On Mon, Mar 06, 2017 at 11:23:04AM +0000, Chris Wilson wrote: > As we may queue addition requests from the submit fence, we may recurse > into i9xx_submit_request() and write a future request's TAIL only to be > then overwritten by the parent. Reorder the hw write before the signal > so that any child fences that then submit fences are ordered correctly. > > Reported-by: Pavel Machek <pavel@xxxxxx> > Reported-by: Josh Holland <anowlcalledjosh@xxxxxxxxx> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99671 > Fixes: d55ac5bf97c6 ("drm/i915: Defer transfer onto execution timeline to actual hw submission") > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > Cc: <stable@xxxxxxxxxxxxxxx> # v4.10+ > --- > drivers/gpu/drm/i915/intel_ringbuffer.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c > index 4a864f8c9387..93cc7b001d0b 100644 > --- a/drivers/gpu/drm/i915/intel_ringbuffer.c > +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c > @@ -782,10 +782,10 @@ static void i9xx_submit_request(struct drm_i915_gem_request *request) > { > struct drm_i915_private *dev_priv = request->i915; > > - i915_gem_request_submit(request); > - > GEM_BUG_ON(!IS_ALIGNED(request->tail, 8)); > I915_WRITE_TAIL(request->engine, request->tail); > + Probably should stick a /* May recurse and cause more TAIL updates - must be after our update! */ here > + i915_gem_request_submit(request); > } -- Chris Wilson, Intel Open Source Technology Centre