1#include "util.h"
  2#include "../perf.h"
  3#include "parse-options.h"
  4#include "evsel.h"
  5#include "cgroup.h"
  6#include "evlist.h"
  7
  8int nr_cgroups;
  9
 10static int
 11cgroupfs_find_mountpoint(char *buf, size_t maxlen)
 12{
 13	FILE *fp;
 14	char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];
 15	char *token, *saved_ptr = NULL;
 16	int found = 0;
 17
 18	fp = fopen("/proc/mounts", "r");
 19	if (!fp)
 20		return -1;
 21
 22	/*
 23	 * in order to handle split hierarchy, we need to scan /proc/mounts
 24	 * and inspect every cgroupfs mount point to find one that has
 25	 * perf_event subsystem
 26	 */
 27	while (fscanf(fp, "%*s %"STR(PATH_MAX)"s %"STR(PATH_MAX)"s %"
 28				STR(PATH_MAX)"s %*d %*d\n",
 29				mountpoint, type, tokens) == 3) {
 30
 31		if (!strcmp(type, "cgroup")) {
 32
 33			token = strtok_r(tokens, ",", &saved_ptr);
 34
 35			while (token != NULL) {
 36				if (!strcmp(token, "perf_event")) {
 37					found = 1;
 38					break;
 39				}
 40				token = strtok_r(NULL, ",", &saved_ptr);
 41			}
 42		}
 43		if (found)
 44			break;
 45	}
 46	fclose(fp);
 47	if (!found)
 48		return -1;
 49
 50	if (strlen(mountpoint) < maxlen) {
 51		strcpy(buf, mountpoint);
 52		return 0;
 53	}
 54	return -1;
 55}
 56
 57static int open_cgroup(char *name)
 58{
 59	char path[PATH_MAX + 1];
 60	char mnt[PATH_MAX + 1];
 61	int fd;
 62
 63
 64	if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1))
 65		return -1;
 66
 67	snprintf(path, PATH_MAX, "%s/%s", mnt, name);
 68
 69	fd = open(path, O_RDONLY);
 70	if (fd == -1)
 71		fprintf(stderr, "no access to cgroup %s\n", path);
 72
 73	return fd;
 74}
 75
 76static int add_cgroup(struct perf_evlist *evlist, char *str)
 77{
 78	struct perf_evsel *counter;
 79	struct cgroup_sel *cgrp = NULL;
 80	int n;
 81	/*
 82	 * check if cgrp is already defined, if so we reuse it
 83	 */
 84	list_for_each_entry(counter, &evlist->entries, node) {
 85		cgrp = counter->cgrp;
 86		if (!cgrp)
 87			continue;
 88		if (!strcmp(cgrp->name, str))
 89			break;
 90
 91		cgrp = NULL;
 92	}
 93
 94	if (!cgrp) {
 95		cgrp = zalloc(sizeof(*cgrp));
 96		if (!cgrp)
 97			return -1;
 98
 99		cgrp->name = str;
100
101		cgrp->fd = open_cgroup(str);
102		if (cgrp->fd == -1) {
103			free(cgrp);
104			return -1;
105		}
106	}
107
108	/*
109	 * find corresponding event
110	 * if add cgroup N, then need to find event N
111	 */
112	n = 0;
113	list_for_each_entry(counter, &evlist->entries, node) {
114		if (n == nr_cgroups)
115			goto found;
116		n++;
117	}
118	if (cgrp->refcnt == 0)
119		free(cgrp);
120
121	return -1;
122found:
123	cgrp->refcnt++;
124	counter->cgrp = cgrp;
125	return 0;
126}
127
128void close_cgroup(struct cgroup_sel *cgrp)
129{
130	if (!cgrp)
131		return;
132
133	/* XXX: not reentrant */
134	if (--cgrp->refcnt == 0) {
135		close(cgrp->fd);
136		free(cgrp->name);
137		free(cgrp);
138	}
139}
140
141int parse_cgroups(const struct option *opt __used, const char *str,
142		  int unset __used)
143{
144	struct perf_evlist *evlist = *(struct perf_evlist **)opt->value;
145	const char *p, *e, *eos = str + strlen(str);
146	char *s;
147	int ret;
148
149	if (list_empty(&evlist->entries)) {
150		fprintf(stderr, "must define events before cgroups\n");
151		return -1;
152	}
153
154	for (;;) {
155		p = strchr(str, ',');
156		e = p ? p : eos;
157
158		/* allow empty cgroups, i.e., skip */
159		if (e - str) {
160			/* termination added */
161			s = strndup(str, e - str);
162			if (!s)
163				return -1;
164			ret = add_cgroup(evlist, s);
165			if (ret) {
166				free(s);
167				return -1;
168			}
169		}
170		/* nr_cgroups is increased een for empty cgroups */
171		nr_cgroups++;
172		if (!p)
173			break;
174		str = p+1;
175	}
176	return 0;
177}