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