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1// SPDX-License-Identifier: GPL-2.0
2#include <subcmd/parse-options.h>
3#include "evsel.h"
4#include "cgroup.h"
5#include "evlist.h"
6#include <linux/zalloc.h>
7#include <sys/types.h>
8#include <sys/stat.h>
9#include <fcntl.h>
10#include <stdlib.h>
11#include <string.h>
12#include <api/fs/fs.h>
13
14int nr_cgroups;
15
16static int open_cgroup(const char *name)
17{
18 char path[PATH_MAX + 1];
19 char mnt[PATH_MAX + 1];
20 int fd;
21
22
23 if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1, "perf_event"))
24 return -1;
25
26 scnprintf(path, PATH_MAX, "%s/%s", mnt, name);
27
28 fd = open(path, O_RDONLY);
29 if (fd == -1)
30 fprintf(stderr, "no access to cgroup %s\n", path);
31
32 return fd;
33}
34
35static struct cgroup *evlist__find_cgroup(struct evlist *evlist, const char *str)
36{
37 struct evsel *counter;
38 /*
39 * check if cgrp is already defined, if so we reuse it
40 */
41 evlist__for_each_entry(evlist, counter) {
42 if (!counter->cgrp)
43 continue;
44 if (!strcmp(counter->cgrp->name, str))
45 return cgroup__get(counter->cgrp);
46 }
47
48 return NULL;
49}
50
51static struct cgroup *cgroup__new(const char *name)
52{
53 struct cgroup *cgroup = zalloc(sizeof(*cgroup));
54
55 if (cgroup != NULL) {
56 refcount_set(&cgroup->refcnt, 1);
57
58 cgroup->name = strdup(name);
59 if (!cgroup->name)
60 goto out_err;
61 cgroup->fd = open_cgroup(name);
62 if (cgroup->fd == -1)
63 goto out_free_name;
64 }
65
66 return cgroup;
67
68out_free_name:
69 zfree(&cgroup->name);
70out_err:
71 free(cgroup);
72 return NULL;
73}
74
75struct cgroup *evlist__findnew_cgroup(struct evlist *evlist, const char *name)
76{
77 struct cgroup *cgroup = evlist__find_cgroup(evlist, name);
78
79 return cgroup ?: cgroup__new(name);
80}
81
82static int add_cgroup(struct evlist *evlist, const char *str)
83{
84 struct evsel *counter;
85 struct cgroup *cgrp = evlist__findnew_cgroup(evlist, str);
86 int n;
87
88 if (!cgrp)
89 return -1;
90 /*
91 * find corresponding event
92 * if add cgroup N, then need to find event N
93 */
94 n = 0;
95 evlist__for_each_entry(evlist, counter) {
96 if (n == nr_cgroups)
97 goto found;
98 n++;
99 }
100
101 cgroup__put(cgrp);
102 return -1;
103found:
104 counter->cgrp = cgrp;
105 return 0;
106}
107
108static void cgroup__delete(struct cgroup *cgroup)
109{
110 if (cgroup->fd >= 0)
111 close(cgroup->fd);
112 zfree(&cgroup->name);
113 free(cgroup);
114}
115
116void cgroup__put(struct cgroup *cgrp)
117{
118 if (cgrp && refcount_dec_and_test(&cgrp->refcnt)) {
119 cgroup__delete(cgrp);
120 }
121}
122
123struct cgroup *cgroup__get(struct cgroup *cgroup)
124{
125 if (cgroup)
126 refcount_inc(&cgroup->refcnt);
127 return cgroup;
128}
129
130static void evsel__set_default_cgroup(struct evsel *evsel, struct cgroup *cgroup)
131{
132 if (evsel->cgrp == NULL)
133 evsel->cgrp = cgroup__get(cgroup);
134}
135
136void evlist__set_default_cgroup(struct evlist *evlist, struct cgroup *cgroup)
137{
138 struct evsel *evsel;
139
140 evlist__for_each_entry(evlist, evsel)
141 evsel__set_default_cgroup(evsel, cgroup);
142}
143
144int parse_cgroups(const struct option *opt, const char *str,
145 int unset __maybe_unused)
146{
147 struct evlist *evlist = *(struct evlist **)opt->value;
148 struct evsel *counter;
149 struct cgroup *cgrp = NULL;
150 const char *p, *e, *eos = str + strlen(str);
151 char *s;
152 int ret, i;
153
154 if (list_empty(&evlist->core.entries)) {
155 fprintf(stderr, "must define events before cgroups\n");
156 return -1;
157 }
158
159 for (;;) {
160 p = strchr(str, ',');
161 e = p ? p : eos;
162
163 /* allow empty cgroups, i.e., skip */
164 if (e - str) {
165 /* termination added */
166 s = strndup(str, e - str);
167 if (!s)
168 return -1;
169 ret = add_cgroup(evlist, s);
170 free(s);
171 if (ret)
172 return -1;
173 }
174 /* nr_cgroups is increased een for empty cgroups */
175 nr_cgroups++;
176 if (!p)
177 break;
178 str = p+1;
179 }
180 /* for the case one cgroup combine to multiple events */
181 i = 0;
182 if (nr_cgroups == 1) {
183 evlist__for_each_entry(evlist, counter) {
184 if (i == 0)
185 cgrp = counter->cgrp;
186 else {
187 counter->cgrp = cgrp;
188 refcount_inc(&cgrp->refcnt);
189 }
190 i++;
191 }
192 }
193 return 0;
194}
195
196static struct cgroup *__cgroup__findnew(struct rb_root *root, uint64_t id,
197 bool create, const char *path)
198{
199 struct rb_node **p = &root->rb_node;
200 struct rb_node *parent = NULL;
201 struct cgroup *cgrp;
202
203 while (*p != NULL) {
204 parent = *p;
205 cgrp = rb_entry(parent, struct cgroup, node);
206
207 if (cgrp->id == id)
208 return cgrp;
209
210 if (cgrp->id < id)
211 p = &(*p)->rb_left;
212 else
213 p = &(*p)->rb_right;
214 }
215
216 if (!create)
217 return NULL;
218
219 cgrp = malloc(sizeof(*cgrp));
220 if (cgrp == NULL)
221 return NULL;
222
223 cgrp->name = strdup(path);
224 if (cgrp->name == NULL) {
225 free(cgrp);
226 return NULL;
227 }
228
229 cgrp->fd = -1;
230 cgrp->id = id;
231 refcount_set(&cgrp->refcnt, 1);
232
233 rb_link_node(&cgrp->node, parent, p);
234 rb_insert_color(&cgrp->node, root);
235
236 return cgrp;
237}
238
239struct cgroup *cgroup__findnew(struct perf_env *env, uint64_t id,
240 const char *path)
241{
242 struct cgroup *cgrp;
243
244 down_write(&env->cgroups.lock);
245 cgrp = __cgroup__findnew(&env->cgroups.tree, id, true, path);
246 up_write(&env->cgroups.lock);
247 return cgrp;
248}
249
250struct cgroup *cgroup__find(struct perf_env *env, uint64_t id)
251{
252 struct cgroup *cgrp;
253
254 down_read(&env->cgroups.lock);
255 cgrp = __cgroup__findnew(&env->cgroups.tree, id, false, NULL);
256 up_read(&env->cgroups.lock);
257 return cgrp;
258}
259
260void perf_env__purge_cgroups(struct perf_env *env)
261{
262 struct rb_node *node;
263 struct cgroup *cgrp;
264
265 down_write(&env->cgroups.lock);
266 while (!RB_EMPTY_ROOT(&env->cgroups.tree)) {
267 node = rb_first(&env->cgroups.tree);
268 cgrp = rb_entry(node, struct cgroup, node);
269
270 rb_erase(node, &env->cgroups.tree);
271 cgroup__put(cgrp);
272 }
273 up_write(&env->cgroups.lock);
274}
1// SPDX-License-Identifier: GPL-2.0
2#include <subcmd/parse-options.h>
3#include "evsel.h"
4#include "cgroup.h"
5#include "evlist.h"
6#include "rblist.h"
7#include "metricgroup.h"
8#include "stat.h"
9#include <linux/zalloc.h>
10#include <sys/types.h>
11#include <sys/stat.h>
12#include <sys/statfs.h>
13#include <fcntl.h>
14#include <stdlib.h>
15#include <string.h>
16#include <api/fs/fs.h>
17#include <ftw.h>
18#include <regex.h>
19
20int nr_cgroups;
21bool cgrp_event_expanded;
22
23/* used to match cgroup name with patterns */
24struct cgroup_name {
25 struct list_head list;
26 bool used;
27 char name[];
28};
29static LIST_HEAD(cgroup_list);
30
31static int open_cgroup(const char *name)
32{
33 char path[PATH_MAX + 1];
34 char mnt[PATH_MAX + 1];
35 int fd;
36
37
38 if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1, "perf_event"))
39 return -1;
40
41 scnprintf(path, PATH_MAX, "%s/%s", mnt, name);
42
43 fd = open(path, O_RDONLY);
44 if (fd == -1)
45 fprintf(stderr, "no access to cgroup %s\n", path);
46
47 return fd;
48}
49
50#ifdef HAVE_FILE_HANDLE
51static u64 __read_cgroup_id(const char *path)
52{
53 struct {
54 struct file_handle fh;
55 uint64_t cgroup_id;
56 } handle;
57 int mount_id;
58
59 handle.fh.handle_bytes = sizeof(handle.cgroup_id);
60 if (name_to_handle_at(AT_FDCWD, path, &handle.fh, &mount_id, 0) < 0)
61 return -1ULL;
62
63 return handle.cgroup_id;
64}
65
66int read_cgroup_id(struct cgroup *cgrp)
67{
68 char path[PATH_MAX + 1];
69 char mnt[PATH_MAX + 1];
70
71 if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1, "perf_event"))
72 return -1;
73
74 scnprintf(path, PATH_MAX, "%s/%s", mnt, cgrp->name);
75
76 cgrp->id = __read_cgroup_id(path);
77 return 0;
78}
79#else
80static inline u64 __read_cgroup_id(const char *path __maybe_unused) { return -1ULL; }
81#endif /* HAVE_FILE_HANDLE */
82
83#ifndef CGROUP2_SUPER_MAGIC
84#define CGROUP2_SUPER_MAGIC 0x63677270
85#endif
86
87int cgroup_is_v2(const char *subsys)
88{
89 char mnt[PATH_MAX + 1];
90 struct statfs stbuf;
91
92 if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1, subsys))
93 return -1;
94
95 if (statfs(mnt, &stbuf) < 0)
96 return -1;
97
98 return (stbuf.f_type == CGROUP2_SUPER_MAGIC);
99}
100
101static struct cgroup *evlist__find_cgroup(struct evlist *evlist, const char *str)
102{
103 struct evsel *counter;
104 /*
105 * check if cgrp is already defined, if so we reuse it
106 */
107 evlist__for_each_entry(evlist, counter) {
108 if (!counter->cgrp)
109 continue;
110 if (!strcmp(counter->cgrp->name, str))
111 return cgroup__get(counter->cgrp);
112 }
113
114 return NULL;
115}
116
117struct cgroup *cgroup__new(const char *name, bool do_open)
118{
119 struct cgroup *cgroup = zalloc(sizeof(*cgroup));
120
121 if (cgroup != NULL) {
122 refcount_set(&cgroup->refcnt, 1);
123
124 cgroup->name = strdup(name);
125 if (!cgroup->name)
126 goto out_err;
127
128 if (do_open) {
129 cgroup->fd = open_cgroup(name);
130 if (cgroup->fd == -1)
131 goto out_free_name;
132 } else {
133 cgroup->fd = -1;
134 }
135 }
136
137 return cgroup;
138
139out_free_name:
140 zfree(&cgroup->name);
141out_err:
142 free(cgroup);
143 return NULL;
144}
145
146struct cgroup *evlist__findnew_cgroup(struct evlist *evlist, const char *name)
147{
148 struct cgroup *cgroup = evlist__find_cgroup(evlist, name);
149
150 return cgroup ?: cgroup__new(name, true);
151}
152
153static int add_cgroup(struct evlist *evlist, const char *str)
154{
155 struct evsel *counter;
156 struct cgroup *cgrp = evlist__findnew_cgroup(evlist, str);
157 int n;
158
159 if (!cgrp)
160 return -1;
161 /*
162 * find corresponding event
163 * if add cgroup N, then need to find event N
164 */
165 n = 0;
166 evlist__for_each_entry(evlist, counter) {
167 if (n == nr_cgroups)
168 goto found;
169 n++;
170 }
171
172 cgroup__put(cgrp);
173 return -1;
174found:
175 counter->cgrp = cgrp;
176 return 0;
177}
178
179static void cgroup__delete(struct cgroup *cgroup)
180{
181 if (cgroup->fd >= 0)
182 close(cgroup->fd);
183 zfree(&cgroup->name);
184 free(cgroup);
185}
186
187void cgroup__put(struct cgroup *cgrp)
188{
189 if (cgrp && refcount_dec_and_test(&cgrp->refcnt)) {
190 cgroup__delete(cgrp);
191 }
192}
193
194struct cgroup *cgroup__get(struct cgroup *cgroup)
195{
196 if (cgroup)
197 refcount_inc(&cgroup->refcnt);
198 return cgroup;
199}
200
201static void evsel__set_default_cgroup(struct evsel *evsel, struct cgroup *cgroup)
202{
203 if (evsel->cgrp == NULL)
204 evsel->cgrp = cgroup__get(cgroup);
205}
206
207void evlist__set_default_cgroup(struct evlist *evlist, struct cgroup *cgroup)
208{
209 struct evsel *evsel;
210
211 evlist__for_each_entry(evlist, evsel)
212 evsel__set_default_cgroup(evsel, cgroup);
213}
214
215/* helper function for ftw() in match_cgroups and list_cgroups */
216static int add_cgroup_name(const char *fpath, const struct stat *sb __maybe_unused,
217 int typeflag, struct FTW *ftwbuf __maybe_unused)
218{
219 struct cgroup_name *cn;
220
221 if (typeflag != FTW_D)
222 return 0;
223
224 cn = malloc(sizeof(*cn) + strlen(fpath) + 1);
225 if (cn == NULL)
226 return -1;
227
228 cn->used = false;
229 strcpy(cn->name, fpath);
230
231 list_add_tail(&cn->list, &cgroup_list);
232 return 0;
233}
234
235static int check_and_add_cgroup_name(const char *fpath)
236{
237 struct cgroup_name *cn;
238
239 list_for_each_entry(cn, &cgroup_list, list) {
240 if (!strcmp(cn->name, fpath))
241 return 0;
242 }
243
244 /* pretend if it's added by ftw() */
245 return add_cgroup_name(fpath, NULL, FTW_D, NULL);
246}
247
248static void release_cgroup_list(void)
249{
250 struct cgroup_name *cn;
251
252 while (!list_empty(&cgroup_list)) {
253 cn = list_first_entry(&cgroup_list, struct cgroup_name, list);
254 list_del(&cn->list);
255 free(cn);
256 }
257}
258
259/* collect given cgroups only */
260static int list_cgroups(const char *str)
261{
262 const char *p, *e, *eos = str + strlen(str);
263 struct cgroup_name *cn;
264 char *s;
265
266 /* use given name as is when no regex is given */
267 for (;;) {
268 p = strchr(str, ',');
269 e = p ? p : eos;
270
271 if (e - str) {
272 int ret;
273
274 s = strndup(str, e - str);
275 if (!s)
276 return -1;
277
278 ret = check_and_add_cgroup_name(s);
279 free(s);
280 if (ret < 0)
281 return -1;
282 } else {
283 if (check_and_add_cgroup_name("/") < 0)
284 return -1;
285 }
286
287 if (!p)
288 break;
289 str = p+1;
290 }
291
292 /* these groups will be used */
293 list_for_each_entry(cn, &cgroup_list, list)
294 cn->used = true;
295
296 return 0;
297}
298
299/* collect all cgroups first and then match with the pattern */
300static int match_cgroups(const char *str)
301{
302 char mnt[PATH_MAX];
303 const char *p, *e, *eos = str + strlen(str);
304 struct cgroup_name *cn;
305 regex_t reg;
306 int prefix_len;
307 char *s;
308
309 if (cgroupfs_find_mountpoint(mnt, sizeof(mnt), "perf_event"))
310 return -1;
311
312 /* cgroup_name will have a full path, skip the root directory */
313 prefix_len = strlen(mnt);
314
315 /* collect all cgroups in the cgroup_list */
316 if (nftw(mnt, add_cgroup_name, 20, 0) < 0)
317 return -1;
318
319 for (;;) {
320 p = strchr(str, ',');
321 e = p ? p : eos;
322
323 /* allow empty cgroups, i.e., skip */
324 if (e - str) {
325 /* termination added */
326 s = strndup(str, e - str);
327 if (!s)
328 return -1;
329 if (regcomp(®, s, REG_NOSUB)) {
330 free(s);
331 return -1;
332 }
333
334 /* check cgroup name with the pattern */
335 list_for_each_entry(cn, &cgroup_list, list) {
336 char *name = cn->name + prefix_len;
337
338 if (name[0] == '/' && name[1])
339 name++;
340 if (!regexec(®, name, 0, NULL, 0))
341 cn->used = true;
342 }
343 regfree(®);
344 free(s);
345 } else {
346 /* first entry to root cgroup */
347 cn = list_first_entry(&cgroup_list, struct cgroup_name,
348 list);
349 cn->used = true;
350 }
351
352 if (!p)
353 break;
354 str = p+1;
355 }
356 return prefix_len;
357}
358
359int parse_cgroups(const struct option *opt, const char *str,
360 int unset __maybe_unused)
361{
362 struct evlist *evlist = *(struct evlist **)opt->value;
363 struct evsel *counter;
364 struct cgroup *cgrp = NULL;
365 const char *p, *e, *eos = str + strlen(str);
366 char *s;
367 int ret, i;
368
369 if (list_empty(&evlist->core.entries)) {
370 fprintf(stderr, "must define events before cgroups\n");
371 return -1;
372 }
373
374 for (;;) {
375 p = strchr(str, ',');
376 e = p ? p : eos;
377
378 /* allow empty cgroups, i.e., skip */
379 if (e - str) {
380 /* termination added */
381 s = strndup(str, e - str);
382 if (!s)
383 return -1;
384 ret = add_cgroup(evlist, s);
385 free(s);
386 if (ret)
387 return -1;
388 }
389 /* nr_cgroups is increased een for empty cgroups */
390 nr_cgroups++;
391 if (!p)
392 break;
393 str = p+1;
394 }
395 /* for the case one cgroup combine to multiple events */
396 i = 0;
397 if (nr_cgroups == 1) {
398 evlist__for_each_entry(evlist, counter) {
399 if (i == 0)
400 cgrp = counter->cgrp;
401 else {
402 counter->cgrp = cgrp;
403 refcount_inc(&cgrp->refcnt);
404 }
405 i++;
406 }
407 }
408 return 0;
409}
410
411static bool has_pattern_string(const char *str)
412{
413 return !!strpbrk(str, "{}[]()|*+?^$");
414}
415
416int evlist__expand_cgroup(struct evlist *evlist, const char *str,
417 struct rblist *metric_events, bool open_cgroup)
418{
419 struct evlist *orig_list, *tmp_list;
420 struct evsel *pos, *evsel, *leader;
421 struct rblist orig_metric_events;
422 struct cgroup *cgrp = NULL;
423 struct cgroup_name *cn;
424 int ret = -1;
425 int prefix_len;
426
427 if (evlist->core.nr_entries == 0) {
428 fprintf(stderr, "must define events before cgroups\n");
429 return -EINVAL;
430 }
431
432 orig_list = evlist__new();
433 tmp_list = evlist__new();
434 if (orig_list == NULL || tmp_list == NULL) {
435 fprintf(stderr, "memory allocation failed\n");
436 return -ENOMEM;
437 }
438
439 /* save original events and init evlist */
440 evlist__splice_list_tail(orig_list, &evlist->core.entries);
441 evlist->core.nr_entries = 0;
442
443 if (metric_events) {
444 orig_metric_events = *metric_events;
445 rblist__init(metric_events);
446 } else {
447 rblist__init(&orig_metric_events);
448 }
449
450 if (has_pattern_string(str))
451 prefix_len = match_cgroups(str);
452 else
453 prefix_len = list_cgroups(str);
454
455 if (prefix_len < 0)
456 goto out_err;
457
458 list_for_each_entry(cn, &cgroup_list, list) {
459 char *name;
460
461 if (!cn->used)
462 continue;
463
464 /* cgroup_name might have a full path, skip the prefix */
465 name = cn->name + prefix_len;
466 if (name[0] == '/' && name[1])
467 name++;
468 cgrp = cgroup__new(name, open_cgroup);
469 if (cgrp == NULL)
470 goto out_err;
471
472 leader = NULL;
473 evlist__for_each_entry(orig_list, pos) {
474 evsel = evsel__clone(pos);
475 if (evsel == NULL)
476 goto out_err;
477
478 cgroup__put(evsel->cgrp);
479 evsel->cgrp = cgroup__get(cgrp);
480
481 if (evsel__is_group_leader(pos))
482 leader = evsel;
483 evsel__set_leader(evsel, leader);
484
485 evlist__add(tmp_list, evsel);
486 }
487 /* cgroup__new() has a refcount, release it here */
488 cgroup__put(cgrp);
489 nr_cgroups++;
490
491 if (metric_events) {
492 if (metricgroup__copy_metric_events(tmp_list, cgrp,
493 metric_events,
494 &orig_metric_events) < 0)
495 goto out_err;
496 }
497
498 evlist__splice_list_tail(evlist, &tmp_list->core.entries);
499 tmp_list->core.nr_entries = 0;
500 }
501
502 if (list_empty(&evlist->core.entries)) {
503 fprintf(stderr, "no cgroup matched: %s\n", str);
504 goto out_err;
505 }
506
507 ret = 0;
508 cgrp_event_expanded = true;
509
510out_err:
511 evlist__delete(orig_list);
512 evlist__delete(tmp_list);
513 rblist__exit(&orig_metric_events);
514 release_cgroup_list();
515
516 return ret;
517}
518
519static struct cgroup *__cgroup__findnew(struct rb_root *root, uint64_t id,
520 bool create, const char *path)
521{
522 struct rb_node **p = &root->rb_node;
523 struct rb_node *parent = NULL;
524 struct cgroup *cgrp;
525
526 while (*p != NULL) {
527 parent = *p;
528 cgrp = rb_entry(parent, struct cgroup, node);
529
530 if (cgrp->id == id)
531 return cgrp;
532
533 if (cgrp->id < id)
534 p = &(*p)->rb_left;
535 else
536 p = &(*p)->rb_right;
537 }
538
539 if (!create)
540 return NULL;
541
542 cgrp = malloc(sizeof(*cgrp));
543 if (cgrp == NULL)
544 return NULL;
545
546 cgrp->name = strdup(path);
547 if (cgrp->name == NULL) {
548 free(cgrp);
549 return NULL;
550 }
551
552 cgrp->fd = -1;
553 cgrp->id = id;
554 refcount_set(&cgrp->refcnt, 1);
555
556 rb_link_node(&cgrp->node, parent, p);
557 rb_insert_color(&cgrp->node, root);
558
559 return cgrp;
560}
561
562struct cgroup *cgroup__findnew(struct perf_env *env, uint64_t id,
563 const char *path)
564{
565 struct cgroup *cgrp;
566
567 down_write(&env->cgroups.lock);
568 cgrp = __cgroup__findnew(&env->cgroups.tree, id, true, path);
569 up_write(&env->cgroups.lock);
570 return cgrp;
571}
572
573struct cgroup *__cgroup__find(struct rb_root *root, uint64_t id)
574{
575 return __cgroup__findnew(root, id, /*create=*/false, /*path=*/NULL);
576}
577
578struct cgroup *cgroup__find(struct perf_env *env, uint64_t id)
579{
580 struct cgroup *cgrp;
581
582 down_read(&env->cgroups.lock);
583 cgrp = __cgroup__findnew(&env->cgroups.tree, id, false, NULL);
584 up_read(&env->cgroups.lock);
585 return cgrp;
586}
587
588void perf_env__purge_cgroups(struct perf_env *env)
589{
590 struct rb_node *node;
591 struct cgroup *cgrp;
592
593 down_write(&env->cgroups.lock);
594 while (!RB_EMPTY_ROOT(&env->cgroups.tree)) {
595 node = rb_first(&env->cgroups.tree);
596 cgrp = rb_entry(node, struct cgroup, node);
597
598 rb_erase(node, &env->cgroups.tree);
599 cgroup__put(cgrp);
600 }
601 up_write(&env->cgroups.lock);
602}
603
604void read_all_cgroups(struct rb_root *root)
605{
606 char mnt[PATH_MAX];
607 struct cgroup_name *cn;
608 int prefix_len;
609
610 if (cgroupfs_find_mountpoint(mnt, sizeof(mnt), "perf_event"))
611 return;
612
613 /* cgroup_name will have a full path, skip the root directory */
614 prefix_len = strlen(mnt);
615
616 /* collect all cgroups in the cgroup_list */
617 if (nftw(mnt, add_cgroup_name, 20, 0) < 0)
618 return;
619
620 list_for_each_entry(cn, &cgroup_list, list) {
621 const char *name;
622 u64 cgrp_id;
623
624 /* cgroup_name might have a full path, skip the prefix */
625 name = cn->name + prefix_len;
626 if (name[0] == '\0')
627 name = "/";
628
629 cgrp_id = __read_cgroup_id(cn->name);
630 __cgroup__findnew(root, cgrp_id, /*create=*/true, name);
631 }
632
633 release_cgroup_list();
634}