Hello Christian König,
The patch 5918045c4ed4: "drm/scheduler: rework job destruction" from
Apr 18, 2019, leads to the following static checker warning:
drivers/gpu/drm/scheduler/sched_main.c:297 drm_sched_job_timedout()
error: potential NULL dereference 'job'.
drivers/gpu/drm/scheduler/sched_main.c
279 static void drm_sched_job_timedout(struct work_struct *work)
280 {
281 struct drm_gpu_scheduler *sched;
282 struct drm_sched_job *job;
283 unsigned long flags;
284
285 sched = container_of(work, struct drm_gpu_scheduler, work_tdr.work);
286 job = list_first_entry_or_null(&sched->ring_mirror_list,
287 struct drm_sched_job, node);
288
289 if (job)
^^^
We assume that job can be NULL.
290 job->sched->ops->timedout_job(job);
291
292 /*
293 * Guilty job did complete and hence needs to be manually removed
294 * See drm_sched_stop doc.
295 */
296 if (sched->free_guilty) {
Originally (last week) this check was "if (list_empty(&job->node))"
which is obviously problematic if job is NULL. It's not clear to me
that this new check ensures that job is non-NULL either.
297 job->sched->ops->free_job(job);
^^^^^
Dereference.
298 sched->free_guilty = false;
299 }
300
301 spin_lock_irqsave(&sched->job_list_lock, flags);
302 drm_sched_start_timeout(sched);
303 spin_unlock_irqrestore(&sched->job_list_lock, flags);
304 }
regards,
dan carpenter
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