Bug 109218

Summary: PresentPixmap doesn't work with XSync fences, crashes server
Product: xorg Reporter: Yuxuan Shui <yshuiv7>
Component: Driver/intelAssignee: Chris Wilson <chris>
Status: RESOLVED MOVED QA Contact: Intel GFX Bugs mailing list <intel-gfx-bugs>
Severity: major    
Priority: medium    
Version: unspecified   
Hardware: x86-64 (AMD64)   
OS: Linux (All)   
Whiteboard:
i915 platform: i915 features:

Description Yuxuan Shui 2019-01-03 23:09:06 UTC
In an experimental branch of compton, I tried using PresentPixmap with xrender to achieve tear free display. I discovered that the XSync fence passed to PresentPixmap never gets triggered, and when I kill compton, the whole server crashes.

I don't have a stack trace, but X server crashed in a function called AttendClient trying to dereference 0x28.

Maybe intel driver only supports fences created via DRI3FenceFromFD. That should've been made clear somewhere (where?), and X server definitely shouldn't crash.
Comment 1 Yuxuan Shui 2019-01-03 23:09:49 UTC
BTW, I suspected the fence because when I don't pass a fence to PresentPixmap, everything seems to work fine.
Comment 2 Yuxuan Shui 2019-01-08 21:55:24 UTC
If you want a testcase, you can try commit 055364431a0706b97c2875d5501dc20dbcf1bdeb of compton.
Comment 3 Martin Peres 2019-11-27 13:49:59 UTC
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