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Subject[PATCH 13/54] perf cgroup: Make the cgroup name be const char *
Date
From: Arnaldo Carvalho de Melo <acme@redhat.com>

The usual thing is for a constructor to allocate space for its members,
not to require that the caller pass a pre-allocated 'name' and then, at
its destructor, to free something not allocated by it.

Fix it by making cgroup__new() to receive a const char pointer, then
allocate cgroup->name that then can continue to be freed at
cgroup__delete(), balancing the alloc/free operations inside the cgroup
struct methods.

This eases calling evlist__findnew_cgroup() from the custom 'perf trace'
cgroup parser, that will only call parse_cgroups() when the '-G cgroup'
is passed on the command line after '-e event' entries, when it'll
behave just like 'perf stat' and 'perf record', i.e. the previous
parse_cgroup() users that mandate that -G only can come after a -e.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-4leugnuyqi10t98990o3xi1t@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/cgroup.c | 24 ++++++++++++++----------
tools/perf/util/cgroup.h | 2 +-
2 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/tools/perf/util/cgroup.c b/tools/perf/util/cgroup.c
index d8cd0e601c56..78408f5c4bad 100644
--- a/tools/perf/util/cgroup.c
+++ b/tools/perf/util/cgroup.c
@@ -71,7 +71,7 @@ cgroupfs_find_mountpoint(char *buf, size_t maxlen)
return -1;
}

-static int open_cgroup(char *name)
+static int open_cgroup(const char *name)
{
char path[PATH_MAX + 1];
char mnt[PATH_MAX + 1];
@@ -90,7 +90,7 @@ static int open_cgroup(char *name)
return fd;
}

-static struct cgroup *evlist__find_cgroup(struct perf_evlist *evlist, char *str)
+static struct cgroup *evlist__find_cgroup(struct perf_evlist *evlist, const char *str)
{
struct perf_evsel *counter;
struct cgroup *cgrp = NULL;
@@ -109,33 +109,38 @@ static struct cgroup *evlist__find_cgroup(struct perf_evlist *evlist, char *str)
return cgrp;
}

-static struct cgroup *cgroup__new(char *name)
+static struct cgroup *cgroup__new(const char *name)
{
struct cgroup *cgroup = zalloc(sizeof(*cgroup));

if (cgroup != NULL) {
- cgroup->name = name;
refcount_set(&cgroup->refcnt, 1);

+ cgroup->name = strdup(name);
+ if (!cgroup->name)
+ goto out_err;
cgroup->fd = open_cgroup(name);
if (cgroup->fd == -1)
- goto out_err;
+ goto out_free_name;
}

return cgroup;
+
+out_free_name:
+ free(cgroup->name);
out_err:
free(cgroup);
return NULL;
}

-struct cgroup *evlist__findnew_cgroup(struct perf_evlist *evlist, char *name)
+struct cgroup *evlist__findnew_cgroup(struct perf_evlist *evlist, const char *name)
{
struct cgroup *cgroup = evlist__find_cgroup(evlist, name);

return cgroup ?: cgroup__new(name);
}

-static int add_cgroup(struct perf_evlist *evlist, char *str)
+static int add_cgroup(struct perf_evlist *evlist, const char *str)
{
struct perf_evsel *counter;
struct cgroup *cgrp = evlist__findnew_cgroup(evlist, str);
@@ -222,10 +227,9 @@ int parse_cgroups(const struct option *opt, const char *str,
if (!s)
return -1;
ret = add_cgroup(evlist, s);
- if (ret) {
- free(s);
+ free(s);
+ if (ret)
return -1;
- }
}
/* nr_cgroups is increased een for empty cgroups */
nr_cgroups++;
diff --git a/tools/perf/util/cgroup.h b/tools/perf/util/cgroup.h
index b213f5e9a3ed..f033a80c1b14 100644
--- a/tools/perf/util/cgroup.h
+++ b/tools/perf/util/cgroup.h
@@ -20,7 +20,7 @@ void cgroup__put(struct cgroup *cgroup);

struct perf_evlist;

-struct cgroup *evlist__findnew_cgroup(struct perf_evlist *evlist, char *name);
+struct cgroup *evlist__findnew_cgroup(struct perf_evlist *evlist, const char *name);

void evlist__set_default_cgroup(struct perf_evlist *evlist, struct cgroup *cgroup);

--
2.14.3
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