[vdr] Re: segmentation fault in select() from cFile::FileReady()

[Klaus Schmidinger <Klaus.Schmidinger@cadsoft.de>]

Stefan Huelswitt wrote:
> 
> Hi,
> in either vdr 0.96 and 0.97 if had nummerous crashes. Backtrace
> with gdb indicates that the crash happens inside select():
> 
> (gdb) bt
> #0  0x401dc95e in __select () from /lib/libc.so.6
> #1  0xbdffba34 in ?? ()
> #2  0x804f91f in Input__13cRecordBuffer (this=0x40700c20) at dvbapi.c:564
> #3  0x808488b in Action__22cRingBufferInputThread (this=0x4075e150)
>     at ringbuffer.c:22
> #4  0x806de3e in StartThread__7cThreadP7cThread (Thread=0x4075e150)
>     at thread.c:118
> #5  0x4008bca3 in pthread_start_thread () from /lib/libpthread.so.0
> (gdb) list dvbapi.c:564
> 559           if (time(NULL) - t > MAXBROKENTIMEOUT) {
> 560              esyslog(LOG_ERR, "ERROR: video data stream broken");
> 561              cThread::EmergencyExit(true);
> 562              t = time(NULL);
> 563              }
> 564           cFile::FileReady(videoDev, 100);
> 565           if (!recording)
> 566              break;
> 567           }
> 568
> 
> Stack frame #1 should have been a reference to FileReady() but
> appearently something has trashed the stack. Right?
> 
> I had the same crash inside select() from the LIRC thread calling
> cFile::FileReady(), too.
> 
> Can't see a reason for this. Or is cFile::FileReady() not thread
> save?

The only actual function call inside cFile::FileReady() is 'select()',
but I can't find any indication that this one would not be thread safe.

When you experience these crashes, are you running VDR in DEBUG_OSD mode
or with the "real" OSD (via the DVB card)? I do have occasional crashes
in DEBUG_OSD mode, too, when recording/replaying, but so far I haven't
found the time to further investigate these - and since I use this mode
only for testing it isn't too much of a problem, although I'd like it to
work correctly, too, of course...

Let me know if you find out any further details.

Klaus
-- 
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Klaus Schmidinger                       Phone: +49-8635-6989-10
CadSoft Computer GmbH                   Fax:   +49-8635-6989-40
Hofmark 2                               Email:   kls@cadsoft.de
D-84568 Pleiskirchen, Germany           URL:     www.cadsoft.de
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