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![Jiri Olsa](/assets/img/avatar_default.png)
With gcc 8 we get new set of snprintf() warnings that breaks the compilation, one example: tests/mem.c: In function ‘check’: tests/mem.c:19:48: error: ‘%s’ directive output may be truncated writing \ up to 99 bytes into a region of size 89 [-Werror=format-truncation=] snprintf(failure, sizeof failure, "unexpected %s", out); The gcc docs says: To avoid the warning either use a bigger buffer or handle the function's return value which indicates whether or not its output has been truncated. Given that all these warnings are harmless, because the code either properly fails due to uncomplete file path or we don't care for truncated output at all, I'm changing all those snprintf() calls to scnprintf(), which actually 'checks' for the snprint return value so the gcc stays silent. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Link: http://lkml.kernel.org/r/20180319082902.4518-1-jolsa@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
254 lines
5 KiB
C
254 lines
5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include "util.h"
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#include "../perf.h"
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#include <subcmd/parse-options.h>
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#include "evsel.h"
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#include "cgroup.h"
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#include "evlist.h"
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#include <linux/stringify.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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int nr_cgroups;
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static int
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cgroupfs_find_mountpoint(char *buf, size_t maxlen)
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{
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FILE *fp;
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char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];
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char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path;
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char *token, *saved_ptr = NULL;
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fp = fopen("/proc/mounts", "r");
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if (!fp)
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return -1;
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/*
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* in order to handle split hierarchy, we need to scan /proc/mounts
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* and inspect every cgroupfs mount point to find one that has
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* perf_event subsystem
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*/
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path_v1[0] = '\0';
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path_v2[0] = '\0';
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while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %"
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__stringify(PATH_MAX)"s %*d %*d\n",
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mountpoint, type, tokens) == 3) {
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if (!path_v1[0] && !strcmp(type, "cgroup")) {
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token = strtok_r(tokens, ",", &saved_ptr);
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while (token != NULL) {
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if (!strcmp(token, "perf_event")) {
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strcpy(path_v1, mountpoint);
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break;
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}
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token = strtok_r(NULL, ",", &saved_ptr);
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}
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}
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if (!path_v2[0] && !strcmp(type, "cgroup2"))
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strcpy(path_v2, mountpoint);
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if (path_v1[0] && path_v2[0])
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break;
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}
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fclose(fp);
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if (path_v1[0])
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path = path_v1;
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else if (path_v2[0])
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path = path_v2;
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else
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return -1;
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if (strlen(path) < maxlen) {
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strcpy(buf, path);
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return 0;
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}
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return -1;
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}
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static int open_cgroup(const char *name)
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{
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char path[PATH_MAX + 1];
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char mnt[PATH_MAX + 1];
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int fd;
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if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1))
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return -1;
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scnprintf(path, PATH_MAX, "%s/%s", mnt, name);
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fd = open(path, O_RDONLY);
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if (fd == -1)
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fprintf(stderr, "no access to cgroup %s\n", path);
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return fd;
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}
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static struct cgroup *evlist__find_cgroup(struct perf_evlist *evlist, const char *str)
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{
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struct perf_evsel *counter;
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struct cgroup *cgrp = NULL;
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/*
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* check if cgrp is already defined, if so we reuse it
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*/
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evlist__for_each_entry(evlist, counter) {
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if (!counter->cgrp)
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continue;
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if (!strcmp(counter->cgrp->name, str)) {
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cgrp = cgroup__get(counter->cgrp);
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break;
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}
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}
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return cgrp;
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}
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static struct cgroup *cgroup__new(const char *name)
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{
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struct cgroup *cgroup = zalloc(sizeof(*cgroup));
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if (cgroup != NULL) {
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refcount_set(&cgroup->refcnt, 1);
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cgroup->name = strdup(name);
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if (!cgroup->name)
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goto out_err;
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cgroup->fd = open_cgroup(name);
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if (cgroup->fd == -1)
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goto out_free_name;
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}
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return cgroup;
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out_free_name:
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free(cgroup->name);
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out_err:
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free(cgroup);
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return NULL;
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}
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struct cgroup *evlist__findnew_cgroup(struct perf_evlist *evlist, const char *name)
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{
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struct cgroup *cgroup = evlist__find_cgroup(evlist, name);
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return cgroup ?: cgroup__new(name);
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}
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static int add_cgroup(struct perf_evlist *evlist, const char *str)
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{
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struct perf_evsel *counter;
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struct cgroup *cgrp = evlist__findnew_cgroup(evlist, str);
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int n;
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if (!cgrp)
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return -1;
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/*
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* find corresponding event
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* if add cgroup N, then need to find event N
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*/
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n = 0;
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evlist__for_each_entry(evlist, counter) {
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if (n == nr_cgroups)
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goto found;
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n++;
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}
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cgroup__put(cgrp);
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return -1;
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found:
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counter->cgrp = cgrp;
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return 0;
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}
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static void cgroup__delete(struct cgroup *cgroup)
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{
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close(cgroup->fd);
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zfree(&cgroup->name);
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free(cgroup);
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}
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void cgroup__put(struct cgroup *cgrp)
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{
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if (cgrp && refcount_dec_and_test(&cgrp->refcnt)) {
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cgroup__delete(cgrp);
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}
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}
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struct cgroup *cgroup__get(struct cgroup *cgroup)
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{
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if (cgroup)
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refcount_inc(&cgroup->refcnt);
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return cgroup;
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}
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static void evsel__set_default_cgroup(struct perf_evsel *evsel, struct cgroup *cgroup)
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{
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if (evsel->cgrp == NULL)
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evsel->cgrp = cgroup__get(cgroup);
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}
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void evlist__set_default_cgroup(struct perf_evlist *evlist, struct cgroup *cgroup)
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{
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struct perf_evsel *evsel;
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evlist__for_each_entry(evlist, evsel)
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evsel__set_default_cgroup(evsel, cgroup);
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}
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int parse_cgroups(const struct option *opt, const char *str,
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int unset __maybe_unused)
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{
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struct perf_evlist *evlist = *(struct perf_evlist **)opt->value;
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struct perf_evsel *counter;
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struct cgroup *cgrp = NULL;
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const char *p, *e, *eos = str + strlen(str);
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char *s;
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int ret, i;
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if (list_empty(&evlist->entries)) {
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fprintf(stderr, "must define events before cgroups\n");
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return -1;
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}
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for (;;) {
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p = strchr(str, ',');
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e = p ? p : eos;
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/* allow empty cgroups, i.e., skip */
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if (e - str) {
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/* termination added */
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s = strndup(str, e - str);
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if (!s)
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return -1;
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ret = add_cgroup(evlist, s);
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free(s);
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if (ret)
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return -1;
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}
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/* nr_cgroups is increased een for empty cgroups */
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nr_cgroups++;
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if (!p)
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break;
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str = p+1;
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}
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/* for the case one cgroup combine to multiple events */
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i = 0;
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if (nr_cgroups == 1) {
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evlist__for_each_entry(evlist, counter) {
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if (i == 0)
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cgrp = counter->cgrp;
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else {
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counter->cgrp = cgrp;
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refcount_inc(&cgrp->refcnt);
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}
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i++;
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}
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}
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return 0;
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}
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