Re: [PATCH v7 3/9] drm/xe: Add dedicated message lock

[Philipp Stanner <pstanner@redhat.com>]

On Mon, 2025-12-01 at 10:39 -0800, Matthew Brost wrote:
> Stop abusing DRM scheduler job list lock for messages, add dedicated
> message lock.
> 
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> Reviewed-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>

Nice! Me gusta.


Acked-by: Philipp Stanner <phasta@kernel.org>

> ---
>  drivers/gpu/drm/xe/xe_gpu_scheduler.c       | 5 +++--
>  drivers/gpu/drm/xe/xe_gpu_scheduler.h       | 4 ++--
>  drivers/gpu/drm/xe/xe_gpu_scheduler_types.h | 2 ++
>  3 files changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gpu_scheduler.c b/drivers/gpu/drm/xe/xe_gpu_scheduler.c
> index f91e06d03511..f4f23317191f 100644
> --- a/drivers/gpu/drm/xe/xe_gpu_scheduler.c
> +++ b/drivers/gpu/drm/xe/xe_gpu_scheduler.c
> @@ -77,6 +77,7 @@ int xe_sched_init(struct xe_gpu_scheduler *sched,
>  	};
>  
>  	sched->ops = xe_ops;
> +	spin_lock_init(&sched->msg_lock);
>  	INIT_LIST_HEAD(&sched->msgs);
>  	INIT_WORK(&sched->work_process_msg, xe_sched_process_msg_work);
>  
> @@ -117,7 +118,7 @@ void xe_sched_add_msg(struct xe_gpu_scheduler *sched,
>  void xe_sched_add_msg_locked(struct xe_gpu_scheduler *sched,
>  			     struct xe_sched_msg *msg)
>  {
> -	lockdep_assert_held(&sched->base.job_list_lock);
> +	lockdep_assert_held(&sched->msg_lock);
>  
>  	list_add_tail(&msg->link, &sched->msgs);
>  	xe_sched_process_msg_queue(sched);
> @@ -131,7 +132,7 @@ void xe_sched_add_msg_locked(struct xe_gpu_scheduler *sched,
>  void xe_sched_add_msg_head(struct xe_gpu_scheduler *sched,
>  			   struct xe_sched_msg *msg)
>  {
> -	lockdep_assert_held(&sched->base.job_list_lock);
> +	lockdep_assert_held(&sched->msg_lock);
>  
>  	list_add(&msg->link, &sched->msgs);
>  	xe_sched_process_msg_queue(sched);
> diff --git a/drivers/gpu/drm/xe/xe_gpu_scheduler.h b/drivers/gpu/drm/xe/xe_gpu_scheduler.h
> index c7a77a3a9681..dceb2cd0ee5b 100644
> --- a/drivers/gpu/drm/xe/xe_gpu_scheduler.h
> +++ b/drivers/gpu/drm/xe/xe_gpu_scheduler.h
> @@ -33,12 +33,12 @@ void xe_sched_add_msg_head(struct xe_gpu_scheduler *sched,
>  
>  static inline void xe_sched_msg_lock(struct xe_gpu_scheduler *sched)
>  {
> -	spin_lock(&sched->base.job_list_lock);
> +	spin_lock(&sched->msg_lock);
>  }
>  
>  static inline void xe_sched_msg_unlock(struct xe_gpu_scheduler *sched)
>  {
> -	spin_unlock(&sched->base.job_list_lock);
> +	spin_unlock(&sched->msg_lock);
>  }
>  
>  static inline void xe_sched_stop(struct xe_gpu_scheduler *sched)
> diff --git a/drivers/gpu/drm/xe/xe_gpu_scheduler_types.h b/drivers/gpu/drm/xe/xe_gpu_scheduler_types.h
> index 6731b13da8bb..63d9bf92583c 100644
> --- a/drivers/gpu/drm/xe/xe_gpu_scheduler_types.h
> +++ b/drivers/gpu/drm/xe/xe_gpu_scheduler_types.h
> @@ -47,6 +47,8 @@ struct xe_gpu_scheduler {
>  	const struct xe_sched_backend_ops	*ops;
>  	/** @msgs: list of messages to be processed in @work_process_msg */
>  	struct list_head			msgs;
> +	/** @msg_lock: Message lock */
> +	spinlock_t				msg_lock;
>  	/** @work_process_msg: processes messages */
>  	struct work_struct		work_process_msg;
>  };