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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
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}