git: drm - Fix panic on DRM_IOCTL_WAIT_VBLANK

[Matthew Dillon]

commit 3256313cd10e4b39701aa9a9cf0aa4347dae42d8
Author: Matthew Dillon <dillon at apollo.backplane.com>
Date:   Sat Dec 26 16:11:04 2015 -0800

    drm - Fix panic on DRM_IOCTL_WAIT_VBLANK
    
    * DRM_IOCTL_WAIT_VBLANK -> drm_wait_vblank() -> DRM_WAIT_ON() -> panic
    
      DRM_WAIT_ON() assumed that the device was locked and tried to unlock
      and relock it around the tsleep.  However, the ioctl paths that use
      this function do not lock the device.
    
    * Remove the unlock/relock sequence.
    
    * Tested on haswell using ioctl call w/vblank.request.type =
       _DRM_VBLANK_RELATIVE and vblank.request.sequence = 10.  Crash reproduced
       before fix, does not occur after fix.
    
    Reported-by: arcade at b1t.name

Summary of changes:
 sys/dev/drm/include/drm/drmP.h | 2 --
 1 file changed, 2 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/3256313cd10e4b39701aa9a9cf0aa4347dae42d8


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