Re: [PATCH] drm/xe: Add NULL check before deferencing pointer

[Jani Nikula <jani.nikula@linux.intel.com>]

On Wed, 14 Aug 2024, apoorva.singh@intel.com wrote:
> From: Apoorva Singh <apoorva.singh@intel.com>
>
> - Add NULL check before deferencing of lrc->bo in
>   xe_lrc_snapshot_capture()
>
> Signed-off-by: Apoorva Singh <apoorva.singh@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_lrc.c | 32 ++++++++++++++++++--------------
>  1 file changed, 18 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_lrc.c b/drivers/gpu/drm/xe/xe_lrc.c
> index 974a9cd8c379..e31d9bc64ff6 100644
> --- a/drivers/gpu/drm/xe/xe_lrc.c
> +++ b/drivers/gpu/drm/xe/xe_lrc.c
> @@ -1652,20 +1652,24 @@ struct xe_lrc_snapshot *xe_lrc_snapshot_capture(struct xe_lrc *lrc)
>  	if (lrc->bo && lrc->bo->vm)
>  		xe_vm_get(lrc->bo->vm);
>  
> -	snapshot->context_desc = xe_lrc_ggtt_addr(lrc);
> -	snapshot->indirect_context_desc = xe_lrc_indirect_ring_ggtt_addr(lrc);
> -	snapshot->head = xe_lrc_ring_head(lrc);
> -	snapshot->tail.internal = lrc->ring.tail;
> -	snapshot->tail.memory = xe_lrc_ring_tail(lrc);
> -	snapshot->start_seqno = xe_lrc_start_seqno(lrc);
> -	snapshot->seqno = xe_lrc_seqno(lrc);
> -	snapshot->lrc_bo = xe_bo_get(lrc->bo);
> -	snapshot->lrc_offset = xe_lrc_pphwsp_offset(lrc);
> -	snapshot->lrc_size = lrc->bo->size - snapshot->lrc_offset;
> -	snapshot->lrc_snapshot = NULL;
> -	snapshot->ctx_timestamp = xe_lrc_ctx_timestamp(lrc);
> -	snapshot->ctx_job_timestamp = xe_lrc_ctx_job_timestamp(lrc);
> -	return snapshot;
> +	if (lrc->bo) {
> +		snapshot->context_desc = xe_lrc_ggtt_addr(lrc);
> +		snapshot->indirect_context_desc = xe_lrc_indirect_ring_ggtt_addr(lrc);
> +		snapshot->head = xe_lrc_ring_head(lrc);
> +		snapshot->tail.internal = lrc->ring.tail;
> +		snapshot->tail.memory = xe_lrc_ring_tail(lrc);
> +		snapshot->start_seqno = xe_lrc_start_seqno(lrc);
> +		snapshot->seqno = xe_lrc_seqno(lrc);
> +		snapshot->lrc_bo = xe_bo_get(lrc->bo);
> +		snapshot->lrc_offset = xe_lrc_pphwsp_offset(lrc);
> +		snapshot->lrc_size = lrc->bo->size - snapshot->lrc_offset;
> +		snapshot->lrc_snapshot = NULL;
> +		snapshot->ctx_timestamp = xe_lrc_ctx_timestamp(lrc);
> +		snapshot->ctx_job_timestamp = xe_lrc_ctx_job_timestamp(lrc);
> +		return snapshot;
> +	}
> +	kfree(snapshot);

Primarily, see Nirmoy's comment. But changes like this kfree here need
to be mentioned in the commit message.

BR,
Jani.


> +	return NULL;
>  }
>  
>  void xe_lrc_snapshot_capture_delayed(struct xe_lrc_snapshot *snapshot)

-- 
Jani Nikula, Intel