From 3fef46e7767b37ee3be9e9027b014025c99fdbac Mon Sep 17 00:00:00 2001
From: Naveen Albert <asterisk@phreaknet.org>
Date: Sat, 9 Sep 2023 11:24:37 -0400
Subject: [PATCH] chan_console: Fix deadlock caused by unclean thread exit.
To terminate a console channel, stop_stream causes pthread_cancel
to make stream_monitor exit. However, commit 5b8fea93d106332bc0faa4b7fa8a6ea71e546cac
added locking to this function which results in deadlock due to
the stream_monitor thread being killed while it's holding the pvt lock.
To resolve this, a flag is now set and read to indicate abort, so
the use of pthread_cancel and pthread_kill can be avoided altogether.
Resolves: #308
(cherry picked from commit 71215561d8d41b9b7993e66e0ab672f38e75eb48)
---
channels/chan_console.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/channels/chan_console.c b/channels/chan_console.c
index 1d1d94cb92..74ff75f0a7 100644
--- a/channels/chan_console.c
+++ b/channels/chan_console.c
@@ -154,6 +154,8 @@ static struct console_pvt {
struct ast_frame fr;
/*! Running = 1, Not running = 0 */
unsigned int streamstate:1;
+ /*! Abort stream processing? */
+ unsigned int abort:1;
/*! On-hook = 0, Off-hook = 1 */
unsigned int hookstate:1;
/*! Unmuted = 0, Muted = 1 */
@@ -277,18 +279,19 @@ static void *stream_monitor(void *data)
};
for (;;) {
- pthread_testcancel();
console_pvt_lock(pvt);
res = Pa_ReadStream(pvt->stream, buf, sizeof(buf) / sizeof(int16_t));
console_pvt_unlock(pvt);
- pthread_testcancel();
- if (!pvt->owner) {
+ if (!pvt->owner || pvt->abort) {
return NULL;
}
- if (res == paNoError)
+ if (res == paNoError) {
ast_queue_frame(pvt->owner, &f);
+ } else {
+ ast_log(LOG_WARNING, "Console ReadStream failed: %s\n", Pa_GetErrorText(res));
+ }
}
return NULL;
@@ -403,8 +406,9 @@ static int stop_stream(struct console_pvt *pvt)
if (!pvt->streamstate || pvt->thread == AST_PTHREADT_NULL)
return 0;
- pthread_cancel(pvt->thread);
- pthread_kill(pvt->thread, SIGURG);
+ pvt->abort = 1;
+ /* Wait for pvt->thread to exit cleanly, to avoid killing it while it's holding a lock. */
+ pthread_kill(pvt->thread, SIGURG); /* Wake it up if needed, but don't cancel it */
pthread_join(pvt->thread, NULL);
console_pvt_lock(pvt);