On 05/05/2013 04:23 PM, Dave Airlie wrote:
On Thu, May 2, 2013 at 5:55 AM, Aaron Plattner <[email protected]> wrote:
On 04/30/2013 11:30 PM, Dave Airlie wrote:
On Wed, May 1, 2013 at 7:14 AM, Aaron Plattner <[email protected]> wrote:
Commit 8f4640bdb9d3988148e09a08d2c7e3bab1d538d6 fixed a bit of a
chicken-and-egg problem by detaching GPU screens when their providers
are destroyed, which happens before CloseScreen is called. However,
this created a new problem: the GPU screen tears down its RandR crtc
objects during CloseScreen and if one of them is active, it tries to
detach the scanout pixmap then. This crashes because
RRCrtcDetachScanoutPixmap tries to get the master screen's screen
pixmap, but crtc->pScreen->current_master is already NULL at that
point.
It doesn't make sense for an unbound GPU screen to still be scanning
out its former master screen's pixmap, so detach them first when the
provider is destroyed.
Any instructions on how to reproduce this? I've been trying to get it
to happen here.
1. Start X on an Intel system with a DisplayLink device attached.
2. xrandr --setprovideroutputsource 1 0
3. xrandr --output DVI-0 --off (unless you apply "xfree86: don't enable anything in
xf86InitialConfiguration for GPU screens")
4. xrandr --auto
5. Terminate the X server.
Program received signal SIGSEGV, Segmentation fault.
0x8010be62 in RRCrtcDetachScanoutPixmap (crtc=crtc@entry=0x80259740) at
../../randr/rrcrtc.c:370
370 ../../randr/rrcrtc.c: No such file or directory.
(gdb) bt
#0 0x8010be62 in RRCrtcDetachScanoutPixmap (crtc=crtc@entry=0x80259740) at
../../randr/rrcrtc.c:370
#1 0x8010bfab in RRCrtcDestroyResource (value=0x80259740, pid=63) at
../../randr/rrcrtc.c:678
#2 0x80062fbe in doFreeResource (res=0x8025bc58, skip=skip@entry=0) at
../../dix/resource.c:873
#3 0x8006415b in FreeClientResources (client=0x8023f350) at
../../dix/resource.c:1139
#4 0x800641fc in FreeAllResources () at ../../dix/resource.c:1154
#5 0x8002b556 in main (argc=3, argv=0xbffff704, envp=0xbffff714) at
../../dix/main.c:321
(gdb) p crtc->pScreen->current_master
$1 = (ScreenPtr) 0x0
(gdb) p crtc->pScreen->myNum
$2 = 256
I did notice that xrandr is now broken for detach? how are you detaching btw?
xrandr --setoutputprovidersource 0x67 0x0 should detach I would think,
but it fails now.
Yeah, I noticed that too, and hacked it up to allow me to test it. I'll try to
clean up the change for review.
The crash doesn't occur at detach time or if I pull the USB cable.
I'm having absolutely no luck reproducing this with the X server
master + my for-keithp tree pulled in.
I'm not sure what I could be doing different than you are, I've even
valgrinded it.
That's really weird. I wonder if stuff is initializing in a different
order on your system for some reason. I just rebuilt at commit
2746c681639f9512e6e45fb8d0151b996b6aff7f and verified that the problem
still occurs.
--
Aaron
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