Am 25.09.19 um 17:14 schrieb Steven Price:
> drm_sched_cleanup_jobs() attempts to free finished jobs, however because
> it is called as the condition of wait_event_interruptible() it must not
> sleep. Unfortunately some free callbacks (notably for Panfrost) do sleep.
>
> Instead let's rename drm_sched_cleanup_jobs() to
> drm_sched_get_cleanup_job() and simply return a job for processing if
> there is one. The caller can then call the free_job() callback outside
> the wait_event_interruptible() where sleeping is possible before
> re-checking and returning to sleep if necessary.
>
> Signed-off-by: Steven Price <steven.pr...@arm.com>
> ---
>   drivers/gpu/drm/scheduler/sched_main.c | 44 ++++++++++++++------------
>   1 file changed, 24 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpu/drm/scheduler/sched_main.c 
> b/drivers/gpu/drm/scheduler/sched_main.c
> index 9a0ee74d82dc..0ed4aaa4e6d1 100644
> --- a/drivers/gpu/drm/scheduler/sched_main.c
> +++ b/drivers/gpu/drm/scheduler/sched_main.c
> @@ -622,43 +622,41 @@ static void drm_sched_process_job(struct dma_fence *f, 
> struct dma_fence_cb *cb)
>   }
>   
>   /**
> - * drm_sched_cleanup_jobs - destroy finished jobs
> + * drm_sched_get_cleanup_job - fetch the next finished job to be destroyed
>    *
>    * @sched: scheduler instance
>    *
> - * Remove all finished jobs from the mirror list and destroy them.
> + * Returns the next finished job from the mirror list (if there is one)
> + * ready for it to be destroyed.
>    */
> -static void drm_sched_cleanup_jobs(struct drm_gpu_scheduler *sched)
> +static struct drm_sched_job *
> +drm_sched_get_cleanup_job(struct drm_gpu_scheduler *sched)
>   {
> +     struct drm_sched_job *job = NULL;
>       unsigned long flags;
>   
>       /* Don't destroy jobs while the timeout worker is running */
>       if (sched->timeout != MAX_SCHEDULE_TIMEOUT &&
>           !cancel_delayed_work(&sched->work_tdr))
> -             return;
> -
> -
> -     while (!list_empty(&sched->ring_mirror_list)) {
> -             struct drm_sched_job *job;
> +             return NULL;
>   
> -             job = list_first_entry(&sched->ring_mirror_list,
> +     job = list_first_entry_or_null(&sched->ring_mirror_list,
>                                      struct drm_sched_job, node);

This is probably better done after taking the lock, apart from that 
looks good to me.

Christian.

> -             if (!dma_fence_is_signaled(&job->s_fence->finished))
> -                     break;
>   
> -             spin_lock_irqsave(&sched->job_list_lock, flags);
> +     spin_lock_irqsave(&sched->job_list_lock, flags);
> +
> +     if (job && dma_fence_is_signaled(&job->s_fence->finished)) {
>               /* remove job from ring_mirror_list */
>               list_del_init(&job->node);
> -             spin_unlock_irqrestore(&sched->job_list_lock, flags);
> -
> -             sched->ops->free_job(job);
> +     } else {
> +             job = NULL;
> +             /* queue timeout for next job */
> +             drm_sched_start_timeout(sched);
>       }
>   
> -     /* queue timeout for next job */
> -     spin_lock_irqsave(&sched->job_list_lock, flags);
> -     drm_sched_start_timeout(sched);
>       spin_unlock_irqrestore(&sched->job_list_lock, flags);
>   
> +     return job;
>   }
>   
>   /**
> @@ -698,12 +696,18 @@ static int drm_sched_main(void *param)
>               struct drm_sched_fence *s_fence;
>               struct drm_sched_job *sched_job;
>               struct dma_fence *fence;
> +             struct drm_sched_job *cleanup_job = NULL;
>   
>               wait_event_interruptible(sched->wake_up_worker,
> -                                      (drm_sched_cleanup_jobs(sched),
> +                                      (cleanup_job = 
> drm_sched_get_cleanup_job(sched)) ||
>                                        (!drm_sched_blocked(sched) &&
>                                         (entity = 
> drm_sched_select_entity(sched))) ||
> -                                      kthread_should_stop()));
> +                                      kthread_should_stop());
> +
> +             while (cleanup_job) {
> +                     sched->ops->free_job(cleanup_job);
> +                     cleanup_job = drm_sched_get_cleanup_job(sched);
> +             }
>   
>               if (!entity)
>                       continue;

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