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drm/sched: Adjust outdated docu for run_job() 

The documentation for drm_sched_backend_ops.run_job() mentions a certain
function called drm_sched_job_recovery(). This function does not exist.
What's actually meant is drm_sched_resubmit_jobs(), which is by now also
deprecated.

Furthermore, the scheduler expects to "inherit" a reference on the fence
from the run_job() callback. This, so far, is also not documented.

Remove the mention of the removed function.

Discourage the behavior of drm_sched_backend_ops.run_job() being called
multiple times for the same job.

Document the necessity of incrementing the refcount in run_job().

Acked-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Philipp Stanner <phasta@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20250305130551.136682-3-phasta@kernel.org
This commit is contained in:
Philipp Stanner 2025-03-05 14:05:50 +01:00
parent b72f66f22c
commit 87edca6261
1 changed files with 30 additions and 4 deletions
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34
include/drm/gpu_scheduler.h
View File

@ -410,10 +410,36 @@ struct drm_sched_backend_ops {
struct drm_sched_entity *s_entity);
/**
* @run_job: Called to execute the job once all of the dependencies
* have been resolved. This may be called multiple times, if
* timedout_job() has happened and drm_sched_job_recovery()
* decides to try it again.
* @run_job: Called to execute the job once all of the dependencies
* have been resolved.
*
* @sched_job: the job to run
*
* The deprecated drm_sched_resubmit_jobs() (called by &struct
* drm_sched_backend_ops.timedout_job) can invoke this again with the
* same parameters. Using this is discouraged because it violates
* dma_fence rules, notably dma_fence_init() has to be called on
* already initialized fences for a second time. Moreover, this is
* dangerous because attempts to allocate memory might deadlock with
* memory management code waiting for the reset to complete.
*
* TODO: Document what drivers should do / use instead.
*
* This method is called in a workqueue context - either from the
* submit_wq the driver passed through drm_sched_init(), or, if the
* driver passed NULL, a separate, ordered workqueue the scheduler
* allocated.
*
* Note that the scheduler expects to 'inherit' its own reference to
* this fence from the callback. It does not invoke an extra
* dma_fence_get() on it. Consequently, this callback must take a
* reference for the scheduler, and additional ones for the driver's
* respective needs.
*
* Return:
* * On success: dma_fence the driver must signal once the hardware has
* completed the job ("hardware fence").
* * On failure: NULL or an ERR_PTR.
*/
struct dma_fence *(*run_job)(struct drm_sched_job *sched_job);