[vdr] [PATCH] mp3-0.9.11 signals end of replay too late

Wolfgang Fritz wolfgang.fritz at gmx.net
Wed Mar 16 19:44:40 CET 2005


Klaus Schmidinger wrote:
> Stefan Huelswitt wrote:
> 
>>On 15 Mar 2005 Wolfgang Fritz <wolfgang.fritz at gmx.net> wrote:
>>
>>
>>
>>>Stefan Huelswitt wrote:
>>>
>>>
>>>>Ok, I changed the location, but I think that the real flaw is in
>>>>VDRs player.h where the "player" var isn't checked before access.
>>>
>>>If tested this (temporarily inserted a test for player == 0 in
>>>player.h), but it didn't help.
>>>
>>>maybe
>>>
>>>void cMP3Control::Stop(void)
>>>{
>>> delete player; player=0;
>>> mgr->Halt();
>>> mgr->Flush(); //XXX remove later
>>>}
>>>
>>>has a concurrency problem? Who guarantees that no other thread
>>>interrupts the mp3 thread while is in the destructor?
>>>
>>>Wouldn't be something like this a little bit safer:
>>>
>>>void cMP3Control::Stop(void)
>>>{
>>> cMP3player *p = player;
>>> player = 0;
>>> delete p;
>>> mgr->Halt();
>>> mgr->Flush(); //XXX remove later
>>>}
>>>
>>>There seem to be more concurrency problems which crop up with the
>>>graphlcd plugin. In rare cases I get a segfault when exiting a normal
>>>vdr replay.
>>
>>
>>Of course it's a concurrency problem.
>>>From the fact that there is no mutex protection for the player
>>var (neither in MP3 plugin nor in any other player code), I would
>>guess that the cControl API was designed for accesses from the
>>VDR foreground thread only (no concurrency problem in this case).
> 
> 
> That's right - a player is not supposed to be accessed from anything
> else than the foreground thread.
> 

As far I can see, cControl::GetIndex() is the only method graphlcd calls
in its own thread context to get periodic information about the replay
progress (for updating its progress bar display). What would be the
correct way to get that information?

Wolfgang

> Klaus
> 
> 
>>If graphlcd is running on another thread, this could be the
>>explanation...
>>
>>Regards.
>>
> 
> 
> 





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