Re: (MGA) DRI locking

[Felix <fx...@gm...>]

Am Donnerstag, den 27.07.2006, 22:08 +0200 schrieb Tilman Sauerbeck:
> Hi,
> I'm trying to fix bug 7265, but I'm stuck.
>=20
> I added some debugging output to the xserver and the mga driver and I
> attached the interesting parts of the lock.
>=20
> What's interesting is that DRILock()/DRIUnlock() are continually called
> about every second even if no DRI client is connected. This might be du=
e
> to XAA rendering though, and it seems XAA cannot be disabled without
> disabling DRI, too.
>=20
> As my test case, I started glxinfo in a xterm (which hangs in
> mgaGetLock(), as expected). This is line 18 in the log.
>=20
> At the end of the log, you'll see that DRIDoBlockHandler() results in
> another DRIUnlock() call, although the lock isn't currently held.
>=20
> Now, the problem is that I cannot figure out why and how
> DRIDoBlockHandler() is called. It's assigned to the DRI
> inforec->wrap.BlockHandler, but I don't see when it's called.
> To make things worse, I cannot get a backtrace either... attaching GDB
> or using xorg_backtrace() will crash the server.
>=20
> Any idea what's wrong with the locking here?
> Hints on when DRIDoBlockHandler is called or why it can be called even
> though the DRI lock isn't held are appreciated :)

DRIDoBlockHandler is called from DRIBlockHandler:

        if (pDRIPriv &&
            pDRIPriv->pDriverInfo->wrap.BlockHandler)
            (*pDRIPriv->pDriverInfo->wrap.BlockHandler)(i, blockData,
                                                        pTimeout, pReadma=
sk);

DRIBlockHandler in turn is registered in DRIExtensionInit using
RegisterBlockAndWakeupHandlers. Block and Wakeup handlers are called
automatically whenever the server starts and stops processing client
commands.

I just notice that DRIBlockHandler is also called through
__glXDRIleaveServer (glxdri.c), which was introduced in the AIGLX merge.
Could it be that DRIBlockHandler gets called twice when it should only
be called once?

Regards,
  Felix

>=20
> Thanks,
> Tilman
>=20
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| Felix K=C3=BChling <fx...@gm...>                     http://fxk.de.v=
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