Re: [PATCH] drm/i915/selftests: Fix build after dma-fence locking rework

[Matthew Brost <matthew.brost@intel.com>]

On Mon, Feb 23, 2026 at 08:33:05PM +0100, Christian König wrote:
> On 2/23/26 20:20, Matthew Brost wrote:
> > On Mon, Feb 23, 2026 at 08:13:34PM +0100, Christian König wrote:
> >> On 2/23/26 18:25, Matthew Brost wrote:
> >>> The i915_active selftest no longer builds after the dma-fence locking
> >>> rework because it directly accessed the fence’s spinlock. The helper
> >>> dma_fence_spinlock() must now be used to obtain the spinlock. Update the
> >>> selftest to use dma_fence_spinlock() accordingly.
> >>>
> >>> Fixes: 1f32f310a13c ("dma-buf: inline spinlock for fence protection v5")
> >>> Cc: Christian König <christian.koenig@amd.com>
> >>> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> >>
> >> Reviewed-by: Christian König <christian.koenig@amd.com>
> >>
> >> Thanks for the patch and sorry for the noise, just one more question below.
> >>
> >>> ---
> >>>  drivers/gpu/drm/i915/selftests/i915_active.c | 4 ++--
> >>>  1 file changed, 2 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/drivers/gpu/drm/i915/selftests/i915_active.c b/drivers/gpu/drm/i915/selftests/i915_active.c
> >>> index 52345073b409..9fea2fabeac4 100644
> >>> --- a/drivers/gpu/drm/i915/selftests/i915_active.c
> >>> +++ b/drivers/gpu/drm/i915/selftests/i915_active.c
> >>> @@ -323,9 +323,9 @@ static void active_flush(struct i915_active *ref,
> >>>  	if (!fence)
> >>>  		return;
> >>>  
> >>> -	spin_lock_irq(fence->lock);
> >>> +	spin_lock_irq(dma_fence_spinlock(fence));
> >>
> >> Is it guaranteed that this is called from interrupt context? E.g. why is spin_lock_irq() instead of spin_lock_irqsafe() used here?
> >>
> > 
> > Idk, this i915 stuff I’ve long intentionally tried to forget to avoid nightmares.
> > 
> >> That's basically the reason why I missed this.
> >>
> > 
> > Also, please include the intel-xe list for CI — that will catch issues as well.
> > 
> > We’re making it a bit further now, but we’re hitting a lockdep splat [1].
> 
> ^^ that actually looks like a bug in dma_fence_chain_enable_signaling() which was there before the patch set and now just get bubbled up because lockdep can finally check on it.
> 
> Just reverting "dma-buf: use inline lock for the dma-fence-chain" should silence that again, but it is clearly not the right fix.
> 

Ah, ok. Well let's just figure this out properly.

> > I can dig into it now; hopefully it’s an easy fix. If not, I may ask for
> > a revert. Give me an hour or so to look into it and I’ll report back.
> > But again, please include the intel-xe list for CI on risky DRM common
> > or dma-buf patches — if the patches apply to drm-tip, CI will run. You
> > should have permission to trigger this; I believe all AMD emails do.
> 
> I did that on an older version of the patch set but never got a report back. My assumption was that it's working but could be that this actually never ran.
> 

Got a link? I working on recreating this now on my dev box. Any hints to
speed up verifying a fix would be helpful.

Matt

> Regards,
> Christian.
> 
> > 
> > Matt  
> > 
> > [1] https://intel-gfx-ci.01.org/tree/intel-xe/xe-pw-161999v1/bat-ptl-1/igt@xe_compute@compute-square.html
> > 
> >> Regards,
> >> Christian.
> >>
> >>>  	__list_del_entry(&active->cb.node);
> >>> -	spin_unlock_irq(fence->lock); /* serialise with fence->cb_list */
> >>> +	spin_unlock_irq(dma_fence_spinlock(fence)); /* serialise with fence->cb_list */
> >>>  	atomic_dec(&ref->count);
> >>>  
> >>>  	GEM_BUG_ON(!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags));
> >>
>