On Fri, Apr 11, 2014 at 11:36:02PM +0200, Daniel Vetter wrote:
The dev->struct_mutex locking in drm_irq.c only protects dev->irq_enabled. Which isn't really much at all and only prevents especially nasty ums userspace from concurrently installing the interrupt handling a few times. Or at least trying.
There are tons of unlocked readers of dev->irqs_enabled in the vblank wait code (and by extension also in the pageflip code since that uses the same vblank timestamp engine).
Real modesetting drivers should ensure that nothing can go haywire with a sane setup teardown sequence. So we only really need this for the drm_control ioctl, everywhere else this will just paper over nastiness.
Note that drm/i915 is a bit specially due to the gem+ums combination. So there we also need to properly protect the entervt and leavevt ioctls. But it's definitely saner to do everything in one go than to drop the lock in-between.
Finally there's the gpu reset code in drm/i915. That one's just race (concurrent userspace calls to for vblank waits of pageflips could spuriously fail). So wrap it up in with a nice comment since fixing this is more involved.
Signed-off-by: Daniel Vetter daniel.vetter@ffwll.ch
drivers/gpu/drm/drm_irq.c | 30 +++++++++++++----------------- drivers/gpu/drm/i915/i915_drv.c | 5 +++++ drivers/gpu/drm/i915/i915_gem.c | 5 +++-- 3 files changed, 21 insertions(+), 19 deletions(-)
Looks good to me:
Reviewed-by: Thierry Reding treding@nvidia.com