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@xxxxxxxx> > --- > 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@xxxxxxxxxx>
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