[PATCH] drm/xe: Do not dereference NULL job->fence in trace points

[Lucas De Marchi]

On Tue, Jun 04, 2024 at 10:50:41PM GMT, Matthew Brost wrote:
>job->fence is not assigned until xe_sched_job_arm(), check for
>job->fence in xe_sched_job_seqno() so any usage of this function (trace
>points) do not result in NULL ptr dereference. Also check job->fence
>before assigning error in job trace points.
>
>Fixes: 0ac7a2c745e8 drm/xe: ("Don't initialize fences at xe_sched_job_create()")
>Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
>Signed-off-by: Matthew Brost <matthew.brost at intel.com>
>---
> drivers/gpu/drm/xe/xe_sched_job.h | 2 +-
> drivers/gpu/drm/xe/xe_trace.h     | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
>diff --git a/drivers/gpu/drm/xe/xe_sched_job.h b/drivers/gpu/drm/xe/xe_sched_job.h
>index 002c3b5c0a5c..f362e28455db 100644
>--- a/drivers/gpu/drm/xe/xe_sched_job.h
>+++ b/drivers/gpu/drm/xe/xe_sched_job.h
>@@ -70,7 +70,7 @@ to_xe_sched_job(struct drm_sched_job *drm)
>
> static inline u32 xe_sched_job_seqno(struct xe_sched_job *job)
> {
>-	return job->fence->seqno;
>+	return job->fence ? job->fence->seqno : 0;
> }
>
> static inline u32 xe_sched_job_lrc_seqno(struct xe_sched_job *job)
>diff --git a/drivers/gpu/drm/xe/xe_trace.h b/drivers/gpu/drm/xe/xe_trace.h
>index 450f407c66e8..e4cba64474e6 100644
>--- a/drivers/gpu/drm/xe/xe_trace.h
>+++ b/drivers/gpu/drm/xe/xe_trace.h
>@@ -270,7 +270,7 @@ DECLARE_EVENT_CLASS(xe_sched_job,
> 			   __entry->guc_state =
> 			   atomic_read(&job->q->guc->state);
> 			   __entry->flags = job->q->flags;
>-			   __entry->error = job->fence->error;
>+			   __entry->error = job->fence ? job->fence->error : 0;

we already include xe_sched_job.h in this file and even call
xe_sched_job_lrc_seqno() a few lines above this. Why can't we call the
function you just fixed? With that changed,

	Reviewed-by: Lucas De Marchi <lucas.demarchi at intel.com>


Lucas De Marchi

> 			   __entry->fence = job->fence;
> 			   __entry->batch_addr = (u64)job->ptrs[0].batch_addr;
> 			   ),
>-- 
>2.34.1
>