AMD General
Regards,
Prike
> -----Original Message-----
> From: Alex Deucher <[email protected]>
> Sent: Wednesday, August 19, 2026 11:52 PM
> To: Liang, Prike <[email protected]>
> Cc: [email protected]; Deucher, Alexander
> <[email protected]>; Koenig, Christian <[email protected]>
> Subject: Re: [PATCH v2] drm/amdgpu/userq: fix lock missing for userq fence
> error
> set
>
> On Thu, Aug 13, 2026 at 11:50 PM Prike Liang <[email protected]> wrote:
> >
> > amdgpu_userq_fence_driver() and amdgpu_userq_fence_driver_destroy()
> > don't acquire the dma_fence spinlock, so locking the dma_fence lock
> > before test the signaled state and set error state.
> >
> > Signed-off-by: Prike Liang <[email protected]>
> > ---
> > .../gpu/drm/amd/amdgpu/amdgpu_userq_fence.c | 20 ++++++++++++-------
> > 1 file changed, 13 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
> > index 19af1adc2921..09e2079cfdbd 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
> > @@ -191,14 +191,15 @@ void amdgpu_userq_fence_driver_destroy(struct kref
> *ref)
> > struct dma_fence *f;
> >
> > spin_lock_irqsave(&fence_drv->fence_list_lock, flags);
> > + lockdep_assert_held(&fence_drv->fence_list_lock);
> > list_for_each_entry_safe(fence, tmp, &fence_drv->fences, link) {
> > f = &fence->base;
> > -
> > - if (!dma_fence_is_signaled(f)) {
> > + spin_lock(dma_fence_spinlock(f));
> > + if (!dma_fence_is_signaled_locked(f)) {
> > dma_fence_set_error(f, -ECANCELED);
> > - dma_fence_signal(f);
> > + dma_fence_signal_locked(f);
> > }
> > -
> > + spin_unlock(dma_fence_spinlock(f));
> > list_del(&fence->link);
> > dma_fence_put(f);
> > }
> > @@ -423,11 +424,16 @@ amdgpu_userq_fence_driver_set_error(struct
> amdgpu_userq_fence *fence,
> > struct dma_fence *f;
> >
> > spin_lock_irqsave(&fence_drv->fence_list_lock, flags);
> > -
> > + lockdep_assert_held(&fence_drv->fence_list_lock);
> > f = rcu_dereference_protected(&fence->base,
> >
> > lockdep_is_held(&fence_drv->fence_list_lock));
> > - if (f && !dma_fence_is_signaled_locked(f))
> > - dma_fence_set_error(f, error);
> > + if (f) {
> > + /* nest f->lock inside fence_list_lock */
> > + spin_lock(dma_fence_spinlock(f));
>
> Why do we need to take the fence spinlock for userqs, but not for kernel
> queues?
> See amdgpu_fence.c
For the kernel queue ring fence, we also need to hold the dma_fence lock when
calling dma_fence_is_signaled_locked(). The reason that does not assert the
lock missing for the kernel ring fence is the .signaled() callback is not
implemented, so dma_fence_signal_locked() will never be invoked.
Thanks,
Prike
> Alex
>
> > + if (!dma_fence_is_signaled_locked(f))
> > + dma_fence_set_error(f, error);
> > + spin_unlock(dma_fence_spinlock(f));
> > + }
> > spin_unlock_irqrestore(&fence_drv->fence_list_lock, flags); }
> >
> > --
> > 2.34.1
> >
