Re: [PATCH v6 07/11] drm/xe: Assert runnable state in handle_sched_done

[John Harrison <john.c.harrison@intel.com>]

On 6/11/2024 07:40, Matthew Brost wrote:
> Ensure G2H and KMD GuC machine match.
>
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> ---
>   drivers/gpu/drm/xe/xe_guc_submit.c | 9 +++++++--
>   1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
> index afd22a8d815d..ab0dc93d7740 100644
> --- a/drivers/gpu/drm/xe/xe_guc_submit.c
> +++ b/drivers/gpu/drm/xe/xe_guc_submit.c
> @@ -1592,16 +1592,21 @@ static void deregister_exec_queue(struct xe_guc *guc, struct xe_exec_queue *q)
>   	xe_guc_ct_send_g2h_handler(&guc->ct, action, ARRAY_SIZE(action));
>   }
>   
> -static void handle_sched_done(struct xe_guc *guc, struct xe_exec_queue *q)
> +static void handle_sched_done(struct xe_guc *guc, struct xe_exec_queue *q,
> +			      u32 runnable_state)
>   {
>   	trace_xe_exec_queue_scheduling_done(q);
>   
>   	if (exec_queue_pending_enable(q)) {
> +		xe_gt_assert(guc_to_gt(guc), runnable_state == 1);
> +
>   		q->guc->resume_time = ktime_get();
>   		clear_exec_queue_pending_enable(q);
>   		smp_wmb();
>   		wake_up_all(&guc->ct.wq);
>   	} else {
> +		xe_gt_assert(guc_to_gt(guc), runnable_state == 0);
> +
Isn't this the wrong way around?

You made an earlier comment that sounded like it is legal for an enable 
to be queued while a disable is still pending? If so, then you would get 
in here for the disable notification but with both enable_pending and 
disable_pending flags set. That would hit the assert. Whereas, if the if 
checks the runnable_state parameter and the assert then checks for 
pending, you will not hit the assert and the code will do the correct thing.

John.

>   		clear_exec_queue_pending_disable(q);
>   		if (q->guc->suspend_pending) {
>   			suspend_fence_signal(q);
> @@ -1640,7 +1645,7 @@ int xe_guc_sched_done_handler(struct xe_guc *guc, u32 *msg, u32 len)
>   		return -EPROTO;
>   	}
>   
> -	handle_sched_done(guc, q);
> +	handle_sched_done(guc, q, runnable_state);
>   
>   	return 0;
>   }