OSCL-LXR linux-6.0.1/​drivers/​gpu/​drm/​scheduler/​sched_main.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 /*
  * Copyright 2015 Advanced Micro Devices, Inc.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  * OTHER DEALINGS IN THE SOFTWARE.
  *
  */
 
 /**
  * DOC: Overview
  *
  * The GPU scheduler provides entities which allow userspace to push jobs
  * into software queues which are then scheduled on a hardware run queue.
  * The software queues have a priority among them. The scheduler selects the entities
  * from the run queue using a FIFO. The scheduler provides dependency handling
  * features among jobs. The driver is supposed to provide callback functions for
  * backend operations to the scheduler like submitting a job to hardware run queue,
  * returning the dependencies of a job etc.
  *
  * The organisation of the scheduler is the following:
  *
  * 1. Each hw run queue has one scheduler
  * 2. Each scheduler has multiple run queues with different priorities
  *    (e.g., HIGH_HW,HIGH_SW, KERNEL, NORMAL)
  * 3. Each scheduler run queue has a queue of entities to schedule
  * 4. Entities themselves maintain a queue of jobs that will be scheduled on
  *    the hardware.
  *
  * The jobs in a entity are always scheduled in the order that they were pushed.
  */
 
 #include <linux/kthread.h>
 #include <linux/wait.h>
 #include <linux/sched.h>
 #include <linux/completion.h>
 #include <linux/dma-resv.h>
 #include <uapi/linux/sched/types.h>
 
 #include <drm/drm_print.h>
 #include <drm/drm_gem.h>
 #include <drm/gpu_scheduler.h>
 #include <drm/spsc_queue.h>
 
 #define CREATE_TRACE_POINTS
 #include "gpu_scheduler_trace.h"
 
 #define to_drm_sched_job(sched_job)     \
         container_of((sched_job), struct drm_sched_job, queue_node)
 
 /**
  * drm_sched_rq_init - initialize a given run queue struct
  *
  * @sched: scheduler instance to associate with this run queue
  * @rq: scheduler run queue
  *
  * Initializes a scheduler runqueue.
  */
 static void drm_sched_rq_init(struct drm_gpu_scheduler *sched,
                   struct drm_sched_rq *rq)
 {
     spin_lock_init(&rq->lock);
     INIT_LIST_HEAD(&rq->entities);
     rq->current_entity = NULL;
     rq->sched = sched;
 }
 
 /**
  * drm_sched_rq_add_entity - add an entity
  *
  * @rq: scheduler run queue
  * @entity: scheduler entity
  *
  * Adds a scheduler entity to the run queue.
  */
 void drm_sched_rq_add_entity(struct drm_sched_rq *rq,
                  struct drm_sched_entity *entity)
 {
     if (!list_empty(&entity->list))
         return;
     spin_lock(&rq->lock);
     atomic_inc(rq->sched->score);
     list_add_tail(&entity->list, &rq->entities);
     spin_unlock(&rq->lock);
 }
 
 /**
  * drm_sched_rq_remove_entity - remove an entity
  *
  * @rq: scheduler run queue
  * @entity: scheduler entity
  *
  * Removes a scheduler entity from the run queue.
  */
 void drm_sched_rq_remove_entity(struct drm_sched_rq *rq,
                 struct drm_sched_entity *entity)
 {
     if (list_empty(&entity->list))
         return;
     spin_lock(&rq->lock);
     atomic_dec(rq->sched->score);
     list_del_init(&entity->list);
     if (rq->current_entity == entity)
         rq->current_entity = NULL;
     spin_unlock(&rq->lock);
 }
 
 /**
  * drm_sched_rq_select_entity - Select an entity which could provide a job to run
  *
  * @rq: scheduler run queue to check.
  *
  * Try to find a ready entity, returns NULL if none found.
  */
 static struct drm_sched_entity *
 drm_sched_rq_select_entity(struct drm_sched_rq *rq)
 {
     struct drm_sched_entity *entity;
 
     spin_lock(&rq->lock);
 
     entity = rq->current_entity;
     if (entity) {
         list_for_each_entry_continue(entity, &rq->entities, list) {
             if (drm_sched_entity_is_ready(entity)) {
                 rq->current_entity = entity;
                 reinit_completion(&entity->entity_idle);
                 spin_unlock(&rq->lock);
                 return entity;
             }
         }
     }
 
     list_for_each_entry(entity, &rq->entities, list) {
 
         if (drm_sched_entity_is_ready(entity)) {
             rq->current_entity = entity;
             reinit_completion(&entity->entity_idle);
             spin_unlock(&rq->lock);
             return entity;
         }
 
         if (entity == rq->current_entity)
             break;
     }
 
     spin_unlock(&rq->lock);
 
     return NULL;
 }
 
 /**
  * drm_sched_job_done - complete a job
  * @s_job: pointer to the job which is done
  *
  * Finish the job's fence and wake up the worker thread.
  */
 static void drm_sched_job_done(struct drm_sched_job *s_job)
 {
     struct drm_sched_fence *s_fence = s_job->s_fence;
     struct drm_gpu_scheduler *sched = s_fence->sched;
 
     atomic_dec(&sched->hw_rq_count);
     atomic_dec(sched->score);
 
     trace_drm_sched_process_job(s_fence);
 
     dma_fence_get(&s_fence->finished);
     drm_sched_fence_finished(s_fence);
     dma_fence_put(&s_fence->finished);
     wake_up_interruptible(&sched->wake_up_worker);
 }
 
 /**
  * drm_sched_job_done_cb - the callback for a done job
  * @f: fence
  * @cb: fence callbacks
  */
 static void drm_sched_job_done_cb(struct dma_fence *f, struct dma_fence_cb *cb)
 {
     struct drm_sched_job *s_job = container_of(cb, struct drm_sched_job, cb);
 
     drm_sched_job_done(s_job);
 }
 
 /**
  * drm_sched_dependency_optimized
  *
  * @fence: the dependency fence
  * @entity: the entity which depends on the above fence
  *
  * Returns true if the dependency can be optimized and false otherwise
  */
 bool drm_sched_dependency_optimized(struct dma_fence* fence,
                     struct drm_sched_entity *entity)
 {
     struct drm_gpu_scheduler *sched = entity->rq->sched;
     struct drm_sched_fence *s_fence;
 
     if (!fence || dma_fence_is_signaled(fence))
         return false;
     if (fence->context == entity->fence_context)
         return true;
     s_fence = to_drm_sched_fence(fence);
     if (s_fence && s_fence->sched == sched)
         return true;
 
     return false;
 }
 EXPORT_SYMBOL(drm_sched_dependency_optimized);
 
 /**
  * drm_sched_start_timeout - start timeout for reset worker
  *
  * @sched: scheduler instance to start the worker for
  *
  * Start the timeout for the given scheduler.
  */
 static void drm_sched_start_timeout(struct drm_gpu_scheduler *sched)
 {
     if (sched->timeout != MAX_SCHEDULE_TIMEOUT &&
         !list_empty(&sched->pending_list))
         queue_delayed_work(sched->timeout_wq, &sched->work_tdr, sched->timeout);
 }
 
 /**
  * drm_sched_fault - immediately start timeout handler
  *
  * @sched: scheduler where the timeout handling should be started.
  *
  * Start timeout handling immediately when the driver detects a hardware fault.
  */
 void drm_sched_fault(struct drm_gpu_scheduler *sched)
 {
     mod_delayed_work(sched->timeout_wq, &sched->work_tdr, 0);
 }
 EXPORT_SYMBOL(drm_sched_fault);
 
 /**
  * drm_sched_suspend_timeout - Suspend scheduler job timeout
  *
  * @sched: scheduler instance for which to suspend the timeout
  *
  * Suspend the delayed work timeout for the scheduler. This is done by
  * modifying the delayed work timeout to an arbitrary large value,
  * MAX_SCHEDULE_TIMEOUT in this case.
  *
  * Returns the timeout remaining
  *
  */
 unsigned long drm_sched_suspend_timeout(struct drm_gpu_scheduler *sched)
 {
     unsigned long sched_timeout, now = jiffies;
 
     sched_timeout = sched->work_tdr.timer.expires;
 
     /*
      * Modify the timeout to an arbitrarily large value. This also prevents
      * the timeout to be restarted when new submissions arrive
      */
     if (mod_delayed_work(sched->timeout_wq, &sched->work_tdr, MAX_SCHEDULE_TIMEOUT)
             && time_after(sched_timeout, now))
         return sched_timeout - now;
     else
         return sched->timeout;
 }
 EXPORT_SYMBOL(drm_sched_suspend_timeout);
 
 /**
  * drm_sched_resume_timeout - Resume scheduler job timeout
  *
  * @sched: scheduler instance for which to resume the timeout
  * @remaining: remaining timeout
  *
  * Resume the delayed work timeout for the scheduler.
  */
 void drm_sched_resume_timeout(struct drm_gpu_scheduler *sched,
         unsigned long remaining)
 {
     spin_lock(&sched->job_list_lock);
 
     if (list_empty(&sched->pending_list))
         cancel_delayed_work(&sched->work_tdr);
     else
         mod_delayed_work(sched->timeout_wq, &sched->work_tdr, remaining);
 
     spin_unlock(&sched->job_list_lock);
 }
 EXPORT_SYMBOL(drm_sched_resume_timeout);
 
 static void drm_sched_job_begin(struct drm_sched_job *s_job)
 {
     struct drm_gpu_scheduler *sched = s_job->sched;
 
     spin_lock(&sched->job_list_lock);
     list_add_tail(&s_job->list, &sched->pending_list);
     drm_sched_start_timeout(sched);
     spin_unlock(&sched->job_list_lock);
 }
 
 static void drm_sched_job_timedout(struct work_struct *work)
 {
     struct drm_gpu_scheduler *sched;
     struct drm_sched_job *job;
     enum drm_gpu_sched_stat status = DRM_GPU_SCHED_STAT_NOMINAL;
 
     sched = container_of(work, struct drm_gpu_scheduler, work_tdr.work);
 
     /* Protects against concurrent deletion in drm_sched_get_cleanup_job */
     spin_lock(&sched->job_list_lock);
     job = list_first_entry_or_null(&sched->pending_list,
                        struct drm_sched_job, list);
 
     if (job) {
         /*
          * Remove the bad job so it cannot be freed by concurrent
          * drm_sched_cleanup_jobs. It will be reinserted back after sched->thread
          * is parked at which point it's safe.
          */
         list_del_init(&job->list);
         spin_unlock(&sched->job_list_lock);
 
         status = job->sched->ops->timedout_job(job);
 
         /*
          * Guilty job did complete and hence needs to be manually removed
          * See drm_sched_stop doc.
          */
         if (sched->free_guilty) {
             job->sched->ops->free_job(job);
             sched->free_guilty = false;
         }
     } else {
         spin_unlock(&sched->job_list_lock);
     }
 
     if (status != DRM_GPU_SCHED_STAT_ENODEV) {
         spin_lock(&sched->job_list_lock);
         drm_sched_start_timeout(sched);
         spin_unlock(&sched->job_list_lock);
     }
 }
 
  /**
   * drm_sched_increase_karma - Update sched_entity guilty flag
   *
   * @bad: The job guilty of time out
   *
   * Increment on every hang caused by the 'bad' job. If this exceeds the hang
   * limit of the scheduler then the respective sched entity is marked guilty and
   * jobs from it will not be scheduled further
   */
 void drm_sched_increase_karma(struct drm_sched_job *bad)
 {
     drm_sched_increase_karma_ext(bad, 1);
 }
 EXPORT_SYMBOL(drm_sched_increase_karma);
 
 void drm_sched_reset_karma(struct drm_sched_job *bad)
 {
     drm_sched_increase_karma_ext(bad, 0);
 }
 EXPORT_SYMBOL(drm_sched_reset_karma);
 
 /**
  * drm_sched_stop - stop the scheduler
  *
  * @sched: scheduler instance
  * @bad: job which caused the time out
  *
  * Stop the scheduler and also removes and frees all completed jobs.
  * Note: bad job will not be freed as it might be used later and so it's
  * callers responsibility to release it manually if it's not part of the
  * pending list any more.
  *
  */
 void drm_sched_stop(struct drm_gpu_scheduler *sched, struct drm_sched_job *bad)
 {
     struct drm_sched_job *s_job, *tmp;
 
     kthread_park(sched->thread);
 
     /*
      * Reinsert back the bad job here - now it's safe as
      * drm_sched_get_cleanup_job cannot race against us and release the
      * bad job at this point - we parked (waited for) any in progress
      * (earlier) cleanups and drm_sched_get_cleanup_job will not be called
      * now until the scheduler thread is unparked.
      */
     if (bad && bad->sched == sched)
         /*
          * Add at the head of the queue to reflect it was the earliest
          * job extracted.
          */
         list_add(&bad->list, &sched->pending_list);
 
     /*
      * Iterate the job list from later to  earlier one and either deactive
      * their HW callbacks or remove them from pending list if they already
      * signaled.
      * This iteration is thread safe as sched thread is stopped.
      */
     list_for_each_entry_safe_reverse(s_job, tmp, &sched->pending_list,
                      list) {
         if (s_job->s_fence->parent &&
             dma_fence_remove_callback(s_job->s_fence->parent,
                           &s_job->cb)) {
             dma_fence_put(s_job->s_fence->parent);
             s_job->s_fence->parent = NULL;
             atomic_dec(&sched->hw_rq_count);
         } else {
             /*
              * remove job from pending_list.
              * Locking here is for concurrent resume timeout
              */
             spin_lock(&sched->job_list_lock);
             list_del_init(&s_job->list);
             spin_unlock(&sched->job_list_lock);
 
             /*
              * Wait for job's HW fence callback to finish using s_job
              * before releasing it.
              *
              * Job is still alive so fence refcount at least 1
              */
             dma_fence_wait(&s_job->s_fence->finished, false);
 
             /*
              * We must keep bad job alive for later use during
              * recovery by some of the drivers but leave a hint
              * that the guilty job must be released.
              */
             if (bad != s_job)
                 sched->ops->free_job(s_job);
             else
                 sched->free_guilty = true;
         }
     }
 
     /*
      * Stop pending timer in flight as we rearm it in  drm_sched_start. This
      * avoids the pending timeout work in progress to fire right away after
      * this TDR finished and before the newly restarted jobs had a
      * chance to complete.
      */
     cancel_delayed_work(&sched->work_tdr);
 }
 
 EXPORT_SYMBOL(drm_sched_stop);
 
 /**
  * drm_sched_start - recover jobs after a reset
  *
  * @sched: scheduler instance
  * @full_recovery: proceed with complete sched restart
  *
  */
 void drm_sched_start(struct drm_gpu_scheduler *sched, bool full_recovery)
 {
     struct drm_sched_job *s_job, *tmp;
     int r;
 
     /*
      * Locking the list is not required here as the sched thread is parked
      * so no new jobs are being inserted or removed. Also concurrent
      * GPU recovers can't run in parallel.
      */
     list_for_each_entry_safe(s_job, tmp, &sched->pending_list, list) {
         struct dma_fence *fence = s_job->s_fence->parent;
 
         atomic_inc(&sched->hw_rq_count);
 
         if (!full_recovery)
             continue;
 
         if (fence) {
             r = dma_fence_add_callback(fence, &s_job->cb,
                            drm_sched_job_done_cb);
             if (r == -ENOENT)
                 drm_sched_job_done(s_job);
             else if (r)
                 DRM_DEV_ERROR(sched->dev, "fence add callback failed (%d)\n",
                       r);
         } else
             drm_sched_job_done(s_job);
     }
 
     if (full_recovery) {
         spin_lock(&sched->job_list_lock);
         drm_sched_start_timeout(sched);
         spin_unlock(&sched->job_list_lock);
     }
 
     kthread_unpark(sched->thread);
 }
 EXPORT_SYMBOL(drm_sched_start);
 
 /**
  * drm_sched_resubmit_jobs - helper to relaunch jobs from the pending list
  *
  * @sched: scheduler instance
  *
  */
 void drm_sched_resubmit_jobs(struct drm_gpu_scheduler *sched)
 {
     drm_sched_resubmit_jobs_ext(sched, INT_MAX);
 }
 EXPORT_SYMBOL(drm_sched_resubmit_jobs);
 
 /**
  * drm_sched_resubmit_jobs_ext - helper to relunch certain number of jobs from mirror ring list
  *
  * @sched: scheduler instance
  * @max: job numbers to relaunch
  *
  */
 void drm_sched_resubmit_jobs_ext(struct drm_gpu_scheduler *sched, int max)
 {
     struct drm_sched_job *s_job, *tmp;
     uint64_t guilty_context;
     bool found_guilty = false;
     struct dma_fence *fence;
     int i = 0;
 
     list_for_each_entry_safe(s_job, tmp, &sched->pending_list, list) {
         struct drm_sched_fence *s_fence = s_job->s_fence;
 
         if (i >= max)
             break;
 
         if (!found_guilty && atomic_read(&s_job->karma) > sched->hang_limit) {
             found_guilty = true;
             guilty_context = s_job->s_fence->scheduled.context;
         }
 
         if (found_guilty && s_job->s_fence->scheduled.context == guilty_context)
             dma_fence_set_error(&s_fence->finished, -ECANCELED);
 
         fence = sched->ops->run_job(s_job);
         i++;
 
         if (IS_ERR_OR_NULL(fence)) {
             if (IS_ERR(fence))
                 dma_fence_set_error(&s_fence->finished, PTR_ERR(fence));
 
             s_job->s_fence->parent = NULL;
         } else {
 
             s_job->s_fence->parent = dma_fence_get(fence);
 
             /* Drop for orignal kref_init */
             dma_fence_put(fence);
         }
     }
 }
 EXPORT_SYMBOL(drm_sched_resubmit_jobs_ext);
 
 /**
  * drm_sched_job_init - init a scheduler job
  * @job: scheduler job to init
  * @entity: scheduler entity to use
  * @owner: job owner for debugging
  *
  * Refer to drm_sched_entity_push_job() documentation
  * for locking considerations.
  *
  * Drivers must make sure drm_sched_job_cleanup() if this function returns
  * successfully, even when @job is aborted before drm_sched_job_arm() is called.
  *
  * WARNING: amdgpu abuses &drm_sched.ready to signal when the hardware
  * has died, which can mean that there's no valid runqueue for a @entity.
  * This function returns -ENOENT in this case (which probably should be -EIO as
  * a more meanigful return value).
  *
  * Returns 0 for success, negative error code otherwise.
  */
 int drm_sched_job_init(struct drm_sched_job *job,
                struct drm_sched_entity *entity,
                void *owner)
 {
     drm_sched_entity_select_rq(entity);
     if (!entity->rq)
         return -ENOENT;
 
     job->entity = entity;
     job->s_fence = drm_sched_fence_alloc(entity, owner);
     if (!job->s_fence)
         return -ENOMEM;
 
     INIT_LIST_HEAD(&job->list);
 
     xa_init_flags(&job->dependencies, XA_FLAGS_ALLOC);
 
     return 0;
 }
 EXPORT_SYMBOL(drm_sched_job_init);
 
 /**
  * drm_sched_job_arm - arm a scheduler job for execution
  * @job: scheduler job to arm
  *
  * This arms a scheduler job for execution. Specifically it initializes the
  * &drm_sched_job.s_fence of @job, so that it can be attached to struct dma_resv
  * or other places that need to track the completion of this job.
  *
  * Refer to drm_sched_entity_push_job() documentation for locking
  * considerations.
  *
  * This can only be called if drm_sched_job_init() succeeded.
  */
 void drm_sched_job_arm(struct drm_sched_job *job)
 {
     struct drm_gpu_scheduler *sched;
     struct drm_sched_entity *entity = job->entity;
 
     BUG_ON(!entity);
 
     sched = entity->rq->sched;
 
     job->sched = sched;
     job->s_priority = entity->rq - sched->sched_rq;
     job->id = atomic64_inc_return(&sched->job_id_count);
 
     drm_sched_fence_init(job->s_fence, job->entity);
 }
 EXPORT_SYMBOL(drm_sched_job_arm);
 
 /**
  * drm_sched_job_add_dependency - adds the fence as a job dependency
  * @job: scheduler job to add the dependencies to
  * @fence: the dma_fence to add to the list of dependencies.
  *
  * Note that @fence is consumed in both the success and error cases.
  *
  * Returns:
  * 0 on success, or an error on failing to expand the array.
  */
 int drm_sched_job_add_dependency(struct drm_sched_job *job,
                  struct dma_fence *fence)
 {
     struct dma_fence *entry;
     unsigned long index;
     u32 id = 0;
     int ret;
 
     if (!fence)
         return 0;
 
     /* Deduplicate if we already depend on a fence from the same context.
      * This lets the size of the array of deps scale with the number of
      * engines involved, rather than the number of BOs.
      */
     xa_for_each(&job->dependencies, index, entry) {
         if (entry->context != fence->context)
             continue;
 
         if (dma_fence_is_later(fence, entry)) {
             dma_fence_put(entry);
             xa_store(&job->dependencies, index, fence, GFP_KERNEL);
         } else {
             dma_fence_put(fence);
         }
         return 0;
     }
 
     ret = xa_alloc(&job->dependencies, &id, fence, xa_limit_32b, GFP_KERNEL);
     if (ret != 0)
         dma_fence_put(fence);
 
     return ret;
 }
 EXPORT_SYMBOL(drm_sched_job_add_dependency);
 
 /**
  * drm_sched_job_add_implicit_dependencies - adds implicit dependencies as job
  *   dependencies
  * @job: scheduler job to add the dependencies to
  * @obj: the gem object to add new dependencies from.
  * @write: whether the job might write the object (so we need to depend on
  * shared fences in the reservation object).
  *
  * This should be called after drm_gem_lock_reservations() on your array of
  * GEM objects used in the job but before updating the reservations with your
  * own fences.
  *
  * Returns:
  * 0 on success, or an error on failing to expand the array.
  */
 int drm_sched_job_add_implicit_dependencies(struct drm_sched_job *job,
                         struct drm_gem_object *obj,
                         bool write)
 {
     struct dma_resv_iter cursor;
     struct dma_fence *fence;
     int ret;
 
     dma_resv_assert_held(obj->resv);
 
     dma_resv_for_each_fence(&cursor, obj->resv, dma_resv_usage_rw(write),
                 fence) {
         /* Make sure to grab an additional ref on the added fence */
         dma_fence_get(fence);
         ret = drm_sched_job_add_dependency(job, fence);
         if (ret) {
             dma_fence_put(fence);
             return ret;
         }
     }
     return 0;
 }
 EXPORT_SYMBOL(drm_sched_job_add_implicit_dependencies);
 
 
 /**
  * drm_sched_job_cleanup - clean up scheduler job resources
  * @job: scheduler job to clean up
  *
  * Cleans up the resources allocated with drm_sched_job_init().
  *
  * Drivers should call this from their error unwind code if @job is aborted
  * before drm_sched_job_arm() is called.
  *
  * After that point of no return @job is committed to be executed by the
  * scheduler, and this function should be called from the
  * &drm_sched_backend_ops.free_job callback.
  */
 void drm_sched_job_cleanup(struct drm_sched_job *job)
 {
     struct dma_fence *fence;
     unsigned long index;
 
     if (kref_read(&job->s_fence->finished.refcount)) {
         /* drm_sched_job_arm() has been called */
         dma_fence_put(&job->s_fence->finished);
     } else {
         /* aborted job before committing to run it */
         drm_sched_fence_free(job->s_fence);
     }
 
     job->s_fence = NULL;
 
     xa_for_each(&job->dependencies, index, fence) {
         dma_fence_put(fence);
     }
     xa_destroy(&job->dependencies);
 
 }
 EXPORT_SYMBOL(drm_sched_job_cleanup);
 
 /**
  * drm_sched_ready - is the scheduler ready
  *
  * @sched: scheduler instance
  *
  * Return true if we can push more jobs to the hw, otherwise false.
  */
 static bool drm_sched_ready(struct drm_gpu_scheduler *sched)
 {
     return atomic_read(&sched->hw_rq_count) <
         sched->hw_submission_limit;
 }
 
 /**
  * drm_sched_wakeup - Wake up the scheduler when it is ready
  *
  * @sched: scheduler instance
  *
  */
 void drm_sched_wakeup(struct drm_gpu_scheduler *sched)
 {
     if (drm_sched_ready(sched))
         wake_up_interruptible(&sched->wake_up_worker);
 }
 
 /**
  * drm_sched_select_entity - Select next entity to process
  *
  * @sched: scheduler instance
  *
  * Returns the entity to process or NULL if none are found.
  */
 static struct drm_sched_entity *
 drm_sched_select_entity(struct drm_gpu_scheduler *sched)
 {
     struct drm_sched_entity *entity;
     int i;
 
     if (!drm_sched_ready(sched))
         return NULL;
 
     /* Kernel run queue has higher priority than normal run queue*/
     for (i = DRM_SCHED_PRIORITY_COUNT - 1; i >= DRM_SCHED_PRIORITY_MIN; i--) {
         entity = drm_sched_rq_select_entity(&sched->sched_rq[i]);
         if (entity)
             break;
     }
 
     return entity;
 }
 
 /**
  * drm_sched_get_cleanup_job - fetch the next finished job to be destroyed
  *
  * @sched: scheduler instance
  *
  * Returns the next finished job from the pending list (if there is one)
  * ready for it to be destroyed.
  */
 static struct drm_sched_job *
 drm_sched_get_cleanup_job(struct drm_gpu_scheduler *sched)
 {
     struct drm_sched_job *job, *next;
 
     spin_lock(&sched->job_list_lock);
 
     job = list_first_entry_or_null(&sched->pending_list,
                        struct drm_sched_job, list);
 
     if (job && dma_fence_is_signaled(&job->s_fence->finished)) {
         /* remove job from pending_list */
         list_del_init(&job->list);
 
         /* cancel this job's TO timer */
         cancel_delayed_work(&sched->work_tdr);
         /* make the scheduled timestamp more accurate */
         next = list_first_entry_or_null(&sched->pending_list,
                         typeof(*next), list);
 
         if (next) {
             next->s_fence->scheduled.timestamp =
                 job->s_fence->finished.timestamp;
             /* start TO timer for next job */
             drm_sched_start_timeout(sched);
         }
     } else {
         job = NULL;
     }
 
     spin_unlock(&sched->job_list_lock);
 
     return job;
 }
 
 /**
  * drm_sched_pick_best - Get a drm sched from a sched_list with the least load
  * @sched_list: list of drm_gpu_schedulers
  * @num_sched_list: number of drm_gpu_schedulers in the sched_list
  *
  * Returns pointer of the sched with the least load or NULL if none of the
  * drm_gpu_schedulers are ready
  */
 struct drm_gpu_scheduler *
 drm_sched_pick_best(struct drm_gpu_scheduler **sched_list,
              unsigned int num_sched_list)
 {
     struct drm_gpu_scheduler *sched, *picked_sched = NULL;
     int i;
     unsigned int min_score = UINT_MAX, num_score;
 
     for (i = 0; i < num_sched_list; ++i) {
         sched = sched_list[i];
 
         if (!sched->ready) {
             DRM_WARN("scheduler %s is not ready, skipping",
                  sched->name);
             continue;
         }
 
         num_score = atomic_read(sched->score);
         if (num_score < min_score) {
             min_score = num_score;
             picked_sched = sched;
         }
     }
 
     return picked_sched;
 }
 EXPORT_SYMBOL(drm_sched_pick_best);
 
 /**
  * drm_sched_blocked - check if the scheduler is blocked
  *
  * @sched: scheduler instance
  *
  * Returns true if blocked, otherwise false.
  */
 static bool drm_sched_blocked(struct drm_gpu_scheduler *sched)
 {
     if (kthread_should_park()) {
         kthread_parkme();
         return true;
     }
 
     return false;
 }
 
 /**
  * drm_sched_main - main scheduler thread
  *
  * @param: scheduler instance
  *
  * Returns 0.
  */
 static int drm_sched_main(void *param)
 {
     struct drm_gpu_scheduler *sched = (struct drm_gpu_scheduler *)param;
     int r;
 
     sched_set_fifo_low(current);
 
     while (!kthread_should_stop()) {
         struct drm_sched_entity *entity = NULL;
         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,
                      (cleanup_job = drm_sched_get_cleanup_job(sched)) ||
                      (!drm_sched_blocked(sched) &&
                       (entity = drm_sched_select_entity(sched))) ||
                      kthread_should_stop());
 
         if (cleanup_job)
             sched->ops->free_job(cleanup_job);
 
         if (!entity)
             continue;
 
         sched_job = drm_sched_entity_pop_job(entity);
 
         if (!sched_job) {
             complete(&entity->entity_idle);
             continue;
         }
 
         s_fence = sched_job->s_fence;
 
         atomic_inc(&sched->hw_rq_count);
         drm_sched_job_begin(sched_job);
 
         trace_drm_run_job(sched_job, entity);
         fence = sched->ops->run_job(sched_job);
         complete(&entity->entity_idle);
         drm_sched_fence_scheduled(s_fence);
 
         if (!IS_ERR_OR_NULL(fence)) {
             s_fence->parent = dma_fence_get(fence);
             /* Drop for original kref_init of the fence */
             dma_fence_put(fence);
 
             r = dma_fence_add_callback(fence, &sched_job->cb,
                            drm_sched_job_done_cb);
             if (r == -ENOENT)
                 drm_sched_job_done(sched_job);
             else if (r)
                 DRM_DEV_ERROR(sched->dev, "fence add callback failed (%d)\n",
                       r);
         } else {
             if (IS_ERR(fence))
                 dma_fence_set_error(&s_fence->finished, PTR_ERR(fence));
 
             drm_sched_job_done(sched_job);
         }
 
         wake_up(&sched->job_scheduled);
     }
     return 0;
 }
 
 /**
  * drm_sched_init - Init a gpu scheduler instance
  *
  * @sched: scheduler instance
  * @ops: backend operations for this scheduler
  * @hw_submission: number of hw submissions that can be in flight
  * @hang_limit: number of times to allow a job to hang before dropping it
  * @timeout: timeout value in jiffies for the scheduler
  * @timeout_wq: workqueue to use for timeout work. If NULL, the system_wq is
  *      used
  * @score: optional score atomic shared with other schedulers
  * @name: name used for debugging
  *
  * Return 0 on success, otherwise error code.
  */
 int drm_sched_init(struct drm_gpu_scheduler *sched,
            const struct drm_sched_backend_ops *ops,
            unsigned hw_submission, unsigned hang_limit,
            long timeout, struct workqueue_struct *timeout_wq,
            atomic_t *score, const char *name, struct device *dev)
 {
     int i, ret;
     sched->ops = ops;
     sched->hw_submission_limit = hw_submission;
     sched->name = name;
     sched->timeout = timeout;
     sched->timeout_wq = timeout_wq ? : system_wq;
     sched->hang_limit = hang_limit;
     sched->score = score ? score : &sched->_score;
     sched->dev = dev;
     for (i = DRM_SCHED_PRIORITY_MIN; i < DRM_SCHED_PRIORITY_COUNT; i++)
         drm_sched_rq_init(sched, &sched->sched_rq[i]);
 
     init_waitqueue_head(&sched->wake_up_worker);
     init_waitqueue_head(&sched->job_scheduled);
     INIT_LIST_HEAD(&sched->pending_list);
     spin_lock_init(&sched->job_list_lock);
     atomic_set(&sched->hw_rq_count, 0);
     INIT_DELAYED_WORK(&sched->work_tdr, drm_sched_job_timedout);
     atomic_set(&sched->_score, 0);
     atomic64_set(&sched->job_id_count, 0);
 
     /* Each scheduler will run on a seperate kernel thread */
     sched->thread = kthread_run(drm_sched_main, sched, sched->name);
     if (IS_ERR(sched->thread)) {
         ret = PTR_ERR(sched->thread);
         sched->thread = NULL;
         DRM_DEV_ERROR(sched->dev, "Failed to create scheduler for %s.\n", name);
         return ret;
     }
 
     sched->ready = true;
     return 0;
 }
 EXPORT_SYMBOL(drm_sched_init);
 
 /**
  * drm_sched_fini - Destroy a gpu scheduler
  *
  * @sched: scheduler instance
  *
  * Tears down and cleans up the scheduler.
  */
 void drm_sched_fini(struct drm_gpu_scheduler *sched)
 {
     struct drm_sched_entity *s_entity;
     int i;
 
     if (sched->thread)
         kthread_stop(sched->thread);
 
     for (i = DRM_SCHED_PRIORITY_COUNT - 1; i >= DRM_SCHED_PRIORITY_MIN; i--) {
         struct drm_sched_rq *rq = &sched->sched_rq[i];
 
         if (!rq)
             continue;
 
         spin_lock(&rq->lock);
         list_for_each_entry(s_entity, &rq->entities, list)
             /*
              * Prevents reinsertion and marks job_queue as idle,
              * it will removed from rq in drm_sched_entity_fini
              * eventually
              */
             s_entity->stopped = true;
         spin_unlock(&rq->lock);
 
     }
 
     /* Wakeup everyone stuck in drm_sched_entity_flush for this scheduler */
     wake_up_all(&sched->job_scheduled);
 
     /* Confirm no work left behind accessing device structures */
     cancel_delayed_work_sync(&sched->work_tdr);
 
     sched->ready = false;
 }
 EXPORT_SYMBOL(drm_sched_fini);
 
 /**
  * drm_sched_increase_karma_ext - Update sched_entity guilty flag
  *
  * @bad: The job guilty of time out
  * @type: type for increase/reset karma
  *
  */
 void drm_sched_increase_karma_ext(struct drm_sched_job *bad, int type)
 {
     int i;
     struct drm_sched_entity *tmp;
     struct drm_sched_entity *entity;
     struct drm_gpu_scheduler *sched = bad->sched;
 
     /* don't change @bad's karma if it's from KERNEL RQ,
      * because sometimes GPU hang would cause kernel jobs (like VM updating jobs)
      * corrupt but keep in mind that kernel jobs always considered good.
      */
     if (bad->s_priority != DRM_SCHED_PRIORITY_KERNEL) {
         if (type == 0)
             atomic_set(&bad->karma, 0);
         else if (type == 1)
             atomic_inc(&bad->karma);
 
         for (i = DRM_SCHED_PRIORITY_MIN; i < DRM_SCHED_PRIORITY_KERNEL;
              i++) {
             struct drm_sched_rq *rq = &sched->sched_rq[i];
 
             spin_lock(&rq->lock);
             list_for_each_entry_safe(entity, tmp, &rq->entities, list) {
                 if (bad->s_fence->scheduled.context ==
                     entity->fence_context) {
                     if (entity->guilty)
                         atomic_set(entity->guilty, type);
                     break;
                 }
             }
             spin_unlock(&rq->lock);
             if (&entity->list != &rq->entities)
                 break;
         }
     }
 }
 EXPORT_SYMBOL(drm_sched_increase_karma_ext);

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