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	evlist__for_each(evlist, counter) {
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	evlist__for_each(evlist, counter) {
114		if (n == nr_cgroups)
115			goto found;
116		n++;
117	}
118	if (atomic_read(&cgrp->refcnt) == 0)
119		free(cgrp);
120
121	return -1;
122found:
123	atomic_inc(&cgrp->refcnt);
124	counter->cgrp = cgrp;
125	return 0;
126}
127
128void close_cgroup(struct cgroup_sel *cgrp)
129{
130	if (cgrp && atomic_dec_and_test(&cgrp->refcnt)) {
131		close(cgrp->fd);
132		zfree(&cgrp->name);
133		free(cgrp);
134	}
135}
136
137int parse_cgroups(const struct option *opt __maybe_unused, const char *str,
138		  int unset __maybe_unused)
139{
140	struct perf_evlist *evlist = *(struct perf_evlist **)opt->value;
141	const char *p, *e, *eos = str + strlen(str);
142	char *s;
143	int ret;
144
145	if (list_empty(&evlist->entries)) {
146		fprintf(stderr, "must define events before cgroups\n");
147		return -1;
148	}
149
150	for (;;) {
151		p = strchr(str, ',');
152		e = p ? p : eos;
153
154		/* allow empty cgroups, i.e., skip */
155		if (e - str) {
156			/* termination added */
157			s = strndup(str, e - str);
158			if (!s)
159				return -1;
160			ret = add_cgroup(evlist, s);
161			if (ret) {
162				free(s);
163				return -1;
164			}
165		}
166		/* nr_cgroups is increased een for empty cgroups */
167		nr_cgroups++;
168		if (!p)
169			break;
170		str = p+1;
171	}
172	return 0;
173}
174