[vlc-devel] Deadlock in freetype module

[Sergey E. Galanov]

Jean-Baptiste Kempf wrote:
> On Sun, Aug 17, 2008 at 11:11:26PM +0400, Sergey E. Galanov wrote :
>   
>> After upgrading to the latest version of vlc in my gentoo distribution 
>> (0.9.0-beta3)
>> there has appeared a problem: while playing any video file the window 
>> with video
>> output remains black, while sound goes normally.
>>     
> Is it the 0.9.0-test3 tag or top-of tree git ?
>
>   

Both of them: I checked it yesterday against the latest snapshot and the 
issue was there.

>> When, compiled in debug mode, vlc simply crashes because of mutex 
>> acquisition
>> assertion failure. This problem is caused by a deadlock situation in the 
>> freetype module.
>> Here is a code excerpt from file 'modules/misc/freetype.c':
>>     
> [...]
>
>   
>> Here we have an obvious deadlock: FontBuilderAttach acquires mutex 
>> "fontbuilder", and FontBuilderDone
>> which is being called from that function (via var_TriggerCallback) 
>> acquires the same mutex.
>> Perhaps, it is assumed that in this case 'newval.b_bool' is always 
>> false, but since it deadlocks, this assumption is wrong :)
>>
>> Of course I don't have any insight into this code and contexts from 
>> which it may be called, but it seems to me that the
>> call to var_TriggerCallback is erroneous, since callback should be 
>> called when builder thread has finished its work. So I just
>> commented this call. It worked fine for me.
>>     
>
> Is someone skilled to look at it ?
>
>   
>> With this bug vlc is absolutely unusable.
>>     
>
> This can happen with test versions...
>
> Best Regards,
>
>