Don't call pthread_join() to join a thread from a different
process than the thread was created in. Doing so can lead to
undefined behaviour.
On OpenBSD, the symptom was a pulseaudio process with a single
thread waiting forever for other threads to join. Since that
process also held the autospawn lock, starting new pulseaudio
processes with --start kept failing. The problem was analyzed
with help from Philip Guenther.
This patch adds a pa_thread_free_nojoin() function which can
be used to free resources for a thread without a join, as
suggested by Tanu Kaskinen.
See https://bugs.freedesktop.org/show_bug.cgi?id=71738
if (n_ref > 0)
return;
+ /* Join threads only in the process the new thread was created in
+ * to avoid undefined behaviour.
+ * POSIX.1-2008 XSH 2.9.2 Thread IDs: "applications should only assume
+ * that thread IDs are usable and unique within a single process." */
if (thread) {
- pa_thread_free(thread);
+ if (after_fork)
+ pa_thread_free_nojoin(thread);
+ else
+ pa_thread_free(thread);
thread = NULL;
}
pa_xfree(t);
}
+void pa_thread_free_nojoin(pa_thread *t) {
+ pa_assert(t);
+
+ pa_xfree(t->name);
+ pa_xfree(t);
+}
+
int pa_thread_join(pa_thread *t) {
pa_assert(t);
pa_assert(t->thread_func);
pa_thread* pa_thread_new(const char *name, pa_thread_func_t thread_func, void *userdata);
void pa_thread_free(pa_thread *t);
+void pa_thread_free_nojoin(pa_thread *t);
int pa_thread_join(pa_thread *t);
int pa_thread_is_running(pa_thread *t);
pa_thread *pa_thread_self(void);