linux-kernel - [PATCH v1 4/4] perf thread: Fixes to thread_

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Date: Tue,  7 May 2024 20:53:01 -0700
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	Kan Liang <kan.liang@...ux.intel.com>, James Clark <james.clark@....com>, 
	Leo Yan <leo.yan@...ux.dev>, linux-perf-users@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: [PATCH v1 4/4] perf thread: Fixes to thread__new

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: f6005cafebab ("perf thread: Add reference count checking")
Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 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 0a473112f881..87c59aa9fe38 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;
 }
 
-- 
2.45.0.rc1.225.g2a3ae87e7f-goog