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

[Jason Ekstrand]

On Thu, Jun 3, 2021 at 3:28 AM Daniel Vetter <daniel at ffwll.ch> wrote:
>
> 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."

Done.

> > > 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.

Done.

> 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.

Drp.  I thought I'd gotten that but I guess I failed.  Fixed now.

> -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