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/stringify.h>
 
 
  7#include <linux/zalloc.h>
  8#include <sys/types.h>
  9#include <sys/stat.h>
 
 10#include <fcntl.h>
 11#include <stdlib.h>
 12#include <string.h>
 
 
 
 13
 14int nr_cgroups;
 
 15
 16static int
 17cgroupfs_find_mountpoint(char *buf, size_t maxlen)
 
 
 
 
 
 
 
 18{
 19	FILE *fp;
 20	char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];
 21	char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path;
 22	char *token, *saved_ptr = NULL;
 23
 24	fp = fopen("/proc/mounts", "r");
 25	if (!fp)
 26		return -1;
 27
 28	/*
 29	 * in order to handle split hierarchy, we need to scan /proc/mounts
 30	 * and inspect every cgroupfs mount point to find one that has
 31	 * perf_event subsystem
 32	 */
 33	path_v1[0] = '\0';
 34	path_v2[0] = '\0';
 35
 36	while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %"
 37				__stringify(PATH_MAX)"s %*d %*d\n",
 38				mountpoint, type, tokens) == 3) {
 39
 40		if (!path_v1[0] && !strcmp(type, "cgroup")) {
 41
 42			token = strtok_r(tokens, ",", &saved_ptr);
 43
 44			while (token != NULL) {
 45				if (!strcmp(token, "perf_event")) {
 46					strcpy(path_v1, mountpoint);
 47					break;
 48				}
 49				token = strtok_r(NULL, ",", &saved_ptr);
 50			}
 51		}
 52
 53		if (!path_v2[0] && !strcmp(type, "cgroup2"))
 54			strcpy(path_v2, mountpoint);
 55
 56		if (path_v1[0] && path_v2[0])
 57			break;
 58	}
 59	fclose(fp);
 
 
 
 
 60
 61	if (path_v1[0])
 62		path = path_v1;
 63	else if (path_v2[0])
 64		path = path_v2;
 65	else
 66		return -1;
 67
 68	if (strlen(path) < maxlen) {
 69		strcpy(buf, path);
 70		return 0;
 71	}
 72	return -1;
 73}
 74
 75static int open_cgroup(const char *name)
 76{
 77	char path[PATH_MAX + 1];
 78	char mnt[PATH_MAX + 1];
 79	int fd;
 80
 81
 82	if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1))
 83		return -1;
 84
 85	scnprintf(path, PATH_MAX, "%s/%s", mnt, name);
 86
 87	fd = open(path, O_RDONLY);
 88	if (fd == -1)
 89		fprintf(stderr, "no access to cgroup %s\n", path);
 
 
 
 
 
 
 
 90
 91	return fd;
 
 
 
 
 
 
 
 
 
 
 
 92}
 93
 94static struct cgroup *evlist__find_cgroup(struct evlist *evlist, const char *str)
 95{
 96	struct evsel *counter;
 97	/*
 98	 * check if cgrp is already defined, if so we reuse it
 99	 */
100	evlist__for_each_entry(evlist, counter) {
101		if (!counter->cgrp)
102			continue;
103		if (!strcmp(counter->cgrp->name, str))
104			return cgroup__get(counter->cgrp);
105	}
106
107	return NULL;
108}
109
110static struct cgroup *cgroup__new(const char *name)
111{
112	struct cgroup *cgroup = zalloc(sizeof(*cgroup));
113
114	if (cgroup != NULL) {
115		refcount_set(&cgroup->refcnt, 1);
116
117		cgroup->name = strdup(name);
118		if (!cgroup->name)
119			goto out_err;
120		cgroup->fd = open_cgroup(name);
121		if (cgroup->fd == -1)
122			goto out_free_name;
 
 
 
 
 
123	}
124
125	return cgroup;
126
127out_free_name:
128	zfree(&cgroup->name);
129out_err:
130	free(cgroup);
131	return NULL;
132}
133
134struct cgroup *evlist__findnew_cgroup(struct evlist *evlist, const char *name)
135{
136	struct cgroup *cgroup = evlist__find_cgroup(evlist, name);
137
138	return cgroup ?: cgroup__new(name);
139}
140
141static int add_cgroup(struct evlist *evlist, const char *str)
142{
143	struct evsel *counter;
144	struct cgroup *cgrp = evlist__findnew_cgroup(evlist, str);
145	int n;
146
147	if (!cgrp)
148		return -1;
149	/*
150	 * find corresponding event
151	 * if add cgroup N, then need to find event N
152	 */
153	n = 0;
154	evlist__for_each_entry(evlist, counter) {
155		if (n == nr_cgroups)
156			goto found;
157		n++;
158	}
159
160	cgroup__put(cgrp);
161	return -1;
162found:
163	counter->cgrp = cgrp;
164	return 0;
165}
166
167static void cgroup__delete(struct cgroup *cgroup)
168{
169	close(cgroup->fd);
 
170	zfree(&cgroup->name);
171	free(cgroup);
172}
173
174void cgroup__put(struct cgroup *cgrp)
175{
176	if (cgrp && refcount_dec_and_test(&cgrp->refcnt)) {
177		cgroup__delete(cgrp);
178	}
179}
180
181struct cgroup *cgroup__get(struct cgroup *cgroup)
182{
183       if (cgroup)
184		refcount_inc(&cgroup->refcnt);
185       return cgroup;
186}
187
188static void evsel__set_default_cgroup(struct evsel *evsel, struct cgroup *cgroup)
189{
190	if (evsel->cgrp == NULL)
191		evsel->cgrp = cgroup__get(cgroup);
192}
193
194void evlist__set_default_cgroup(struct evlist *evlist, struct cgroup *cgroup)
195{
196	struct evsel *evsel;
197
198	evlist__for_each_entry(evlist, evsel)
199		evsel__set_default_cgroup(evsel, cgroup);
200}
201
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
202int parse_cgroups(const struct option *opt, const char *str,
203		  int unset __maybe_unused)
204{
205	struct evlist *evlist = *(struct evlist **)opt->value;
206	struct evsel *counter;
207	struct cgroup *cgrp = NULL;
208	const char *p, *e, *eos = str + strlen(str);
209	char *s;
210	int ret, i;
211
212	if (list_empty(&evlist->core.entries)) {
213		fprintf(stderr, "must define events before cgroups\n");
214		return -1;
215	}
216
217	for (;;) {
218		p = strchr(str, ',');
219		e = p ? p : eos;
220
221		/* allow empty cgroups, i.e., skip */
222		if (e - str) {
223			/* termination added */
224			s = strndup(str, e - str);
225			if (!s)
226				return -1;
227			ret = add_cgroup(evlist, s);
228			free(s);
229			if (ret)
230				return -1;
231		}
232		/* nr_cgroups is increased een for empty cgroups */
233		nr_cgroups++;
234		if (!p)
235			break;
236		str = p+1;
237	}
238	/* for the case one cgroup combine to multiple events */
239	i = 0;
240	if (nr_cgroups == 1) {
241		evlist__for_each_entry(evlist, counter) {
242			if (i == 0)
243				cgrp = counter->cgrp;
244			else {
245				counter->cgrp = cgrp;
246				refcount_inc(&cgrp->refcnt);
247			}
248			i++;
249		}
250	}
251	return 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
252}

  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(&reg, 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(&reg, name, 0, NULL, 0))
341					cn->used = true;
342			}
343			regfree(&reg);
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
469		/* the cgroup can go away in the meantime */
470		cgrp = cgroup__new(name, open_cgroup);
471		if (cgrp == NULL)
472			continue;
473
474		leader = NULL;
475		evlist__for_each_entry(orig_list, pos) {
476			evsel = evsel__clone(pos);
477			if (evsel == NULL)
478				goto out_err;
479
480			cgroup__put(evsel->cgrp);
481			evsel->cgrp = cgroup__get(cgrp);
482
483			if (evsel__is_group_leader(pos))
484				leader = evsel;
485			evsel__set_leader(evsel, leader);
486
487			evlist__add(tmp_list, evsel);
488		}
489		/* cgroup__new() has a refcount, release it here */
490		cgroup__put(cgrp);
491		nr_cgroups++;
492
493		if (metric_events) {
494			if (metricgroup__copy_metric_events(tmp_list, cgrp,
495							    metric_events,
496							    &orig_metric_events) < 0)
497				goto out_err;
498		}
499
500		evlist__splice_list_tail(evlist, &tmp_list->core.entries);
501		tmp_list->core.nr_entries = 0;
502	}
503
504	if (list_empty(&evlist->core.entries)) {
505		fprintf(stderr, "no cgroup matched: %s\n", str);
506		goto out_err;
507	}
508
509	ret = 0;
510	cgrp_event_expanded = true;
511
512out_err:
513	evlist__delete(orig_list);
514	evlist__delete(tmp_list);
515	rblist__exit(&orig_metric_events);
516	release_cgroup_list();
517
518	return ret;
519}
520
521static struct cgroup *__cgroup__findnew(struct rb_root *root, uint64_t id,
522					bool create, const char *path)
523{
524	struct rb_node **p = &root->rb_node;
525	struct rb_node *parent = NULL;
526	struct cgroup *cgrp;
527
528	while (*p != NULL) {
529		parent = *p;
530		cgrp = rb_entry(parent, struct cgroup, node);
531
532		if (cgrp->id == id)
533			return cgrp;
534
535		if (cgrp->id < id)
536			p = &(*p)->rb_left;
537		else
538			p = &(*p)->rb_right;
539	}
540
541	if (!create)
542		return NULL;
543
544	cgrp = malloc(sizeof(*cgrp));
545	if (cgrp == NULL)
546		return NULL;
547
548	cgrp->name = strdup(path);
549	if (cgrp->name == NULL) {
550		free(cgrp);
551		return NULL;
552	}
553
554	cgrp->fd = -1;
555	cgrp->id = id;
556	refcount_set(&cgrp->refcnt, 1);
557
558	rb_link_node(&cgrp->node, parent, p);
559	rb_insert_color(&cgrp->node, root);
560
561	return cgrp;
562}
563
564struct cgroup *cgroup__findnew(struct perf_env *env, uint64_t id,
565			       const char *path)
566{
567	struct cgroup *cgrp;
568
569	down_write(&env->cgroups.lock);
570	cgrp = __cgroup__findnew(&env->cgroups.tree, id, true, path);
571	up_write(&env->cgroups.lock);
572	return cgrp;
573}
574
575struct cgroup *__cgroup__find(struct rb_root *root, uint64_t id)
576{
577	return __cgroup__findnew(root, id, /*create=*/false, /*path=*/NULL);
578}
579
580struct cgroup *cgroup__find(struct perf_env *env, uint64_t id)
581{
582	struct cgroup *cgrp;
583
584	down_read(&env->cgroups.lock);
585	cgrp = __cgroup__findnew(&env->cgroups.tree, id, false, NULL);
586	up_read(&env->cgroups.lock);
587	return cgrp;
588}
589
590void perf_env__purge_cgroups(struct perf_env *env)
591{
592	struct rb_node *node;
593	struct cgroup *cgrp;
594
595	down_write(&env->cgroups.lock);
596	while (!RB_EMPTY_ROOT(&env->cgroups.tree)) {
597		node = rb_first(&env->cgroups.tree);
598		cgrp = rb_entry(node, struct cgroup, node);
599
600		rb_erase(node, &env->cgroups.tree);
601		cgroup__put(cgrp);
602	}
603	up_write(&env->cgroups.lock);
604}
605
606void read_all_cgroups(struct rb_root *root)
607{
608	char mnt[PATH_MAX];
609	struct cgroup_name *cn;
610	int prefix_len;
611
612	if (cgroupfs_find_mountpoint(mnt, sizeof(mnt), "perf_event"))
613		return;
614
615	/* cgroup_name will have a full path, skip the root directory */
616	prefix_len = strlen(mnt);
617
618	/* collect all cgroups in the cgroup_list */
619	if (nftw(mnt, add_cgroup_name, 20, 0) < 0)
620		return;
621
622	list_for_each_entry(cn, &cgroup_list, list) {
623		const char *name;
624		u64 cgrp_id;
625
626		/* cgroup_name might have a full path, skip the prefix */
627		name = cn->name + prefix_len;
628		if (name[0] == '\0')
629			name = "/";
630
631		cgrp_id = __read_cgroup_id(cn->name);
632		__cgroup__findnew(root, cgrp_id, /*create=*/true, name);
633	}
634
635	release_cgroup_list();
636}