick_next_task(rq, prev); 2669 if (unlikely(p == RETRY_TASK)) 2670 goto again; 2671 2672 /* assumes fair_sched_class->next == idle_sched_class */ 2673 if (unlikely(!p)) 2674 p = idle_sched_class.pick_next_task(rq, prev); 2675 2676 return p; 2677 } 2678 2679 again: 2680 for_each_class(class) { 2681 p = class->pick_next_task(rq, prev); 2682 if (p) { 2683 if (unlikely(p == RETRY_TASK)) 2684 goto again; 2685 return p; 2686 } 2687 } 2688 2689 BUG(); /* the idle class will always have a runnable task */ 2690 } 2691 2692 /* 2693 * __schedule() is the main scheduler function. 2694 * 2695 * The main means of driving the scheduler and thus entering this function are: 2696 * 2697 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc. 2698 * 2699 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return 2700 * paths. For example, see arch/x86/entry_64.S. 2701 * 2702 * To drive preemption between tasks, the scheduler sets the flag in timer 2703 * interrupt handler scheduler_tick(). 2704 * 2705 * 3. Wakeups don't really cause entry into schedule(). They add a 2706 * task to the run-queue and that's it. 2707 * 2708 * Now, if the new task added to the run-queue preempts the current 2709 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets 2710 * called on the nearest possible occasion: 2711 * 2712 * - If the kernel is preemptible (CONFIG_PREEMPT=y): 2713 * 2714 * - in syscall or exception context, at the next outmost 2715 * preempt_enable(). (this might be as soon as the wake_up()'s 2716 * spin_unlock()!) 2717 * 2718 * - in IRQ context, return from interrupt-handler to 2719 * preemptible context 2720 * 2721 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set) 2722 * then at the next: 2723 * 2724 * - cond_resched() call 2725 * - explicit schedule() call 2726 * - return from syscall or exception to user-space 2727 * - return from interrupt-handler to user-space 2728 * 2729 * WARNING: all callers must re-check need_resched() afterward and reschedule 2730 * accordingly in case an event triggered the need for rescheduling (such as 2731 * an interrupt waking up a task) while preemption was disabled in __schedule(). 2732 */ 2733 static void __sched __schedule(void) 2734 { 2735 struct task_struct *prev, *next; 2736 unsigned long *switch_count; 2737 struct rq *rq; 2738 int cpu; 2739 2740 preempt_disable(); 2741 cpu = smp_processor_id(); 2742 rq = cpu_rq(cpu); 2743 rcu_note_context_switch(); 2744 prev = rq->curr; 2745 2746 schedule_debug(prev); 2747 2748 if (sched_feat(HRTICK)) 2749 hrtick_clear(rq); 2750 2751 /* 2752 * Make sure that signal_pending_state()->signal_pending() below 2753 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE) 2754 * done by the caller to avoid the race with signal_wake_up(). 2755 */ 2756 smp_mb__before_spinlock(); 2757 raw_spin_lock_irq(&rq->lock); 2758 2759 rq->clock_skip_update <<= 1; /* promote REQ to ACT */ 2760 2761 switch_count = &prev->nivcsw; 2762 if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) { 2763 if (unlikely(signal_pending_state(prev->state, prev))) { 2764 prev->state = TASK_RUNNING; 2765 } else { 2766 deactivate_task(rq, prev, DEQUEUE_SLEEP); 2767 prev->on_rq = 0; 2768 2769 /* 2770 * If a worker went to sleep, notify and ask workqueue 2771 * whether it wants to wake up a task to maintain 2772 * concurrency. 2773 */ 2774 if (prev->flags & PF_WQ_WORKER) { 2775 struct task_struct *to_wakeup; 2776 2777 to_wakeup = wq_worker_sleeping(prev, cpu); 2778 if (to_wakeup) 2779 try_to_wake_up_local(to_wakeup); 2780 } 2781 } 2782 switch_count = &prev->nvcsw; 2783 } 2784 2785 if (task_on_rq_queued(prev)) 2786 update_rq_clock(rq); 2787 2788 next = pick_next_task(rq, prev); 2789 clear_tsk_need_resched(prev); 2790 clear_preempt_need_resched(); 2791 rq->clock_skip_update = 0; 2792 2793 if (likely(prev != next)) { 2794 rq->nr_switches++; 2795 rq->curr = next; 2796 ++*switch_count; 2797 2798 rq = context_switch(rq, prev, next); /* unlocks the rq */ 2799 cpu = cpu_of(rq); 2800 } else 2801 raw_spin_unlock_irq(&rq->lock); 2802 2803 post_schedule(rq); 2804 2805 sched_preempt_enable_no_resched(); 2806 } 2807 2808 static inline void sched_submit_work(struct task_struct *tsk) 2809 { 2810 if (!tsk->state || tsk_is_pi_blocked(tsk)) 2811 return; 2812 /* 2813 * If we are going to sleep and we have plugged IO queued, 2814 * make sure to submit it to avoid deadlocks. 2815 */ 2816 if (blk_needs_flush_plug(tsk)) 2817 blk_schedule_flush_plug(tsk); 2818 } 2819 2820 asmlinkage __visible void __sched schedule(void) 2821 { 2822 struct task_struct *tsk = current; 2823 2824 sched_submit_work(tsk); 2825 do { 2826 __schedule(); 2827 } while (need_resched()); 2828 } 2829 EXPORT_SYMBOL(schedule); 2830 2831 #ifdef CONFIG_CONTEXT_TRACKING 2832 asmlinkage __visible void __sched schedule_user(void) 2833 { 2834 /* 2835 * If we come here after a random call to set_need_resched(), 2836 * or we have been woken up remotely but the IPI has not yet arrived, 2837 * we haven't yet exited the RCU idle mode. Do it here manually until 2838 * we find a better solution. 2839 * 2840 * NB: There are buggy callers of this function. Ideally we 2841 * should warn if prev_state != CONTEXT_USER, but that will trigger 2842 * too frequently to make sense yet. 2843 */ 2844 enum ctx_state prev_state = exception_enter(); 2845 schedule(); 2846 exception_exit(prev_state); 2847 } 2848 #endif 2849 2850 /** 2851 * schedule_preempt_disabled - called with preemption disabled 2852 * 2853 * Returns with preemption disabled. Note: preempt_count must be 1 2854 */ 2855 void __sched schedule_preempt_disabled(void) 2856 { 2857 sched_preempt_enable_no_resched(); 2858 schedule(); 2859 preempt_disable(); 2860 } 2861 2862 static void __sched notrace preempt_schedule_common(void) 2863 { 2864 do { 2865 __preempt_count_add(PREEMPT_ACTIVE); 2866 __schedule(); 2867 __preempt_count_sub(PREEMPT_ACTIVE); 2868 2869 /* 2870 * Check again in case we missed a preemption opportunity 2871 * between schedule and now. 2872 */ 2873 barrier(); 2874 } while (need_resched()); 2875 } 2876 2877 #ifdef CONFIG_PREEMPT 2878 /* 2879 * this is the entry point to schedule() from in-kernel preemption 2880 * off of preempt_enable. Kernel preemptions off return from interrupt 2881 * occur there and call schedule directly. 2882 */ 2883 asmlinkage __visible void __sched notrace preempt_schedule(void) 2884 { 2885 /* 2886 * If there is a non-zero preempt_count or interrupts are disabled, 2887 * we do not want to preempt the current task. Just return.. 2888 */ 2889 if (likely(!preemptible())) 2890 return; 2891 2892 preempt_schedule_common(); 2893 } 2894 NOKPROBE_SYMBOL(preempt_schedule); 2895 EXPORT_SYMBOL(preempt_schedule); 2896 2897 #ifdef CONFIG_CONTEXT_TRACKING 2898 /** 2899 * preempt_schedule_context - preempt_schedule called by tracing 2900 * 2901 * The tracing infrastructure uses preempt_enable_notrace to prevent 2902 * recursion and tracing preempt enabling caused by the tracing 2903 * infrastructure itself. But as tracing can happen in areas coming 2904 * from userspace or just about to enter userspace, a preempt enable 2905 * can occur before user_exit() is called. This will cause the scheduler 2906 * to be called when the system is still in usermode. 2907 * 2908 * To prevent this, the preempt_enable_notrace will use this function 2909 * instead of preempt_schedule() to exit user context if needed before 2910 * calling the scheduler. 2911 */ 2912 asmlinkage __visible void __sched notrace preempt_schedule_context(void) 2913 { 2914 enum ctx_state prev_ctx; 2915 2916 if (likely(!preemptible())) 2917 return; 2918 2919 do { 2920 __preempt_count_add(PREEMPT_ACTIVE); 2921 /* 2922 * Needs preempt disabled in case user_exit() is traced 2923 * and the tracer calls preempt_enable_notrace() causing 2924 * an infinite recursion. 2925 */ 2926 prev_ctx = exception_enter(); 2927 __schedule(); 2928 exception_exit(prev_ctx); 2929 2930 __preempt_count_sub(PREEMPT_ACTIVE); 2931 barrier(); 2932 } while (need_resched()); 2933 } 2934 EXPORT_SYMBOL_GPL(preempt_schedule_context); 2935 #endif /* CONFIG_CONTEXT_TRACKING */ 2936 2937 #endif /* CONFIG_PREEMPT */ 2938 2939 /* 2940 * this is the entry point to schedule() from kernel preemption 2941 * off of irq context. 2942 * Note, that this is called and return with irqs disabled. This will 2943 * protect us against recursive calling from irq. 2944 */ 2945 asmlinkage __visible void __sched preempt_schedule_irq(void) 2946 { 2947 enum ctx_state prev_state; 2948 2949 /* Catch callers which need to be fixed */ 2950 BUG_ON(preempt_count() || !irqs_disabled()); 2951 2952 prev_state = exception_enter(); 2953 2954 do { 2955 __preempt_count_add(PREEMPT_ACTIVE); 2956 local_irq_enable(); 2957 __schedule(); 2958 local_irq_disable(); 2959 __preempt_count_sub(PREEMPT_ACTIVE); 2960 2961 /* 2962 * Check again in case we missed a preemption opportunity 2963 * between schedule and now. 2964 */ 2965 barrier(); 2966 } while (need_resched()); 2967 2968 exception_exit(prev_state); 2969 } 2970 2971 int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags, 2972 void *key) 2973 { 2974 return try_to_wake_up(curr->private, mode, wake_flags); 2975 } 2976 EXPORT_SYMBOL(default_wake_function); 2977 2978 #ifdef CONFIG_RT_MUTEXES 2979 2980 /* 2981 * rt_mutex_setprio - set the current priority of a task 2982 * @p: task 2983 * @prio: prio value (kernel-internal form) 2984 * 2985 * This function changes the 'effective' priority of a task. It does 2986 * not touch ->normal_prio like __setscheduler(). 2987 * 2988 * Used by the rt_mutex code to implement priority inheritance 2989 * logic. Call site only calls if the priority of the task changed. 2990 */ 2991 void rt_mutex_setprio(struct task_struct *p, int prio) 2992 { 2993 int oldprio, queued, running, enqueue_flag = 0; 2994 struct rq *rq; 2995 const struct sched_class *prev_class; 2996 2997 BUG_ON(prio > MAX_PRIO); 2998 2999 rq = __task_rq_lock(p); 3000 3001 /* 3002 * Idle task boosting is a nono in general. There is one 3003 * exception, when PREEMPT_RT and NOHZ is active: 3004 * 3005 * The idle task calls get_next_timer_interrupt() and holds 3006 * the timer wheel base->lock on the CPU and another CPU wants 3007 * to access the timer (probably to cancel it). We can safely 3008 * ignore the boosting request, as the idle CPU runs this code 3009 * with interrupts disabled and will complete the lock 3010 * protected section without being interrupted. So there is no 3011 * real need to boost. 3012 */ 3013 if (unlikely(p == rq->idle)) { 3014 WARN_ON(p != rq->curr); 3015 WARN_ON(p->pi_blocked_on); 3016 goto out_unlock; 3017 } 3018 3019 trace_sched_pi_setprio(p, prio); 3020 oldprio = p->prio; 3021 prev_class = p->sched_class; 3022 queued = task_on_rq_queued(p); 3023 running = task_current(rq, p); 3024 if (queued) 3025 dequeue_task(rq, p, 0); 3026 if (running) 3027 put_prev_task(rq, p); 3028 3029 /* 3030 * Boosting condition are: 3031 * 1. -rt task is running and holds mutex A 3032 * --> -dl task blocks on mutex A 3033 * 3034 * 2. -dl task is running and holds mutex A 3035 * --> -dl task blocks on mutex A and could preempt the 3036 * running task 3037 */ 3038 if (dl_prio(prio)) { 3039 struct task_struct *pi_task = rt_mutex_get_top_task(p); 3040 if (!dl_prio(p->normal_prio) || 3041 (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) { 3042 p->dl.dl_boosted = 1; 3043 p->dl.dl_throttled = 0; 3044 enqueue_flag = ENQUEUE_REPLENISH; 3045 } else 3046 p->dl.dl_boosted = 0; 3047 p->sched_class = &dl_sched_class; 3048 } else if (rt_prio(prio)) { 3049 if (dl_prio(oldprio)) 3050 p->dl.dl_boosted = 0; 3051 if (oldprio < prio) 3052 enqueue_flag = ENQUEUE_HEAD; 3053 p->sched_class = &rt_sched_class; 3054 } else { 3055 if (dl_prio(oldprio)) 3056 p->dl.dl_boosted = 0; 3057 if (rt_prio(oldprio)) 3058 p->rt.timeout = 0; 3059 p->sched_class = &fair_sched_class; 3060 } 3061 3062 p->prio = prio; 3063 3064 if (running) 3065 p->sched_class->set_curr_task(rq); 3066 if (queued) 3067 enqueue_task(rq, p, enqueue_flag); 3068 3069 check_class_changed(rq, p, prev_class, oldprio); 3070 out_unlock: 3071 __task_rq_unlock(rq); 3072 } 3073 #endif 3074 3075 void set_user_nice(struct task_struct *p, long nice) 3076 { 3077 int old_prio, delta, queued; 3078 unsigned long flags; 3079 struct rq *rq; 3080 3081 if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE) 3082 return; 3083 /* 3084 * We have to be careful, if called from sys_setpriority(), 3085 * the task might be in the middle of scheduling on another CPU. 3086 */ 3087 rq = task_rq_lock(p, &flags); 3088 /* 3089 * The RT priorities are set via sched_setscheduler(), but we still 3090 * allow the 'normal' nice value to be set - but as expected 3091 * it wont have any effect on scheduling until the task is 3092 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR: 3093 */ 3094 if (task_has_dl_policy(p) || task_has_rt_policy(p)) { 3095 p->static_prio = NICE_TO_PRIO(nice); 3096 goto out_unlock; 3097 } 3098 queued = task_on_rq_queued(p); 3099 if (queued) 3100 dequeue_task(rq, p, 0); 3101 3102 p->static_prio = NICE_TO_PRIO(nice); 3103 set_load_weight(p); 3104 old_prio = p->prio; 3105 p->prio = effective_prio(p); 3106 delta = p->prio - old_prio; 3107 3108 if (queued) { 3109 enqueue_task(rq, p, 0); 3110 /* 3111 * If the task increased its priority or is running and 3112 * lowered its priority, then reschedule its CPU: 3113 */ 3114 if (delta < 0 || (delta > 0 && task_running(rq, p))) 3115 resched_curr(rq); 3116 } 3117 out_unlock: 3118 task_rq_unlock(rq, p, &flags); 3119 } 3120 EXPORT_SYMBOL(set_user_nice); 3121 3122 /* 3123 * can_nice - check if a task can reduce its nice value 3124 * @p: task 3125 * @nice: nice value 3126 */ 3127 int can_nice(const struct task_struct *p, const int nice) 3128 { 3129 /* convert nice value [19,-20] to rlimit style value [1,40] */ 3130 int nice_rlim = nice_to_rlimit(nice); 3131 3132 return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) || 3133 capable(CAP_SYS_NICE)); 3134 } 3135 3136 #ifdef __ARCH_WANT_SYS_NICE 3137 3138 /* 3139 * sys_nice - change the priority of the current process. 3140 * @increment: priority increment 3141 * 3142 * sys_setpriority is a more generic, but much slower function that 3143 * does similar things. 3144 */ 3145 SYSCALL_DEFINE1(nice, int, increment) 3146 { 3147 long nice, retval; 3148 3149 /* 3150 * Setpriority might change our priority at the same moment. 3151 * We don't have to worry. Conceptually one call occurs first 3152 * and we have a single winner. 3153 */ 3154 increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH); 3155 nice = task_nice(current) + increment; 3156 3157 nice = clamp_val(nice, MIN_NICE, MAX_NICE); 3158 if (increment < 0 && !can_nice(current, nice)) 3159 return -EPERM; 3160 3161 retval = security_task_setnice(current, nice); 3162 if (retval) 3163 return retval; 3164 3165 set_user_nice(current, nice); 3166 return 0; 3167 } 3168 3169 #endif 3170 3171 /** 3172 * task_prio - return the priority value of a given task. 3173 * @p: the task in question. 3174 * 3175 * Return: The priority value as seen by users in /proc. 3176 * RT tasks are offset by -200. Normal tasks are centered 3177 * around 0, value goes from -16 to +15. 3178 */ 3179 int task_prio(const struct task_struct *p) 3180 { 3181 return p->prio - MAX_RT_PRIO; 3182 } 3183 3184 /** 3185 * idle_cpu - is a given cpu idle currently? 3186 * @cpu: the processor in question. 3187 * 3188 * Return: 1 if the CPU is currently idle. 0 otherwise. 3189 */ 3190 int idle_cpu(int cpu) 3191 { 3192 struct rq *rq = cpu_rq(cpu); 3193 3194 if (rq->curr != rq->idle) 3195 return 0; 3196 3197 if (rq->nr_running) 3198 return 0; 3199 3200 #ifdef CONFIG_SMP 3201 if (!llist_empty(&rq->wake_list)) 3202 return 0; 3203 #endif 3204 3205 return 1; 3206 } 3207 3208 /** 3209 * idle_task - return the idle task for a given cpu. 3210 * @cpu: the processor in question. 3211 * 3212 * Return: The idle task for the cpu @cpu. 3213 */ 3214 struct task_struct *idle_task(int cpu) 3215 { 3216 return cpu_rq(cpu)->idle; 3217 } 3218 3219 /** 3220 * find_process_by_pid - find a process with a matching PID value. 3221 * @pid: the pid in question. 3222 * 3223 * The task of @pid, if found. %NULL otherwise. 3224 */ 3225 static struct task_struct *find_process_by_pid(pid_t pid) 3226 { 3227 return pid ? find_task_by_vpid(pid) : current; 3228 } 3229 3230 /* 3231 * This function initializes the sched_dl_entity of a newly becoming 3232 * SCHED_DEADLINE task. 3233 * 3234 * Only the static values are considered here, the actual runtime and the 3235 * absolute deadline will be properly calculated when the task is enqueued 3236 * for the first time with its new policy. 3237 */ 3238 static void 3239 __setparam_dl(struct task_struct *p, const struct sched_attr *attr) 3240 { 3241 struct sched_dl_entity *dl_se = &p->dl; 3242 3243 dl_se->dl_runtime = attr->sched_runtime; 3244 dl_se->dl_deadline = attr->sched_deadline; 3245 dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline; 3246 dl_se->flags = attr->sched_flags; 3247 dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime); 3248 3249 /* 3250 * Changing the parameters of a task is 'tricky' and we're not doing 3251 * the correct thing -- also see task_dead_dl() and switched_from_dl(). 3252 * 3253 * What we SHOULD do is delay the bandwidth release until the 0-lag 3254 * point. This would include retaining the task_struct until that time 3255 * and change dl_overflow() to not immediately decrement the current 3256 * amount. 3257 * 3258 * Instead we retain the current runtime/deadline and let the new 3259 * parameters take effect after the current reservation period lapses. 3260 * This is safe (albeit pessimistic) because the 0-lag point is always 3261 * before the current scheduling deadline. 3262 * 3263 * We can still have temporary overloads because we do not delay the 3264 * change in bandwidth until that time; so admission control is 3265 * not on the safe side. It does however guarantee tasks will never 3266 * consume more than promised. 3267 */ 3268 } 3269 3270 /* 3271 * sched_setparam() passes in -1 for its policy, to let the functions 3272 * it calls know not to change it. 3273 */ 3274 #define SETPARAM_POLICY -1 3275 3276 static void __setscheduler_params(struct task_struct *p, 3277 const struct sched_attr *attr) 3278 { 3279 int policy = attr->sched_policy; 3280 3281 if (policy == SETPARAM_POLICY) 3282 policy = p->policy; 3283 3284 p->policy = policy; 3285 3286 if (dl_policy(policy)) 3287 __setparam_dl(p, attr); 3288 else if (fair_policy(policy)) 3289 p->static_prio = NICE_TO_PRIO(attr->sched_nice); 3290 3291 /* 3292 * __sched_setscheduler() ensures attr->sched_priority == 0 when 3293 * !rt_policy. Always setting this ensures that things like 3294 * getparam()/getattr() don't report silly values for !rt tasks. 3295 */ 3296 p->rt_priority = attr->sched_priority; 3297 p->normal_prio = normal_prio(p); 3298 set_load_weight(p); 3299 } 3300 3301 /* Actually do priority change: must hold pi & rq lock. */ 3302 static void __setscheduler(struct rq *rq, struct task_struct *p, 3303 const struct sched_attr *attr, bool keep_boost) 3304 { 3305 __setscheduler_params(p, attr); 3306 3307 /* 3308 * Keep a potential priority boosting if called from 3309 * sched_setscheduler(). 3310 */ 3311 if (keep_boost) 3312 p->prio = rt_mutex_get_effective_prio(p, normal_prio(p)); 3313 else 3314 p->prio = normal_prio(p); 3315 3316 if (dl_prio(p->prio)) 3317 p->sched_class = &dl_sched_class; 3318 else if (rt_prio(p->prio)) 3319 p->sched_class = &rt_sched_class; 3320 else 3321 p->sched_class = &fair_sched_class; 3322 } 3323 3324 static void 3325 __getparam_dl(struct task_struct *p, struct sched_attr *attr) 3326 { 3327 struct sched_dl_entity *dl_se = &p->dl; 3328 3329 attr->sched_priority = p->rt_priority; 3330 attr->sched_runtime = dl_se->dl_runtime; 3331 attr->sched_deadline = dl_se->dl_deadline; 3332 attr->sched_period = dl_se->dl_period; 3333 attr->sched_flags = dl_se->flags; 3334 } 3335 3336 /* 3337 * This function validates the new parameters of a -deadline task. 3338 * We ask for the deadline not being zero, and greater or equal 3339 * than the runtime, as well as the period of being zero or 3340 * greater than deadline. Furthermore, we have to be sure that 3341 * user parameters are above the internal resolution of 1us (we 3342 * check sched_runtime only since it is always the smaller one) and 3343 * below 2^63 ns (we have to check both sched_deadline and 3344 * sched_period, as the latter can be zero). 3345 */ 3346 static bool 3347 __checkparam_dl(const struct sched_attr *attr) 3348 { 3349 /* deadline != 0 */ 3350 if (attr->sched_deadline == 0) 3351 return false; 3352 3353 /* 3354 * Since we truncate DL_SCALE bits, make sure we're at least 3355 * that big. 3356 */ 3357 if (attr->sched_runtime < (1ULL << DL_SCALE)) 3358 return false; 3359 3360 /* 3361 * Since we use the MSB for wrap-around and sign issues, make 3362 * sure it's not set (mind that period can be equal to zero). 3363 */ 3364 if (attr->sched_deadline & (1ULL << 63) || 3365 attr->sched_period & (1ULL << 63)) 3366 return false; 3367 3368 /* runtime <= deadline <= period (if period != 0) */ 3369 if ((attr->sched_period != 0 && 3370 attr->sched_period < attr->sched_deadline) || 3371 attr->sched_deadline < attr->sched_runtime) 3372 return false; 3373 3374 return true; 3375 } 3376 3377 /* 3378 * check the target process has a UID that matches the current process's 3379 */ 3380 static bool check_same_owner(struct task_struct *p) 3381 { 3382 const struct cred *cred = current_cred(), *pcred; 3383 bool match; 3384 3385 rcu_read_lock(); 3386 pcred = __task_cred(p); 3387 match = (uid_eq(cred->euid, pcred->euid) || 3388 uid_eq(cred->euid, pcred->uid)); 3389 rcu_read_unlock(); 3390 return match; 3391 } 3392 3393 static bool dl_param_changed(struct task_struct *p, 3394 const struct sched_attr *attr) 3395 { 3396 struct sched_dl_entity *dl_se = &p->dl; 3397 3398 if (dl_se->dl_runtime != attr->sched_runtime || 3399 dl_se->dl_deadline != attr->sched_deadline || 3400 dl_se->dl_period != attr->sched_period || 3401 dl_se->flags != attr->sched_flags) 3402 return true; 3403 3404 return false; 3405 } 3406 3407 static int __sched_setscheduler(struct task_struct *p, 3408 const struct sched_attr *attr, 3409 bool user) 3410 { 3411 int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 : 3412 MAX_RT_PRIO - 1 - attr->sched_priority; 3413 int retval, oldprio, oldpolicy = -1, queued, running; 3414 int new_effective_prio, policy = attr->sched_policy; 3415 unsigned long flags; 3416 const struct sched_class *prev_class; 3417 struct rq *rq; 3418 int reset_on_fork; 3419 3420 /* may grab non-irq protected spin_locks */ 3421 BUG_ON(in_interrupt()); 3422 recheck: 3423 /* double check policy once rq lock held */ 3424 if (policy < 0) { 3425 reset_on_fork = p->sched_reset_on_fork; 3426 policy = oldpolicy = p->policy; 3427 } else { 3428 reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK); 3429 3430 if (policy != SCHED_DEADLINE && 3431 policy != SCHED_FIFO && policy != SCHED_RR && 3432 policy != SCHED_NORMAL && policy != SCHED_BATCH && 3433 policy != SCHED_IDLE) 3434 return -EINVAL; 3435 } 3436 3437 if (attr->sched_flags & ~(SCHED_FLAG_RESET_ON_FORK)) 3438 return -EINVAL; 3439 3440 /* 3441 * Valid priorities for SCHED_FIFO and SCHED_RR are 3442 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL, 3443 * SCHED_BATCH and SCHED_IDLE is 0. 3444 */ 3445 if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) || 3446 (!p->mm && attr->sched_priority > MAX_RT_PRIO-1)) 3447 return -EINVAL; 3448 if ((dl_policy(policy) && !__checkparam_dl(attr)) || 3449 (rt_policy(policy) != (attr->sched_priority != 0))) 3450 return -EINVAL; 3451 3452 /* 3453 * Allow unprivileged RT tasks to decrease priority: 3454 */ 3455 if (user && !capable(CAP_SYS_NICE)) { 3456 if (fair_policy(policy)) { 3457 if (attr->sched_nice < task_nice(p) && 3458 !can_nice(p, attr->sched_nice)) 3459 return -EPERM; 3460 } 3461 3462 if (rt_policy(policy)) { 3463 unsigned long rlim_rtprio = 3464 task_rlimit(p, RLIMIT_RTPRIO); 3465 3466 /* can't set/change the rt policy */ 3467 if (policy != p->policy && !rlim_rtprio) 3468 return -EPERM; 3469 3470 /* can't increase priority */ 3471 if (attr->sched_priority > p->rt_priority && 3472 attr->sched_priority > rlim_rtprio) 3473 return -EPERM; 3474 } 3475 3476 /* 3477 * Can't set/change SCHED_DEADLINE policy at all for now 3478 * (safest behavior); in the future we would like to allow 3479 * unprivileged DL tasks to increase their relative deadline 3480 * or reduce their runtime (both ways reducing utilization) 3481 */ 3482 if (dl_policy(policy)) 3483 return -EPERM; 3484 3485 /* 3486 * Treat SCHED_IDLE as nice 20. Only allow a switch to 3487 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it. 3488 */ 3489 if (p->policy == SCHED_IDLE && policy != SCHED_IDLE) { 3490 if (!can_nice(p, task_nice(p))) 3491 return -EPERM; 3492 } 3493 3494 /* can't change other user's priorities */ 3495 if (!check_same_owner(p)) 3496 return -EPERM; 3497 3498 /* Normal users shall not reset the sched_reset_on_fork flag */ 3499 if (p->sched_reset_on_fork && !reset_on_fork) 3500 return -EPERM; 3501 } 3502 3503 if (user) { 3504 retval = security_task_setscheduler(p); 3505 if (retval) 3506 return retval; 3507 } 3508 3509 /* 3510 * make sure no PI-waiters arrive (or leave) while we are 3511 * changing the priority of the task: 3512 * 3513 * To be able to change p->policy safely, the appropriate 3514 * runqueue lock must be held. 3515 */ 3516 rq = task_rq_lock(p, &flags); 3517 3518 /* 3519 * Changing the policy of the stop threads its a very bad idea 3520 */ 3521 if (p == rq->stop) { 3522 task_rq_unlock(rq, p, &flags); 3523 return -EINVAL; 3524 } 3525 3526 /* 3527 * If not changing anything there's no need to proceed further, 3528 * but store a possible modification of reset_on_fork. 3529 */ 3530 if (unlikely(policy == p->policy)) { 3531 if (fair_policy(policy) && attr->sched_nice != task_nice(p)) 3532 goto change; 3533 if (rt_policy(policy) && attr->sched_priority != p->rt_priority) 3534 goto change; 3535 if (dl_policy(policy) && dl_param_changed(p, attr)) 3536 goto change; 3537 3538 p->sched_reset_on_fork = reset_on_fork; 3539 task_rq_unlock(rq, p, &flags); 3540 return 0; 3541 } 3542 change: 3543 3544 if (user) { 3545 #ifdef CONFIG_RT_GROUP_SCHED 3546 /* 3547 * Do not allow realtime tasks into groups that have no runtime 3548 * assigned. 3549 */ 3550 if (rt_bandwidth_enabled() && rt_policy(policy) && 3551 task_group(p)->rt_bandwidth.rt_runtime == 0 && 3552 !task_group_is_autogroup(task_group(p))) { 3553 task_rq_unlock(rq, p, &flags); 3554 return -EPERM; 3555 } 3556 #endif 3557 #ifdef CONFIG_SMP 3558 if (dl_bandwidth_enabled() && dl_policy(policy)) { 3559 cpumask_t *span = rq->rd->span; 3560 3561 /* 3562 * Don't allow tasks with an affinity mask smaller than 3563 * the entire root_domain to become SCHED_DEADLINE. We 3564 * will also fail if there's no bandwidth available. 3565 */ 3566 if (!cpumask_subset(span, &p->cpus_allowed) || 3567 rq->rd->dl_bw.bw == 0) { 3568 task_rq_unlock(rq, p, &flags); 3569 return -EPERM; 3570 } 3571 } 3572 #endif 3573 } 3574 3575 /* recheck policy now with rq lock held */ 3576 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) { 3577 policy = oldpolicy = -1; 3578 task_rq_unlock(rq, p, &flags); 3579 goto recheck; 3580 } 3581 3582 /* 3583 * If setscheduling to SCHED_DEADLINE (or changing the parameters 3584 * of a SCHED_DEADLINE task) we need to check if enough bandwidth 3585 * is available. 3586 */ 3587 if ((dl_policy(policy) || dl_task(p)) && dl_overflow(p, policy, attr)) { 3588 task_rq_unlock(rq, p, &flags); 3589 return -EBUSY; 3590 } 3591 3592 p->sched_reset_on_fork = reset_on_fork; 3593 oldprio = p->prio; 3594 3595 /* 3596 * Take priority boosted tasks into account. If the new 3597 * effective priority is unchanged, we just store the new 3598 * normal parameters and do not touch the scheduler class and 3599 * the runqueue. This will be done when the task deboost 3600 * itself. 3601 */ 3602 new_effective_prio = rt_mutex_get_effective_prio(p, newprio); 3603 if (new_effective_prio == oldprio) { 3604 __setscheduler_params(p, attr); 3605 task_rq_unlock(rq, p, &flags); 3606 return 0; 3607 } 3608 3609 queued = task_on_rq_queued(p); 3610 running = task_current(rq, p); 3611 if (queued) 3612 dequeue_task(rq, p, 0); 3613 if (running) 3614 put_prev_task(rq, p); 3615 3616 prev_class = p->sched_class; 3617 __setscheduler(rq, p, attr, true); 3618 3619 if (running) 3620 p->sched_class->set_curr_task(rq); 3621 if (queued) { 3622 /* 3623 * We enqueue to tail when the priority of a task is 3624 * increased (user space view). 3625 */ 3626 enqueue_task(rq, p, oldprio <= p->prio ? ENQUEUE_HEAD : 0); 3627 } 3628 3629 check_class_changed(rq, p, prev_class, oldprio); 3630 task_rq_unlock(rq, p, &flags); 3631 3632 rt_mutex_adjust_pi(p); 3633 3634 return 0; 3635 } 3636 3637 static int _sched_setscheduler(struct task_struct *p, int policy, 3638 const struct sched_param *param, bool check) 3639 { 3640 struct sched_attr attr = { 3641 .sched_policy = policy, 3642 .sched_priority = param->sched_priority, 3643 .sched_nice = PRIO_TO_NICE(p->static_prio), 3644 }; 3645 3646 /* Fixup the legacy SCHED_RESET_ON_FORK hack. */ 3647 if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) { 3648 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK; 3649 policy &= ~SCHED_RESET_ON_FORK; 3650 attr.sched_policy = policy; 3651 } 3652 3653 return __sched_setscheduler(p, &attr, check); 3654 } 3655 /** 3656 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread. 3657 * @p: the task in question. 3658 * @policy: new policy. 3659 * @param: structure containing the new RT priority. 3660 * 3661 * Return: 0 on success. An error code otherwise. 3662 * 3663 * NOTE that the task may be already dead. 3664 */ 3665 int sched_setscheduler(struct task_struct *p, int policy, 3666 const struct sched_param *param) 3667 { 3668 return _sched_setscheduler(p, policy, param, true); 3669 } 3670 EXPORT_SYMBOL_GPL(sched_setscheduler); 3671 3672 int sched_setattr(struct task_struct *p, const struct sched_attr *attr) 3673 { 3674 return __sched_setscheduler(p, attr, true); 3675 } 3676 EXPORT_SYMBOL_GPL(sched_setattr); 3677 3678 /** 3679 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace. 3680 * @p: the task in question. 3681 * @policy: new policy. 3682 * @param: structure containing the new RT priority. 3683 * 3684 * Just like sched_setscheduler, only don't bother checking if the 3685 * current context has permission. For example, this is needed in 3686 * stop_machine(): we create temporary high priority worker threads, 3687 * but our caller might not have that capability. 3688 * 3689 * Return: 0 on success. An error code otherwise. 3690 */ 3691 int sched_setscheduler_nocheck(struct task_struct *p, int policy, 3692 const struct sched_param *param) 3693 { 3694 return _sched_setscheduler(p, policy, param, false); 3695 } 3696 3697 static int 3698 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) 3699 { 3700 struct sched_param lparam; 3701 struct task_struct *p; 3702 int retval; 3703 3704 if (!param || pid < 0) 3705 return -EINVAL; 3706 if (copy_from_user(&lparam, param, sizeof(struct sched_param))) 3707 return -EFAULT; 3708 3709 rcu_read_lock(); 3710 retval = -ESRCH; 3711 p = find_process_by_pid(pid); 3712 if (p != NULL) 3713 retval = sched_setscheduler(p, policy, &lparam); 3714 rcu_read_unlock(); 3715 3716 return retval; 3717 } 3718 3719 /* 3720 * Mimics kernel/events/core.c perf_copy_attr(). 3721 */ 3722 static int sched_copy_attr(struct sched_attr __user *uattr, 3723 struct sched_attr *attr) 3724 { 3725 u32 size; 3726 int ret; 3727 3728 if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0)) 3729 return -EFAULT; 3730 3731 /* 3732 * zero the full structure, so that a short copy will be nice. 3733 */ 3734 memset(attr, 0, sizeof(*attr)); 3735 3736 ret = get_user(size, &uattr->size); 3737 if (ret) 3738 return ret; 3739 3740 if (size > PAGE_SIZE) /* silly large */ 3741 goto err_size; 3742 3743 if (!size) /* abi compat */ 3744 size = SCHED_ATTR_SIZE_VER0; 3745 3746 if (size < SCHED_ATTR_SIZE_VER0) 3747 goto err_size; 3748 3749 /* 3750 * If we're handed a bigger struct than we know of, 3751 * ensure all the unknown bits are 0 - i.e. new 3752 * user-space does not rely on any kernel feature 3753 * extensions we dont know about yet. 3754 */ 3755 if (size > sizeof(*attr)) { 3756 unsigned char __user *addr; 3757 unsigned char __user *end; 3758 unsigned char val; 3759 3760 addr = (void __user *)uattr + sizeof(*attr); 3761 end = (void __user *)uattr + size; 3762 3763 for (; addr < end; addr++) { 3764 ret = get_user(val, addr); 3765 if (ret) 3766 return ret; 3767 if (val) 3768 goto err_size; 3769 } 3770 size = sizeof(*attr); 3771 } 3772 3773 ret = copy_from_user(attr, uattr, size); 3774 if (ret) 3775 return -EFAULT; 3776 3777 /* 3778 * XXX: do we want to be lenient like existing syscalls; or do we want 3779 * to be strict and return an error on out-of-bounds values? 3780 */ 3781 attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE); 3782 3783 return 0; 3784 3785 err_size: 3786 put_user(sizeof(*attr), &uattr->size); 3787 return -E2BIG; 3788 } 3789 3790 /** 3791 * sys_sched_setscheduler - set/change the scheduler policy and RT priority 3792 * @pid: the pid in question. 3793 * @policy: new policy. 3794 * @param: structure containing the new RT priority. 3795 * 3796 * Return: 0 on success. An error code otherwise. 3797 */ 3798 SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy, 3799 struct sched_param __user *, param) 3800 { 3801 /* negative values for policy are not valid */ 3802 if (policy < 0) 3803 return -EINVAL; 3804 3805 return do_sched_setscheduler(pid, policy, param); 3806 } 3807 3808 /** 3809 * sys_sched_setparam - set/change the RT priority of a thread 3810 * @pid: the pid in question. 3811 * @param: structure containing the new RT priority. 3812 * 3813 * Return: 0 on success. An error code otherwise. 3814 */ 3815 SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param) 3816 { 3817 return do_sched_setscheduler(pid, SETPARAM_POLICY, param); 3818 } 3819 3820 /** 3821 * sys_sched_setattr - same as above, but with extended sched_attr 3822 * @pid: the pid in question. 3823 * @uattr: structure containing the extended parameters. 3824 * @flags: for future extension. 3825 */ 3826 SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr, 3827 unsigned int, flags) 3828 { 3829 struct sched_attr attr; 3830 struct task_struct *p; 3831 int retval; 3832 3833 if (!uattr || pid < 0 || flags) 3834 return -EINVAL; 3835 3836 retval = sched_copy_attr(uattr, &attr); 3837 if (retval) 3838 return retval; 3839 3840 if ((int)attr.sched_policy < 0) 3841 return -EINVAL; 3842 3843 rcu_read_lock(); 3844 retval = -ESRCH; 3845 p = find_process_by_pid(pid); 3846 if (p != NULL) 3847 retval = sched_setattr(p, &attr); 3848 rcu_read_unlock(); 3849 3850 return retval; 3851 } 3852 3853 /** 3854 * sys_sched_getscheduler - get the policy (scheduling class) of a thread 3855 * @pid: the pid in question. 3856 * 3857 * Return: On success, the policy of the thread. Otherwise, a negative error 3858 * code. 3859 */ 3860 SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid) 3861 { 3862 struct task_struct *p; 3863 int retval; 3864 3865 if (pid < 0) 3866 return -EINVAL; 3867 3868 retval = -ESRCH; 3869 rcu_read_lock(); 3870 p = find_process_by_pid(pid); 3871 if (p) { 3872 retval = security_task_getscheduler(p); 3873 if (!retval) 3874 retval = p->policy 3875 | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0); 3876 } 3877 rcu_read_unlock(); 3878 return retval; 3879 } 3880 3881 /** 3882 * sys_sched_getparam - get the RT priority of a thread 3883 * @pid: the pid in question. 3884 * @param: structure containing the RT priority. 3885 * 3886 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error 3887 * code. 3888 */ 3889 SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param) 3890 { 3891 struct sched_param lp = { .sched_priority = 0 }; 3892 struct task_struct *p; 3893 int retval; 3894 3895 if (!param || pid < 0) 3896 return -EINVAL; 3897 3898 rcu_read_lock(); 3899 p = find_process_by_pid(pid); 3900 retval = -ESRCH; 3901 if (!p) 3902 goto out_unlock; 3903 3904 retval = security_task_getscheduler(p); 3905 if (retval) 3906 goto out_unlock; 3907 3908 if (task_has_rt_policy(p)) 3909 lp.sched_priority = p->rt_priority; 3910 rcu_read_unlock(); 3911 3912 /* 3913 * This one might sleep, we cannot do it with a spinlock held ... 3914 */ 3915 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0; 3916 3917 return retval; 3918 3919 out_unlock: 3920 rcu_read_unlock(); 3921 return retval; 3922 } 3923 3924 static int sched_read_attr(struct sched_attr __user *uattr, 3925 struct sched_attr *attr, 3926 unsigned int usize) 3927 { 3928 int ret; 3929 3930 if (!access_ok(VERIFY_WRITE, uattr, usize)) 3931 return -EFAULT; 3932 3933 /* 3934 * If we're handed a smaller struct than we know of, 3935 * ensure all the unknown bits are 0 - i.e. old 3936 * user-space does not get uncomplete information. 3937 */ 3938 if (usize < sizeof(*attr)) { 3939 unsigned char *addr; 3940 unsigned char *end; 3941 3942 addr = (void *)attr + usize; 3943 end = (void *)attr + sizeof(*attr); 3944 3945 for (; addr < end; addr++) { 3946 if (*addr) 3947 return -EFBIG; 3948 } 3949 3950 attr->size = usize; 3951 } 3952 3953 ret = copy_to_user(uattr, attr, attr->size); 3954 if (ret) 3955 return -EFAULT; 3956 3957 return 0; 3958 } 3959 3960 /** 3961 * sys_sched_getattr - similar to sched_getparam, but with sched_attr 3962 * @pid: the pid in question. 3963 * @uattr: structure containing the extended parameters. 3964 * @size: sizeof(attr) for fwd/bwd comp. 3965 * @flags: for future extension. 3966 */ 3967 SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr, 3968 unsigned int, size, unsigned int, flags) 3969 { 3970 struct sched_attr attr = { 3971 .size = sizeof(struct sched_attr), 3972 }; 3973 struct task_struct *p; 3974 int retval; 3975 3976 if (!uattr || pid < 0 || size > PAGE_SIZE || 3977 size < SCHED_ATTR_SIZE_VER0 || flags) 3978 return -EINVAL; 3979 3980 rcu_read_lock(); 3981 p = find_process_by_pid(pid); 3982 retval = -ESRCH; 3983 if (!p) 3984 goto out_unlock; 3985 3986 retval = security_task_getscheduler(p); 3987 if (retval) 3988 goto out_unlock; 3989 3990 attr.sched_policy = p->policy; 3991 if (p->sched_reset_on_fork) 3992 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK; 3993 if (task_has_dl_policy(p)) 3994 __getparam_dl(p, &attr); 3995 else if (task_has_rt_policy(p)) 3996 attr.sched_priority = p->rt_priority; 3997 else 3998 attr.sched_nice = task_nice(p); 3999 4000 rcu_read_unlock(); 4001 4002 retval = sched_read_attr(uattr, &attr, size); 4003 return retval; 4004 4005 out_unlock: 4006 rcu_read_unlock(); 4007 return retval; 4008 } 4009 4010 long sched_setaffinity(pid_t pid, const struct cpumask *in_mask) 4011 { 4012 cpumask_var_t cpus_allowed, new_mask; 4013 struct task_struct *p; 4014 int retval; 4015 4016 rcu_read_lock(); 4017 4018 p = find_process_by_pid(pid); 4019 if (!p) { 4020 rcu_read_unlock(); 4021 return -ESRCH; 4022 } 4023 4024 /* Prevent p going away */ 4025 get_task_struct(p); 4026 rcu_read_unlock(); 4027 4028 if (p->flags & PF_NO_SETAFFINITY) { 4029 retval = -EINVAL; 4030 goto out_put_task; 4031 } 4032 if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) { 4033 retval = -ENOMEM; 4034 goto out_put_task; 4035 } 4036 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) { 4037 retval = -ENOMEM; 4038 goto out_free_cpus_allowed; 4039 } 4040 retval = -EPERM; 4041 if (!check_same_owner(p)) { 4042 rcu_read_lock(); 4043 if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) { 4044 rcu_read_unlock(); 4045 goto out_free_new_mask; 4046 } 4047 rcu_read_unlock(); 4048 } 4049 4050 retval = security_task_setscheduler(p); 4051 if (retval) 4052 goto out_free_new_mask; 4053 4054 4055 cpuset_cpus_allowed(p, cpus_allowed); 4056 cpumask_and(new_mask, in_mask, cpus_allowed); 4057 4058 /* 4059 * Since bandwidth control happens on root_domain basis, 4060 * if admission test is enabled, we only admit -deadline 4061 * tasks allowed to run on all the CPUs in the task's 4062 * root_domain. 4063 */ 4064 #ifdef CONFIG_SMP 4065 if (task_has_dl_policy(p) && dl_bandwidth_enabled()) { 4066 rcu_read_lock(); 4067 if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) { 4068 retval = -EBUSY; 4069 rcu_read_unlock(); 4070 goto out_free_new_mask; 4071 } 4072 rcu_read_unlock(); 4073 } 4074 #endif 4075 again: 4076 retval = set_cpus_allowed_ptr(p, new_mask); 4077 4078 if (!retval) { 4079 cpuset_cpus_allowed(p, cpus_allowed); 4080 if (!cpumask_subset(new_mask, cpus_allowed)) { 4081 /* 4082 * We must have raced with a concurrent cpuset 4083 * update. Just reset the cpus_allowed to the 4084 * cpuset's cpus_allowed 4085 */ 4086 cpumask_copy(new_mask, cpus_allowed); 4087 goto again; 4088 } 4089 } 4090 out_free_new_mask: 4091 free_cpumask_var(new_mask); 4092 out_free_cpus_allowed: 4093 free_cpumask_var(cpus_allowed); 4094 out_put_task: 4095 put_task_struct(p); 4096 return retval; 4097 } 4098 4099 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len, 4100 struct cpumask *new_mask) 4101 { 4102 if (len < cpumask_size()) 4103 cpumask_clear(new_mask); 4104 else if (len > cpumask_size()) 4105 len = cpumask_size(); 4106 4107 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0; 4108 } 4109 4110 /** 4111 * sys_sched_setaffinity - set the cpu affinity of a process 4112 * @pid: pid of the process 4113 * @len: length in bytes of the bitmask pointed to by user_mask_ptr 4114 * @user_mask_ptr: user-space pointer to the new cpu mask 4115 * 4116 * Return: 0 on success. An error code otherwise. 4117 */ 4118 SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len, 4119 unsigned long __user *, user_mask_ptr) 4120 { 4121 cpumask_var_t new_mask; 4122 int retval; 4123 4124 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) 4125 return -ENOMEM; 4126 4127 retval = get_user_cpu_mask(user_mask_ptr, len, new_mask); 4128 if (retval == 0) 4129 retval = sched_setaffinity(pid, new_mask); 4130 free_cpumask_var(new_mask); 4131 return retval; 4132 } 4133 4134 long sched_getaffinity(pid_t pid, struct cpumask *mask) 4135 { 4136 struct task_struct *p; 4137 unsigned long flags; 4138 int retval; 4139 4140 rcu_read_lock(); 4141 4142 retval = -ESRCH; 4143 p = find_process_by_pid(pid); 4144 if (!p) 4145 goto out_unlock; 4146 4147 retval = security_task_getscheduler(p); 4148 if (retval) 4149 goto out_unlock; 4150 4151 raw_spin_lock_irqsave(&p->pi_lock, flags); 4152 cpumask_and(mask, &p->cpus_allowed, cpu_active_mask); 4153 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 4154 4155 out_unlock: 4156 rcu_read_unlock(); 4157 4158 return retval; 4159 } 4160 4161 /** 4162 * sys_sched_getaffinity - get the cpu affinity of a process 4163 * @pid: pid of the process 4164 * @len: length in bytes of the bitmask pointed to by user_mask_ptr 4165 * @user_mask_ptr: user-space pointer to hold the current cpu mask 4166 * 4167 * Return: 0 on success. An error code otherwise. 4168 */ 4169 SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len, 4170 unsigned long __user *, user_mask_ptr) 4171 { 4172 int ret; 4173 cpumask_var_t mask; 4174 4175 if ((len * BITS_PER_BYTE) < nr_cpu_ids) 4176 return -EINVAL; 4177 if (len & (sizeof(unsigned long)-1)) 4178 return -EINVAL; 4179 4180 if (!alloc_cpumask_var(&mask, GFP_KERNEL)) 4181 return -ENOMEM; 4182 4183 ret = sched_getaffinity(pid, mask); 4184 if (ret == 0) { 4185 size_t retlen = min_t(size_t, len, cpumask_size()); 4186 4187 if (copy_to_user(user_mask_ptr, mask, retlen)) 4188 ret = -EFAULT; 4189 else 4190 ret = retlen; 4191 } 4192 free_cpumask_var(mask); 4193 4194 return ret; 4195 } 4196 4197 /** 4198 * sys_sched_yield - yield the current processor to other threads. 4199 * 4200 * This function yields the current CPU to other tasks. If there are no 4201 * other threads running on this CPU then this function will return. 4202 * 4203 * Return: 0. 4204 */ 4205 SYSCALL_DEFINE0(sched_yield) 4206 { 4207 struct rq *rq = this_rq_lock(); 4208 4209 schedstat_inc(rq, yld_count); 4210 current->sched_class->yield_task(rq); 4211 4212 /* 4213 * Since we are going to call schedule() anyway, there's 4214 * no need to preempt or enable interrupts: 4215 */ 4216 __release(rq->lock); 4217 spin_release(&rq->lock.dep_map, 1, _THIS_IP_); 4218 do_raw_spin_unlock(&rq->lock); 4219 sched_preempt_enable_no_resched(); 4220 4221 schedule(); 4222 4223 return 0; 4224 } 4225 4226 int __sched _cond_resched(void) 4227 { 4228 if (should_resched()) { 4229 preempt_schedule_common(); 4230 return 1; 4231 } 4232 return 0; 4233 } 4234 EXPORT_SYMBOL(_cond_resched); 4235 4236 /* 4237 * __cond_resched_lock() - if a reschedule is pending, drop the given lock, 4238 * call schedule, and on return reacquire the lock. 4239 * 4240 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level 4241 * operations here to prevent schedule() from being called twice (once via 4242 * spin_unlock(), once by hand). 4243 */ 4244 int __cond_resched_lock(spinlock_t *lock) 4245 { 4246 int resched = should_resched(); 4247 int ret = 0; 4248 4249 lockdep_assert_held(lock); 4250 4251 if (spin_needbreak(lock) || resched) { 4252 spin_unlock(lock); 4253 if (resched) 4254 preempt_schedule_common(); 4255 else 4256 cpu_relax(); 4257 ret = 1; 4258 spin_lock(lock); 4259 } 4260 return ret; 4261 } 4262 EXPORT_SYMBOL(__cond_resched_lock); 4263 4264 int __sched __cond_resched_softirq(void) 4265 { 4266 BUG_ON(!in_softirq()); 4267 4268 if (should_resched()) { 4269 local_bh_enable(); 4270 preempt_schedule_common(); 4271 local_bh_disable(); 4272 return 1; 4273 } 4274 return 0; 4275 } 4276 EXPORT_SYMBOL(__cond_resched_softirq); 4277 4278 /** 4279 * yield - yield the current processor to other threads. 4280 * 4281 * Do not ever use this function, there's a 99% chance you're doing it wrong. 4282 * 4283 * The scheduler is at all times free to pick the calling task as the most 4284 * eligible task to run, if removing the yield() call from your code breaks 4285 * it, its already broken. 4286 * 4287 * Typical broken usage is: 4288 * 4289 * while (!event) 4290 * yield(); 4291 * 4292 * where one assumes that yield() will let 'the other' process run that will 4293 * make event true. If the current task is a SCHED_FIFO task that will never 4294 * happen. Never use yield() as a progress guarantee!! 4295 * 4296 * If you want to use yield() to wait for something, use wait_event(). 4297 * If you want to use yield() to be 'nice' for others, use cond_resched(). 4298 * If you still want to use yield(), do not! 4299 */ 4300 void __sched yield(void) 4301 { 4302 set_current_state(TASK_RUNNING); 4303 sys_sched_yield(); 4304 } 4305 EXPORT_SYMBOL(yield); 4306 4307 /** 4308 * yield_to - yield the current processor to another thread in 4309 * your thread group, or accelerate that thread toward the 4310 * processor it's on. 4311 * @p: target task 4312 * @preempt: whether task preemption is allowed or not 4313 * 4314 * It's the caller's job to ensure that the target task struct 4315 * can't go away on us before we can do any checks. 4316 * 4317 * Return: 4318 * true (>0) if we indeed boosted the target task. 4319 * false (0) if we failed to boost the target. 4320 * -ESRCH if there's no task to yield to. 4321 */ 4322 int __sched yield_to(struct task_struct *p, bool preempt) 4323 { 4324 struct task_struct *curr = current; 4325 struct rq *rq, *p_rq; 4326 unsigned long flags; 4327 int yielded = 0; 4328 4329 local_irq_save(flags); 4330 rq = this_rq(); 4331 4332 again: 4333 p_rq = task_rq(p); 4334 /* 4335 * If we're the only runnable task on the rq and target rq also 4336 * has only one task, there's absolutely no point in yielding. 4337 */ 4338 if (rq->nr_running == 1 && p_rq->nr_running == 1) { 4339 yielded = -ESRCH; 4340 goto out_irq; 4341 } 4342 4343 double_rq_lock(rq, p_rq); 4344 if (task_rq(p) != p_rq) { 4345 double_rq_unlock(rq, p_rq); 4346 goto again; 4347 } 4348 4349 if (!curr->sched_class->yield_to_task) 4350 goto out_unlock; 4351 4352 if (curr->sched_class != p->sched_class) 4353 goto out_unlock; 4354 4355 if (task_running(p_rq, p) || p->state) 4356 goto out_unlock; 4357 4358 yielded = curr->sched_class->yield_to_task(rq, p, preempt); 4359 if (yielded) { 4360 schedstat_inc(rq, yld_count); 4361 /* 4362 * Make p's CPU reschedule; pick_next_entity takes care of 4363 * fairness. 4364 */ 4365 if (preempt && rq != p_rq) 4366 resched_curr(p_rq); 4367 } 4368 4369 out_unlock: 4370 double_rq_unlock(rq, p_rq); 4371 out_irq: 4372 local_irq_restore(flags); 4373 4374 if (yielded > 0) 4375 schedule(); 4376 4377 return yielded; 4378 } 4379 EXPORT_SYMBOL_GPL(yield_to); 4380 4381 /* 4382 * This task is about to go to sleep on IO. Increment rq->nr_iowait so 4383 * that process accounting knows that this is a task in IO wait state. 4384 */ 4385 long __sched io_schedule_timeout(long timeout) 4386 { 4387 int old_iowait = current->in_iowait; 4388 struct rq *rq; 4389 long ret; 4390 4391 current->in_iowait = 1; 4392 blk_schedule_flush_plug(current); 4393 4394 delayacct_blkio_start(); 4395 rq = raw_rq(); 4396 atomic_inc(&rq->nr_iowait); 4397 ret = schedule_timeout(timeout); 4398 current->in_iowait = old_iowait; 4399 atomic_dec(&rq->nr_iowait); 4400 delayacct_blkio_end(); 4401 4402 return ret; 4403 } 4404 EXPORT_SYMBOL(io_schedule_timeout); 4405 4406 /** 4407 * sys_sched_get_priority_max - return maximum RT priority. 4408 * @policy: scheduling class. 4409 * 4410 * Return: On success, this syscall returns the maximum 4411 * rt_priority that can be used by a given scheduling class. 4412 * On failure, a negative error code is returned. 4413 */ 4414 SYSCALL_DEFINE1(sched_get_priority_max, int, policy) 4415 { 4416 int ret = -EINVAL; 4417 4418 switch (policy) { 4419 case SCHED_FIFO: 4420 case SCHED_RR: 4421 ret = MAX_USER_RT_PRIO-1; 4422 break; 4423 case SCHED_DEADLINE: 4424 case SCHED_NORMAL: 4425 case SCHED_BATCH: 4426 case SCHED_IDLE: 4427 ret = 0; 4428 break; 4429 } 4430 return ret; 4431 } 4432 4433 /** 4434 * sys_sched_get_priority_min - return minimum RT priority. 4435 * @policy: scheduling class. 4436 * 4437 * Return: On success, this syscall returns the minimum 4438 * rt_priority that can be used by a given scheduling class. 4439 * On failure, a negative error code is returned. 4440 */ 4441 SYSCALL_DEFINE1(sched_get_priority_min, int, policy) 4442 { 4443 int ret = -EINVAL; 4444 4445 switch (policy) { 4446 case SCHED_FIFO: 4447 case SCHED_RR: 4448 ret = 1; 4449 break; 4450 case SCHED_DEADLINE: 4451 case SCHED_NORMAL: 4452 case SCHED_BATCH: 4453 case SCHED_IDLE: 4454 ret = 0; 4455 } 4456 return ret; 4457 } 4458 4459 /** 4460 * sys_sched_rr_get_interval - return the default timeslice of a process. 4461 * @pid: pid of the process. 4462 * @interval: userspace pointer to the timeslice value. 4463 * 4464 * this syscall writes the default timeslice value of a given process 4465 * into the user-space timespec buffer. A value of '0' means infinity. 4466 * 4467 * Return: On success, 0 and the timeslice is in @interval. Otherwise, 4468 * an error code. 4469 */ 4470 SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid, 4471 struct timespec __user *, interval) 4472 { 4473 struct task_struct *p; 4474 unsigned int time_slice; 4475 unsigned long flags; 4476 struct rq *rq; 4477 int retval; 4478 struct timespec t; 4479 4480 if (pid < 0) 4481 return -EINVAL; 4482 4483 retval = -ESRCH; 4484 rcu_read_lock(); 4485 p = find_process_by_pid(pid); 4486 if (!p) 4487 goto out_unlock; 4488 4489 retval = security_task_getscheduler(p); 4490 if (retval) 4491 goto out_unlock; 4492 4493 rq = task_rq_lock(p, &flags); 4494 time_slice = 0; 4495 if (p->sched_class->get_rr_interval) 4496 time_slice = p->sched_class->get_rr_interval(rq, p); 4497 task_rq_unlock(rq, p, &flags); 4498 4499 rcu_read_unlock(); 4500 jiffies_to_timespec(time_slice, &t); 4501 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0; 4502 return retval; 4503 4504 out_unlock: 4505 rcu_read_unlock(); 4506 return retval; 4507 } 4508 4509 static const char stat_nam[] = TASK_STATE_TO_CHAR_STR; 4510 4511 void sched_show_task(struct task_struct *p) 4512 { 4513 unsigned long free = 0; 4514 int ppid; 4515 unsigned long state = p->state; 4516 4517 if (state) 4518 state = __ffs(state) + 1; 4519 printk(KERN_INFO "%-15.15s %c", p->comm, 4520 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?'); 4521 #if BITS_PER_LONG == 32 4522 if (state == TASK_RUNNING) 4523 printk(KERN_CONT " running "); 4524 else 4525 printk(KERN_CONT " %08lx ", thread_saved_pc(p)); 4526 #else 4527 if (state == TASK_RUNNING) 4528 printk(KERN_CONT " running task "); 4529 else 4530 printk(KERN_CONT " %016lx ", thread_saved_pc(p)); 4531 #endif 4532 #ifdef CONFIG_DEBUG_STACK_USAGE 4533 free = stack_not_used(p); 4534 #endif 4535 ppid = 0; 4536 rcu_read_lock(); 4537 if (pid_alive(p)) 4538 ppid = task_pid_nr(rcu_dereference(p->real_parent)); 4539 rcu_read_unlock(); 4540 printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free, 4541 task_pid_nr(p), ppid, 4542 (unsigned long)task_thread_info(p)->flags); 4543 4544 print_worker_info(KERN_INFO, p); 4545 show_stack(p, NULL); 4546 } 4547 4548 void show_state_filter(unsigned long state_filter) 4549 { 4550 struct task_struct *g, *p; 4551 4552 #if BITS_PER_LONG == 32 4553 printk(KERN_INFO 4554 " task PC stack pid father\n"); 4555 #else 4556 printk(KERN_INFO 4557 " task PC stack pid father\n"); 4558 #endif 4559 rcu_read_lock(); 4560 for_each_process_thread(g, p) { 4561 /* 4562 * reset the NMI-timeout, listing all files on a slow 4563 * console might take a lot of time: 4564 */ 4565 touch_nmi_watchdog(); 4566 if (!state_filter || (p->state & state_filter)) 4567 sched_show_task(p); 4568 } 4569 4570 touch_all_softlockup_watchdogs(); 4571 4572 #ifdef CONFIG_SCHED_DEBUG 4573 sysrq_sched_debug_show(); 4574 #endif 4575 rcu_read_unlock(); 4576 /* 4577 * Only show locks if all tasks are dumped: 4578 */ 4579 if (!state_filter) 4580 debug_show_all_locks(); 4581 } 4582 4583 void init_idle_bootup_task(struct task_struct *idle) 4584 { 4585 idle->sched_class = &idle_sched_class; 4586 } 4587 4588 /** 4589 * init_idle - set up an idle thread for a given CPU 4590 * @idle: task in question 4591 * @cpu: cpu the idle task belongs to 4592 * 4593 * NOTE: this function does not set the idle thread's NEED_RESCHED 4594 * flag, to make booting more robust. 4595 */ 4596 void init_idle(struct task_struct *idle, int cpu) 4597 { 4598 struct rq *rq = cpu_rq(cpu); 4599 unsigned long flags; 4600 4601 raw_spin_lock_irqsave(&rq->lock, flags); 4602 4603 __sched_fork(0, idle); 4604 idle->state = TASK_RUNNING; 4605 idle->se.exec_start = sched_clock(); 4606 4607 do_set_cpus_allowed(idle, cpumask_of(cpu)); 4608 /* 4609 * We're having a chicken and egg problem, even though we are 4610 * holding rq->lock, the cpu isn't yet set to this cpu so the 4611 * lockdep check in task_group() will fail. 4612 * 4613 * Similar case to sched_fork(). / Alternatively we could 4614 * use task_rq_lock() here and obtain the other rq->lock. 4615 * 4616 * Silence PROVE_RCU 4617 */ 4618 rcu_read_lock(); 4619 __set_task_cpu(idle, cpu); 4620 rcu_read_unlock(); 4621 4622 rq->curr = rq->idle = idle; 4623 idle->on_rq = TASK_ON_RQ_QUEUED; 4624 #if defined(CONFIG_SMP) 4625 idle->on_cpu = 1; 4626 #endif 4627 raw_spin_unlock_irqrestore(&rq->lock, flags); 4628 4629 /* Set the preempt count _outside_ the spinlocks! */ 4630 init_idle_preempt_count(idle, cpu); 4631 4632 /* 4633 * The idle tasks have their own, simple scheduling class: 4634 */ 4635 idle->sched_class = &idle_sched_class; 4636 ftrace_graph_init_idle_task(idle, cpu); 4637 vtime_init_idle(idle, cpu); 4638 #if defined(CONFIG_SMP) 4639 sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu); 4640 #endif 4641 } 4642 4643 int cpuset_cpumask_can_shrink(const struct cpumask *cur, 4644 const struct cpumask *trial) 4645 { 4646 int ret = 1, trial_cpus; 4647 struct dl_bw *cur_dl_b; 4648 unsigned long flags; 4649 4650 if (!cpumask_weight(cur)) 4651 return ret; 4652 4653 rcu_read_lock_sched(); 4654 cur_dl_b = dl_bw_of(cpumask_any(cur)); 4655 trial_cpus = cpumask_weight(trial); 4656 4657 raw_spin_lock_irqsave(&cur_dl_b->lock, flags); 4658 if (cur_dl_b->bw != -1 && 4659 cur_dl_b->bw * trial_cpus < cur_dl_b->total_bw) 4660 ret = 0; 4661 raw_spin_unlock_irqrestore(&cur_dl_b->lock, flags); 4662 rcu_read_unlock_sched(); 4663 4664 return ret; 4665 } 4666 4667 int task_can_attach(struct task_struct *p, 4668 const struct cpumask *cs_cpus_allowed) 4669 { 4670 int ret = 0; 4671 4672 /* 4673 * Kthreads which disallow setaffinity shouldn't be moved 4674 * to a new cpuset; we don't want to change their cpu 4675 * affinity and isolating such threads by their set of 4676 * allowed nodes is unnecessary. Thus, cpusets are not 4677 * applicable for such threads. This prevents checking for 4678 * success of set_cpus_allowed_ptr() on all attached tasks 4679 * before cpus_allowed may be changed. 4680 */ 4681 if (p->flags & PF_NO_SETAFFINITY) { 4682 ret = -EINVAL; 4683 goto out; 4684 } 4685 4686 #ifdef CONFIG_SMP 4687 if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span, 4688 cs_cpus_allowed)) { 4689 unsigned int dest_cpu = cpumask_any_and(cpu_active_mask, 4690 cs_cpus_allowed); 4691 struct dl_bw *dl_b; 4692 bool overflow; 4693 int cpus; 4694 unsigned long flags; 4695 4696 rcu_read_lock_sched(); 4697 dl_b = dl_bw_of(dest_cpu); 4698 raw_spin_lock_irqsave(&dl_b->lock, flags); 4699 cpus = dl_bw_cpus(dest_cpu); 4700 overflow = __dl_overflow(dl_b, cpus, 0, p->dl.dl_bw); 4701 if (overflow) 4702 ret = -EBUSY; 4703 else { 4704 /* 4705 * We reserve space for this task in the destination 4706 * root_domain, as we can't fail after this point. 4707 * We will free resources in the source root_domain 4708 * later on (see set_cpus_allowed_dl()). 4709 */ 4710 __dl_add(dl_b, p->dl.dl_bw); 4711 } 4712 raw_spin_unlock_irqrestore(&dl_b->lock, flags); 4713 rcu_read_unlock_sched(); 4714 4715 } 4716 #endif 4717 out: 4718 return ret; 4719 } 4720 4721 #ifdef CONFIG_SMP 4722 /* 4723 * move_queued_task - move a queued task to new rq. 4724 * 4725 * Returns (locked) new rq. Old rq's lock is released. 4726 */ 4727 static struct rq *move_queued_task(struct task_struct *p, int new_cpu) 4728 { 4729 struct rq *rq = task_rq(p); 4730 4731 lockdep_assert_held(&rq->lock); 4732 4733 dequeue_task(rq, p, 0); 4734 p->on_rq = TASK_ON_RQ_MIGRATING; 4735 set_task_cpu(p, new_cpu); 4736 raw_spin_unlock(&rq->lock); 4737 4738 rq = cpu_rq(new_cpu); 4739 4740 raw_spin_lock(&rq->lock); 4741 BUG_ON(task_cpu(p) != new_cpu); 4742 p->on_rq = TASK_ON_RQ_QUEUED; 4743 enqueue_task(rq, p, 0); 4744 check_preempt_curr(rq, p, 0); 4745 4746 return rq; 4747 } 4748 4749 void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) 4750 { 4751 if (p->sched_class->set_cpus_allowed) 4752 p->sched_class->set_cpus_allowed(p, new_mask); 4753 4754 cpumask_copy(&p->cpus_allowed, new_mask); 4755 p->nr_cpus_allowed = cpumask_weight(new_mask); 4756 } 4757 4758 /* 4759 * This is how migration works: 4760 * 4761 * 1) we invoke migration_cpu_stop() on the target CPU using 4762 * stop_one_cpu(). 4763 * 2) stopper starts to run (implicitly forcing the migrated thread 4764 * off the CPU) 4765 * 3) it checks whether the migrated task is still in the wrong runqueue. 4766 * 4) if it's in the wrong runqueue then the migration thread removes 4767 * it and puts it into the right queue. 4768 * 5) stopper completes and stop_one_cpu() returns and the migration 4769 * is done. 4770 */ 4771 4772 /* 4773 * Change a given task's CPU affinity. Migrate the thread to a 4774 * proper CPU and schedule it away if the CPU it's executing on 4775 * is removed from the allowed bitmask. 4776 * 4777 * NOTE: the caller must have a valid reference to the task, the 4778 * task must not exit() & deallocate itself prematurely. The 4779 * call is not atomic; no spinlocks may be held. 4780 */ 4781 int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) 4782 { 4783 unsigned long flags; 4784 struct rq *rq; 4785 unsigned int dest_cpu; 4786 int ret = 0; 4787 4788 rq = task_rq_lock(p, &flags); 4789 4790 if (cpumask_equal(&p->cpus_allowed, new_mask)) 4791 goto out; 4792 4793 if (!cpumask_intersects(new_mask, cpu_active_mask)) { 4794 ret = -EINVAL; 4795 goto out; 4796 } 4797 4798 do_set_cpus_allowed(p, new_mask); 4799 4800 /* Can the task run on the task's current CPU? If so, we're done */ 4801 if (cpumask_test_cpu(task_cpu(p), new_mask)) 4802 goto out; 4803 4804 dest_cpu = cpumask_any_and(cpu_active_mask, new_mask); 4805 if (task_running(rq, p) || p->state == TASK_WAKING) { 4806 struct migration_arg arg = { p, dest_cpu }; 4807 /* Need help from migration thread: drop lock and wait. */ 4808 task_rq_unlock(rq, p, &flags); 4809 stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg); 4810 tlb_migrate_finish(p->mm); 4811 return 0; 4812 } else if (task_on_rq_queued(p)) 4813 rq = move_queued_task(p, dest_cpu); 4814 out: 4815 task_rq_unlock(rq, p, &flags); 4816 4817 return ret; 4818 } 4819 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr); 4820 4821 /* 4822 * Move (not current) task off this cpu, onto dest cpu. We're doing 4823 * this because either it can't run here any more (set_cpus_allowed() 4824 * away from this CPU, or CPU going down), or because we're 4825 * attempting to rebalance this task on exec (sched_exec). 4826 * 4827 * So we race with normal scheduler movements, but that's OK, as long 4828 * as the task is no longer on this CPU. 4829 * 4830 * Returns non-zero if task was successfully migrated. 4831 */ 4832 static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu) 4833 { 4834 struct rq *rq; 4835 int ret = 0; 4836 4837 if (unlikely(!cpu_active(dest_cpu))) 4838 return ret; 4839 4840 rq = cpu_rq(src_cpu); 4841 4842 raw_spin_lock(&p->pi_lock); 4843 raw_spin_lock(&rq->lock); 4844 /* Already moved. */ 4845 if (task_cpu(p) != src_cpu) 4846 goto done; 4847 4848 /* Affinity changed (again). */ 4849 if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p))) 4850 goto fail; 4851 4852 /* 4853 * If we're not on a rq, the next wake-up will ensure we're 4854 * placed properly. 4855 */ 4856 if (task_on_rq_queued(p)) 4857 rq = move_queued_task(p, dest_cpu); 4858 done: 4859 ret = 1; 4860 fail: 4861 raw_spin_unlock(&rq->lock); 4862 raw_spin_unlock(&p->pi_lock); 4863 return ret; 4864 } 4865 4866 #ifdef CONFIG_NUMA_BALANCING 4867 /* Migrate current task p to target_cpu */ 4868 int migrate_task_to(struct task_struct *p, int target_cpu) 4869 { 4870 struct migration_arg arg = { p, target_cpu }; 4871 int curr_cpu = task_cpu(p); 4872 4873 if (curr_cpu == target_cpu) 4874 return 0; 4875 4876 if (!cpumask_test_cpu(target_cpu, tsk_cpus_allowed(p))) 4877 return -EINVAL; 4878 4879 /* TODO: This is not properly updating schedstats */ 4880 4881 trace_sched_move_numa(p, curr_cpu, target_cpu); 4882 return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg); 4883 } 4884 4885 /* 4886 * Requeue a task on a given node and accurately track the number of NUMA 4887 * tasks on the runqueues 4888 */ 4889 void sched_setnuma(struct task_struct *p, int nid) 4890 { 4891 struct rq *rq; 4892 unsigned long flags; 4893 bool queued, running; 4894 4895 rq = task_rq_lock(p, &flags); 4896 queued = task_on_rq_queued(p); 4897 running = task_current(rq, p); 4898 4899 if (queued) 4900 dequeue_task(rq, p, 0); 4901 if (running) 4902 put_prev_task(rq, p); 4903 4904 p->numa_preferred_nid = nid; 4905 4906 if (running) 4907 p->sched_class->set_curr_task(rq); 4908 if (queued) 4909 enqueue_task(rq, p, 0); 4910 task_rq_unlock(rq, p, &flags); 4911 } 4912 #endif 4913 4914 /* 4915 * migration_cpu_stop - this will be executed by a highprio stopper thread 4916 * and performs thread migration by bumping thread off CPU then 4917 * 'pushing' onto another runqueue. 4918 */ 4919 static int migration_cpu_stop(void *data) 4920 { 4921 struct migration_arg *arg = data; 4922 4923 /* 4924 * The original target cpu might have gone down and we might 4925 * be on another cpu but it doesn't matter. 4926 */ 4927 local_irq_disable(); 4928 /* 4929 * We need to explicitly wake pending tasks before running 4930 * __migrate_task() such that we will not miss enforcing cpus_allowed 4931 * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test. 4932 */ 4933 sched_ttwu_pending(); 4934 __migrate_task(arg->task, raw_smp_processor_id(), arg->dest_cpu); 4935 local_irq_enable(); 4936 return 0; 4937 } 4938 4939 #ifdef CONFIG_HOTPLUG_CPU 4940 4941 /* 4942 * Ensures that the idle task is using init_mm right before its cpu goes 4943 * offline. 4944 */ 4945 void idle_task_exit(void) 4946 { 4947 struct mm_struct *mm = current->active_mm; 4948 4949 BUG_ON(cpu_online(smp_processor_id())); 4950 4951 if (mm != &init_mm) { 4952 switch_mm(mm, &init_mm, current); 4953 finish_arch_post_lock_switch(); 4954 } 4955 mmdrop(mm); 4956 } 4957 4958 /* 4959 * Since this CPU is going 'away' for a while, fold any nr_active delta 4960 * we might have. Assumes we're called after migrate_tasks() so that the 4961 * nr_active count is stable. 4962 * 4963 * Also see the comment "Global load-average calculations". 4964 */ 4965 static void calc_load_migrate(struct rq *rq) 4966 { 4967 long delta = calc_load_fold_active(rq); 4968 if (delta) 4969 atomic_long_add(delta, &calc_load_tasks); 4970 } 4971 4972 static void put_prev_task_fake(struct rq *rq, struct task_struct *prev) 4973 { 4974 } 4975 4976 static const struct sched_class fake_sched_class = { 4977 .put_prev_task = put_prev_task_fake, 4978 }; 4979 4980 static struct task_struct fake_task = { 4981 /* 4982 * Avoid pull_{rt,dl}_task() 4983 */ 4984 .prio = MAX_PRIO + 1, 4985 .sched_class = &fake_sched_class, 4986 }; 4987 4988 /* 4989 * Migrate all tasks from the rq, sleeping tasks will be migrated by 4990 * try_to_wake_up()->select_task_rq(). 4991 * 4992 * Called with rq->lock held even though we'er in stop_machine() and 4993 * there's no concurrency possible, we hold the required locks anyway 4994 * because of lock validation efforts. 4995 */ 4996 static void migrate_tasks(unsigned int dead_cpu) 4997 { 4998 struct rq *rq = cpu_rq(dead_cpu); 4999 struct task_struct *next, *stop = rq->stop; 5000 int dest_cpu; 5001 5002 /* 5003 * Fudge the rq selection such that the below task selection loop 5004 * doesn't get stuck on the currently eligible stop task. 5005 * 5006 * We're currently inside stop_machine() and the rq is either stuck 5007 * in the stop_machine_cpu_stop() loop, or we're executing this code, 5008 * either way we should never end up calling schedule() until we're 5009 * done here. 5010 */ 5011 rq->stop = NULL; 5012 5013 /* 5014 * put_prev_task() and pick_next_task() sched 5015 * class method both need to have an up-to-date 5016 * value of rq->clock[_task] 5017 */ 5018 update_rq_clock(rq); 5019 5020 for ( ; ; ) { 5021 /* 5022 * There's this thread running, bail when that's the only 5023 * remaining thread. 5024 */ 5025 if (rq->nr_running == 1) 5026 break; 5027 5028 next = pick_next_task(rq, &fake_task); 5029 BUG_ON(!next); 5030 next->sched_class->put_prev_task(rq, next); 5031 5032 /* Find suitable destination for @next, with force if needed. */ 5033 dest_cpu = select_fallback_rq(dead_cpu, next); 5034 raw_spin_unlock(&rq->lock); 5035 5036 __migrate_task(next, dead_cpu, dest_cpu); 5037 5038 raw_spin_lock(&rq->lock); 5039 } 5040 5041 rq->stop = stop; 5042 } 5043 5044 #endif /* CONFIG_HOTPLUG_CPU */ 5045 5046 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL) 5047 5048 static struct ctl_table sd_ctl_dir[] = { 5049 { 5050 .procname = "sched_domain", 5051 .mode = 0555, 5052 }, 5053 {} 5054 }; 5055 5056 static struct ctl_table sd_ctl_root[] = { 5057 { 5058 .procname = "kernel", 5059 .mode = 0555, 5060 .child = sd_ctl_dir, 5061 }, 5062 {} 5063 }; 5064 5065 static struct ctl_table *sd_alloc_ctl_entry(int n) 5066 { 5067 struct ctl_table *entry = 5068 kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL); 5069 5070 return entry; 5071 } 5072 5073 static void sd_free_ctl_entry(struct ctl_table **tablep) 5074 { 5075 struct ctl_table *entry; 5076 5077 /* 5078 * In the intermediate directories, both the child directory and 5079 * procname are dynamically allocated and could fail but the mode 5080 * will always be set. In the lowest directory the names are 5081 * static strings and all have proc handlers. 5082 */ 5083 for (entry = *tablep; entry->mode; entry++) { 5084 if (entry->child) 5085 sd_free_ctl_entry(&entry->child); 5086 if (entry->proc_handler == NULL) 5087 kfree(entry->procname); 5088 } 5089 5090 kfree(*tablep); 5091 *tablep = NULL; 5092 } 5093 5094 static int min_load_idx = 0; 5095 static int max_load_idx = CPU_LOAD_IDX_MAX-1; 5096 5097 static void 5098 set_table_entry(struct ctl_table *entry, 5099 const char *procname, void *data, int maxlen, 5100 umode_t mode, proc_handler *proc_handler, 5101 bool load_idx) 5102 { 5103 entry->procname = procname; 5104 entry->data = data; 5105 entry->maxlen = maxlen; 5106 entry->mode = mode; 5107 entry->proc_handler = proc_handler; 5108 5109 if (load_idx) { 5110 entry->extra1 = &min_load_idx; 5111 entry->extra2 = &max_load_idx; 5112 } 5113 } 5114 5115 static struct ctl_table * 5116 sd_alloc_ctl_domain_table(struct sched_domain *sd) 5117 { 5118 struct ctl_table *table = sd_alloc_ctl_entry(14); 5119 5120 if (table == NULL) 5121 return NULL; 5122 5123 set_table_entry(&table[0], "min_interval", &sd->min_interval, 5124 sizeof(long), 0644, proc_doulongvec_minmax, false); 5125 set_table_entry(&table[1], "max_interval", &sd->max_interval, 5126 sizeof(long), 0644, proc_doulongvec_minmax, false); 5127 set_table_entry(&table[2], "busy_idx", &sd->busy_idx, 5128 sizeof(int), 0644, proc_dointvec_minmax, true); 5129 set_table_entry(&table[3], "idle_idx", &sd->idle_idx, 5130 sizeof(int), 0644, proc_dointvec_minmax, true); 5131 set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx, 5132 sizeof(int), 0644, proc_dointvec_minmax, true); 5133 set_table_entry(&table[5], "wake_idx", &sd->wake_idx, 5134 sizeof(int), 0644, proc_dointvec_minmax, true); 5135 set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx, 5136 sizeof(int), 0644, proc_dointvec_minmax, true); 5137 set_table_entry(&table[7], "busy_factor", &sd->busy_factor, 5138 sizeof(int), 0644, proc_dointvec_minmax, false); 5139 set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct, 5140 sizeof(int), 0644, proc_dointvec_minmax, false); 5141 set_table_entry(&table[9], "cache_nice_tries", 5142 &sd->cache_nice_tries, 5143 sizeof(int), 0644, proc_dointvec_minmax, false); 5144 set_table_entry(&table[10], "flags", &sd->flags, 5145 sizeof(int), 0644, proc_dointvec_minmax, false); 5146 set_table_entry(&table[11], "max_newidle_lb_cost", 5147 &sd->max_newidle_lb_cost, 5148 sizeof(long), 0644, proc_doulongvec_minmax, false); 5149 set_table_entry(&table[12], "name", sd->name, 5150 CORENAME_MAX_SIZE, 0444, proc_dostring, false); 5151 /* &table[13] is terminator */ 5152 5153 return table; 5154 } 5155 5156 static struct ctl_table *sd_alloc_ctl_cpu_table(int cpu) 5157 { 5158 struct ctl_table *entry, *table; 5159 struct sched_domain *sd; 5160 int domain_num = 0, i; 5161 char buf[32]; 5162 5163 for_each_domain(cpu, sd) 5164 domain_num++; 5165 entry = table = sd_alloc_ctl_entry(domain_num + 1); 5166 if (table == NULL) 5167 return NULL; 5168 5169 i = 0; 5170 for_each_domain(cpu, sd) { 5171 snprintf(buf, 32, "domain%d", i); 5172 entry->procname = kstrdup(buf, GFP_KERNEL); 5173 entry->mode = 0555; 5174 entry->child = sd_alloc_ctl_domain_table(sd); 5175 entry++; 5176 i++; 5177 } 5178 return table; 5179 } 5180 5181 static struct ctl_table_header *sd_sysctl_header; 5182 static void register_sched_domain_sysctl(void) 5183 { 5184 int i, cpu_num = num_possible_cpus(); 5185 struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1); 5186 char buf[32]; 5187 5188 WARN_ON(sd_ctl_dir[0].child); 5189 sd_ctl_dir[0].child = entry; 5190 5191 if (entry == NULL) 5192 return; 5193 5194 for_each_possible_cpu(i) { 5195 snprintf(buf, 32, "cpu%d", i); 5196 entry->procname = kstrdup(buf, GFP_KERNEL); 5197 entry->mode = 0555; 5198 entry->child = sd_alloc_ctl_cpu_table(i); 5199 entry++; 5200 } 5201 5202 WARN_ON(sd_sysctl_header); 5203 sd_sysctl_header = register_sysctl_table(sd_ctl_root); 5204 } 5205 5206 /* may be called multiple times per register */ 5207 static void unregister_sched_domain_sysctl(void) 5208 { 5209 if (sd_sysctl_header) 5210 unregister_sysctl_table(sd_sysctl_header); 5211 sd_sysctl_header = NULL; 5212 if (sd_ctl_dir[0].child) 5213 sd_free_ctl_entry(&sd_ctl_dir[0].child); 5214 } 5215 #else 5216 static void register_sched_domain_sysctl(void) 5217 { 5218 } 5219 static void unregister_sched_domain_sysctl(void) 5220 { 5221 } 5222 #endif 5223 5224 static void set_rq_online(struct rq *rq) 5225 { 5226 if (!rq->online) { 5227 const struct sched_class *class; 5228 5229 cpumask_set_cpu(rq->cpu, rq->rd->online); 5230 rq->online = 1; 5231 5232 for_each_class(class) { 5233 if (class->rq_online) 5234 class->rq_online(rq); 5235 } 5236 } 5237 } 5238 5239 static void set_rq_offline(struct rq *rq) 5240 { 5241 if (rq->online) { 5242 const struct sched_class *class; 5243 5244 for_each_class(class) { 5245 if (class->rq_offline) 5246 class->rq_offline(rq); 5247 } 5248 5249 cpumask_clear_cpu(rq->cpu, rq->rd->online); 5250 rq->online = 0; 5251 } 5252 } 5253 5254 /* 5255 * migration_call - callback that gets triggered when a CPU is added. 5256 * Here we can start up the necessary migration thread for the new CPU. 5257 */ 5258 static int 5259 migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu) 5260 { 5261 int cpu = (long)hcpu; 5262 unsigned long flags; 5263 struct rq *rq = cpu_rq(cpu); 5264 5265 switch (action & ~CPU_TASKS_FROZEN) { 5266 5267 case CPU_UP_PREPARE: 5268 rq->calc_load_update = calc_load_update; 5269 break; 5270 5271 case CPU_ONLINE: 5272 /* Update our root-domain */ 5273 raw_spin_lock_irqsave(&rq->lock, flags); 5274 if (rq->rd) { 5275 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); 5276 5277 set_rq_online(rq); 5278 } 5279 raw_spin_unlock_irqrestore(&rq->lock, flags); 5280 break; 5281 5282 #ifdef CONFIG_HOTPLUG_CPU 5283 case CPU_DYING: 5284 sched_ttwu_pending(); 5285 /* Update our root-domain */ 5286 raw_spin_lock_irqsave(&rq->lock, flags); 5287 if (rq->rd) { 5288 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); 5289 set_rq_offline(rq); 5290 } 5291 migrate_tasks(cpu); 5292 BUG_ON(rq->nr_running != 1); /* the migration thread */ 5293 raw_spin_unlock_irqrestore(&rq->lock, flags); 5294 break; 5295 5296 case CPU_DEAD: 5297 calc_load_migrate(rq); 5298 break; 5299 #endif 5300 } 5301 5302 update_max_interval(); 5303 5304 return NOTIFY_OK; 5305 } 5306 5307 /* 5308 * Register at high priority so that task migration (migrate_all_tasks) 5309 * happens before everything else. This has to be lower priority than 5310 * the notifier in the perf_event subsystem, though. 5311 */ 5312 static struct notifier_block migration_notifier = { 5313 .notifier_call = migration_call, 5314 .priority = CPU_PRI_MIGRATION, 5315 }; 5316 5317 static void __cpuinit set_cpu_rq_start_time(void) 5318 { 5319 int cpu = smp_processor_id(); 5320 struct rq *rq = cpu_rq(cpu); 5321 rq->age_stamp = sched_clock_cpu(cpu); 5322 } 5323 5324 static int sched_cpu_active(struct notifier_block *nfb, 5325 unsigned long action, void *hcpu) 5326 { 5327 switch (action & ~CPU_TASKS_FROZEN) { 5328 case CPU_STARTING: 5329 set_cpu_rq_start_time(); 5330 return NOTIFY_OK; 5331 case CPU_DOWN_FAILED: 5332 set_cpu_active((long)hcpu, true); 5333 return NOTIFY_OK; 5334 default: 5335 return NOTIFY_DONE; 5336 } 5337 } 5338 5339 static int sched_cpu_inactive(struct notifier_block *nfb, 5340 unsigned long action, void *hcpu) 5341 { 5342 switch (action & ~CPU_TASKS_FROZEN) { 5343 case CPU_DOWN_PREPARE: 5344 set_cpu_active((long)hcpu, false); 5345 return NOTIFY_OK; 5346 default: 5347 return NOTIFY_DONE; 5348 } 5349 } 5350 5351 static int __init migration_init(void) 5352 { 5353 void *cpu = (void *)(long)smp_processor_id(); 5354 int err; 5355 5356 /* Initialize migration for the boot CPU */ 5357 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu); 5358 BUG_ON(err == NOTIFY_BAD); 5359 migration_call(&migration_notifier, CPU_ONLINE, cpu); 5360 register_cpu_notifier(&migration_notifier); 5361 5362 /* Register cpu active notifiers */ 5363 cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE); 5364 cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE); 5365 5366 return 0; 5367 } 5368 early_initcall(migration_init); 5369 #endif 5370 5371 #ifdef CONFIG_SMP 5372 5373 static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */ 5374 5375 #ifdef CONFIG_SCHED_DEBUG 5376 5377 static __read_mostly int sched_debug_enabled; 5378 5379 static int __init sched_debug_setup(char *str) 5380 { 5381 sched_debug_enabled = 1; 5382 5383 return 0; 5384 } 5385 early_param("sched_debug", sched_debug_setup); 5386 5387 static inline bool sched_debug(void) 5388 { 5389 return sched_debug_enabled; 5390 } 5391 5392 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level, 5393 struct cpumask *groupmask) 5394 { 5395 struct sched_group *group = sd->groups; 5396 5397 cpumask_clear(groupmask); 5398 5399 printk(KERN_DEBUG "%*s domain %d: ", level, "", level); 5400 5401 if (!(sd->flags & SD_LOAD_BALANCE)) { 5402 printk("does not load-balance\n"); 5403 if (sd->parent) 5404 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain" 5405 " has parent"); 5406 return -1; 5407 } 5408 5409 printk(KERN_CONT "span %*pbl level %s\n", 5410 cpumask_pr_args(sched_domain_span(sd)), sd->name); 5411 5412 if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) { 5413 printk(KERN_ERR "ERROR: domain->span does not contain " 5414 "CPU%d\n", cpu); 5415 } 5416 if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) { 5417 printk(KERN_ERR "ERROR: domain->groups does not contain" 5418 " CPU%d\n", cpu); 5419 } 5420 5421 printk(KERN_DEBUG "%*s groups:", level + 1, ""); 5422 do { 5423 if (!group) { 5424 printk("\n"); 5425 printk(KERN_ERR "ERROR: group is NULL\n"); 5426 break; 5427 } 5428 5429 if (!cpumask_weight(sched_group_cpus(group))) { 5430 printk(KERN_CONT "\n"); 5431 printk(KERN_ERR "ERROR: empty group\n"); 5432 break; 5433 } 5434 5435 if (!(sd->flags & SD_OVERLAP) && 5436 cpumask_intersects(groupmask, sched_group_cpus(group))) { 5437 printk(KERN_CONT "\n"); 5438 printk(KERN_ERR "ERROR: repeated CPUs\n"); 5439 break; 5440 } 5441 5442 cpumask_or(groupmask, groupmask, sched_group_cpus(group)); 5443 5444 printk(KERN_CONT " %*pbl", 5445 cpumask_pr_args(sched_group_cpus(group))); 5446 if (group->sgc->capacity != SCHED_CAPACITY_SCALE) { 5447 printk(KERN_CONT " (cpu_capacity = %d)", 5448 group->sgc->capacity); 5449 } 5450 5451 group = group->next; 5452 } while (group != sd->groups); 5453 printk(KERN_CONT "\n"); 5454 5455 if (!cpumask_equal(sched_domain_span(sd), groupmask)) 5456 printk(KERN_ERR "ERROR: groups don't span domain->span\n"); 5457 5458 if (sd->parent && 5459 !cpumask_subset(groupmask, sched_domain_span(sd->parent))) 5460 printk(KERN_ERR "ERROR: parent span is not a superset " 5461 "of domain->span\n"); 5462 return 0; 5463 } 5464 5465 static void sched_domain_debug(struct sched_domain *sd, int cpu) 5466 { 5467 int level = 0; 5468 5469 if (!sched_debug_enabled) 5470 return; 5471 5472 if (!sd) { 5473 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu); 5474 return; 5475 } 5476 5477 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu); 5478 5479 for (;;) { 5480 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask)) 5481 break; 5482 level++; 5483 sd = sd->parent; 5484 if (!sd) 5485 break; 5486 } 5487 } 5488 #else /* !CONFIG_SCHED_DEBUG */ 5489 # define sched_domain_debug(sd, cpu) do { } while (0) 5490 static inline bool sched_debug(void) 5491 { 5492 return false; 5493 } 5494 #endif /* CONFIG_SCHED_DEBUG */ 5495 5496 static int sd_degenerate(struct sched_domain *sd) 5497 { 5498 if (cpumask_weight(sched_domain_span(sd)) == 1) 5499 return 1; 5500 5501 /* Following flags need at least 2 groups */ 5502 if (sd->flags & (SD_LOAD_BALANCE | 5503 SD_BALANCE_NEWIDLE | 5504 SD_BALANCE_FORK | 5505 SD_BALANCE_EXEC | 5506 SD_SHARE_CPUCAPACITY | 5507 SD_SHARE_PKG_RESOURCES | 5508 SD_SHARE_POWERDOMAIN)) { 5509 if (sd->groups != sd->groups->next) 5510 return 0; 5511 } 5512 5513 /* Following flags don't use groups */ 5514 if (sd->flags & (SD_WAKE_AFFINE)) 5515 return 0; 5516 5517 return 1; 5518 } 5519 5520 static int 5521 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) 5522 { 5523 unsigned long cflags = sd->flags, pflags = parent->flags; 5524 5525 if (sd_degenerate(parent)) 5526 return 1; 5527 5528 if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent))) 5529 return 0; 5530 5531 /* Flags needing groups don't count if only 1 group in parent */ 5532 if (parent->groups == parent->groups->next) { 5533 pflags &= ~(SD_LOAD_BALANCE | 5534 SD_BALANCE_NEWIDLE | 5535 SD_BALANCE_FORK | 5536 SD_BALANCE_EXEC | 5537 SD_SHARE_CPUCAPACITY | 5538 SD_SHARE_PKG_RESOURCES | 5539 SD_PREFER_SIBLING | 5540 SD_SHARE_POWERDOMAIN); 5541 if (nr_node_ids == 1) 5542 pflags &= ~SD_SERIALIZE; 5543 } 5544 if (~cflags & pflags) 5545 return 0; 5546 5547 return 1; 5548 } 5549 5550 static void free_rootdomain(struct rcu_head *rcu) 5551 { 5552 struct root_domain *rd = container_of(rcu, struct root_domain, rcu); 5553 5554 cpupri_cleanup(&rd->cpupri); 5555 cpudl_cleanup(&rd->cpudl); 5556 free_cpumask_var(rd->dlo_mask); 5557 free_cpumask_var(rd->rto_mask); 5558 free_cpumask_var(rd->online); 5559 free_cpumask_var(rd->span); 5560 kfree(rd); 5561 } 5562 5563 static void rq_attach_root(struct rq *rq, struct root_domain *rd) 5564 { 5565 struct root_domain *old_rd = NULL; 5566 unsigned long flags; 5567 5568 raw_spin_lock_irqsave(&rq->lock, flags); 5569 5570 if (rq->rd) { 5571 old_rd = rq->rd; 5572 5573 if (cpumask_test_cpu(rq->cpu, old_rd->online)) 5574 set_rq_offline(rq); 5575 5576 cpumask_clear_cpu(rq->cpu, old_rd->span); 5577 5578 /* 5579 * If we dont want to free the old_rd yet then 5580 * set old_rd to NULL to skip the freeing later 5581 * in this function: 5582 */ 5583 if (!atomic_dec_and_test(&old_rd->refcount)) 5584 old_rd = NULL; 5585 } 5586 5587 atomic_inc(&rd->refcount); 5588 rq->rd = rd; 5589 5590 cpumask_set_cpu(rq->cpu, rd->span); 5591 if (cpumask_test_cpu(rq->cpu, cpu_active_mask)) 5592 set_rq_online(rq); 5593 5594 raw_spin_unlock_irqrestore(&rq->lock, flags); 5595 5596 if (old_rd) 5597 call_rcu_sched(&old_rd->rcu, free_rootdomain); 5598 } 5599 5600 static int init_rootdomain(struct root_domain *rd) 5601 { 5602 memset(rd, 0, sizeof(*rd)); 5603 5604 if (!alloc_cpumask_var(&rd->span, GFP_KERNEL)) 5605 goto out; 5606 if (!alloc_cpumask_var(&rd->online, GFP_KERNEL)) 5607 goto free_span; 5608 if (!alloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL)) 5609 goto free_online; 5610 if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL)) 5611 goto free_dlo_mask; 5612 5613 init_dl_bw(&rd->dl_bw); 5614 if (cpudl_init(&rd->cpudl) != 0) 5615 goto free_dlo_mask; 5616 5617 if (cpupri_init(&rd->cpupri) != 0) 5618 goto free_rto_mask; 5619 return 0; 5620 5621 free_rto_mask: 5622 free_cpumask_var(rd->rto_mask); 5623 free_dlo_mask: 5624 free_cpumask_var(rd->dlo_mask); 5625 free_online: 5626 free_cpumask_var(rd->online); 5627 free_span: 5628 free_cpumask_var(rd->span); 5629 out: 5630 return -ENOMEM; 5631 } 5632 5633 /* 5634 * By default the system creates a single root-domain with all cpus as 5635 * members (mimicking the global state we have today). 5636 */ 5637 struct root_domain def_root_domain; 5638 5639 static void init_defrootdomain(void) 5640 { 5641 init_rootdomain(&def_root_domain); 5642 5643 atomic_set(&def_root_domain.refcount, 1); 5644 } 5645 5646 static struct root_domain *alloc_rootdomain(void) 5647 { 5648 struct root_domain *rd; 5649 5650 rd = kmalloc(sizeof(*rd), GFP_KERNEL); 5651 if (!rd) 5652 return NULL; 5653 5654 if (init_rootdomain(rd) != 0) { 5655 kfree(rd); 5656 return NULL; 5657 } 5658 5659 return rd; 5660 } 5661 5662 static void free_sched_groups(struct sched_group *sg, int free_sgc) 5663 { 5664 struct sched_group *tmp, *first; 5665 5666 if (!sg) 5667 return; 5668 5669 first = sg; 5670 do { 5671 tmp = sg->next; 5672 5673 if (free_sgc && atomic_dec_and_test(&sg->sgc->ref)) 5674 kfree(sg->sgc); 5675 5676 kfree(sg); 5677 sg = tmp; 5678 } while (sg != first); 5679 } 5680 5681 static void free_sched_domain(struct rcu_head *rcu) 5682 { 5683 struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu); 5684 5685 /* 5686 * If its an overlapping domain it has private groups, iterate and 5687 * nuke them all. 5688 */ 5689 if (sd->flags & SD_OVERLAP) { 5690 free_sched_groups(sd->groups, 1); 5691 } else if (atomic_dec_and_test(&sd->groups->ref)) { 5692 kfree(sd->groups->sgc); 5693 kfree(sd->groups); 5694 } 5695 kfree(sd); 5696 } 5697 5698 static void destroy_sched_domain(struct sched_domain *sd, int cpu) 5699 { 5700 call_rcu(&sd->rcu, free_sched_domain); 5701 } 5702 5703 static void destroy_sched_domains(struct sched_domain *sd, int cpu) 5704 { 5705 for (; sd; sd = sd->parent) 5706 destroy_sched_domain(sd, cpu); 5707 } 5708 5709 /* 5710 * Keep a special pointer to the highest sched_domain that has 5711 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this 5712 * allows us to avoid some pointer chasing select_idle_sibling(). 5713 * 5714 * Also keep a unique ID per domain (we use the first cpu number in 5715 * the cpumask of the domain), this allows us to quickly tell if 5716 * two cpus are in the same cache domain, see cpus_share_cache(). 5717 */ 5718 DEFINE_PER_CPU(struct sched_domain *, sd_llc); 5719 DEFINE_PER_CPU(int, sd_llc_size); 5720 DEFINE_PER_CPU(int, sd_llc_id); 5721 DEFINE_PER_CPU(struct sched_domain *, sd_numa); 5722 DEFINE_PER_CPU(struct sched_domain *, sd_busy); 5723 DEFINE_PER_CPU(struct sched_domain *, sd_asym); 5724 5725 static void update_top_cache_domain(int cpu) 5726 { 5727 struct sched_domain *sd; 5728 struct sched_domain *busy_sd = NULL; 5729 int id = cpu; 5730 int size = 1; 5731 5732 sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES); 5733 if (sd) { 5734 id = cpumask_first(sched_domain_span(sd)); 5735 size = cpumask_weight(sched_domain_span(sd)); 5736 busy_sd = sd->parent; /* sd_busy */ 5737 } 5738 rcu_assign_pointer(per_cpu(sd_busy, cpu), busy_sd); 5739 5740 rcu_assign_pointer(per_cpu(sd_llc, cpu), sd); 5741 per_cpu(sd_llc_size, cpu) = size; 5742 per_cpu(sd_llc_id, cpu) = id; 5743 5744 sd = lowest_flag_domain(cpu, SD_NUMA); 5745 rcu_assign_pointer(per_cpu(sd_numa, cpu), sd); 5746 5747 sd = highest_flag_domain(cpu, SD_ASYM_PACKING); 5748 rcu_assign_pointer(per_cpu(sd_asym, cpu), sd); 5749 } 5750 5751 /* 5752 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must 5753 * hold the hotplug lock. 5754 */ 5755 static void 5756 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu) 5757 { 5758 struct rq *rq = cpu_rq(cpu); 5759 struct sched_domain *tmp; 5760 5761 /* Remove the sched domains which do not contribute to scheduling. */ 5762 for (tmp = sd; tmp; ) { 5763 struct sched_domain *parent = tmp->parent; 5764 if (!parent) 5765 break; 5766 5767 if (sd_parent_degenerate(tmp, parent)) { 5768 tmp->parent = parent->parent; 5769 if (parent->parent) 5770 parent->parent->child = tmp; 5771 /* 5772 * Transfer SD_PREFER_SIBLING down in case of a 5773 * degenerate parent; the spans match for this 5774 * so the property transfers. 5775 */ 5776 if (parent->flags & SD_PREFER_SIBLING) 5777 tmp->flags |= SD_PREFER_SIBLING; 5778 destroy_sched_domain(parent, cpu); 5779 } else 5780 tmp = tmp->parent; 5781 } 5782 5783 if (sd && sd_degenerate(sd)) { 5784 tmp = sd; 5785 sd = sd->parent; 5786 destroy_sched_domain(tmp, cpu); 5787 if (sd) 5788 sd->child = NULL; 5789 } 5790 5791 sched_domain_debug(sd, cpu); 5792 5793 rq_attach_root(rq, rd); 5794 tmp = rq->sd; 5795 rcu_assign_pointer(rq->sd, sd); 5796 destroy_sched_domains(tmp, cpu); 5797 5798 update_top_cache_domain(cpu); 5799 } 5800 5801 /* Setup the mask of cpus configured for isolated domains */ 5802 static int __init isolated_cpu_setup(char *str) 5803 { 5804 alloc_bootmem_cpumask_var(&cpu_isolated_map); 5805 cpulist_parse(str, cpu_isolated_map); 5806 return 1; 5807 } 5808 5809 __setup("isolcpus=", isolated_cpu_setup); 5810 5811 struct s_data { 5812 struct sched_domain ** __percpu sd; 5813 struct root_domain *rd; 5814 }; 5815 5816 enum s_alloc { 5817 sa_rootdomain, 5818 sa_sd, 5819 sa_sd_storage, 5820 sa_none, 5821 }; 5822 5823 /* 5824 * Build an iteration mask that can exclude certain CPUs from the upwards 5825 * domain traversal. 5826 * 5827 * Asymmetric node setups can result in situations where the domain tree is of 5828 * unequal depth, make sure to skip domains that already cover the entire 5829 * range. 5830 * 5831 * In that case build_sched_domains() will have terminated the iteration early 5832 * and our sibling sd spans will be empty. Domains should always include the 5833 * cpu they're built on, so check that. 5834 * 5835 */ 5836 static void build_group_mask(struct sched_domain *sd, struct sched_group *sg) 5837 { 5838 const struct cpumask *span = sched_domain_span(sd); 5839 struct sd_data *sdd = sd->private; 5840 struct sched_domain *sibling; 5841 int i; 5842 5843 for_each_cpu(i, span) { 5844 sibling = *per_cpu_ptr(sdd->sd, i); 5845 if (!cpumask_test_cpu(i, sched_domain_span(sibling))) 5846 continue; 5847 5848 cpumask_set_cpu(i, sched_group_mask(sg)); 5849 } 5850 } 5851 5852 /* 5853 * Return the canonical balance cpu for this group, this is the first cpu 5854 * of this group that's also in the iteration mask. 5855 */ 5856 int group_balance_cpu(struct sched_group *sg) 5857 { 5858 return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg)); 5859 } 5860 5861 static int 5862 build_overlap_sched_groups(struct sched_domain *sd, int cpu) 5863 { 5864 struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg; 5865 const struct cpumask *span = sched_domain_span(sd); 5866 struct cpumask *covered = sched_domains_tmpmask; 5867 struct sd_data *sdd = sd->private; 5868 struct sched_domain *sibling; 5869 int i; 5870 5871 cpumask_clear(covered); 5872 5873 for_each_cpu(i, span) { 5874 struct cpumask *sg_span; 5875 5876 if (cpumask_test_cpu(i, covered)) 5877 continue; 5878 5879 sibling = *per_cpu_ptr(sdd->sd, i); 5880 5881 /* See the comment near build_group_mask(). */ 5882 if (!cpumask_test_cpu(i, sched_domain_span(sibling))) 5883 continue; 5884 5885 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), 5886 GFP_KERNEL, cpu_to_node(cpu)); 5887 5888 if (!sg) 5889 goto fail; 5890 5891 sg_span = sched_group_cpus(sg); 5892 if (sibling->child) 5893 cpumask_copy(sg_span, sched_domain_span(sibling->child)); 5894 else 5895 cpumask_set_cpu(i, sg_span); 5896 5897 cpumask_or(covered, covered, sg_span); 5898 5899 sg->sgc = *per_cpu_ptr(sdd->sgc, i); 5900 if (atomic_inc_return(&sg->sgc->ref) == 1) 5901 build_group_mask(sd, sg); 5902 5903 /* 5904 * Initialize sgc->capacity such that even if we mess up the 5905 * domains and no possible iteration will get us here, we won't 5906 * die on a /0 trap. 5907 */ 5908 sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span); 5909 5910 /* 5911 * Make sure the first group of this domain contains the 5912 * canonical balance cpu. Otherwise the sched_domain iteration 5913 * breaks. See update_sg_lb_stats(). 5914 */ 5915 if ((!groups && cpumask_test_cpu(cpu, sg_span)) || 5916 group_balance_cpu(sg) == cpu) 5917 groups = sg; 5918 5919 if (!first) 5920 first = sg; 5921 if (last) 5922 last->next = sg; 5923 last = sg; 5924 last->next = first; 5925 } 5926 sd->groups = groups; 5927 5928 return 0; 5929 5930 fail: 5931 free_sched_groups(first, 0); 5932 5933 return -ENOMEM; 5934 } 5935 5936 static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg) 5937 { 5938 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu); 5939 struct sched_domain *child = sd->child; 5940 5941 if (child) 5942 cpu = cpumask_first(sched_domain_span(child)); 5943 5944 if (sg) { 5945 *sg = *per_cpu_ptr(sdd->sg, cpu); 5946 (*sg)->sgc = *per_cpu_ptr(sdd->sgc, cpu); 5947 atomic_set(&(*sg)->sgc->ref, 1); /* for claim_allocations */ 5948 } 5949 5950 return cpu; 5951 } 5952 5953 /* 5954 * build_sched_groups will build a circular linked list of the groups 5955 * covered by the given span, and will set each group's ->cpumask correctly, 5956 * and ->cpu_capacity to 0. 5957 * 5958 * Assumes the sched_domain tree is fully constructed 5959 */ 5960 static int 5961 build_sched_groups(struct sched_domain *sd, int cpu) 5962 { 5963 struct sched_group *first = NULL, *last = NULL; 5964 struct sd_data *sdd = sd->private; 5965 const struct cpumask *span = sched_domain_span(sd); 5966 struct cpumask *covered; 5967 int i; 5968 5969 get_group(cpu, sdd, &sd->groups); 5970 atomic_inc(&sd->groups->ref); 5971 5972 if (cpu != cpumask_first(span)) 5973 return 0; 5974 5975 lockdep_assert_held(&sched_domains_mutex); 5976 covered = sched_domains_tmpmask; 5977 5978 cpumask_clear(covered); 5979 5980 for_each_cpu(i, span) { 5981 struct sched_group *sg; 5982 int group, j; 5983 5984 if (cpumask_test_cpu(i, covered)) 5985 continue; 5986 5987 group = get_group(i, sdd, &sg); 5988 cpumask_setall(sched_group_mask(sg)); 5989 5990 for_each_cpu(j, span) { 5991 if (get_group(j, sdd, NULL) != group) 5992 continue; 5993 5994 cpumask_set_cpu(j, covered); 5995 cpumask_set_cpu(j, sched_group_cpus(sg)); 5996 } 5997 5998 if (!first) 5999 first = sg; 6000 if (last) 6001 last->next = sg; 6002 last = sg; 6003 } 6004 last->next = first; 6005 6006 return 0; 6007 } 6008 6009 /* 6010 * Initialize sched groups cpu_capacity. 6011 * 6012 * cpu_capacity indicates the capacity of sched group, which is used while 6013 * distributing the load between different sched groups in a sched domain. 6014 * Typically cpu_capacity for all the groups in a sched domain will be same 6015 * unless there are asymmetries in the topology. If there are asymmetries, 6016 * group having more cpu_capacity will pickup more load compared to the 6017 * group having less cpu_capacity. 6018 */ 6019 static void init_sched_groups_capacity(int cpu, struct sched_domain *sd) 6020 { 6021 struct sched_group *sg = sd->groups; 6022 6023 WARN_ON(!sg); 6024 6025 do { 6026 sg->group_weight = cpumask_weight(sched_group_cpus(sg)); 6027 sg = sg->next; 6028 } while (sg != sd->groups); 6029 6030 if (cpu != group_balance_cpu(sg)) 6031 return; 6032 6033 update_group_capacity(sd, cpu); 6034 atomic_set(&sg->sgc->nr_busy_cpus, sg->group_weight); 6035 } 6036 6037 /* 6038 * Initializers for schedule domains 6039 * Non-inlined to reduce accumulated stack pressure in build_sched_domains() 6040 */ 6041 6042 static int default_relax_domain_level = -1; 6043 int sched_domain_level_max; 6044 6045 static int __init setup_relax_domain_level(char *str) 6046 { 6047 if (kstrtoint(str, 0, &default_relax_domain_level)) 6048 pr_warn("Unable to set relax_domain_level\n"); 6049 6050 return 1; 6051 } 6052 __setup("relax_domain_level=", setup_relax_domain_level); 6053 6054 static void set_domain_attribute(struct sched_domain *sd, 6055 struct sched_domain_attr *attr) 6056 { 6057 int request; 6058 6059 if (!attr || attr->relax_domain_level < 0) { 6060 if (default_relax_domain_level < 0) 6061 return; 6062 else 6063 request = default_relax_domain_level; 6064 } else 6065 request = attr->relax_domain_level; 6066 if (request < sd->level) { 6067 /* turn off idle balance on this domain */ 6068 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); 6069 } else { 6070 /* turn on idle balance on this domain */ 6071 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); 6072 } 6073 } 6074 6075 static void __sdt_free(const struct cpumask *cpu_map); 6076 static int __sdt_alloc(const struct cpumask *cpu_map); 6077 6078 static void __free_domain_allocs(struct s_data *d, enum s_alloc what, 6079 const struct cpumask *cpu_map) 6080 { 6081 switch (what) { 6082 case sa_rootdomain: 6083 if (!atomic_read(&d->rd->refcount)) 6084 free_rootdomain(&d->rd->rcu); /* fall through */ 6085 case sa_sd: 6086 free_percpu(d->sd); /* fall through */ 6087 case sa_sd_storage: 6088 __sdt_free(cpu_map); /* fall through */ 6089 case sa_none: 6090 break; 6091 } 6092 } 6093 6094 static enum s_alloc __visit_domain_allocation_hell(struct s_data *d, 6095 const struct cpumask *cpu_map) 6096 { 6097 memset(d, 0, sizeof(*d)); 6098 6099 if (__sdt_alloc(cpu_map)) 6100 return sa_sd_storage; 6101 d->sd = alloc_percpu(struct sched_domain *); 6102 if (!d->sd) 6103 return sa_sd_storage; 6104 d->rd = alloc_rootdomain(); 6105 if (!d->rd) 6106 return sa_sd; 6107 return sa_rootdomain; 6108 } 6109 6110 /* 6111 * NULL the sd_data elements we've used to build the sched_domain and 6112 * sched_group structure so that the subsequent __free_domain_allocs() 6113 * will not free the data we're using. 6114 */ 6115 static void claim_allocations(int cpu, struct sched_domain *sd) 6116 { 6117 struct sd_data *sdd = sd->private; 6118 6119 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd); 6120 *per_cpu_ptr(sdd->sd, cpu) = NULL; 6121 6122 if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref)) 6123 *per_cpu_ptr(sdd->sg, cpu) = NULL; 6124 6125 if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref)) 6126 *per_cpu_ptr(sdd->sgc, cpu) = NULL; 6127 } 6128 6129 #ifdef CONFIG_NUMA 6130 static int sched_domains_numa_levels; 6131 enum numa_topology_type sched_numa_topology_type; 6132 static int *sched_domains_numa_distance; 6133 int sched_max_numa_distance; 6134 static struct cpumask ***sched_domains_numa_masks; 6135 static int sched_domains_curr_level; 6136 #endif 6137 6138 /* 6139 * SD_flags allowed in topology descriptions. 6140 * 6141 * SD_SHARE_CPUCAPACITY - describes SMT topologies 6142 * SD_SHARE_PKG_RESOURCES - describes shared caches 6143 * SD_NUMA - describes NUMA topologies 6144 * SD_SHARE_POWERDOMAIN - describes shared power domain 6145 * 6146 * Odd one out: 6147 * SD_ASYM_PACKING - describes SMT quirks 6148 */ 6149 #define TOPOLOGY_SD_FLAGS \ 6150 (SD_SHARE_CPUCAPACITY | \ 6151 SD_SHARE_PKG_RESOURCES | \ 6152 SD_NUMA | \ 6153 SD_ASYM_PACKING | \ 6154 SD_SHARE_POWERDOMAIN) 6155 6156 static struct sched_domain * 6157 sd_init(struct sched_domain_topology_level *tl, int cpu) 6158 { 6159 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); 6160 int sd_weight, sd_flags = 0; 6161 6162 #ifdef CONFIG_NUMA 6163 /* 6164 * Ugly hack to pass state to sd_numa_mask()... 6165 */ 6166 sched_domains_curr_level = tl->numa_level; 6167 #endif 6168 6169 sd_weight = cpumask_weight(tl->mask(cpu)); 6170 6171 if (tl->sd_flags) 6172 sd_flags = (*tl->sd_flags)(); 6173 if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS, 6174 "wrong sd_flags in topology description\n")) 6175 sd_flags &= ~TOPOLOGY_SD_FLAGS; 6176 6177 *sd = (struct sched_domain){ 6178 .min_interval = sd_weight, 6179 .max_interval = 2*sd_weight, 6180 .busy_factor = 32, 6181 .imbalance_pct = 125, 6182 6183 .cache_nice_tries = 0, 6184 .busy_idx = 0, 6185 .idle_idx = 0, 6186 .newidle_idx = 0, 6187 .wake_idx = 0, 6188 .forkexec_idx = 0, 6189 6190 .flags = 1*SD_LOAD_BALANCE 6191 | 1*SD_BALANCE_NEWIDLE 6192 | 1*SD_BALANCE_EXEC 6193 | 1*SD_BALANCE_FORK 6194 | 0*SD_BALANCE_WAKE 6195 | 1*SD_WAKE_AFFINE 6196 | 0*SD_SHARE_CPUCAPACITY 6197 | 0*SD_SHARE_PKG_RESOURCES 6198 | 0*SD_SERIALIZE 6199 | 0*SD_PREFER_SIBLING 6200 | 0*SD_NUMA 6201 | sd_flags 6202 , 6203 6204 .last_balance = jiffies, 6205 .balance_interval = sd_weight, 6206 .smt_gain = 0, 6207 .max_newidle_lb_cost = 0, 6208 .next_decay_max_lb_cost = jiffies, 6209 #ifdef CONFIG_SCHED_DEBUG 6210 .name = tl->name, 6211 #endif 6212 }; 6213 6214 /* 6215 * Convert topological properties into behaviour. 6216 */ 6217 6218 if (sd->flags & SD_SHARE_CPUCAPACITY) { 6219 sd->flags |= SD_PREFER_SIBLING; 6220 sd->imbalance_pct = 110; 6221 sd->smt_gain = 1178; /* ~15% */ 6222 6223 } else if (sd->flags & SD_SHARE_PKG_RESOURCES) { 6224 sd->imbalance_pct = 117; 6225 sd->cache_nice_tries = 1; 6226 sd->busy_idx = 2; 6227 6228 #ifdef CONFIG_NUMA 6229 } else if (sd->flags & SD_NUMA) { 6230 sd->cache_nice_tries = 2; 6231 sd->busy_idx = 3; 6232 sd->idle_idx = 2; 6233 6234 sd->flags |= SD_SERIALIZE; 6235 if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) { 6236 sd->flags &= ~(SD_BALANCE_EXEC | 6237 SD_BALANCE_FORK | 6238 SD_WAKE_AFFINE); 6239 } 6240 6241 #endif 6242 } else { 6243 sd->flags |= SD_PREFER_SIBLING; 6244 sd->cache_nice_tries = 1; 6245 sd->busy_idx = 2; 6246 sd->idle_idx = 1; 6247 } 6248 6249 sd->private = &tl->data; 6250 6251 return sd; 6252 } 6253 6254 /* 6255 * Topology list, bottom-up. 6256 */ 6257 static struct sched_domain_topology_level default_topology[] = { 6258 #ifdef CONFIG_SCHED_SMT 6259 { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) }, 6260 #endif 6261 #ifdef CONFIG_SCHED_MC 6262 { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) }, 6263 #endif 6264 { cpu_cpu_mask, SD_INIT_NAME(DIE) }, 6265 { NULL, }, 6266 }; 6267 6268 struct sched_domain_topology_level *sched_domain_topology = default_topology; 6269 6270 #define for_each_sd_topology(tl) \ 6271 for (tl = sched_domain_topology; tl->mask; tl++) 6272 6273 void set_sched_topology(struct sched_domain_topology_level *tl) 6274 { 6275 sched_domain_topology = tl; 6276 } 6277 6278 #ifdef CONFIG_NUMA 6279 6280 static const struct cpumask *sd_numa_mask(int cpu) 6281 { 6282 return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)]; 6283 } 6284 6285 static void sched_numa_warn(const char *str) 6286 { 6287 static int done = false; 6288 int i,j; 6289 6290 if (done) 6291 return; 6292 6293 done = true; 6294 6295 printk(KERN_WARNING "ERROR: %s\n\n", str); 6296 6297 for (i = 0; i < nr_node_ids; i++) { 6298 printk(KERN_WARNING " "); 6299 for (j = 0; j < nr_node_ids; j++) 6300 printk(KERN_CONT "%02d ", node_distance(i,j)); 6301 printk(KERN_CONT "\n"); 6302 } 6303 printk(KERN_WARNING "\n"); 6304 } 6305 6306 bool find_numa_distance(int distance) 6307 { 6308 int i; 6309 6310 if (distance == node_distance(0, 0)) 6311 return true; 6312 6313 for (i = 0; i < sched_domains_numa_levels; i++) { 6314 if (sched_domains_numa_distance[i] == distance) 6315 return true; 6316 } 6317 6318 return false; 6319 } 6320 6321 /* 6322 * A system can have three types of NUMA topology: 6323 * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system 6324 * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes 6325 * NUMA_BACKPLANE: nodes can reach other nodes through a backplane 6326 * 6327 * The difference between a glueless mesh topology and a backplane 6328 * topology lies in whether communication between not directly 6329 * connected nodes goes through intermediary nodes (where programs 6330 * could run), or through backplane controllers. This affects 6331 * placement of programs. 6332 * 6333 * The type of topology can be discerned with the following tests: 6334 * - If the maximum distance between any nodes is 1 hop, the system 6335 * is directly connected. 6336 * - If for two nodes A and B, located N > 1 hops away from each other, 6337 * there is an intermediary node C, which is < N hops away from both 6338 * nodes A and B, the system is a glueless mesh. 6339 */ 6340 static void init_numa_topology_type(void) 6341 { 6342 int a, b, c, n; 6343 6344 n = sched_max_numa_distance; 6345 6346 if (n <= 1) 6347 sched_numa_topology_type = NUMA_DIRECT; 6348 6349 for_each_online_node(a) { 6350 for_each_online_node(b) { 6351 /* Find two nodes furthest removed from each other. */ 6352 if (node_distance(a, b) < n) 6353 continue; 6354 6355 /* Is there an intermediary node between a and b? */ 6356 for_each_online_node(c) { 6357 if (node_distance(a, c) < n && 6358 node_distance(b, c) < n) { 6359 sched_numa_topology_type = 6360 NUMA_GLUELESS_MESH; 6361 return; 6362 } 6363 } 6364 6365 sched_numa_topology_type = NUMA_BACKPLANE; 6366 return; 6367 } 6368 } 6369 } 6370 6371 static void sched_init_numa(void) 6372 { 6373 int next_distance, curr_distance = node_distance(0, 0); 6374 struct sched_domain_topology_level *tl; 6375 int level = 0; 6376 int i, j, k; 6377 6378 sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL); 6379 if (!sched_domains_numa_distance) 6380 return; 6381 6382 /* 6383 * O(nr_nodes^2) deduplicating selection sort -- in order to find the 6384 * unique distances in the node_distance() table. 6385 * 6386 * Assumes node_distance(0,j) includes all distances in 6387 * node_distance(i,j) in order to avoid cubic time. 6388 */ 6389 next_distance = curr_distance; 6390 for (i = 0; i < nr_node_ids; i++) { 6391 for (j = 0; j < nr_node_ids; j++) { 6392 for (k = 0; k < nr_node_ids; k++) { 6393 int distance = node_distance(i, k); 6394 6395 if (distance > curr_distance && 6396 (distance < next_distance || 6397 next_distance == curr_distance)) 6398 next_distance = distance; 6399 6400 /* 6401 * While not a strong assumption it would be nice to know 6402 * about cases where if node A is connected to B, B is not 6403 * equally connected to A. 6404 */ 6405 if (sched_debug() && node_distance(k, i) != distance) 6406 sched_numa_warn("Node-distance not symmetric"); 6407 6408 if (sched_debug() && i && !find_numa_distance(distance)) 6409 sched_numa_warn("Node-0 not representative"); 6410 } 6411 if (next_distance != curr_distance) { 6412 sched_domains_numa_distance[level++] = next_distance; 6413 sched_domains_numa_levels = level; 6414 curr_distance = next_distance; 6415 } else break; 6416 } 6417 6418 /* 6419 * In case of sched_debug() we verify the above assumption. 6420 */ 6421 if (!sched_debug()) 6422 break; 6423 } 6424 6425 if (!level) 6426 return; 6427 6428 /* 6429 * 'level' contains the number of unique distances, excluding the 6430 * identity distance node_distance(i,i). 6431 * 6432 * The sched_domains_numa_distance[] array includes the actual distance 6433 * numbers. 6434 */ 6435 6436 /* 6437 * Here, we should temporarily reset sched_domains_numa_levels to 0. 6438 * If it fails to allocate memory for array sched_domains_numa_masks[][], 6439 * the array will contain less then 'level' members. This could be 6440 * dangerous when we use it to iterate array sched_domains_numa_masks[][] 6441 * in other functions. 6442 * 6443 * We reset it to 'level' at the end of this function. 6444 */ 6445 sched_domains_numa_levels = 0; 6446 6447 sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL); 6448 if (!sched_domains_numa_masks) 6449 return; 6450 6451 /* 6452 * Now for each level, construct a mask per node which contains all 6453 * cpus of nodes that are that many hops away from us. 6454 */ 6455 for (i = 0; i < level; i++) { 6456 sched_domains_numa_masks[i] = 6457 kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL); 6458 if (!sched_domains_numa_masks[i]) 6459 return; 6460 6461 for (j = 0; j < nr_node_ids; j++) { 6462 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL); 6463 if (!mask) 6464 return; 6465 6466 sched_domains_numa_masks[i][j] = mask; 6467 6468 for (k = 0; k < nr_node_ids; k++) { 6469 if (node_distance(j, k) > sched_domains_numa_distance[i]) 6470 continue; 6471 6472 cpumask_or(mask, mask, cpumask_of_node(k)); 6473 } 6474 } 6475 } 6476 6477 /* Compute default topology size */ 6478 for (i = 0; sched_domain_topology[i].mask; i++); 6479 6480 tl = kzalloc((i + level + 1) * 6481 sizeof(struct sched_domain_topology_level), GFP_KERNEL); 6482 if (!tl) 6483 return; 6484 6485 /* 6486 * Copy the default topology bits.. 6487 */ 6488 for (i = 0; sched_domain_topology[i].mask; i++) 6489 tl[i] = sched_domain_topology[i]; 6490 6491 /* 6492 * .. and append 'j' levels of NUMA goodness. 6493 */ 6494 for (j = 0; j < level; i++, j++) { 6495 tl[i] = (struct sched_domain_topology_level){ 6496 .mask = sd_numa_mask, 6497 .sd_flags = cpu_numa_flags, 6498 .flags = SDTL_OVERLAP, 6499 .numa_level = j, 6500 SD_INIT_NAME(NUMA) 6501 }; 6502 } 6503 6504 sched_domain_topology = tl; 6505 6506 sched_domains_numa_levels = level; 6507 sched_max_numa_distance = sched_domains_numa_distance[level - 1]; 6508 6509 init_numa_topology_type(); 6510 } 6511 6512 static void sched_domains_numa_masks_set(int cpu) 6513 { 6514 int i, j; 6515 int node = cpu_to_node(cpu); 6516 6517 for (i = 0; i < sched_domains_numa_levels; i++) { 6518 for (j = 0; j < nr_node_ids; j++) { 6519 if (node_distance(j, node) <= sched_domains_numa_distance[i]) 6520 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]); 6521 } 6522 } 6523 } 6524 6525 static void sched_domains_numa_masks_clear(int cpu) 6526 { 6527 int i, j; 6528 for (i = 0; i < sched_domains_numa_levels; i++) { 6529 for (j = 0; j < nr_node_ids; j++) 6530 cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]); 6531 } 6532 } 6533 6534 /* 6535 * Update sched_domains_numa_masks[level][node] array when new cpus 6536 * are onlined. 6537 */ 6538 static int sched_domains_numa_masks_update(struct notifier_block *nfb, 6539 unsigned long action, 6540 void *hcpu) 6541 { 6542 int cpu = (long)hcpu; 6543 6544 switch (action & ~CPU_TASKS_FROZEN) { 6545 case CPU_ONLINE: 6546 sched_domains_numa_masks_set(cpu); 6547 break; 6548 6549 case CPU_DEAD: 6550 sched_domains_numa_masks_clear(cpu); 6551 break; 6552 6553 default: 6554 return NOTIFY_DONE; 6555 } 6556 6557 return NOTIFY_OK; 6558 } 6559 #else 6560 static inline void sched_init_numa(void) 6561 { 6562 } 6563 6564 static int sched_domains_numa_masks_update(struct notifier_block *nfb, 6565 unsigned long action, 6566 void *hcpu) 6567 { 6568 return 0; 6569 } 6570 #endif /* CONFIG_NUMA */ 6571 6572 static int __sdt_alloc(const struct cpumask *cpu_map) 6573 { 6574 struct sched_domain_topology_level *tl; 6575 int j; 6576 6577 for_each_sd_topology(tl) { 6578 struct sd_data *sdd = &tl->data; 6579 6580 sdd->sd = alloc_percpu(struct sched_domain *); 6581 if (!sdd->sd) 6582 return -ENOMEM; 6583 6584 sdd->sg = alloc_percpu(struct sched_group *); 6585 if (!sdd->sg) 6586 return -ENOMEM; 6587 6588 sdd->sgc = alloc_percpu(struct sched_group_capacity *); 6589 if (!sdd->sgc) 6590 return -ENOMEM; 6591 6592 for_each_cpu(j, cpu_map) { 6593 struct sched_domain *sd; 6594 struct sched_group *sg; 6595 struct sched_group_capacity *sgc; 6596 6597 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(), 6598 GFP_KERNEL, cpu_to_node(j)); 6599 if (!sd) 6600 return -ENOMEM; 6601 6602 *per_cpu_ptr(sdd->sd, j) = sd; 6603 6604 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), 6605 GFP_KERNEL, cpu_to_node(j)); 6606 if (!sg) 6607 return -ENOMEM; 6608 6609 sg->next = sg; 6610 6611 *per_cpu_ptr(sdd->sg, j) = sg; 6612 6613 sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(), 6614 GFP_KERNEL, cpu_to_node(j)); 6615 if (!sgc) 6616 return -ENOMEM; 6617 6618 *per_cpu_ptr(sdd->sgc, j) = sgc; 6619 } 6620 } 6621 6622 return 0; 6623 } 6624 6625 static void __sdt_free(const struct cpumask *cpu_map) 6626 { 6627 struct sched_domain_topology_level *tl; 6628 int j; 6629 6630 for_each_sd_topology(tl) { 6631 struct sd_data *sdd = &tl->data; 6632 6633 for_each_cpu(j, cpu_map) { 6634 struct sched_domain *sd; 6635 6636 if (sdd->sd) { 6637 sd = *per_cpu_ptr(sdd->sd, j); 6638 if (sd && (sd->flags & SD_OVERLAP)) 6639 free_sched_groups(sd->groups, 0); 6640 kfree(*per_cpu_ptr(sdd->sd, j)); 6641 } 6642 6643 if (sdd->sg) 6644 kfree(*per_cpu_ptr(sdd->sg, j)); 6645 if (sdd->sgc) 6646 kfree(*per_cpu_ptr(sdd->sgc, j)); 6647 } 6648 free_percpu(sdd->sd); 6649 sdd->sd = NULL; 6650 free_percpu(sdd->sg); 6651 sdd->sg = NULL; 6652 free_percpu(sdd->sgc); 6653 sdd->sgc = NULL; 6654 } 6655 } 6656 6657 struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl, 6658 const struct cpumask *cpu_map, struct sched_domain_attr *attr, 6659 struct sched_domain *child, int cpu) 6660 { 6661 struct sched_domain *sd = sd_init(tl, cpu); 6662 if (!sd) 6663 return child; 6664 6665 cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu)); 6666 if (child) { 6667 sd->level = child->level + 1; 6668 sched_domain_level_max = max(sched_domain_level_max, sd->level); 6669 child->parent = sd; 6670 sd->child = child; 6671 6672 if (!cpumask_subset(sched_domain_span(child), 6673 sched_domain_span(sd))) { 6674 pr_err("BUG: arch topology borken\n"); 6675 #ifdef CONFIG_SCHED_DEBUG 6676 pr_err(" the %s domain not a subset of the %s domain\n", 6677 child->name, sd->name); 6678 #endif 6679 /* Fixup, ensure @sd has at least @child cpus. */ 6680 cpumask_or(sched_domain_span(sd), 6681 sched_domain_span(sd), 6682 sched_domain_span(child)); 6683 } 6684 6685 } 6686 set_domain_attribute(sd, attr); 6687 6688 return sd; 6689 } 6690 6691 /* 6692 * Build sched domains for a given set of cpus and attach the sched domains 6693 * to the individual cpus 6694 */ 6695 static int build_sched_domains(const struct cpumask *cpu_map, 6696 struct sched_domain_attr *attr) 6697 { 6698 enum s_alloc alloc_state; 6699 struct sched_domain *sd; 6700 struct s_data d; 6701 int i, ret = -ENOMEM; 6702 6703 alloc_state = __visit_domain_allocation_hell(&d, cpu_map); 6704 if (alloc_state != sa_rootdomain) 6705 goto error; 6706 6707 /* Set up domains for cpus specified by the cpu_map. */ 6708 for_each_cpu(i, cpu_map) { 6709 struct sched_domain_topology_level *tl; 6710 6711 sd = NULL; 6712 for_each_sd_topology(tl) { 6713 sd = build_sched_domain(tl, cpu_map, attr, sd, i); 6714 if (tl == sched_domain_topology) 6715 *per_cpu_ptr(d.sd, i) = sd; 6716 if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP)) 6717 sd->flags |= SD_OVERLAP; 6718 if (cpumask_equal(cpu_map, sched_domain_span(sd))) 6719 break; 6720 } 6721 } 6722 6723 /* Build the groups for the domains */ 6724 for_each_cpu(i, cpu_map) { 6725 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { 6726 sd->span_weight = cpumask_weight(sched_domain_span(sd)); 6727 if (sd->flags & SD_OVERLAP) { 6728 if (build_overlap_sched_groups(sd, i)) 6729 goto error; 6730 } else { 6731 if (build_sched_groups(sd, i)) 6732 goto error; 6733 } 6734 } 6735 } 6736 6737 /* Calculate CPU capacity for physical packages and nodes */ 6738 for (i = nr_cpumask_bits-1; i >= 0; i--) { 6739 if (!cpumask_test_cpu(i, cpu_map)) 6740 continue; 6741 6742 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { 6743 claim_allocations(i, sd); 6744 init_sched_groups_capacity(i, sd); 6745 } 6746 } 6747 6748 /* Attach the domains */ 6749 rcu_read_lock(); 6750 for_each_cpu(i, cpu_map) { 6751 sd = *per_cpu_ptr(d.sd, i); 6752 cpu_attach_domain(sd, d.rd, i); 6753 } 6754 rcu_read_unlock(); 6755 6756 ret = 0; 6757 error: 6758 __free_domain_allocs(&d, alloc_state, cpu_map); 6759 return ret; 6760 } 6761 6762 static cpumask_var_t *doms_cur; /* current sched domains */ 6763 static int ndoms_cur; /* number of sched domains in 'doms_cur' */ 6764 static struct sched_domain_attr *dattr_cur; 6765 /* attribues of custom domains in 'doms_cur' */ 6766 6767 /* 6768 * Special case: If a kmalloc of a doms_cur partition (array of 6769 * cpumask) fails, then fallback to a single sched domain, 6770 * as determined by the single cpumask fallback_doms. 6771 */ 6772 static cpumask_var_t fallback_doms; 6773 6774 /* 6775 * arch_update_cpu_topology lets virtualized architectures update the 6776 * cpu core maps. It is supposed to return 1 if the topology changed 6777 * or 0 if it stayed the same. 6778 */ 6779 int __weak arch_update_cpu_topology(void) 6780 { 6781 return 0; 6782 } 6783 6784 cpumask_var_t *alloc_sched_domains(unsigned int ndoms) 6785 { 6786 int i; 6787 cpumask_var_t *doms; 6788 6789 doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL); 6790 if (!doms) 6791 return NULL; 6792 for (i = 0; i < ndoms; i++) { 6793 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) { 6794 free_sched_domains(doms, i); 6795 return NULL; 6796 } 6797 } 6798 return doms; 6799 } 6800 6801 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms) 6802 { 6803 unsigned int i; 6804 for (i = 0; i < ndoms; i++) 6805 free_cpumask_var(doms[i]); 6806 kfree(doms); 6807 } 6808 6809 /* 6810 * Set up scheduler domains and groups. Callers must hold the hotplug lock. 6811 * For now this just excludes isolated cpus, but could be used to 6812 * exclude other special cases in the future. 6813 */ 6814 static int init_sched_domains(const struct cpumask *cpu_map) 6815 { 6816 int err; 6817 6818 arch_update_cpu_topology(); 6819 ndoms_cur = 1; 6820 doms_cur = alloc_sched_domains(ndoms_cur); 6821 if (!doms_cur) 6822 doms_cur = &fallback_doms; 6823 cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map); 6824 err = build_sched_domains(doms_cur[0], NULL); 6825 register_sched_domain_sysctl(); 6826 6827 return err; 6828 } 6829 6830 /* 6831 * Detach sched domains from a group of cpus specified in cpu_map 6832 * These cpus will now be attached to the NULL domain 6833 */ 6834 static void detach_destroy_domains(const struct cpumask *cpu_map) 6835 { 6836 int i; 6837 6838 rcu_read_lock(); 6839 for_each_cpu(i, cpu_map) 6840 cpu_attach_domain(NULL, &def_root_domain, i); 6841 rcu_read_unlock(); 6842 } 6843 6844 /* handle null as "default" */ 6845 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur, 6846 struct sched_domain_attr *new, int idx_new) 6847 { 6848 struct sched_domain_attr tmp; 6849 6850 /* fast path */ 6851 if (!new && !cur) 6852 return 1; 6853 6854 tmp = SD_ATTR_INIT; 6855 return !memcmp(cur ? (cur + idx_cur) : &tmp, 6856 new ? (new + idx_new) : &tmp, 6857 sizeof(struct sched_domain_attr)); 6858 } 6859 6860 /* 6861 * Partition sched domains as specified by the 'ndoms_new' 6862 * cpumasks in the array doms_new[] of cpumasks. This compares 6863 * doms_new[] to the current sched domain partitioning, doms_cur[]. 6864 * It destroys each deleted domain and builds each new domain. 6865 * 6866 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'. 6867 * The masks don't intersect (don't overlap.) We should setup one 6868 * sched domain for each mask. CPUs not in any of the cpumasks will 6869 * not be load balanced. If the same cpumask appears both in the 6870 * current 'doms_cur' domains and in the new 'doms_new', we can leave 6871 * it as it is. 6872 * 6873 * The passed in 'doms_new' should be allocated using 6874 * alloc_sched_domains. This routine takes ownership of it and will 6875 * free_sched_domains it when done with it. If the caller failed the 6876 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1, 6877 * and partition_sched_domains() will fallback to the single partition 6878 * 'fallback_doms', it also forces the domains to be rebuilt. 6879 * 6880 * If doms_new == NULL it will be replaced with cpu_online_mask. 6881 * ndoms_new == 0 is a special case for destroying existing domains, 6882 * and it will not create the default domain. 6883 * 6884 * Call with hotplug lock held 6885 */ 6886 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[], 6887 struct sched_domain_attr *dattr_new) 6888 { 6889 int i, j, n; 6890 int new_topology; 6891 6892 mutex_lock(&sched_domains_mutex); 6893 6894 /* always unregister in case we don't destroy any domains */ 6895 unregister_sched_domain_sysctl(); 6896 6897 /* Let architecture update cpu core mappings. */ 6898 new_topology = arch_update_cpu_topology(); 6899 6900 n = doms_new ? ndoms_new : 0; 6901 6902 /* Destroy deleted domains */ 6903 for (i = 0; i < ndoms_cur; i++) { 6904 for (j = 0; j < n && !new_topology; j++) { 6905 if (cpumask_equal(doms_cur[i], doms_new[j]) 6906 && dattrs_equal(dattr_cur, i, dattr_new, j)) 6907 goto match1; 6908 } 6909 /* no match - a current sched domain not in new doms_new[] */ 6910 detach_destroy_domains(doms_cur[i]); 6911 match1: 6912 ; 6913 } 6914 6915 n = ndoms_cur; 6916 if (doms_new == NULL) { 6917 n = 0; 6918 doms_new = &fallback_doms; 6919 cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map); 6920 WARN_ON_ONCE(dattr_new); 6921 } 6922 6923 /* Build new domains */ 6924 for (i = 0; i < ndoms_new; i++) { 6925 for (j = 0; j < n && !new_topology; j++) { 6926 if (cpumask_equal(doms_new[i], doms_cur[j]) 6927 && dattrs_equal(dattr_new, i, dattr_cur, j)) 6928 goto match2; 6929 } 6930 /* no match - add a new doms_new */ 6931 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL); 6932 match2: 6933 ; 6934 } 6935 6936 /* Remember the new sched domains */ 6937 if (doms_cur != &fallback_doms) 6938 free_sched_domains(doms_cur, ndoms_cur); 6939 kfree(dattr_cur); /* kfree(NULL) is safe */ 6940 doms_cur = doms_new; 6941 dattr_cur = dattr_new; 6942 ndoms_cur = ndoms_new; 6943 6944 register_sched_domain_sysctl(); 6945 6946 mutex_unlock(&sched_domains_mutex); 6947 } 6948 6949 static int num_cpus_frozen; /* used to mark begin/end of suspend/resume */ 6950 6951 /* 6952 * Update cpusets according to cpu_active mask. If cpusets are 6953 * disabled, cpuset_update_active_cpus() becomes a simple wrapper 6954 * around partition_sched_domains(). 6955 * 6956 * If we come here as part of a suspend/resume, don't touch cpusets because we 6957 * want to restore it back to its original state upon resume anyway. 6958 */ 6959 static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action, 6960 void *hcpu) 6961 { 6962 switch (action) { 6963 case CPU_ONLINE_FROZEN: 6964 case CPU_DOWN_FAILED_FROZEN: 6965 6966 /* 6967 * num_cpus_frozen tracks how many CPUs are involved in suspend 6968 * resume sequence. As long as this is not the last online 6969 * operation in the resume sequence, just build a single sched 6970 * domain, ignoring cpusets. 6971 */ 6972 num_cpus_frozen--; 6973 if (likely(num_cpus_frozen)) { 6974 partition_sched_domains(1, NULL, NULL); 6975 break; 6976 } 6977 6978 /* 6979 * This is the last CPU online operation. So fall through and 6980 * restore the original sched domains by considering the 6981 * cpuset configurations. 6982 */ 6983 6984 case CPU_ONLINE: 6985 cpuset_update_active_cpus(true); 6986 break; 6987 default: 6988 return NOTIFY_DONE; 6989 } 6990 return NOTIFY_OK; 6991 } 6992 6993 static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action, 6994 void *hcpu) 6995 { 6996 unsigned long flags; 6997 long cpu = (long)hcpu; 6998 struct dl_bw *dl_b; 6999 bool overflow; 7000 int cpus; 7001 7002 switch (action) { 7003 case CPU_DOWN_PREPARE: 7004 rcu_read_lock_sched(); 7005 dl_b = dl_bw_of(cpu); 7006 7007 raw_spin_lock_irqsave(&dl_b->lock, flags); 7008 cpus = dl_bw_cpus(cpu); 7009 overflow = __dl_overflow(dl_b, cpus, 0, 0); 7010 raw_spin_unlock_irqrestore(&dl_b->lock, flags); 7011 7012 rcu_read_unlock_sched(); 7013 7014 if (overflow) 7015 return notifier_from_errno(-EBUSY); 7016 cpuset_update_active_cpus(false); 7017 break; 7018 case CPU_DOWN_PREPARE_FROZEN: 7019 num_cpus_frozen++; 7020 partition_sched_domains(1, NULL, NULL); 7021 break; 7022 default: 7023 return NOTIFY_DONE; 7024 } 7025 return NOTIFY_OK; 7026 } 7027 7028 void __init sched_init_smp(void) 7029 { 7030 cpumask_var_t non_isolated_cpus; 7031 7032 alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL); 7033 alloc_cpumask_var(&fallback_doms, GFP_KERNEL); 7034 7035 sched_init_numa(); 7036 7037 /* 7038 * There's no userspace yet to cause hotplug operations; hence all the 7039 * cpu masks are stable and all blatant races in the below code cannot 7040 * happen. 7041 */ 7042 mutex_lock(&sched_domains_mutex); 7043 init_sched_domains(cpu_active_mask); 7044 cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map); 7045 if (cpumask_empty(non_isolated_cpus)) 7046 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus); 7047 mutex_unlock(&sched_domains_mutex); 7048 7049 hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE); 7050 hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE); 7051 hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE); 7052 7053 init_hrtick(); 7054 7055 /* Move init over to a non-isolated CPU */ 7056 if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0) 7057 BUG(); 7058 sched_init_granularity(); 7059 free_cpumask_var(non_isolated_cpus); 7060 7061 init_sched_rt_class(); 7062 init_sched_dl_class(); 7063 } 7064 #else 7065 void __init sched_init_smp(void) 7066 { 7067 sched_init_granularity(); 7068 } 7069 #endif /* CONFIG_SMP */ 7070 7071 const_debug unsigned int sysctl_timer_migration = 1; 7072 7073 int in_sched_functions(unsigned long addr) 7074 { 7075 return in_lock_functions(addr) || 7076 (addr >= (unsigned long)__sched_text_start 7077 && addr < (unsigned long)__sched_text_end); 7078 } 7079 7080 #ifdef CONFIG_CGROUP_SCHED 7081 /* 7082 * Default task group. 7083 * Every task in system belongs to this group at bootup. 7084 */ 7085 struct task_group root_task_group; 7086 LIST_HEAD(task_groups); 7087 #endif 7088 7089 DECLARE_PER_CPU(cpumask_var_t, load_balance_mask); 7090 7091 void __init sched_init(void) 7092 { 7093 int i, j; 7094 unsigned long alloc_size = 0, ptr; 7095 7096 #ifdef CONFIG_FAIR_GROUP_SCHED 7097 alloc_size += 2 * nr_cpu_ids * sizeof(void **); 7098 #endif 7099 #ifdef CONFIG_RT_GROUP_SCHED 7100 alloc_size += 2 * nr_cpu_ids * sizeof(void **); 7101 #endif 7102 if (alloc_size) { 7103 ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT); 7104 7105 #ifdef CONFIG_FAIR_GROUP_SCHED 7106 root_task_group.se = (struct sched_entity **)ptr; 7107 ptr += nr_cpu_ids * sizeof(void **); 7108 7109 root_task_group.cfs_rq = (struct cfs_rq **)ptr; 7110 ptr += nr_cpu_ids * sizeof(void **); 7111 7112 #endif /* CONFIG_FAIR_GROUP_SCHED */ 7113 #ifdef CONFIG_RT_GROUP_SCHED 7114 root_task_group.rt_se = (struct sched_rt_entity **)ptr; 7115 ptr += nr_cpu_ids * sizeof(void **); 7116 7117 root_task_group.rt_rq = (struct rt_rq **)ptr; 7118 ptr += nr_cpu_ids * sizeof(void **); 7119 7120 #endif /* CONFIG_RT_GROUP_SCHED */ 7121 } 7122 #ifdef CONFIG_CPUMASK_OFFSTACK 7123 for_each_possible_cpu(i) { 7124 per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node( 7125 cpumask_size(), GFP_KERNEL, cpu_to_node(i)); 7126 } 7127 #endif /* CONFIG_CPUMASK_OFFSTACK */ 7128 7129 init_rt_bandwidth(&def_rt_bandwidth, 7130 global_rt_period(), global_rt_runtime()); 7131 init_dl_bandwidth(&def_dl_bandwidth, 7132 global_rt_period(), global_rt_runtime()); 7133 7134 #ifdef CONFIG_SMP 7135 init_defrootdomain(); 7136 #endif 7137 7138 #ifdef CONFIG_RT_GROUP_SCHED 7139 init_rt_bandwidth(&root_task_group.rt_bandwidth, 7140 global_rt_period(), global_rt_runtime()); 7141 #endif /* CONFIG_RT_GROUP_SCHED */ 7142 7143 #ifdef CONFIG_CGROUP_SCHED 7144 list_add(&root_task_group.list, &task_groups); 7145 INIT_LIST_HEAD(&root_task_group.children); 7146 INIT_LIST_HEAD(&root_task_group.siblings); 7147 autogroup_init(&init_task); 7148 7149 #endif /* CONFIG_CGROUP_SCHED */ 7150 7151 for_each_possible_cpu(i) { 7152 struct rq *rq; 7153 7154 rq = cpu_rq(i); 7155 raw_spin_lock_init(&rq->lock); 7156 rq->nr_running = 0; 7157 rq->calc_load_active = 0; 7158 rq->calc_load_update = jiffies + LOAD_FREQ; 7159 init_cfs_rq(&rq->cfs); 7160 init_rt_rq(&rq->rt); 7161 init_dl_rq(&rq->dl); 7162 #ifdef CONFIG_FAIR_GROUP_SCHED 7163 root_task_group.shares = ROOT_TASK_GROUP_LOAD; 7164 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list); 7165 /* 7166 * How much cpu bandwidth does root_task_group get? 7167 * 7168 * In case of task-groups formed thr' the cgroup filesystem, it 7169 * gets 100% of the cpu resources in the system. This overall 7170 * system cpu resource is divided among the tasks of 7171 * root_task_group and its child task-groups in a fair manner, 7172 * based on each entity's (task or task-group's) weight 7173 * (se->load.weight). 7174 * 7175 * In other words, if root_task_group has 10 tasks of weight 7176 * 1024) and two child groups A0 and A1 (of weight 1024 each), 7177 * then A0's share of the cpu resource is: 7178 * 7179 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33% 7180 * 7181 * We achieve this by letting root_task_group's tasks sit 7182 * directly in rq->cfs (i.e root_task_group->se[] = NULL). 7183 */ 7184 init_cfs_bandwidth(&root_task_group.cfs_bandwidth); 7185 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL); 7186 #endif /* CONFIG_FAIR_GROUP_SCHED */ 7187 7188 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime; 7189 #ifdef CONFIG_RT_GROUP_SCHED 7190 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL); 7191 #endif 7192 7193 for (j = 0; j < CPU_LOAD_IDX_MAX; j++) 7194 rq->cpu_load[j] = 0; 7195 7196 rq->last_load_update_tick = jiffies; 7197 7198 #ifdef CONFIG_SMP 7199 rq->sd = NULL; 7200 rq->rd = NULL; 7201 rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE; 7202 rq->post_schedule = 0; 7203 rq->active_balance = 0; 7204 rq->next_balance = jiffies; 7205 rq->push_cpu = 0; 7206 rq->cpu = i; 7207 rq->online = 0; 7208 rq->idle_stamp = 0; 7209 rq->avg_idle = 2*sysctl_sched_migration_cost; 7210 rq->max_idle_balance_cost = sysctl_sched_migration_cost; 7211 7212 INIT_LIST_HEAD(&rq->cfs_tasks); 7213 7214 rq_attach_root(rq, &def_root_domain); 7215 #ifdef CONFIG_NO_HZ_COMMON 7216 rq->nohz_flags = 0; 7217 #endif 7218 #ifdef CONFIG_NO_HZ_FULL 7219 rq->last_sched_tick = 0; 7220 #endif 7221 #endif 7222 init_rq_hrtick(rq); 7223 atomic_set(&rq->nr_iowait, 0); 7224 } 7225 7226 set_load_weight(&init_task); 7227 7228 #ifdef CONFIG_PREEMPT_NOTIFIERS 7229 INIT_HLIST_HEAD(&init_task.preempt_notifiers); 7230 #endif 7231 7232 /* 7233 * The boot idle thread does lazy MMU switching as well: 7234 */ 7235 atomic_inc(&init_mm.mm_count); 7236 enter_lazy_tlb(&init_mm, current); 7237 7238 /* 7239 * During early bootup we pretend to be a normal task: 7240 */ 7241 current->sched_class = &fair_sched_class; 7242 7243 /* 7244 * Make us the idle thread. Technically, schedule() should not be 7245 * called from this thread, however somewhere below it might be, 7246 * but because we are the idle thread, we just pick up running again 7247 * when this runqueue becomes "idle". 7248 */ 7249 init_idle(current, smp_processor_id()); 7250 7251 calc_load_update = jiffies + LOAD_FREQ; 7252 7253 #ifdef CONFIG_SMP 7254 zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT); 7255 /* May be allocated at isolcpus cmdline parse time */ 7256 if (cpu_isolated_map == NULL) 7257 zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT); 7258 idle_thread_set_boot_cpu(); 7259 set_cpu_rq_start_time(); 7260 #endif 7261 init_sched_fair_class(); 7262 7263 scheduler_running = 1; 7264 } 7265 7266 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP 7267 static inline int preempt_count_equals(int preempt_offset) 7268 { 7269 int nested = (preempt_count() & ~PREEMPT_ACTIVE) + rcu_preempt_depth(); 7270 7271 return (nested == preempt_offset); 7272 } 7273 7274 void __might_sleep(const char *file, int line, int preempt_offset) 7275 { 7276 /* 7277 * Blocking primitives will set (and therefore destroy) current->state, 7278 * since we will exit with TASK_RUNNING make sure we enter with it, 7279 * otherwise we will destroy state. 7280 */ 7281 WARN_ONCE(current->state != TASK_RUNNING && current->task_state_change, 7282 "do not call blocking ops when !TASK_RUNNING; " 7283 "state=%lx set at [<%p>] %pS\n", 7284 current->state, 7285 (void *)current->task_state_change, 7286 (void *)current->task_state_change); 7287 7288 ___might_sleep(file, line, preempt_offset); 7289 } 7290 EXPORT_SYMBOL(__might_sleep); 7291 7292 void ___might_sleep(const char *file, int line, int preempt_offset) 7293 { 7294 static unsigned long prev_jiffy; /* ratelimiting */ 7295 7296 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */ 7297 if ((preempt_count_equals(preempt_offset) && !irqs_disabled() && 7298 !is_idle_task(current)) || 7299 system_state != SYSTEM_RUNNING || oops_in_progress) 7300 return; 7301 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) 7302 return; 7303 prev_jiffy = jiffies; 7304 7305 printk(KERN_ERR 7306 "BUG: sleeping function called from invalid context at %s:%d\n", 7307 file, line); 7308 printk(KERN_ERR 7309 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n", 7310 in_atomic(), irqs_disabled(), 7311 current->pid, current->comm); 7312 7313 if (task_stack_end_corrupted(current)) 7314 printk(KERN_EMERG "Thread overran stack, or stack corrupted\n"); 7315 7316 debug_show_held_locks(current); 7317 if (irqs_disabled()) 7318 print_irqtrace_events(current); 7319 #ifdef CONFIG_DEBUG_PREEMPT 7320 if (!preempt_count_equals(preempt_offset)) { 7321 pr_err("Preemption disabled at:"); 7322 print_ip_sym(current->preempt_disable_ip); 7323 pr_cont("\n"); 7324 } 7325 #endif 7326 dump_stack(); 7327 } 7328 EXPORT_SYMBOL(___might_sleep); 7329 #endif 7330 7331 #ifdef CONFIG_MAGIC_SYSRQ 7332 static void normalize_task(struct rq *rq, struct task_struct *p) 7333 { 7334 const struct sched_class *prev_class = p->sched_class; 7335 struct sched_attr attr = { 7336 .sched_policy = SCHED_NORMAL, 7337 }; 7338 int old_prio = p->prio; 7339 int queued; 7340 7341 queued = task_on_rq_queued(p); 7342 if (queued) 7343 dequeue_task(rq, p, 0); 7344 __setscheduler(rq, p, &attr, false); 7345 if (queued) { 7346 enqueue_task(rq, p, 0); 7347 resched_curr(rq); 7348 } 7349 7350 check_class_changed(rq, p, prev_class, old_prio); 7351 } 7352 7353 void normalize_rt_tasks(void) 7354 { 7355 struct task_struct *g, *p; 7356 unsigned long flags; 7357 struct rq *rq; 7358 7359 read_lock(&tasklist_lock); 7360 for_each_process_thread(g, p) { 7361 /* 7362 * Only normalize user tasks: 7363 */ 7364 if (p->flags & PF_KTHREAD) 7365 continue; 7366 7367 p->se.exec_start = 0; 7368 #ifdef CONFIG_SCHEDSTATS 7369 p->se.statistics.wait_start = 0; 7370 p->se.statistics.sleep_start = 0; 7371 p->se.statistics.block_start = 0; 7372 #endif 7373 7374 if (!dl_task(p) && !rt_task(p)) { 7375 /* 7376 * Renice negative nice level userspace 7377 * tasks back to 0: 7378 */ 7379 if (task_nice(p) < 0) 7380 set_user_nice(p, 0); 7381 continue; 7382 } 7383 7384 rq = task_rq_lock(p, &flags); 7385 normalize_task(rq, p); 7386 task_rq_unlock(rq, p, &flags); 7387 } 7388 read_unlock(&tasklist_lock); 7389 } 7390 7391 #endif /* CONFIG_MAGIC_SYSRQ */ 7392 7393 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) 7394 /* 7395 * These functions are only useful for the IA64 MCA handling, or kdb. 7396 * 7397 * They can only be called when the whole system has been 7398 * stopped - every CPU needs to be quiescent, and no scheduling 7399 * activity can take place. Using them for anything else would 7400 * be a serious bug, and as a result, they aren't even visible 7401 * under any other configuration. 7402 */ 7403 7404 /** 7405 * curr_task - return the current task for a given cpu. 7406 * @cpu: the processor in question. 7407 * 7408 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! 7409 * 7410 * Return: The current task for @cpu. 7411 */ 7412 struct task_struct *curr_task(int cpu) 7413 { 7414 return cpu_curr(cpu); 7415 } 7416 7417 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */ 7418 7419 #ifdef CONFIG_IA64 7420 /** 7421 * set_curr_task - set the current task for a given cpu. 7422 * @cpu: the processor in question. 7423 * @p: the task pointer to set. 7424 * 7425 * Description: This function must only be used when non-maskable interrupts 7426 * are serviced on a separate stack. It allows the architecture to switch the 7427 * notion of the current task on a cpu in a non-blocking manner. This function 7428 * must be called with all CPU's synchronized, and interrupts disabled, the 7429 * and caller must save the original value of the current task (see 7430 * curr_task() above) and restore that value before reenabling interrupts and 7431 * re-starting the system. 7432 * 7433 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! 7434 */ 7435 void set_curr_task(int cpu, struct task_struct *p) 7436 { 7437 cpu_curr(cpu) = p; 7438 } 7439 7440 #endif 7441 7442 #ifdef CONFIG_CGROUP_SCHED 7443 /* task_group_lock serializes the addition/removal of task groups */ 7444 static DEFINE_SPINLOCK(task_group_lock); 7445 7446 static void free_sched_group(struct task_group *tg) 7447 { 7448 free_fair_sched_group(tg); 7449 free_rt_sched_group(tg); 7450 autogroup_free(tg); 7451 kfree(tg); 7452 } 7453 7454 /* allocate runqueue etc for a new task group */ 7455 struct task_group *sched_create_group(struct task_group *parent) 7456 { 7457 struct task_group *tg; 7458 7459 tg = kzalloc(sizeof(*tg), GFP_KERNEL); 7460 if (!tg) 7461 return ERR_PTR(-ENOMEM); 7462 7463 if (!alloc_fair_sched_group(tg, parent)) 7464 goto err; 7465 7466 if (!alloc_rt_sched_group(tg, parent)) 7467 goto err; 7468 7469 return tg; 7470 7471 err: 7472 free_sched_group(tg); 7473 return ERR_PTR(-ENOMEM); 7474 } 7475 7476 void sched_online_group(struct task_group *tg, struct task_group *parent) 7477 { 7478 unsigned long flags; 7479 7480 spin_lock_irqsave(&task_group_lock, flags); 7481 list_add_rcu(&tg->list, &task_groups); 7482 7483 WARN_ON(!parent); /* root should already exist */ 7484 7485 tg->parent = parent; 7486 INIT_LIST_HEAD(&tg->children); 7487 list_add_rcu(&tg->siblings, &parent->children); 7488 spin_unlock_irqrestore(&task_group_lock, flags); 7489 } 7490 7491 /* rcu callback to free various structures associated with a task group */ 7492 static void free_sched_group_rcu(struct rcu_head *rhp) 7493 { 7494 /* now it should be safe to free those cfs_rqs */ 7495 free_sched_group(container_of(rhp, struct task_group, rcu)); 7496 } 7497 7498 /* Destroy runqueue etc associated with a task group */ 7499 void sched_destroy_group(struct task_group *tg) 7500 { 7501 /* wait for possible concurrent references to cfs_rqs complete */ 7502 call_rcu(&tg->rcu, free_sched_group_rcu); 7503 } 7504 7505 void sched_offline_group(struct task_group *tg) 7506 { 7507 unsigned long flags; 7508 int i; 7509 7510 /* end participation in shares distribution */ 7511 for_each_possible_cpu(i) 7512 unregister_fair_sched_group(tg, i); 7513 7514 spin_lock_irqsave(&task_group_lock, flags); 7515 list_del_rcu(&tg->list); 7516 list_del_rcu(&tg->siblings); 7517 spin_unlock_irqrestore(&task_group_lock, flags); 7518 } 7519 7520 /* change task's runqueue when it moves between groups. 7521 * The caller of this function should have put the task in its new group 7522 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to 7523 * reflect its new group. 7524 */ 7525 void sched_move_task(struct task_struct *tsk) 7526 { 7527 struct task_group *tg; 7528 int queued, running; 7529 unsigned long flags; 7530 struct rq *rq; 7531 7532 rq = task_rq_lock(tsk, &flags); 7533 7534 running = task_current(rq, tsk); 7535 queued = task_on_rq_queued(tsk); 7536 7537 if (queued) 7538 dequeue_task(rq, tsk, 0); 7539 if (unlikely(running)) 7540 put_prev_task(rq, tsk); 7541 7542 /* 7543 * All callers are synchronized by task_rq_lock(); we do not use RCU 7544 * which is pointless here. Thus, we pass "true" to task_css_check() 7545 * to prevent lockdep warnings. 7546 */ 7547 tg = container_of(task_css_check(tsk, cpu_cgrp_id, true), 7548 struct task_group, css); 7549 tg = autogroup_task_group(tsk, tg); 7550 tsk->sched_task_group = tg; 7551 7552 #ifdef CONFIG_FAIR_GROUP_SCHED 7553 if (tsk->sched_class->task_move_group) 7554 tsk->sched_class->task_move_group(tsk, queued); 7555 else 7556 #endif 7557 set_task_rq(tsk, task_cpu(tsk)); 7558 7559 if (unlikely(running)) 7560 tsk->sched_class->set_curr_task(rq); 7561 if (queued) 7562 enqueue_task(rq, tsk, 0); 7563 7564 task_rq_unlock(rq, tsk, &flags); 7565 } 7566 #endif /* CONFIG_CGROUP_SCHED */ 7567 7568 #ifdef CONFIG_RT_GROUP_SCHED 7569 /* 7570 * Ensure that the real time constraints are schedulable. 7571 */ 7572 static DEFINE_MUTEX(rt_constraints_mutex); 7573 7574 /* Must be called with tasklist_lock held */ 7575 static inline int tg_has_rt_tasks(struct task_group *tg) 7576 { 7577 struct task_struct *g, *p; 7578 7579 /* 7580 * Autogroups do not have RT tasks; see autogroup_create(). 7581 */ 7582 if (task_group_is_autogroup(tg)) 7583 return 0; 7584 7585 for_each_process_thread(g, p) { 7586 if (rt_task(p) && task_group(p) == tg) 7587 return 1; 7588 } 7589 7590 return 0; 7591 } 7592 7593 struct rt_schedulable_data { 7594 struct task_group *tg; 7595 u64 rt_period; 7596 u64 rt_runtime; 7597 }; 7598 7599 static int tg_rt_schedulable(struct task_group *tg, void *data) 7600 { 7601 struct rt_schedulable_data *d = data; 7602 struct task_group *child; 7603 unsigned long total, sum = 0; 7604 u64 period, runtime; 7605 7606 period = ktime_to_ns(tg->rt_bandwidth.rt_period); 7607 runtime = tg->rt_bandwidth.rt_runtime; 7608 7609 if (tg == d->tg) { 7610 period = d->rt_period; 7611 runtime = d->rt_runtime; 7612 } 7613 7614 /* 7615 * Cannot have more runtime than the period. 7616 */ 7617 if (runtime > period && runtime != RUNTIME_INF) 7618 return -EINVAL; 7619 7620 /* 7621 * Ensure we don't starve existing RT tasks. 7622 */ 7623 if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg)) 7624 return -EBUSY; 7625 7626 total = to_ratio(period, runtime); 7627 7628 /* 7629 * Nobody can have more than the global setting allows. 7630 */ 7631 if (total > to_ratio(global_rt_period(), global_rt_runtime())) 7632 return -EINVAL; 7633 7634 /* 7635 * The sum of our children's runtime should not exceed our own. 7636 */ 7637 list_for_each_entry_rcu(child, &tg->children, siblings) { 7638 period = ktime_to_ns(child->rt_bandwidth.rt_period); 7639 runtime = child->rt_bandwidth.rt_runtime; 7640 7641 if (child == d->tg) { 7642 period = d->rt_period; 7643 runtime = d->rt_runtime; 7644 } 7645 7646 sum += to_ratio(period, runtime); 7647 } 7648 7649 if (sum > total) 7650 return -EINVAL; 7651 7652 return 0; 7653 } 7654 7655 static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime) 7656 { 7657 int ret; 7658 7659 struct rt_schedulable_data data = { 7660 .tg = tg, 7661 .rt_period = period, 7662 .rt_runtime = runtime, 7663 }; 7664 7665 rcu_read_lock(); 7666 ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data); 7667 rcu_read_unlock(); 7668 7669 return ret; 7670 } 7671 7672 static int tg_set_rt_bandwidth(struct task_group *tg, 7673 u64 rt_period, u64 rt_runtime) 7674 { 7675 int i, err = 0; 7676 7677 /* 7678 * Disallowing the root group RT runtime is BAD, it would disallow the 7679 * kernel creating (and or operating) RT threads. 7680 */ 7681 if (tg == &root_task_group && rt_runtime == 0) 7682 return -EINVAL; 7683 7684 /* No period doesn't make any sense. */ 7685 if (rt_period == 0) 7686 return -EINVAL; 7687 7688 mutex_lock(&rt_constraints_mutex); 7689 read_lock(&tasklist_lock); 7690 err = __rt_schedulable(tg, rt_period, rt_runtime); 7691 if (err) 7692 goto unlock; 7693 7694 raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock); 7695 tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period); 7696 tg->rt_bandwidth.rt_runtime = rt_runtime; 7697 7698 for_each_possible_cpu(i) { 7699 struct rt_rq *rt_rq = tg->rt_rq[i]; 7700 7701 raw_spin_lock(&rt_rq->rt_runtime_lock); 7702 rt_rq->rt_runtime = rt_runtime; 7703 raw_spin_unlock(&rt_rq->rt_runtime_lock); 7704 } 7705 raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock); 7706 unlock: 7707 read_unlock(&tasklist_lock); 7708 mutex_unlock(&rt_constraints_mutex); 7709 7710 return err; 7711 } 7712 7713 static int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us) 7714 { 7715 u64 rt_runtime, rt_period; 7716 7717 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period); 7718 rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC; 7719 if (rt_runtime_us < 0) 7720 rt_runtime = RUNTIME_INF; 7721 7722 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime); 7723 } 7724 7725 static long sched_group_rt_runtime(struct task_group *tg) 7726 { 7727 u64 rt_runtime_us; 7728 7729 if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF) 7730 return -1; 7731 7732 rt_runtime_us = tg->rt_bandwidth.rt_runtime; 7733 do_div(rt_runtime_us, NSEC_PER_USEC); 7734 return rt_runtime_us; 7735 } 7736 7737 static int sched_group_set_rt_period(struct task_group *tg, long rt_period_us) 7738 { 7739 u64 rt_runtime, rt_period; 7740 7741 rt_period = (u64)rt_period_us * NSEC_PER_USEC; 7742 rt_runtime = tg->rt_bandwidth.rt_runtime; 7743 7744 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime); 7745 } 7746 7747 static long sched_group_rt_period(struct task_group *tg) 7748 { 7749 u64 rt_period_us; 7750 7751 rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period); 7752 do_div(rt_period_us, NSEC_PER_USEC); 7753 return rt_period_us; 7754 } 7755 #endif /* CONFIG_RT_GROUP_SCHED */ 7756 7757 #ifdef CONFIG_RT_GROUP_SCHED 7758 static int sched_rt_global_constraints(void) 7759 { 7760 int ret = 0; 7761 7762 mutex_lock(&rt_constraints_mutex); 7763 read_lock(&tasklist_lock); 7764 ret = __rt_schedulable(NULL, 0, 0); 7765 read_unlock(&tasklist_lock); 7766 mutex_unlock(&rt_constraints_mutex); 7767 7768 return ret; 7769 } 7770 7771 static int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk) 7772 { 7773 /* Don't accept realtime tasks when there is no way for them to run */ 7774 if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0) 7775 return 0; 7776 7777 return 1; 7778 } 7779 7780 #else /* !CONFIG_RT_GROUP_SCHED */ 7781 static int sched_rt_global_constraints(void) 7782 { 7783 unsigned long flags; 7784 int i, ret = 0; 7785 7786 raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags); 7787 for_each_possible_cpu(i) { 7788 struct rt_rq *rt_rq = &cpu_rq(i)->rt; 7789 7790 raw_spin_lock(&rt_rq->rt_runtime_lock); 7791 rt_rq->rt_runtime = global_rt_runtime(); 7792 raw_spin_unlock(&rt_rq->rt_runtime_lock); 7793 } 7794 raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags); 7795 7796 return ret; 7797 } 7798 #endif /* CONFIG_RT_GROUP_SCHED */ 7799 7800 static int sched_dl_global_validate(void) 7801 { 7802 u64 runtime = global_rt_runtime(); 7803 u64 period = global_rt_period(); 7804 u64 new_bw = to_ratio(period, runtime); 7805 struct dl_bw *dl_b; 7806 int cpu, ret = 0; 7807 unsigned long flags; 7808 7809 /* 7810 * Here we want to check the bandwidth not being set to some 7811 * value smaller than the currently allocated bandwidth in 7812 * any of the root_domains. 7813 * 7814 * FIXME: Cycling on all the CPUs is overdoing, but simpler than 7815 * cycling on root_domains... Discussion on different/better 7816 * solutions is welcome! 7817 */ 7818 for_each_possible_cpu(cpu) { 7819 rcu_read_lock_sched(); 7820 dl_b = dl_bw_of(cpu); 7821 7822 raw_spin_lock_irqsave(&dl_b->lock, flags); 7823 if (new_bw < dl_b->total_bw) 7824 ret = -EBUSY; 7825 raw_spin_unlock_irqrestore(&dl_b->lock, flags); 7826 7827 rcu_read_unlock_sched(); 7828 7829 if (ret) 7830 break; 7831 } 7832 7833 return ret; 7834 } 7835 7836 static void sched_dl_do_global(void) 7837 { 7838 u64 new_bw = -1; 7839 struct dl_bw *dl_b; 7840 int cpu; 7841 unsigned long flags; 7842 7843 def_dl_bandwidth.dl_period = global_rt_period(); 7844 def_dl_bandwidth.dl_runtime = global_rt_runtime(); 7845 7846 if (global_rt_runtime() != RUNTIME_INF) 7847 new_bw = to_ratio(global_rt_period(), global_rt_runtime()); 7848 7849 /* 7850 * FIXME: As above... 7851 */ 7852 for_each_possible_cpu(cpu) { 7853 rcu_read_lock_sched(); 7854 dl_b = dl_bw_of(cpu); 7855 7856 raw_spin_lock_irqsave(&dl_b->lock, flags); 7857 dl_b->bw = new_bw; 7858 raw_spin_unlock_irqrestore(&dl_b->lock, flags); 7859 7860 rcu_read_unlock_sched(); 7861 } 7862 } 7863 7864 static int sched_rt_global_validate(void) 7865 { 7866 if (sysctl_sched_rt_period <= 0) 7867 return -EINVAL; 7868 7869 if ((sysctl_sched_rt_runtime != RUNTIME_INF) && 7870 (sysctl_sched_rt_runtime > sysctl_sched_rt_period)) 7871 return -EINVAL; 7872 7873 return 0; 7874 } 7875 7876 static void sched_rt_do_global(void) 7877 { 7878 def_rt_bandwidth.rt_runtime = global_rt_runtime(); 7879 def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period()); 7880 } 7881 7882 int sched_rt_handler(struct ctl_table *table, int write, 7883 void __user *buffer, size_t *lenp, 7884 loff_t *ppos) 7885 { 7886 int old_period, old_runtime; 7887 static DEFINE_MUTEX(mutex); 7888 int ret; 7889 7890 mutex_lock(&mutex); 7891 old_period = sysctl_sched_rt_period; 7892 old_runtime = sysctl_sched_rt_runtime; 7893 7894 ret = proc_dointvec(table, write, buffer, lenp, ppos); 7895 7896 if (!ret && write) { 7897 ret = sched_rt_global_validate(); 7898 if (ret) 7899 goto undo; 7900 7901 ret = sched_dl_global_validate(); 7902 if (ret) 7903 goto undo; 7904 7905 ret = sched_rt_global_constraints(); 7906 if (ret) 7907 goto undo; 7908 7909 sched_rt_do_global(); 7910 sched_dl_do_global(); 7911 } 7912 if (0) { 7913 undo: 7914 sysctl_sched_rt_period = old_period; 7915 sysctl_sched_rt_runtime = old_runtime; 7916 } 7917 mutex_unlock(&mutex); 7918 7919 return ret; 7920 } 7921 7922 int sched_rr_handler(struct ctl_table *table, int write, 7923 void __user *buffer, size_t *lenp, 7924 loff_t *ppos) 7925 { 7926 int ret; 7927 static DEFINE_MUTEX(mutex); 7928 7929 mutex_lock(&mutex); 7930 ret = proc_dointvec(table, write, buffer, lenp, ppos); 7931 /* make sure that internally we keep jiffies */ 7932 /* also, writing zero resets timeslice to default */ 7933 if (!ret && write) { 7934 sched_rr_timeslice = sched_rr_timeslice <= 0 ? 7935 RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice); 7936 } 7937 mutex_unlock(&mutex); 7938 return ret; 7939 } 7940 7941 #ifdef CONFIG_CGROUP_SCHED 7942 7943 static inline struct task_group *css_tg(struct cgroup_subsys_state *css) 7944 { 7945 return css ? container_of(css, struct task_group, css) : NULL; 7946 } 7947 7948 static struct cgroup_subsys_state * 7949 cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) 7950 { 7951 struct task_group *parent = css_tg(parent_css); 7952 struct task_group *tg; 7953 7954 if (!parent) { 7955 /* This is early initialization for the top cgroup */ 7956 return &root_task_group.css; 7957 } 7958 7959 tg = sched_create_group(parent); 7960 if (IS_ERR(tg)) 7961 return ERR_PTR(-ENOMEM); 7962 7963 return &tg->css; 7964 } 7965 7966 static int cpu_cgroup_css_online(struct cgroup_subsys_state *css) 7967 { 7968 struct task_group *tg = css_tg(css); 7969 struct task_group *parent = css_tg(css->parent); 7970 7971 if (parent) 7972 sched_online_group(tg, parent); 7973 return 0; 7974 } 7975 7976 static void cpu_cgroup_css_free(struct cgroup_subsys_state *css) 7977 { 7978 struct task_group *tg = css_tg(css); 7979 7980 sched_destroy_group(tg); 7981 } 7982 7983 static void cpu_cgroup_css_offline(struct cgroup_subsys_state *css) 7984 { 7985 struct task_group *tg = css_tg(css); 7986 7987 sched_offline_group(tg); 7988 } 7989 7990 static void cpu_cgroup_fork(struct task_struct *task) 7991 { 7992 sched_move_task(task); 7993 } 7994 7995 static int cpu_cgroup_can_attach(struct cgroup_subsys_state *css, 7996 struct cgroup_taskset *tset) 7997 { 7998 struct task_struct *task; 7999 8000 cgroup_taskset_for_each(task, tset) { 8001 #ifdef CONFIG_RT_GROUP_SCHED 8002 if (!sched_rt_can_attach(css_tg(css), task)) 8003 return -EINVAL; 8004 #else 8005 /* We don't support RT-tasks being in separate groups */ 8006 if (task->sched_class != &fair_sched_class) 8007 return -EINVAL; 8008 #endif 8009 } 8010 return 0; 8011 } 8012 8013 static void cpu_cgroup_attach(struct cgroup_subsys_state *css, 8014 struct cgroup_taskset *tset) 8015 { 8016 struct task_struct *task; 8017 8018 cgroup_taskset_for_each(task, tset) 8019 sched_move_task(task); 8020 } 8021 8022 static void cpu_cgroup_exit(struct cgroup_subsys_state *css, 8023 struct cgroup_subsys_state *old_css, 8024 struct task_struct *task) 8025 { 8026 /* 8027 * cgroup_exit() is called in the copy_process() failure path. 8028 * Ignore this case since the task hasn't ran yet, this avoids 8029 * trying to poke a half freed task state from generic code. 8030 */ 8031 if (!(task->flags & PF_EXITING)) 8032 return; 8033 8034 sched_move_task(task); 8035 } 8036 8037 #ifdef CONFIG_FAIR_GROUP_SCHED 8038 static int cpu_shares_write_u64(struct cgroup_subsys_state *css, 8039 struct cftype *cftype, u64 shareval) 8040 { 8041 return sched_group_set_shares(css_tg(css), scale_load(shareval)); 8042 } 8043 8044 static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css, 8045 struct cftype *cft) 8046 { 8047 struct task_group *tg = css_tg(css); 8048 8049 return (u64) scale_load_down(tg->shares); 8050 } 8051 8052 #ifdef CONFIG_CFS_BANDWIDTH 8053 static DEFINE_MUTEX(cfs_constraints_mutex); 8054 8055 const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */ 8056 const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */ 8057 8058 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime); 8059 8060 static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota) 8061 { 8062 int i, ret = 0, runtime_enabled, runtime_was_enabled; 8063 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 8064 8065 if (tg == &root_task_group) 8066 return -EINVAL; 8067 8068 /* 8069 * Ensure we have at some amount of bandwidth every period. This is 8070 * to prevent reaching a state of large arrears when throttled via 8071 * entity_tick() resulting in prolonged exit starvation. 8072 */ 8073 if (quota < min_cfs_quota_period || period < min_cfs_quota_period) 8074 return -EINVAL; 8075 8076 /* 8077 * Likewise, bound things on the otherside by preventing insane quota 8078 * periods. This also allows us to normalize in computing quota 8079 * feasibility. 8080 */ 8081 if (period > max_cfs_quota_period) 8082 return -EINVAL; 8083 8084 /* 8085 * Prevent race between setting of cfs_rq->runtime_enabled and 8086 * unthrottle_offline_cfs_rqs(). 8087 */ 8088 get_online_cpus(); 8089 mutex_lock(&cfs_constraints_mutex); 8090 ret = __cfs_schedulable(tg, period, quota); 8091 if (ret) 8092 goto out_unlock; 8093 8094 runtime_enabled = quota != RUNTIME_INF; 8095 runtime_was_enabled = cfs_b->quota != RUNTIME_INF; 8096 /* 8097 * If we need to toggle cfs_bandwidth_used, off->on must occur 8098 * before making related changes, and on->off must occur afterwards 8099 */ 8100 if (runtime_enabled && !runtime_was_enabled) 8101 cfs_bandwidth_usage_inc(); 8102 raw_spin_lock_irq(&cfs_b->lock); 8103 cfs_b->period = ns_to_ktime(period); 8104 cfs_b->quota = quota; 8105 8106 __refill_cfs_bandwidth_runtime(cfs_b); 8107 /* restart the period timer (if active) to handle new period expiry */ 8108 if (runtime_enabled && cfs_b->timer_active) { 8109 /* force a reprogram */ 8110 __start_cfs_bandwidth(cfs_b, true); 8111 } 8112 raw_spin_unlock_irq(&cfs_b->lock); 8113 8114 for_each_online_cpu(i) { 8115 struct cfs_rq *cfs_rq = tg->cfs_rq[i]; 8116 struct rq *rq = cfs_rq->rq; 8117 8118 raw_spin_lock_irq(&rq->lock); 8119 cfs_rq->runtime_enabled = runtime_enabled; 8120 cfs_rq->runtime_remaining = 0; 8121 8122 if (cfs_rq->throttled) 8123 unthrottle_cfs_rq(cfs_rq); 8124 raw_spin_unlock_irq(&rq->lock); 8125 } 8126 if (runtime_was_enabled && !runtime_enabled) 8127 cfs_bandwidth_usage_dec(); 8128 out_unlock: 8129 mutex_unlock(&cfs_constraints_mutex); 8130 put_online_cpus(); 8131 8132 return ret; 8133 } 8134 8135 int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us) 8136 { 8137 u64 quota, period; 8138 8139 period = ktime_to_ns(tg->cfs_bandwidth.period); 8140 if (cfs_quota_us < 0) 8141 quota = RUNTIME_INF; 8142 else 8143 quota = (u64)cfs_quota_us * NSEC_PER_USEC; 8144 8145 return tg_set_cfs_bandwidth(tg, period, quota); 8146 } 8147 8148 long tg_get_cfs_quota(struct task_group *tg) 8149 { 8150 u64 quota_us; 8151 8152 if (tg->cfs_bandwidth.quota == RUNTIME_INF) 8153 return -1; 8154 8155 quota_us = tg->cfs_bandwidth.quota; 8156 do_div(quota_us, NSEC_PER_USEC); 8157 8158 return quota_us; 8159 } 8160 8161 int tg_set_cfs_period(struct task_group *tg, long cfs_period_us) 8162 { 8163 u64 quota, period; 8164 8165 period = (u64)cfs_period_us * NSEC_PER_USEC; 8166 quota = tg->cfs_bandwidth.quota; 8167 8168 return tg_set_cfs_bandwidth(tg, period, quota); 8169 } 8170 8171 long tg_get_cfs_period(struct task_group *tg) 8172 { 8173 u64 cfs_period_us; 8174 8175 cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period); 8176 do_div(cfs_period_us, NSEC_PER_USEC); 8177 8178 return cfs_period_us; 8179 } 8180 8181 static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css, 8182 struct cftype *cft) 8183 { 8184 return tg_get_cfs_quota(css_tg(css)); 8185 } 8186 8187 static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css, 8188 struct cftype *cftype, s64 cfs_quota_us) 8189 { 8190 return tg_set_cfs_quota(css_tg(css), cfs_quota_us); 8191 } 8192 8193 static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css, 8194 struct cftype *cft) 8195 { 8196 return tg_get_cfs_period(css_tg(css)); 8197 } 8198 8199 static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css, 8200 struct cftype *cftype, u64 cfs_period_us) 8201 { 8202 return tg_set_cfs_period(css_tg(css), cfs_period_us); 8203 } 8204 8205 struct cfs_schedulable_data { 8206 struct task_group *tg; 8207 u64 period, quota; 8208 }; 8209 8210 /* 8211 * normalize group quota/period to be quota/max_period 8212 * note: units are usecs 8213 */ 8214 static u64 normalize_cfs_quota(struct task_group *tg, 8215 struct cfs_schedulable_data *d) 8216 { 8217 u64 quota, period; 8218 8219 if (tg == d->tg) { 8220 period = d->period; 8221 quota = d->quota; 8222 } else { 8223 period = tg_get_cfs_period(tg); 8224 quota = tg_get_cfs_quota(tg); 8225 } 8226 8227 /* note: these should typically be equivalent */ 8228 if (quota == RUNTIME_INF || quota == -1) 8229 return RUNTIME_INF; 8230 8231 return to_ratio(period, quota); 8232 } 8233 8234 static int tg_cfs_schedulable_down(struct task_group *tg, void *data) 8235 { 8236 struct cfs_schedulable_data *d = data; 8237 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 8238 s64 quota = 0, parent_quota = -1; 8239 8240 if (!tg->parent) { 8241 quota = RUNTIME_INF; 8242 } else { 8243 struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth; 8244 8245 quota = normalize_cfs_quota(tg, d); 8246 parent_quota = parent_b->hierarchical_quota; 8247 8248 /* 8249 * ensure max(child_quota) <= parent_quota, inherit when no 8250 * limit is set 8251 */ 8252 if (quota == RUNTIME_INF) 8253 quota = parent_quota; 8254 else if (parent_quota != RUNTIME_INF && quota > parent_quota) 8255 return -EINVAL; 8256 } 8257 cfs_b->hierarchical_quota = quota; 8258 8259 return 0; 8260 } 8261 8262 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota) 8263 { 8264 int ret; 8265 struct cfs_schedulable_data data = { 8266 .tg = tg, 8267 .period = period, 8268 .quota = quota, 8269 }; 8270 8271 if (quota != RUNTIME_INF) { 8272 do_div(data.period, NSEC_PER_USEC); 8273 do_div(data.quota, NSEC_PER_USEC); 8274 } 8275 8276 rcu_read_lock(); 8277 ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data); 8278 rcu_read_unlock(); 8279 8280 return ret; 8281 } 8282 8283 static int cpu_stats_show(struct seq_file *sf, void *v) 8284 { 8285 struct task_group *tg = css_tg(seq_css(sf)); 8286 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 8287 8288 seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods); 8289 seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled); 8290 seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time); 8291 8292 return 0; 8293 } 8294 #endif /* CONFIG_CFS_BANDWIDTH */ 8295 #endif /* CONFIG_FAIR_GROUP_SCHED */ 8296 8297 #ifdef CONFIG_RT_GROUP_SCHED 8298 static int cpu_rt_runtime_write(struct cgroup_subsys_state *css, 8299 struct cftype *cft, s64 val) 8300 { 8301 return sched_group_set_rt_runtime(css_tg(css), val); 8302 } 8303 8304 static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css, 8305 struct cftype *cft) 8306 { 8307 return sched_group_rt_runtime(css_tg(css)); 8308 } 8309 8310 static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css, 8311 struct cftype *cftype, u64 rt_period_us) 8312 { 8313 return sched_group_set_rt_period(css_tg(css), rt_period_us); 8314 } 8315 8316 static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css, 8317 struct cftype *cft) 8318 { 8319 return sched_group_rt_period(css_tg(css)); 8320 } 8321 #endif /* CONFIG_RT_GROUP_SCHED */ 8322 8323 static struct cftype cpu_files[] = { 8324 #ifdef CONFIG_FAIR_GROUP_SCHED 8325 { 8326 .name = "shares", 8327 .read_u64 = cpu_shares_read_u64, 8328 .write_u64 = cpu_shares_write_u64, 8329 }, 8330 #endif 8331 #ifdef CONFIG_CFS_BANDWIDTH 8332 { 8333 .name = "cfs_quota_us", 8334 .read_s64 = cpu_cfs_quota_read_s64, 8335 .write_s64 = cpu_cfs_quota_write_s64, 8336 }, 8337 { 8338 .name = "cfs_period_us", 8339 .read_u64 = cpu_cfs_period_read_u64, 8340 .write_u64 = cpu_cfs_period_write_u64, 8341 }, 8342 { 8343 .name = "stat", 8344 .seq_show = cpu_stats_show, 8345 }, 8346 #endif 8347 #ifdef CONFIG_RT_GROUP_SCHED 8348 { 8349 .name = "rt_runtime_us", 8350 .read_s64 = cpu_rt_runtime_read, 8351 .write_s64 = cpu_rt_runtime_write, 8352 }, 8353 { 8354 .name = "rt_period_us", 8355 .read_u64 = cpu_rt_period_read_uint, 8356 .write_u64 = cpu_rt_period_write_uint, 8357 }, 8358 #endif 8359 { } /* terminate */ 8360 }; 8361 8362 struct cgroup_subsys cpu_cgrp_subsys = { 8363 .css_alloc = cpu_cgroup_css_alloc, 8364 .css_free = cpu_cgroup_css_free, 8365 .css_online = cpu_cgroup_css_online, 8366 .css_offline = cpu_cgroup_css_offline, 8367 .fork = cpu_cgroup_fork, 8368 .can_attach = cpu_cgroup_can_attach, 8369 .attach = cpu_cgroup_attach, 8370 .exit = cpu_cgroup_exit, 8371 .legacy_cftypes = cpu_files, 8372 .early_init = 1, 8373 }; 8374 8375 #endif /* CONFIG_CGROUP_SCHED */ 8376 8377 void dump_cpu_task(int cpu) 8378 { 8379 pr_info("Task dump for CPU %d:\n", cpu); 8380 sched_show_task(cpu_curr(cpu)); 8381 } 8382