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1// SPDX-License-Identifier: GPL-2.0-only
2#include "cgroup-internal.h"
3
4#include <linux/sched/cputime.h>
5
6#include <linux/bpf.h>
7#include <linux/btf.h>
8#include <linux/btf_ids.h>
9
10#include <trace/events/cgroup.h>
11
12static DEFINE_SPINLOCK(cgroup_rstat_lock);
13static DEFINE_PER_CPU(raw_spinlock_t, cgroup_rstat_cpu_lock);
14
15static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu);
16
17static struct cgroup_rstat_cpu *cgroup_rstat_cpu(struct cgroup *cgrp, int cpu)
18{
19 return per_cpu_ptr(cgrp->rstat_cpu, cpu);
20}
21
22/*
23 * Helper functions for rstat per CPU lock (cgroup_rstat_cpu_lock).
24 *
25 * This makes it easier to diagnose locking issues and contention in
26 * production environments. The parameter @fast_path determine the
27 * tracepoints being added, allowing us to diagnose "flush" related
28 * operations without handling high-frequency fast-path "update" events.
29 */
30static __always_inline
31unsigned long _cgroup_rstat_cpu_lock(raw_spinlock_t *cpu_lock, int cpu,
32 struct cgroup *cgrp, const bool fast_path)
33{
34 unsigned long flags;
35 bool contended;
36
37 /*
38 * The _irqsave() is needed because cgroup_rstat_lock is
39 * spinlock_t which is a sleeping lock on PREEMPT_RT. Acquiring
40 * this lock with the _irq() suffix only disables interrupts on
41 * a non-PREEMPT_RT kernel. The raw_spinlock_t below disables
42 * interrupts on both configurations. The _irqsave() ensures
43 * that interrupts are always disabled and later restored.
44 */
45 contended = !raw_spin_trylock_irqsave(cpu_lock, flags);
46 if (contended) {
47 if (fast_path)
48 trace_cgroup_rstat_cpu_lock_contended_fastpath(cgrp, cpu, contended);
49 else
50 trace_cgroup_rstat_cpu_lock_contended(cgrp, cpu, contended);
51
52 raw_spin_lock_irqsave(cpu_lock, flags);
53 }
54
55 if (fast_path)
56 trace_cgroup_rstat_cpu_locked_fastpath(cgrp, cpu, contended);
57 else
58 trace_cgroup_rstat_cpu_locked(cgrp, cpu, contended);
59
60 return flags;
61}
62
63static __always_inline
64void _cgroup_rstat_cpu_unlock(raw_spinlock_t *cpu_lock, int cpu,
65 struct cgroup *cgrp, unsigned long flags,
66 const bool fast_path)
67{
68 if (fast_path)
69 trace_cgroup_rstat_cpu_unlock_fastpath(cgrp, cpu, false);
70 else
71 trace_cgroup_rstat_cpu_unlock(cgrp, cpu, false);
72
73 raw_spin_unlock_irqrestore(cpu_lock, flags);
74}
75
76/**
77 * cgroup_rstat_updated - keep track of updated rstat_cpu
78 * @cgrp: target cgroup
79 * @cpu: cpu on which rstat_cpu was updated
80 *
81 * @cgrp's rstat_cpu on @cpu was updated. Put it on the parent's matching
82 * rstat_cpu->updated_children list. See the comment on top of
83 * cgroup_rstat_cpu definition for details.
84 */
85__bpf_kfunc void cgroup_rstat_updated(struct cgroup *cgrp, int cpu)
86{
87 raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu);
88 unsigned long flags;
89
90 /*
91 * Speculative already-on-list test. This may race leading to
92 * temporary inaccuracies, which is fine.
93 *
94 * Because @parent's updated_children is terminated with @parent
95 * instead of NULL, we can tell whether @cgrp is on the list by
96 * testing the next pointer for NULL.
97 */
98 if (data_race(cgroup_rstat_cpu(cgrp, cpu)->updated_next))
99 return;
100
101 flags = _cgroup_rstat_cpu_lock(cpu_lock, cpu, cgrp, true);
102
103 /* put @cgrp and all ancestors on the corresponding updated lists */
104 while (true) {
105 struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
106 struct cgroup *parent = cgroup_parent(cgrp);
107 struct cgroup_rstat_cpu *prstatc;
108
109 /*
110 * Both additions and removals are bottom-up. If a cgroup
111 * is already in the tree, all ancestors are.
112 */
113 if (rstatc->updated_next)
114 break;
115
116 /* Root has no parent to link it to, but mark it busy */
117 if (!parent) {
118 rstatc->updated_next = cgrp;
119 break;
120 }
121
122 prstatc = cgroup_rstat_cpu(parent, cpu);
123 rstatc->updated_next = prstatc->updated_children;
124 prstatc->updated_children = cgrp;
125
126 cgrp = parent;
127 }
128
129 _cgroup_rstat_cpu_unlock(cpu_lock, cpu, cgrp, flags, true);
130}
131
132/**
133 * cgroup_rstat_push_children - push children cgroups into the given list
134 * @head: current head of the list (= subtree root)
135 * @child: first child of the root
136 * @cpu: target cpu
137 * Return: A new singly linked list of cgroups to be flush
138 *
139 * Iteratively traverse down the cgroup_rstat_cpu updated tree level by
140 * level and push all the parents first before their next level children
141 * into a singly linked list built from the tail backward like "pushing"
142 * cgroups into a stack. The root is pushed by the caller.
143 */
144static struct cgroup *cgroup_rstat_push_children(struct cgroup *head,
145 struct cgroup *child, int cpu)
146{
147 struct cgroup *chead = child; /* Head of child cgroup level */
148 struct cgroup *ghead = NULL; /* Head of grandchild cgroup level */
149 struct cgroup *parent, *grandchild;
150 struct cgroup_rstat_cpu *crstatc;
151
152 child->rstat_flush_next = NULL;
153
154next_level:
155 while (chead) {
156 child = chead;
157 chead = child->rstat_flush_next;
158 parent = cgroup_parent(child);
159
160 /* updated_next is parent cgroup terminated */
161 while (child != parent) {
162 child->rstat_flush_next = head;
163 head = child;
164 crstatc = cgroup_rstat_cpu(child, cpu);
165 grandchild = crstatc->updated_children;
166 if (grandchild != child) {
167 /* Push the grand child to the next level */
168 crstatc->updated_children = child;
169 grandchild->rstat_flush_next = ghead;
170 ghead = grandchild;
171 }
172 child = crstatc->updated_next;
173 crstatc->updated_next = NULL;
174 }
175 }
176
177 if (ghead) {
178 chead = ghead;
179 ghead = NULL;
180 goto next_level;
181 }
182 return head;
183}
184
185/**
186 * cgroup_rstat_updated_list - return a list of updated cgroups to be flushed
187 * @root: root of the cgroup subtree to traverse
188 * @cpu: target cpu
189 * Return: A singly linked list of cgroups to be flushed
190 *
191 * Walks the updated rstat_cpu tree on @cpu from @root. During traversal,
192 * each returned cgroup is unlinked from the updated tree.
193 *
194 * The only ordering guarantee is that, for a parent and a child pair
195 * covered by a given traversal, the child is before its parent in
196 * the list.
197 *
198 * Note that updated_children is self terminated and points to a list of
199 * child cgroups if not empty. Whereas updated_next is like a sibling link
200 * within the children list and terminated by the parent cgroup. An exception
201 * here is the cgroup root whose updated_next can be self terminated.
202 */
203static struct cgroup *cgroup_rstat_updated_list(struct cgroup *root, int cpu)
204{
205 raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu);
206 struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(root, cpu);
207 struct cgroup *head = NULL, *parent, *child;
208 unsigned long flags;
209
210 flags = _cgroup_rstat_cpu_lock(cpu_lock, cpu, root, false);
211
212 /* Return NULL if this subtree is not on-list */
213 if (!rstatc->updated_next)
214 goto unlock_ret;
215
216 /*
217 * Unlink @root from its parent. As the updated_children list is
218 * singly linked, we have to walk it to find the removal point.
219 */
220 parent = cgroup_parent(root);
221 if (parent) {
222 struct cgroup_rstat_cpu *prstatc;
223 struct cgroup **nextp;
224
225 prstatc = cgroup_rstat_cpu(parent, cpu);
226 nextp = &prstatc->updated_children;
227 while (*nextp != root) {
228 struct cgroup_rstat_cpu *nrstatc;
229
230 nrstatc = cgroup_rstat_cpu(*nextp, cpu);
231 WARN_ON_ONCE(*nextp == parent);
232 nextp = &nrstatc->updated_next;
233 }
234 *nextp = rstatc->updated_next;
235 }
236
237 rstatc->updated_next = NULL;
238
239 /* Push @root to the list first before pushing the children */
240 head = root;
241 root->rstat_flush_next = NULL;
242 child = rstatc->updated_children;
243 rstatc->updated_children = root;
244 if (child != root)
245 head = cgroup_rstat_push_children(head, child, cpu);
246unlock_ret:
247 _cgroup_rstat_cpu_unlock(cpu_lock, cpu, root, flags, false);
248 return head;
249}
250
251/*
252 * A hook for bpf stat collectors to attach to and flush their stats.
253 * Together with providing bpf kfuncs for cgroup_rstat_updated() and
254 * cgroup_rstat_flush(), this enables a complete workflow where bpf progs that
255 * collect cgroup stats can integrate with rstat for efficient flushing.
256 *
257 * A static noinline declaration here could cause the compiler to optimize away
258 * the function. A global noinline declaration will keep the definition, but may
259 * optimize away the callsite. Therefore, __weak is needed to ensure that the
260 * call is still emitted, by telling the compiler that we don't know what the
261 * function might eventually be.
262 */
263
264__bpf_hook_start();
265
266__weak noinline void bpf_rstat_flush(struct cgroup *cgrp,
267 struct cgroup *parent, int cpu)
268{
269}
270
271__bpf_hook_end();
272
273/*
274 * Helper functions for locking cgroup_rstat_lock.
275 *
276 * This makes it easier to diagnose locking issues and contention in
277 * production environments. The parameter @cpu_in_loop indicate lock
278 * was released and re-taken when collection data from the CPUs. The
279 * value -1 is used when obtaining the main lock else this is the CPU
280 * number processed last.
281 */
282static inline void __cgroup_rstat_lock(struct cgroup *cgrp, int cpu_in_loop)
283 __acquires(&cgroup_rstat_lock)
284{
285 bool contended;
286
287 contended = !spin_trylock_irq(&cgroup_rstat_lock);
288 if (contended) {
289 trace_cgroup_rstat_lock_contended(cgrp, cpu_in_loop, contended);
290 spin_lock_irq(&cgroup_rstat_lock);
291 }
292 trace_cgroup_rstat_locked(cgrp, cpu_in_loop, contended);
293}
294
295static inline void __cgroup_rstat_unlock(struct cgroup *cgrp, int cpu_in_loop)
296 __releases(&cgroup_rstat_lock)
297{
298 trace_cgroup_rstat_unlock(cgrp, cpu_in_loop, false);
299 spin_unlock_irq(&cgroup_rstat_lock);
300}
301
302/* see cgroup_rstat_flush() */
303static void cgroup_rstat_flush_locked(struct cgroup *cgrp)
304 __releases(&cgroup_rstat_lock) __acquires(&cgroup_rstat_lock)
305{
306 int cpu;
307
308 lockdep_assert_held(&cgroup_rstat_lock);
309
310 for_each_possible_cpu(cpu) {
311 struct cgroup *pos = cgroup_rstat_updated_list(cgrp, cpu);
312
313 for (; pos; pos = pos->rstat_flush_next) {
314 struct cgroup_subsys_state *css;
315
316 cgroup_base_stat_flush(pos, cpu);
317 bpf_rstat_flush(pos, cgroup_parent(pos), cpu);
318
319 rcu_read_lock();
320 list_for_each_entry_rcu(css, &pos->rstat_css_list,
321 rstat_css_node)
322 css->ss->css_rstat_flush(css, cpu);
323 rcu_read_unlock();
324 }
325
326 /* play nice and yield if necessary */
327 if (need_resched() || spin_needbreak(&cgroup_rstat_lock)) {
328 __cgroup_rstat_unlock(cgrp, cpu);
329 if (!cond_resched())
330 cpu_relax();
331 __cgroup_rstat_lock(cgrp, cpu);
332 }
333 }
334}
335
336/**
337 * cgroup_rstat_flush - flush stats in @cgrp's subtree
338 * @cgrp: target cgroup
339 *
340 * Collect all per-cpu stats in @cgrp's subtree into the global counters
341 * and propagate them upwards. After this function returns, all cgroups in
342 * the subtree have up-to-date ->stat.
343 *
344 * This also gets all cgroups in the subtree including @cgrp off the
345 * ->updated_children lists.
346 *
347 * This function may block.
348 */
349__bpf_kfunc void cgroup_rstat_flush(struct cgroup *cgrp)
350{
351 might_sleep();
352
353 __cgroup_rstat_lock(cgrp, -1);
354 cgroup_rstat_flush_locked(cgrp);
355 __cgroup_rstat_unlock(cgrp, -1);
356}
357
358/**
359 * cgroup_rstat_flush_hold - flush stats in @cgrp's subtree and hold
360 * @cgrp: target cgroup
361 *
362 * Flush stats in @cgrp's subtree and prevent further flushes. Must be
363 * paired with cgroup_rstat_flush_release().
364 *
365 * This function may block.
366 */
367void cgroup_rstat_flush_hold(struct cgroup *cgrp)
368 __acquires(&cgroup_rstat_lock)
369{
370 might_sleep();
371 __cgroup_rstat_lock(cgrp, -1);
372 cgroup_rstat_flush_locked(cgrp);
373}
374
375/**
376 * cgroup_rstat_flush_release - release cgroup_rstat_flush_hold()
377 * @cgrp: cgroup used by tracepoint
378 */
379void cgroup_rstat_flush_release(struct cgroup *cgrp)
380 __releases(&cgroup_rstat_lock)
381{
382 __cgroup_rstat_unlock(cgrp, -1);
383}
384
385int cgroup_rstat_init(struct cgroup *cgrp)
386{
387 int cpu;
388
389 /* the root cgrp has rstat_cpu preallocated */
390 if (!cgrp->rstat_cpu) {
391 cgrp->rstat_cpu = alloc_percpu(struct cgroup_rstat_cpu);
392 if (!cgrp->rstat_cpu)
393 return -ENOMEM;
394 }
395
396 /* ->updated_children list is self terminated */
397 for_each_possible_cpu(cpu) {
398 struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
399
400 rstatc->updated_children = cgrp;
401 u64_stats_init(&rstatc->bsync);
402 }
403
404 return 0;
405}
406
407void cgroup_rstat_exit(struct cgroup *cgrp)
408{
409 int cpu;
410
411 cgroup_rstat_flush(cgrp);
412
413 /* sanity check */
414 for_each_possible_cpu(cpu) {
415 struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
416
417 if (WARN_ON_ONCE(rstatc->updated_children != cgrp) ||
418 WARN_ON_ONCE(rstatc->updated_next))
419 return;
420 }
421
422 free_percpu(cgrp->rstat_cpu);
423 cgrp->rstat_cpu = NULL;
424}
425
426void __init cgroup_rstat_boot(void)
427{
428 int cpu;
429
430 for_each_possible_cpu(cpu)
431 raw_spin_lock_init(per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu));
432}
433
434/*
435 * Functions for cgroup basic resource statistics implemented on top of
436 * rstat.
437 */
438static void cgroup_base_stat_add(struct cgroup_base_stat *dst_bstat,
439 struct cgroup_base_stat *src_bstat)
440{
441 dst_bstat->cputime.utime += src_bstat->cputime.utime;
442 dst_bstat->cputime.stime += src_bstat->cputime.stime;
443 dst_bstat->cputime.sum_exec_runtime += src_bstat->cputime.sum_exec_runtime;
444#ifdef CONFIG_SCHED_CORE
445 dst_bstat->forceidle_sum += src_bstat->forceidle_sum;
446#endif
447 dst_bstat->ntime += src_bstat->ntime;
448}
449
450static void cgroup_base_stat_sub(struct cgroup_base_stat *dst_bstat,
451 struct cgroup_base_stat *src_bstat)
452{
453 dst_bstat->cputime.utime -= src_bstat->cputime.utime;
454 dst_bstat->cputime.stime -= src_bstat->cputime.stime;
455 dst_bstat->cputime.sum_exec_runtime -= src_bstat->cputime.sum_exec_runtime;
456#ifdef CONFIG_SCHED_CORE
457 dst_bstat->forceidle_sum -= src_bstat->forceidle_sum;
458#endif
459 dst_bstat->ntime -= src_bstat->ntime;
460}
461
462static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu)
463{
464 struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
465 struct cgroup *parent = cgroup_parent(cgrp);
466 struct cgroup_rstat_cpu *prstatc;
467 struct cgroup_base_stat delta;
468 unsigned seq;
469
470 /* Root-level stats are sourced from system-wide CPU stats */
471 if (!parent)
472 return;
473
474 /* fetch the current per-cpu values */
475 do {
476 seq = __u64_stats_fetch_begin(&rstatc->bsync);
477 delta = rstatc->bstat;
478 } while (__u64_stats_fetch_retry(&rstatc->bsync, seq));
479
480 /* propagate per-cpu delta to cgroup and per-cpu global statistics */
481 cgroup_base_stat_sub(&delta, &rstatc->last_bstat);
482 cgroup_base_stat_add(&cgrp->bstat, &delta);
483 cgroup_base_stat_add(&rstatc->last_bstat, &delta);
484 cgroup_base_stat_add(&rstatc->subtree_bstat, &delta);
485
486 /* propagate cgroup and per-cpu global delta to parent (unless that's root) */
487 if (cgroup_parent(parent)) {
488 delta = cgrp->bstat;
489 cgroup_base_stat_sub(&delta, &cgrp->last_bstat);
490 cgroup_base_stat_add(&parent->bstat, &delta);
491 cgroup_base_stat_add(&cgrp->last_bstat, &delta);
492
493 delta = rstatc->subtree_bstat;
494 prstatc = cgroup_rstat_cpu(parent, cpu);
495 cgroup_base_stat_sub(&delta, &rstatc->last_subtree_bstat);
496 cgroup_base_stat_add(&prstatc->subtree_bstat, &delta);
497 cgroup_base_stat_add(&rstatc->last_subtree_bstat, &delta);
498 }
499}
500
501static struct cgroup_rstat_cpu *
502cgroup_base_stat_cputime_account_begin(struct cgroup *cgrp, unsigned long *flags)
503{
504 struct cgroup_rstat_cpu *rstatc;
505
506 rstatc = get_cpu_ptr(cgrp->rstat_cpu);
507 *flags = u64_stats_update_begin_irqsave(&rstatc->bsync);
508 return rstatc;
509}
510
511static void cgroup_base_stat_cputime_account_end(struct cgroup *cgrp,
512 struct cgroup_rstat_cpu *rstatc,
513 unsigned long flags)
514{
515 u64_stats_update_end_irqrestore(&rstatc->bsync, flags);
516 cgroup_rstat_updated(cgrp, smp_processor_id());
517 put_cpu_ptr(rstatc);
518}
519
520void __cgroup_account_cputime(struct cgroup *cgrp, u64 delta_exec)
521{
522 struct cgroup_rstat_cpu *rstatc;
523 unsigned long flags;
524
525 rstatc = cgroup_base_stat_cputime_account_begin(cgrp, &flags);
526 rstatc->bstat.cputime.sum_exec_runtime += delta_exec;
527 cgroup_base_stat_cputime_account_end(cgrp, rstatc, flags);
528}
529
530void __cgroup_account_cputime_field(struct cgroup *cgrp,
531 enum cpu_usage_stat index, u64 delta_exec)
532{
533 struct cgroup_rstat_cpu *rstatc;
534 unsigned long flags;
535
536 rstatc = cgroup_base_stat_cputime_account_begin(cgrp, &flags);
537
538 switch (index) {
539 case CPUTIME_NICE:
540 rstatc->bstat.ntime += delta_exec;
541 fallthrough;
542 case CPUTIME_USER:
543 rstatc->bstat.cputime.utime += delta_exec;
544 break;
545 case CPUTIME_SYSTEM:
546 case CPUTIME_IRQ:
547 case CPUTIME_SOFTIRQ:
548 rstatc->bstat.cputime.stime += delta_exec;
549 break;
550#ifdef CONFIG_SCHED_CORE
551 case CPUTIME_FORCEIDLE:
552 rstatc->bstat.forceidle_sum += delta_exec;
553 break;
554#endif
555 default:
556 break;
557 }
558
559 cgroup_base_stat_cputime_account_end(cgrp, rstatc, flags);
560}
561
562/*
563 * compute the cputime for the root cgroup by getting the per cpu data
564 * at a global level, then categorizing the fields in a manner consistent
565 * with how it is done by __cgroup_account_cputime_field for each bit of
566 * cpu time attributed to a cgroup.
567 */
568static void root_cgroup_cputime(struct cgroup_base_stat *bstat)
569{
570 struct task_cputime *cputime = &bstat->cputime;
571 int i;
572
573 memset(bstat, 0, sizeof(*bstat));
574 for_each_possible_cpu(i) {
575 struct kernel_cpustat kcpustat;
576 u64 *cpustat = kcpustat.cpustat;
577 u64 user = 0;
578 u64 sys = 0;
579
580 kcpustat_cpu_fetch(&kcpustat, i);
581
582 user += cpustat[CPUTIME_USER];
583 user += cpustat[CPUTIME_NICE];
584 cputime->utime += user;
585
586 sys += cpustat[CPUTIME_SYSTEM];
587 sys += cpustat[CPUTIME_IRQ];
588 sys += cpustat[CPUTIME_SOFTIRQ];
589 cputime->stime += sys;
590
591 cputime->sum_exec_runtime += user;
592 cputime->sum_exec_runtime += sys;
593
594#ifdef CONFIG_SCHED_CORE
595 bstat->forceidle_sum += cpustat[CPUTIME_FORCEIDLE];
596#endif
597 bstat->ntime += cpustat[CPUTIME_NICE];
598 }
599}
600
601
602static void cgroup_force_idle_show(struct seq_file *seq, struct cgroup_base_stat *bstat)
603{
604#ifdef CONFIG_SCHED_CORE
605 u64 forceidle_time = bstat->forceidle_sum;
606
607 do_div(forceidle_time, NSEC_PER_USEC);
608 seq_printf(seq, "core_sched.force_idle_usec %llu\n", forceidle_time);
609#endif
610}
611
612void cgroup_base_stat_cputime_show(struct seq_file *seq)
613{
614 struct cgroup *cgrp = seq_css(seq)->cgroup;
615 u64 usage, utime, stime, ntime;
616
617 if (cgroup_parent(cgrp)) {
618 cgroup_rstat_flush_hold(cgrp);
619 usage = cgrp->bstat.cputime.sum_exec_runtime;
620 cputime_adjust(&cgrp->bstat.cputime, &cgrp->prev_cputime,
621 &utime, &stime);
622 ntime = cgrp->bstat.ntime;
623 cgroup_rstat_flush_release(cgrp);
624 } else {
625 /* cgrp->bstat of root is not actually used, reuse it */
626 root_cgroup_cputime(&cgrp->bstat);
627 usage = cgrp->bstat.cputime.sum_exec_runtime;
628 utime = cgrp->bstat.cputime.utime;
629 stime = cgrp->bstat.cputime.stime;
630 ntime = cgrp->bstat.ntime;
631 }
632
633 do_div(usage, NSEC_PER_USEC);
634 do_div(utime, NSEC_PER_USEC);
635 do_div(stime, NSEC_PER_USEC);
636 do_div(ntime, NSEC_PER_USEC);
637
638 seq_printf(seq, "usage_usec %llu\n"
639 "user_usec %llu\n"
640 "system_usec %llu\n"
641 "nice_usec %llu\n",
642 usage, utime, stime, ntime);
643
644 cgroup_force_idle_show(seq, &cgrp->bstat);
645}
646
647/* Add bpf kfuncs for cgroup_rstat_updated() and cgroup_rstat_flush() */
648BTF_KFUNCS_START(bpf_rstat_kfunc_ids)
649BTF_ID_FLAGS(func, cgroup_rstat_updated)
650BTF_ID_FLAGS(func, cgroup_rstat_flush, KF_SLEEPABLE)
651BTF_KFUNCS_END(bpf_rstat_kfunc_ids)
652
653static const struct btf_kfunc_id_set bpf_rstat_kfunc_set = {
654 .owner = THIS_MODULE,
655 .set = &bpf_rstat_kfunc_ids,
656};
657
658static int __init bpf_rstat_kfunc_init(void)
659{
660 return register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING,
661 &bpf_rstat_kfunc_set);
662}
663late_initcall(bpf_rstat_kfunc_init);
1// SPDX-License-Identifier: GPL-2.0-only
2#include "cgroup-internal.h"
3
4#include <linux/sched/cputime.h>
5
6static DEFINE_SPINLOCK(cgroup_rstat_lock);
7static DEFINE_PER_CPU(raw_spinlock_t, cgroup_rstat_cpu_lock);
8
9static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu);
10
11static struct cgroup_rstat_cpu *cgroup_rstat_cpu(struct cgroup *cgrp, int cpu)
12{
13 return per_cpu_ptr(cgrp->rstat_cpu, cpu);
14}
15
16/**
17 * cgroup_rstat_updated - keep track of updated rstat_cpu
18 * @cgrp: target cgroup
19 * @cpu: cpu on which rstat_cpu was updated
20 *
21 * @cgrp's rstat_cpu on @cpu was updated. Put it on the parent's matching
22 * rstat_cpu->updated_children list. See the comment on top of
23 * cgroup_rstat_cpu definition for details.
24 */
25void cgroup_rstat_updated(struct cgroup *cgrp, int cpu)
26{
27 raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu);
28 struct cgroup *parent;
29 unsigned long flags;
30
31 /* nothing to do for root */
32 if (!cgroup_parent(cgrp))
33 return;
34
35 /*
36 * Speculative already-on-list test. This may race leading to
37 * temporary inaccuracies, which is fine.
38 *
39 * Because @parent's updated_children is terminated with @parent
40 * instead of NULL, we can tell whether @cgrp is on the list by
41 * testing the next pointer for NULL.
42 */
43 if (cgroup_rstat_cpu(cgrp, cpu)->updated_next)
44 return;
45
46 raw_spin_lock_irqsave(cpu_lock, flags);
47
48 /* put @cgrp and all ancestors on the corresponding updated lists */
49 for (parent = cgroup_parent(cgrp); parent;
50 cgrp = parent, parent = cgroup_parent(cgrp)) {
51 struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
52 struct cgroup_rstat_cpu *prstatc = cgroup_rstat_cpu(parent, cpu);
53
54 /*
55 * Both additions and removals are bottom-up. If a cgroup
56 * is already in the tree, all ancestors are.
57 */
58 if (rstatc->updated_next)
59 break;
60
61 rstatc->updated_next = prstatc->updated_children;
62 prstatc->updated_children = cgrp;
63 }
64
65 raw_spin_unlock_irqrestore(cpu_lock, flags);
66}
67
68/**
69 * cgroup_rstat_cpu_pop_updated - iterate and dismantle rstat_cpu updated tree
70 * @pos: current position
71 * @root: root of the tree to traversal
72 * @cpu: target cpu
73 *
74 * Walks the udpated rstat_cpu tree on @cpu from @root. %NULL @pos starts
75 * the traversal and %NULL return indicates the end. During traversal,
76 * each returned cgroup is unlinked from the tree. Must be called with the
77 * matching cgroup_rstat_cpu_lock held.
78 *
79 * The only ordering guarantee is that, for a parent and a child pair
80 * covered by a given traversal, if a child is visited, its parent is
81 * guaranteed to be visited afterwards.
82 */
83static struct cgroup *cgroup_rstat_cpu_pop_updated(struct cgroup *pos,
84 struct cgroup *root, int cpu)
85{
86 struct cgroup_rstat_cpu *rstatc;
87
88 if (pos == root)
89 return NULL;
90
91 /*
92 * We're gonna walk down to the first leaf and visit/remove it. We
93 * can pick whatever unvisited node as the starting point.
94 */
95 if (!pos)
96 pos = root;
97 else
98 pos = cgroup_parent(pos);
99
100 /* walk down to the first leaf */
101 while (true) {
102 rstatc = cgroup_rstat_cpu(pos, cpu);
103 if (rstatc->updated_children == pos)
104 break;
105 pos = rstatc->updated_children;
106 }
107
108 /*
109 * Unlink @pos from the tree. As the updated_children list is
110 * singly linked, we have to walk it to find the removal point.
111 * However, due to the way we traverse, @pos will be the first
112 * child in most cases. The only exception is @root.
113 */
114 if (rstatc->updated_next) {
115 struct cgroup *parent = cgroup_parent(pos);
116 struct cgroup_rstat_cpu *prstatc = cgroup_rstat_cpu(parent, cpu);
117 struct cgroup_rstat_cpu *nrstatc;
118 struct cgroup **nextp;
119
120 nextp = &prstatc->updated_children;
121 while (true) {
122 nrstatc = cgroup_rstat_cpu(*nextp, cpu);
123 if (*nextp == pos)
124 break;
125
126 WARN_ON_ONCE(*nextp == parent);
127 nextp = &nrstatc->updated_next;
128 }
129
130 *nextp = rstatc->updated_next;
131 rstatc->updated_next = NULL;
132
133 return pos;
134 }
135
136 /* only happens for @root */
137 return NULL;
138}
139
140/* see cgroup_rstat_flush() */
141static void cgroup_rstat_flush_locked(struct cgroup *cgrp, bool may_sleep)
142 __releases(&cgroup_rstat_lock) __acquires(&cgroup_rstat_lock)
143{
144 int cpu;
145
146 lockdep_assert_held(&cgroup_rstat_lock);
147
148 for_each_possible_cpu(cpu) {
149 raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock,
150 cpu);
151 struct cgroup *pos = NULL;
152
153 raw_spin_lock(cpu_lock);
154 while ((pos = cgroup_rstat_cpu_pop_updated(pos, cgrp, cpu))) {
155 struct cgroup_subsys_state *css;
156
157 cgroup_base_stat_flush(pos, cpu);
158
159 rcu_read_lock();
160 list_for_each_entry_rcu(css, &pos->rstat_css_list,
161 rstat_css_node)
162 css->ss->css_rstat_flush(css, cpu);
163 rcu_read_unlock();
164 }
165 raw_spin_unlock(cpu_lock);
166
167 /* if @may_sleep, play nice and yield if necessary */
168 if (may_sleep && (need_resched() ||
169 spin_needbreak(&cgroup_rstat_lock))) {
170 spin_unlock_irq(&cgroup_rstat_lock);
171 if (!cond_resched())
172 cpu_relax();
173 spin_lock_irq(&cgroup_rstat_lock);
174 }
175 }
176}
177
178/**
179 * cgroup_rstat_flush - flush stats in @cgrp's subtree
180 * @cgrp: target cgroup
181 *
182 * Collect all per-cpu stats in @cgrp's subtree into the global counters
183 * and propagate them upwards. After this function returns, all cgroups in
184 * the subtree have up-to-date ->stat.
185 *
186 * This also gets all cgroups in the subtree including @cgrp off the
187 * ->updated_children lists.
188 *
189 * This function may block.
190 */
191void cgroup_rstat_flush(struct cgroup *cgrp)
192{
193 might_sleep();
194
195 spin_lock_irq(&cgroup_rstat_lock);
196 cgroup_rstat_flush_locked(cgrp, true);
197 spin_unlock_irq(&cgroup_rstat_lock);
198}
199
200/**
201 * cgroup_rstat_flush_irqsafe - irqsafe version of cgroup_rstat_flush()
202 * @cgrp: target cgroup
203 *
204 * This function can be called from any context.
205 */
206void cgroup_rstat_flush_irqsafe(struct cgroup *cgrp)
207{
208 unsigned long flags;
209
210 spin_lock_irqsave(&cgroup_rstat_lock, flags);
211 cgroup_rstat_flush_locked(cgrp, false);
212 spin_unlock_irqrestore(&cgroup_rstat_lock, flags);
213}
214
215/**
216 * cgroup_rstat_flush_begin - flush stats in @cgrp's subtree and hold
217 * @cgrp: target cgroup
218 *
219 * Flush stats in @cgrp's subtree and prevent further flushes. Must be
220 * paired with cgroup_rstat_flush_release().
221 *
222 * This function may block.
223 */
224void cgroup_rstat_flush_hold(struct cgroup *cgrp)
225 __acquires(&cgroup_rstat_lock)
226{
227 might_sleep();
228 spin_lock_irq(&cgroup_rstat_lock);
229 cgroup_rstat_flush_locked(cgrp, true);
230}
231
232/**
233 * cgroup_rstat_flush_release - release cgroup_rstat_flush_hold()
234 */
235void cgroup_rstat_flush_release(void)
236 __releases(&cgroup_rstat_lock)
237{
238 spin_unlock_irq(&cgroup_rstat_lock);
239}
240
241int cgroup_rstat_init(struct cgroup *cgrp)
242{
243 int cpu;
244
245 /* the root cgrp has rstat_cpu preallocated */
246 if (!cgrp->rstat_cpu) {
247 cgrp->rstat_cpu = alloc_percpu(struct cgroup_rstat_cpu);
248 if (!cgrp->rstat_cpu)
249 return -ENOMEM;
250 }
251
252 /* ->updated_children list is self terminated */
253 for_each_possible_cpu(cpu) {
254 struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
255
256 rstatc->updated_children = cgrp;
257 u64_stats_init(&rstatc->bsync);
258 }
259
260 return 0;
261}
262
263void cgroup_rstat_exit(struct cgroup *cgrp)
264{
265 int cpu;
266
267 cgroup_rstat_flush(cgrp);
268
269 /* sanity check */
270 for_each_possible_cpu(cpu) {
271 struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
272
273 if (WARN_ON_ONCE(rstatc->updated_children != cgrp) ||
274 WARN_ON_ONCE(rstatc->updated_next))
275 return;
276 }
277
278 free_percpu(cgrp->rstat_cpu);
279 cgrp->rstat_cpu = NULL;
280}
281
282void __init cgroup_rstat_boot(void)
283{
284 int cpu;
285
286 for_each_possible_cpu(cpu)
287 raw_spin_lock_init(per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu));
288
289 BUG_ON(cgroup_rstat_init(&cgrp_dfl_root.cgrp));
290}
291
292/*
293 * Functions for cgroup basic resource statistics implemented on top of
294 * rstat.
295 */
296static void cgroup_base_stat_add(struct cgroup_base_stat *dst_bstat,
297 struct cgroup_base_stat *src_bstat)
298{
299 dst_bstat->cputime.utime += src_bstat->cputime.utime;
300 dst_bstat->cputime.stime += src_bstat->cputime.stime;
301 dst_bstat->cputime.sum_exec_runtime += src_bstat->cputime.sum_exec_runtime;
302}
303
304static void cgroup_base_stat_sub(struct cgroup_base_stat *dst_bstat,
305 struct cgroup_base_stat *src_bstat)
306{
307 dst_bstat->cputime.utime -= src_bstat->cputime.utime;
308 dst_bstat->cputime.stime -= src_bstat->cputime.stime;
309 dst_bstat->cputime.sum_exec_runtime -= src_bstat->cputime.sum_exec_runtime;
310}
311
312static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu)
313{
314 struct cgroup *parent = cgroup_parent(cgrp);
315 struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
316 struct cgroup_base_stat cur, delta;
317 unsigned seq;
318
319 /* fetch the current per-cpu values */
320 do {
321 seq = __u64_stats_fetch_begin(&rstatc->bsync);
322 cur.cputime = rstatc->bstat.cputime;
323 } while (__u64_stats_fetch_retry(&rstatc->bsync, seq));
324
325 /* propagate percpu delta to global */
326 delta = cur;
327 cgroup_base_stat_sub(&delta, &rstatc->last_bstat);
328 cgroup_base_stat_add(&cgrp->bstat, &delta);
329 cgroup_base_stat_add(&rstatc->last_bstat, &delta);
330
331 /* propagate global delta to parent */
332 if (parent) {
333 delta = cgrp->bstat;
334 cgroup_base_stat_sub(&delta, &cgrp->last_bstat);
335 cgroup_base_stat_add(&parent->bstat, &delta);
336 cgroup_base_stat_add(&cgrp->last_bstat, &delta);
337 }
338}
339
340static struct cgroup_rstat_cpu *
341cgroup_base_stat_cputime_account_begin(struct cgroup *cgrp)
342{
343 struct cgroup_rstat_cpu *rstatc;
344
345 rstatc = get_cpu_ptr(cgrp->rstat_cpu);
346 u64_stats_update_begin(&rstatc->bsync);
347 return rstatc;
348}
349
350static void cgroup_base_stat_cputime_account_end(struct cgroup *cgrp,
351 struct cgroup_rstat_cpu *rstatc)
352{
353 u64_stats_update_end(&rstatc->bsync);
354 cgroup_rstat_updated(cgrp, smp_processor_id());
355 put_cpu_ptr(rstatc);
356}
357
358void __cgroup_account_cputime(struct cgroup *cgrp, u64 delta_exec)
359{
360 struct cgroup_rstat_cpu *rstatc;
361
362 rstatc = cgroup_base_stat_cputime_account_begin(cgrp);
363 rstatc->bstat.cputime.sum_exec_runtime += delta_exec;
364 cgroup_base_stat_cputime_account_end(cgrp, rstatc);
365}
366
367void __cgroup_account_cputime_field(struct cgroup *cgrp,
368 enum cpu_usage_stat index, u64 delta_exec)
369{
370 struct cgroup_rstat_cpu *rstatc;
371
372 rstatc = cgroup_base_stat_cputime_account_begin(cgrp);
373
374 switch (index) {
375 case CPUTIME_USER:
376 case CPUTIME_NICE:
377 rstatc->bstat.cputime.utime += delta_exec;
378 break;
379 case CPUTIME_SYSTEM:
380 case CPUTIME_IRQ:
381 case CPUTIME_SOFTIRQ:
382 rstatc->bstat.cputime.stime += delta_exec;
383 break;
384 default:
385 break;
386 }
387
388 cgroup_base_stat_cputime_account_end(cgrp, rstatc);
389}
390
391/*
392 * compute the cputime for the root cgroup by getting the per cpu data
393 * at a global level, then categorizing the fields in a manner consistent
394 * with how it is done by __cgroup_account_cputime_field for each bit of
395 * cpu time attributed to a cgroup.
396 */
397static void root_cgroup_cputime(struct task_cputime *cputime)
398{
399 int i;
400
401 cputime->stime = 0;
402 cputime->utime = 0;
403 cputime->sum_exec_runtime = 0;
404 for_each_possible_cpu(i) {
405 struct kernel_cpustat kcpustat;
406 u64 *cpustat = kcpustat.cpustat;
407 u64 user = 0;
408 u64 sys = 0;
409
410 kcpustat_cpu_fetch(&kcpustat, i);
411
412 user += cpustat[CPUTIME_USER];
413 user += cpustat[CPUTIME_NICE];
414 cputime->utime += user;
415
416 sys += cpustat[CPUTIME_SYSTEM];
417 sys += cpustat[CPUTIME_IRQ];
418 sys += cpustat[CPUTIME_SOFTIRQ];
419 cputime->stime += sys;
420
421 cputime->sum_exec_runtime += user;
422 cputime->sum_exec_runtime += sys;
423 cputime->sum_exec_runtime += cpustat[CPUTIME_STEAL];
424 cputime->sum_exec_runtime += cpustat[CPUTIME_GUEST];
425 cputime->sum_exec_runtime += cpustat[CPUTIME_GUEST_NICE];
426 }
427}
428
429void cgroup_base_stat_cputime_show(struct seq_file *seq)
430{
431 struct cgroup *cgrp = seq_css(seq)->cgroup;
432 u64 usage, utime, stime;
433 struct task_cputime cputime;
434
435 if (cgroup_parent(cgrp)) {
436 cgroup_rstat_flush_hold(cgrp);
437 usage = cgrp->bstat.cputime.sum_exec_runtime;
438 cputime_adjust(&cgrp->bstat.cputime, &cgrp->prev_cputime,
439 &utime, &stime);
440 cgroup_rstat_flush_release();
441 } else {
442 root_cgroup_cputime(&cputime);
443 usage = cputime.sum_exec_runtime;
444 utime = cputime.utime;
445 stime = cputime.stime;
446 }
447
448 do_div(usage, NSEC_PER_USEC);
449 do_div(utime, NSEC_PER_USEC);
450 do_div(stime, NSEC_PER_USEC);
451
452 seq_printf(seq, "usage_usec %llu\n"
453 "user_usec %llu\n"
454 "system_usec %llu\n",
455 usage, utime, stime);
456}