[PATCH] drm/i915/guc: Check if expecting reply before decrementing outstanding_submission_g2h

[Daniele Ceraolo Spurio]

On 5/14/2025 3:52 PM, Jesus Narvaez wrote:
> When sending a H2G message where a reply is expected in
> guc_submission_send_busy_loop(), outstanding_submission_g2h is
> incremented before the send. However, if there is an error sending the
> message, outstanding_submission_g2h is decremented without checking if a
> reply is expected.
>
> Therefore, check if reply is expected when there is a failure before
> decrementing outstanding_submission_g2h.
>
> Fixes: 2f2cc53b5fe7 ("drm/i915/guc: Close deregister-context race against CT-loss")
> Signed-off-by: Jesus Narvaez <jesus.narvaez at intel.com>
> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> Cc: Alan Previn <alan.previn.teres.alexis at intel.com>
> Cc: Anshuman Gupta <anshuman.gupta at intel.com>
> Cc: Mousumi Jana <mousumi.jana at intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Cc: Matt Roper <matthew.d.roper at intel.com>

Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>

Daniele

> ---
>   drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> index 39696ceea9a5..68bdf0c80ec3 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -633,7 +633,7 @@ static int guc_submission_send_busy_loop(struct intel_guc *guc,
>   		atomic_inc(&guc->outstanding_submission_g2h);
>   
>   	ret = intel_guc_send_busy_loop(guc, action, len, g2h_len_dw, loop);
> -	if (ret)
> +	if (ret && g2h_len_dw)
>   		atomic_dec(&guc->outstanding_submission_g2h);
>   
>   	return ret;