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

[Daniel Vetter]

On Thu, Jun 03, 2021 at 10:25:00AM +0200, Daniel Vetter wrote:
> 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.

Oh also the longer commit message I've done would be nice to add. Or at
least link it or something like that.

https://lore.kernel.org/dri-devel/20210519101523.688398-1-daniel.vetter@ffwll.ch/

I think I mentioned this on irc, but got lost I guess.
-Daniel

> -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

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