cgroup.c
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#include "util.h"
#include "../perf.h"
#include <subcmd/parse-options.h>
#include "evsel.h"
#include "cgroup.h"
#include "evlist.h"
#include <linux/stringify.h>
int nr_cgroups;
static int
cgroupfs_find_mountpoint(char *buf, size_t maxlen)
{
FILE *fp;
char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];
char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path;
char *token, *saved_ptr = NULL;
fp = fopen("/proc/mounts", "r");
if (!fp)
return -1;
/*
* in order to handle split hierarchy, we need to scan /proc/mounts
* and inspect every cgroupfs mount point to find one that has
* perf_event subsystem
*/
path_v1[0] = '\0';
path_v2[0] = '\0';
while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %"
__stringify(PATH_MAX)"s %*d %*d\n",
mountpoint, type, tokens) == 3) {
if (!path_v1[0] && !strcmp(type, "cgroup")) {
token = strtok_r(tokens, ",", &saved_ptr);
while (token != NULL) {
if (!strcmp(token, "perf_event")) {
strcpy(path_v1, mountpoint);
break;
}
token = strtok_r(NULL, ",", &saved_ptr);
}
}
if (!path_v2[0] && !strcmp(type, "cgroup2"))
strcpy(path_v2, mountpoint);
if (path_v1[0] && path_v2[0])
break;
}
fclose(fp);
if (path_v1[0])
path = path_v1;
else if (path_v2[0])
path = path_v2;
else
return -1;
if (strlen(path) < maxlen) {
strcpy(buf, path);
return 0;
}
return -1;
}
static int open_cgroup(char *name)
{
char path[PATH_MAX + 1];
char mnt[PATH_MAX + 1];
int fd;
if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1))
return -1;
snprintf(path, PATH_MAX, "%s/%s", mnt, name);
fd = open(path, O_RDONLY);
if (fd == -1)
fprintf(stderr, "no access to cgroup %s\n", path);
return fd;
}
static int add_cgroup(struct perf_evlist *evlist, char *str)
{
struct perf_evsel *counter;
struct cgroup_sel *cgrp = NULL;
int n;
/*
* check if cgrp is already defined, if so we reuse it
*/
evlist__for_each_entry(evlist, counter) {
cgrp = counter->cgrp;
if (!cgrp)
continue;
if (!strcmp(cgrp->name, str))
break;
cgrp = NULL;
}
if (!cgrp) {
cgrp = zalloc(sizeof(*cgrp));
if (!cgrp)
return -1;
cgrp->name = str;
cgrp->fd = open_cgroup(str);
if (cgrp->fd == -1) {
free(cgrp);
return -1;
}
}
/*
* find corresponding event
* if add cgroup N, then need to find event N
*/
n = 0;
evlist__for_each_entry(evlist, counter) {
if (n == nr_cgroups)
goto found;
n++;
}
if (refcount_read(&cgrp->refcnt) == 0)
free(cgrp);
return -1;
found:
refcount_inc(&cgrp->refcnt);
counter->cgrp = cgrp;
return 0;
}
void close_cgroup(struct cgroup_sel *cgrp)
{
if (cgrp && refcount_dec_and_test(&cgrp->refcnt)) {
close(cgrp->fd);
zfree(&cgrp->name);
free(cgrp);
}
}
int parse_cgroups(const struct option *opt __maybe_unused, const char *str,
int unset __maybe_unused)
{
struct perf_evlist *evlist = *(struct perf_evlist **)opt->value;
const char *p, *e, *eos = str + strlen(str);
char *s;
int ret;
if (list_empty(&evlist->entries)) {
fprintf(stderr, "must define events before cgroups\n");
return -1;
}
for (;;) {
p = strchr(str, ',');
e = p ? p : eos;
/* allow empty cgroups, i.e., skip */
if (e - str) {
/* termination added */
s = strndup(str, e - str);
if (!s)
return -1;
ret = add_cgroup(evlist, s);
if (ret) {
free(s);
return -1;
}
}
/* nr_cgroups is increased een for empty cgroups */
nr_cgroups++;
if (!p)
break;
str = p+1;
}
return 0;
}