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

[Lucas De Marchi]

On Thu, Jun 06, 2024 at 02:55:23AM GMT, Matthew Brost wrote:
>On Wed, Jun 05, 2024 at 06:13:42PM -0500, Lucas De Marchi wrote:
>> 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,
>
>We do call that function above, it just is not in the diff.
>
>We don't have a helper to go from job -> job->fence->error hence the
>open coding here. I could add a helper if you like.

ahh... ok, I misread s/error/seqno/ thinking they were handling the same
thing.

let's just merge this as is then.

thanks
Lucas De Marchi

>
>Matt
>
>>
>> 	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
>> >