[PATCH 6.9 101/374] perf thread: Fixes to thread__new() related to initializing comm

Greg Kroah-Hartman
2024-06-06T14:09:30Z

From: Ian Rogers <irogers@google.com>

[ Upstream commit 3536c2575e88a890cf696b4ccd3da36bc937853b ]

Freeing the thread on failure won't work with reference count checking,
use thread__delete().

Don't allocate the comm_str, use a stack allocation instead.

Fixes: f6005cafebab72f8 ("perf thread: Add reference count checking")
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linux.dev>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240508035301.1554434-5-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/perf/util/thread.c | 14 +++++---------
1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index 1aa8962dcf52c..515726489e36a 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -39,12 +39,13 @@ int thread__init_maps(struct thread *thread, struct machine *machine)

struct thread *thread__new(pid_t pid, pid_t tid)
{
- char *comm_str;
- struct comm *comm;
RC_STRUCT(thread) *_thread = zalloc(sizeof(*_thread));
struct thread *thread;

if (ADD_RC_CHK(thread, _thread) != NULL) {
+ struct comm *comm;
+ char comm_str[32];
+
thread__set_pid(thread, pid);
thread__set_tid(thread, tid);
thread__set_ppid(thread, -1);
@@ -56,13 +57,8 @@ struct thread *thread__new(pid_t pid, pid_t tid)
init_rwsem(thread__namespaces_lock(thread));
init_rwsem(thread__comm_lock(thread));

- comm_str = malloc(32);
- if (!comm_str)
- goto err_thread;
-
- snprintf(comm_str, 32, ":%d", tid);
+ snprintf(comm_str, sizeof(comm_str), ":%d", tid);
comm = comm__new(comm_str, 0, false);
- free(comm_str);
if (!comm)
goto err_thread;

@@ -76,7 +72,7 @@ struct thread *thread__new(pid_t pid, pid_t tid)
return thread;

err_thread:
- free(thread);
+ thread__delete(thread);
return NULL;
}

--
2.43.0