Hi, when developing PulseAudio clients with a threaded mainloop (on OS X in my case), I came across an effect which causes my client to crash out early with a failed assertion like
Assertion 'c->defer_event == e' failed at pulsecore/socket-client.c:172, function connect_defer_cb(). Aborting. Searching for this issue didn't reveal much, except that there has been other people seeing this: https://bugzilla.redhat.com/show_bug.cgi?id=497650 Looking at the code, it seems obvious that this is a simple race condition. In do_connect(), pulsecore/socket-client.c:210, we have this: c->defer_event = c->mainloop->defer_new(c->mainloop, connect_defer_cb, c); and defer_new() calls pa_mainloop_wakeup() before it returns. So in a threaded mainloop, it could be that the defered event has already been dispatched before defer_new() returns. However, c->defer_event is assigned *after* defer_new() returns, and hence the assertion fails consequently. The same counts for defer_enable() in some cases, as the event is enabled by default and could have been executed already, so disabling it after the mainloop was woken up has no effect. As this seems so obvious, and the code has been around for some years, I wonder whether I miss anything obvious here. Is there any mutex (which doesn't work yet on OS X) that should protect the mainloop from this race? I attached a patch ready to fix this issue for me, but I'm not sure whether there is more code left which fails for similar assumptions. Thanks, Daniel
0001-mainloop-api-fix-race-condition-in-defer_new.patch
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