[PATCH 1/2] drm/amdgpu: change job_list_lock to mutex

[Huang Rui]

On Tue, Jun 28, 2016 at 03:04:18PM +0800, Chunming Zhou wrote:
> ring_mirror_list is only used kthread context, no need to spinlock.
> otherwise deadlock happens when kthread_park.
> 

Yes, in process context, we prefer to use mutex, because it avoids to
grab the CPU all the time.

Reviewed-by: Huang Rui <ray.huang at amd.com>

> Change-Id: I906022297015faf14a0ddb5f62a728af3e5f9448
> Signed-off-by: Chunming Zhou <David1.Zhou at amd.com>
> ---
>  drivers/gpu/drm/amd/scheduler/gpu_scheduler.c | 12 +++++-------
>  drivers/gpu/drm/amd/scheduler/gpu_scheduler.h |  2 +-
>  2 files changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
> index b53cf58..3373d97 100644
> --- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
> +++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
> @@ -331,10 +331,9 @@ static void amd_sched_job_finish(struct work_struct *work)
>  	struct amd_sched_job *s_job = container_of(work, struct amd_sched_job,
>  						   finish_work);
>  	struct amd_gpu_scheduler *sched = s_job->sched;
> -	unsigned long flags;
>  
>  	/* remove job from ring_mirror_list */
> -	spin_lock_irqsave(&sched->job_list_lock, flags);
> +	mutex_lock(&sched->job_list_lock);
>  	list_del_init(&s_job->node);
>  	if (sched->timeout != MAX_SCHEDULE_TIMEOUT) {
>  		struct amd_sched_job *next;
> @@ -348,7 +347,7 @@ static void amd_sched_job_finish(struct work_struct *work)
>  		if (next)
>  			schedule_delayed_work(&next->work_tdr, sched->timeout);
>  	}
> -	spin_unlock_irqrestore(&sched->job_list_lock, flags);
> +	mutex_unlock(&sched->job_list_lock);
>  	sched->ops->free_job(s_job);
>  }
>  
> @@ -362,15 +361,14 @@ static void amd_sched_job_finish_cb(struct fence *f, struct fence_cb *cb)
>  static void amd_sched_job_begin(struct amd_sched_job *s_job)
>  {
>  	struct amd_gpu_scheduler *sched = s_job->sched;
> -	unsigned long flags;
>  
> -	spin_lock_irqsave(&sched->job_list_lock, flags);
> +	mutex_lock(&sched->job_list_lock);
>  	list_add_tail(&s_job->node, &sched->ring_mirror_list);
>  	if (sched->timeout != MAX_SCHEDULE_TIMEOUT &&
>  	    list_first_entry_or_null(&sched->ring_mirror_list,
>  				     struct amd_sched_job, node) == s_job)
>  		schedule_delayed_work(&s_job->work_tdr, sched->timeout);
> -	spin_unlock_irqrestore(&sched->job_list_lock, flags);
> +	mutex_unlock(&sched->job_list_lock);
>  }
>  
>  static void amd_sched_job_timedout(struct work_struct *work)
> @@ -564,7 +562,7 @@ int amd_sched_init(struct amd_gpu_scheduler *sched,
>  	init_waitqueue_head(&sched->wake_up_worker);
>  	init_waitqueue_head(&sched->job_scheduled);
>  	INIT_LIST_HEAD(&sched->ring_mirror_list);
> -	spin_lock_init(&sched->job_list_lock);
> +	mutex_init(&sched->job_list_lock);
>  	atomic_set(&sched->hw_rq_count, 0);
>  	if (atomic_inc_return(&sched_fence_slab_ref) == 1) {
>  		sched_fence_slab = kmem_cache_create(
> diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
> index 221a515..5675906 100644
> --- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
> +++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
> @@ -132,7 +132,7 @@ struct amd_gpu_scheduler {
>  	atomic_t			hw_rq_count;
>  	struct task_struct		*thread;
>  	struct list_head	ring_mirror_list;
> -	spinlock_t			job_list_lock;
> +	struct mutex			job_list_lock;
>  };
>  
>  int amd_sched_init(struct amd_gpu_scheduler *sched,
> -- 
> 1.9.1
> 
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