[GStreamer] Race condition causing deadlocks

• Component: Media
• Status: RESOLVED FIXED

[Sebastian Dröge (slomo)]

Hi,
currently there's a race condition in the GStreamer video sink. Problem is, if unlock() is called and then render(). It would wait forever on the cond.

Attached patch fixes this.

[Sebastian Dröge (slomo)]

Created attachment 41156 [details]
0001-Fix-race-condition-in-unlock-render-that-would-lead-.patch

[Benjamin Otte]

Created attachment 41157 [details]
Stacktrace showing the deadlock

[Gustavo Noronha (kov)]

Comment on attachment 41156 [details]
0001-Fix-race-condition-in-unlock-render-that-would-lead-.patch

Man, threading is hairy =). So, what's causing the deadlock, exactly, again? The cond_wait in render and the mutex_lock in timeout_func racing when gstreamer fires ::unlock? Then you fix it by avoiding creating the timeout and doing the cond_wait in the first place if ::unlock() has fired on the element, is that it? Can you add a comment block somewhere explaining this?

[Sebastian Dröge (slomo)]

Created attachment 41223 [details]
0001-Fix-race-condition-in-unlock-render-that-would-lead-.patch

[Gustavo Noronha (kov)]

Comment on attachment 41223 [details]
0001-Fix-race-condition-in-unlock-render-that-would-lead-.patch

Thanks!

[WebKit Commit Bot]

Comment on attachment 41223 [details]
0001-Fix-race-condition-in-unlock-render-that-would-lead-.patch

Clearing flags on attachment: 41223

Committed r49623: <http://trac.webkit.org/changeset/49623>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.