Re: [Intel-gfx] [PATCH 5/7] drm/i915: Always wait for the exclusive fence

[Daniel Vetter <daniel.vetter@ffwll.ch>]

On Tue, Jul 6, 2021 at 2:47 PM Matthew Auld
<matthew.william.auld@gmail.com> wrote:
>
> On Tue, 6 Jul 2021 at 11:12, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> >
> > We're lifting, or well, clarifying that the restriction that shared
> > fences have to be strictly after the exclusive one doesn't apply
> > anymore.
> >
> > So adjust the code to always also wait for the exclusive fence.
> >
> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> > Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> > Cc: "Thomas Hellström" <thomas.hellstrom@linux.intel.com>
> > Cc: Jason Ekstrand <jason@jlekstrand.net>
> > ---
> >  drivers/gpu/drm/i915/i915_sw_fence.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c
> > index 91711a46b1c7..271d321cea83 100644
> > --- a/drivers/gpu/drm/i915/i915_sw_fence.c
> > +++ b/drivers/gpu/drm/i915/i915_sw_fence.c
> > @@ -601,10 +601,10 @@ int i915_sw_fence_await_reservation(struct i915_sw_fence *fence,
> >                 for (i = 0; i < count; i++)
> >                         dma_fence_put(shared[i]);
> >                 kfree(shared);
> > -       } else {
> > -               excl = dma_resv_get_excl_unlocked(resv);
> >         }
> >
> > +       excl = dma_resv_get_excl_unlocked(resv);
> > +
>
> The dma_resv_get_fences() call looks like it already fishes out the
> exclusive fence. Does this not leak the extra ref now?

Oh right I overlooked this, we already pick up the exclusive fence
unconditionally. Control flow here was a bit too clever for my parser.
I'll drop this patch in the next round.
-Daniel

>
> >         if (ret >= 0 && excl) {
> >                 pending = i915_sw_fence_await_dma_fence(fence,
> >                                                         excl,
> > --
> > 2.32.0
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx



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