Re: [PATCH 3/6] drm/amdgpu: screen freeze and userq driver crash

["Paneer Selvam, Arunpravin" <arunpravin.paneerselvam@xxxxxxx>]

Hi Christian,

On 9/5/2024 4:50 PM, Christian König wrote:
> Am 30.08.24 um 20:43 schrieb Arunpravin Paneer Selvam:
> > Screen freeze and userq fence driver crash while playing Xonotic
> >
> > Signed-off-by: Arunpravin Paneer Selvam 
> > <Arunpravin.PaneerSelvam@xxxxxxx>
> > ---
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c | 12 +++++++-----
> >   1 file changed, 7 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c 
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
> > index d2e1d0d0f29f..8a3b5374cc1a 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
> > @@ -187,6 +187,7 @@ int amdgpu_userq_fence_create(struct 
> > amdgpu_usermode_queue *userq,
> >       struct amdgpu_userq_fence_driver *fence_drv;
> >       struct amdgpu_userq_fence *userq_fence;
> >       struct dma_fence *fence;
> > +    unsigned long flags;
> >         fence_drv = userq->fence_drv;
> >       if (!fence_drv)
> > @@ -230,14 +231,15 @@ int amdgpu_userq_fence_create(struct 
> > amdgpu_usermode_queue *userq,
> >           }
> >       }
> >   -    spin_lock(&fence_drv->fence_list_lock);
> >       /* Check if hardware has already processed the job */
> > -    if (!dma_fence_is_signaled(fence))
> > +    if (!dma_fence_is_signaled(fence)) {
> > +        spin_lock_irqsave(&fence_drv->fence_list_lock, flags);
>
> As far as I can see that still won't work correctly since you can't 
> guarantee that the fence doesn't signal in between testing and 
> grabbing the lock.
Can I move the spin lock little up before the if .. else check.

Thanks,
Arun.
> Christian.
>
>
>
> > list_add_tail(&userq_fence->link, &fence_drv->fences);
> > -    else
> > -        dma_fence_put(fence);
> >   -    spin_unlock(&fence_drv->fence_list_lock);
> > + spin_unlock_irqrestore(&fence_drv->fence_list_lock, flags);
> > +    } else {
> > +        dma_fence_put(fence);
> > +    }
> >         *f = fence;