perf thread: Fixes to thread__new() related to initializing comm

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>

diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index 0a473112f881533e3dd0d6314940c02847ea9af8..87c59aa9fe38bfb4c38f94ab5431fa06a6f859d2 100644 (file)
--- 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;
 }