[Intel-gfx] [PATCH 4/5] Revert "drm/i915: Propagate errors on awaiting already signaled fences"

[Daniel Vetter]

On Thu, Jun 03, 2021 at 10:24:21AM +0200, Daniel Vetter wrote:
> On Wed, Jun 02, 2021 at 11:41:48AM -0500, Jason Ekstrand wrote:
> > This reverts commit 9e31c1fe45d555a948ff66f1f0e3fe1f83ca63f7.  Ever
> > since that commit, we've been having issues where a hang in one client
> > can propagate to another.  In particular, a hang in an app can propagate
> > to the X server which causes the whole desktop to lock up.
> 
> I think we need a note to backporters here:
> 
> "For backporters: Please note that you _must_ have a backport of
> https://lore.kernel.org/dri-devel/20210602164149.391653-2-jason@jlekstrand.net/
> for otherwise backporting just this patch opens up a security bug."
>  
> Or something like that.

Oh also reordering the patch set so the 2 reverts which are cc: stable are
first, then the other stuff on top that cleans up the fallout.
-Daniel

> -Daniel
> 
> > Signed-off-by: Jason Ekstrand <jason.ekstrand at intel.com>
> > Reported-by: Marcin Slusarz <marcin.slusarz at intel.com>
> > Cc: <stable at vger.kernel.org> # v5.6+
> > Cc: Jason Ekstrand <jason.ekstrand at intel.com>
> > Cc: Marcin Slusarz <marcin.slusarz at intel.com>
> > Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/3080
> > Fixes: 9e31c1fe45d5 ("drm/i915: Propagate errors on awaiting already signaled fences")
> > Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> > Reviewed-by: Jon Bloomfield <jon.bloomfield at intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_request.c | 8 ++------
> >  1 file changed, 2 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> > index 970d8f4986bbe..b796197c07722 100644
> > --- a/drivers/gpu/drm/i915/i915_request.c
> > +++ b/drivers/gpu/drm/i915/i915_request.c
> > @@ -1426,10 +1426,8 @@ i915_request_await_execution(struct i915_request *rq,
> >  
> >  	do {
> >  		fence = *child++;
> > -		if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
> > -			i915_sw_fence_set_error_once(&rq->submit, fence->error);
> > +		if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
> >  			continue;
> > -		}
> >  
> >  		if (fence->context == rq->fence.context)
> >  			continue;
> > @@ -1527,10 +1525,8 @@ i915_request_await_dma_fence(struct i915_request *rq, struct dma_fence *fence)
> >  
> >  	do {
> >  		fence = *child++;
> > -		if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
> > -			i915_sw_fence_set_error_once(&rq->submit, fence->error);
> > +		if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
> >  			continue;
> > -		}
> >  
> >  		/*
> >  		 * Requests on the same timeline are explicitly ordered, along
> > -- 
> > 2.31.1
> > 
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch