[poppler] XRef::fetch mutex lock

Sat Apr 6 08:19:20 PDT 2013

El Dimarts, 2 d'abril de 2013, a les 10:36:53, Thomas Freitag va escriure:
> Am 02.04.2013 09:22, schrieb Thomas Freitag:
> > Hi Albert!
> > 
> > Am 27.03.2013 12:29, schrieb Thomas Freitag:
> >> Sorry, pushed the wrong button, here my answer to the list:
> >> 
> >> Am 27.03.2013 11:41, schrieb Albert Astals Cid:
> >>> Why do we pass around the recursion integer around?
> >> 
> >> No idea: The recursive integer wasn't introduced by the thread safe
> >> patch, it was already there. I just used it and extend some functions
> >> which incorrectly ignore that parameter instead of passing it to the
> >> called functions. Probably I missed some more than only the one in
> >> DCTStream::DCTStream.
> > 
> > I just ran a regression test over my PDF files, but I didn't get any
> > dead locks. So if You want me to solve that problem, You should
> > provide me that PDF. (Regardless if You prefer to use recursive mutex:
> > the endless loop detection need to pass the recursive integer
> > everywhere!)
> 
> Attached a patch which corrects it. I made it in my sleep, 'cause the
> dead lock was probably caused by my patch for bug 61994 (even if that
> PDF doesn't cause any dead locks). This time I also respect the
> DCTStream usage if LIBJPEG is disabled :-)

Commited this one too in addition to the recursive mutex one.

Cheers,
  Albert

> 
> Cheers,
> Thomas
> 
> > Cheers,
> > Thomas
> > 
> >>> Wouldn't a real recursive mutex be enough?
> >> 
> >> No idea: I used in the thread safe patch just the pthread_lock which
> >> was defined. I'm not knowing what happens when we change it globally
> >> i.e. if it affects other usages of the GooMutex. Just feel free to
> >> change it, You should have the better overview of usages than I have.
> >> 
> >> Cheers,
> >> Thomas
> >> 
> >>> I'm asking because i have a document here (that sadly i can't share)
> >>> that is deadlocking
> >>> itself there because we are not passing the recursion integer
> >>> everywhere (we lose it in DCTStream::DCTStream)
> >>> as shown in this backtrace
> >>> 
> >>> #0  __lll_lock_wait () at
> >>> ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:135
> >>> #1  0x00007ffff599217c in _L_lock_982 () from
> >>> /lib/x86_64-linux-gnu/libpthread.so.0
> >>> #2  0x00007ffff5991fcb in __GI___pthread_mutex_lock (mutex=0x71dc10)
> >>> at pthread_mutex_lock.c:64
> >>> #3  0x00007ffff5f02f73 in MutexLocker::MutexLocker
> >>> (this=0x7fffffffcfb0, mutexA=0x71dc10, modeA=DoLockMutex) at
> >>> /home/tsdgeos/devel/poppler/goo/GooMutex.h:72
> >>> #4  0x00007ffff5fac8e2 in XRef::fetch (this=0x71db50, num=5, gen=0,
> >>> obj=0x7fffffffd0b0, recursion=0) at
> >>> /home/tsdgeos/devel/poppler/poppler/XRef.cc:1137
> >>> #5  0x00007ffff5f8a013 in Object::fetch (this=0x71fe08,
> >>> xref=0x71db50, obj=0x7fffffffd0b0, recursion=0) at
> >>> /home/tsdgeos/devel/poppler/poppler/Object.cc:122
> >>> #6  0x00007ffff5f19de4 in Dict::lookup (this=0x71fb60,
> >>> key=0x7ffff606fbba "Height", obj=0x7fffffffd0b0, recursion=0) at
> >>> /home/tsdgeos/devel/poppler/poppler/Dict.cc:256
> >>> #7  0x00007ffff5f032e9 in Object::dictLookup (this=0x7fffffffd5a0,
> >>> key=0x7ffff606fbba "Height", obj=0x7fffffffd0b0, recursion=0) at
> >>> /home/tsdgeos/devel/poppler/poppler/Object.h:315
> >>> #8  0x00007ffff601f8a3 in DCTStream::DCTStream (this=0x7832b0,
> >>> strA=0x720780, colorXformA=-1, dict=0x7fffffffd5a0) at
> >>> /home/tsdgeos/devel/poppler/poppler/DCTStream.cc:72
> >>> #9  0x00007ffff5f9bf6d in Stream::makeFilter (this=0x720780,
> >>> name=0x71fef0 "DCTDecode", str=0x720780, params=0x7fffffffd1e0,
> >>> recursion=1, dict=0x7fffffffd5a0) at
> >>> /home/tsdgeos/devel/poppler/poppler/Stream.cc:311
> >>> #10 0x00007ffff5f9b71a in Stream::addFilters (this=0x720780,
> >>> dict=0x7fffffffd5a0, recursion=1) at
> >>> /home/tsdgeos/devel/poppler/poppler/Stream.cc:184
> >>> #11 0x00007ffff5f9204b in Parser::makeStream (this=0x71fcd0,
> >>> dict=0x7fffffffd5a0, fileKey=0x0, encAlgorithm=cryptRC4,
> >>> keyLength=1146103040, objNum=3, objGen=0, recursion=1, strict=false)
> >>> at /home/tsdgeos/devel/poppler/poppler/Parser.cc:280
> >>> #12 0x00007ffff5f918e6 in Parser::getObj (this=0x71fcd0,
> >>> obj=0x7fffffffd5a0, simpleOnly=false, fileKey=0x0,
> >>> encAlgorithm=cryptRC4, keyLength=1146103040, objNum=3, objGen=0,
> >>> recursion=0, strict=false) at
> >>> /home/tsdgeos/devel/poppler/poppler/Parser.cc:131
> >>> #13 0x00007ffff5facdd3 in XRef::fetch (this=0x71db50, num=3, gen=0,
> >>> obj=0x7fffffffd5a0, recursion=0) at
> >>> /home/tsdgeos/devel/poppler/poppler/XRef.cc:1197
> >>> #14 0x00007ffff5f8a013 in Object::fetch (this=0x71e128,
> >>> xref=0x71db50, obj=0x7fffffffd5a0, recursion=0) at
> >>> /home/tsdgeos/devel/poppler/poppler/Object.cc:122
> >>> #15 0x00007ffff5f19de4 in Dict::lookup (this=0x71e660, key=0x7206e0
> >>> "Im1", obj=0x7fffffffd5a0, recursion=0) at
> >>> /home/tsdgeos/devel/poppler/poppler/Dict.cc:256
> >>> #16 0x00007ffff5f032e9 in Object::dictLookup (this=0x71e598,
> >>> key=0x7206e0 "Im1", obj=0x7fffffffd5a0, recursion=0) at
> >>> /home/tsdgeos/devel/poppler/poppler/Object.h:315
> >>> #17 0x00007ffff5f2a647 in GfxResources::lookupXObject
> >>> (this=0x71e590, name=0x7206e0 "Im1", obj=0x7fffffffd5a0) at
> >>> /home/tsdgeos/devel/poppler/poppler/Gfx.cc:411
> >>> #18 0x00007ffff5f3f41e in Gfx::opXObject (this=0x71e440,
> >>> args=0x7fffffffd720, numArgs=1) at
> >>> /home/tsdgeos/devel/poppler/poppler/Gfx.cc:4114
> >>> #19 0x00007ffff5f2bfd6 in Gfx::execOp (this=0x71e440,
> >>> cmd=0x7fffffffd6e0, args=0x7fffffffd720, numArgs=1) at
> >>> /home/tsdgeos/devel/poppler/poppler/Gfx.cc:858
> >>> #20 0x00007ffff5f2b82b in Gfx::go (this=0x71e440, topLevel=true) at
> >>> /home/tsdgeos/devel/poppler/poppler/Gfx.cc:717
> >>> 
> >>> 
> >>> Cheers,
> >>> 
> >>>    Albert
> >>> 
> >>> _______________________________________________
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> >>> poppler at lists.freedesktop.org
> >>> http://lists.freedesktop.org/mailman/listinfo/poppler
> >>> 
> >>> .
> >> 
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> >> 
> >> .
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