[Intel-gfx] [PATCH] drm/i915: Allow interrupts when taking the timeline->mutex

[Tvrtko Ursulin]

On 10/06/2019 11:36, Chris Wilson wrote:
> Before we commit ourselves to writing commands into the
> ringbuffer and submitting the request, allow signals to interrupt
> acquisition of the timeline mutex. We allow ourselves to be interrupted
> at any time later if we need to block for space in the ring, anyway.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/gt/intel_context.h | 5 +++--
>   drivers/gpu/drm/i915/i915_request.c     | 5 ++++-
>   2 files changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_context.h b/drivers/gpu/drm/i915/gt/intel_context.h
> index 63392c88cd98..6d5453ba2c1e 100644
> --- a/drivers/gpu/drm/i915/gt/intel_context.h
> +++ b/drivers/gpu/drm/i915/gt/intel_context.h
> @@ -113,10 +113,11 @@ static inline void intel_context_put(struct intel_context *ce)
>   	kref_put(&ce->ref, ce->ops->destroy);
>   }
>   
> -static inline void intel_context_timeline_lock(struct intel_context *ce)
> +static inline int __must_check
> +intel_context_timeline_lock(struct intel_context *ce)
>   	__acquires(&ce->ring->timeline->mutex)
>   {
> -	mutex_lock(&ce->ring->timeline->mutex);
> +	return mutex_lock_interruptible(&ce->ring->timeline->mutex);
>   }
>   
>   static inline void intel_context_timeline_unlock(struct intel_context *ce)
> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> index da1e6984a8cc..e9b59eea4f10 100644
> --- a/drivers/gpu/drm/i915/i915_request.c
> +++ b/drivers/gpu/drm/i915/i915_request.c
> @@ -784,8 +784,11 @@ struct i915_request *
>   i915_request_create(struct intel_context *ce)
>   {
>   	struct i915_request *rq;
> +	int err;
>   
> -	intel_context_timeline_lock(ce);
> +	err = intel_context_timeline_lock(ce);
> +	if (err)
> +		return ERR_PTR(err);
>   
>   	/* Move our oldest request to the slab-cache (if not in use!) */
>   	rq = list_first_entry(&ce->ring->request_list, typeof(*rq), ring_link);
> 

Patch triggered by a bug, issue, report?

We had this conundrum in a few of the other patches which added new 
mutexes. Sometimes it is less important, but in this case I suppose it 
is better to handle signals.

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Regards,

Tvrtko