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drm/sched: Clarify docu concerning drm_sched_job_arm()

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The documentation for drm_sched_job_arm() and especially
drm_sched_job_cleanup() does not make it very clear why
drm_sched_job_arm() is a point of no return, which it indeed is.

Make the nature of drm_sched_job_arm() in the docu as clear as possible.

Suggested-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Philipp Stanner <phasta@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20250313093053.65001-2-phasta@kernel.org
This commit is contained in:
Philipp Stanner 2025-03-13 10:30:54 +01:00
parent 6df22c6f18
commit 9df13c356d
1 changed files with 18 additions and 6 deletions
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24
drivers/gpu/drm/scheduler/sched_main.c
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@ -828,11 +828,15 @@ EXPORT_SYMBOL(drm_sched_job_init);
*
* 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.
* or other places that need to track the completion of this job. It also
* initializes sequence numbers, which are fundamental for fence ordering.
*
* Refer to drm_sched_entity_push_job() documentation for locking
* considerations.
*
* Once this function was called, you *must* submit @job with
* drm_sched_entity_push_job().
*
* This can only be called if drm_sched_job_init() succeeded.
*/
void drm_sched_job_arm(struct drm_sched_job *job)
@ -1017,9 +1021,12 @@ EXPORT_SYMBOL(drm_sched_job_has_dependency);
* 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.
* drm_sched_job_arm() is a point of no return since it initializes the fences
* and their sequence number etc. Once that function has been called, you *must*
* submit it with drm_sched_entity_push_job() and cannot simply abort it by
* calling drm_sched_job_cleanup().
*
* This function should be called in the &drm_sched_backend_ops.free_job callback.
*/
void drm_sched_job_cleanup(struct drm_sched_job *job)
{
@ -1027,10 +1034,15 @@ void drm_sched_job_cleanup(struct drm_sched_job *job)
unsigned long index;
if (kref_read(&job->s_fence->finished.refcount)) {
/* drm_sched_job_arm() has been called */
/* The job has been processed by the scheduler, i.e.,
* drm_sched_job_arm() and drm_sched_entity_push_job() have
* been called.
*/
dma_fence_put(&job->s_fence->finished);
} else {
/* aborted job before committing to run it */
/* The job was aborted before it has been committed to be run;
* notably, drm_sched_job_arm() has not been called.
*/
drm_sched_fence_free(job->s_fence);
}