Re: [PATCH 2/5] drm/xe/guc: Wake disable waiters after clearing pending state

["Yadav, Arvind" <arvind.yadav@intel.com>]

On 19-09-2026 04:06, Matthew Brost wrote:
> On Wed, Sep 16, 2026 at 03:23:34PM +0530, Arvind Yadav wrote:
>> disable_scheduling_deregister() waits for any pending scheduling
>> operation to complete before destroying an exec queue.
>>
>> For a disable completion, handle_sched_done() can wake the waiter before
>> clearing pending_disable, or not wake it at all. The waiter can then miss
>> a completed operation and expire after five seconds. This causes a
>> spurious GT reset and immediate TDR.
>>
>> Clear pending_disable before waking the waitqueue on every completion
>> path. Sample the destroyed state before clearing the pending state, as
>> required by the existing destroy protocol.
>>
>> Also wake CT waiters after a suspend completion.
>> The queue remains alive until deregistration completes, so waking
>> waiters before sending the deregister request does not release it.
>>
>> Cc: Matthew Brost <matthew.brost@intel.com>
>> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
>> Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
>> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> I feel like this is an independent fix (like patch 1) that can be sent
> on its own with a Fixes tag and CC'd to stable. This also looks very
> similar to [1].
>
> Can you coordinate with the author of [1]? Alternatively, if that patch
> looks good to you, could you give it an RB?

Thank you for review.

Noted,

Arvind

>
> Matt
>
> [1] https://patchwork.freedesktop.org/patch/753791/?series=174199&rev=1
>
>> Assisted-by: Claude:claude-opus-4-8
>> Signed-off-by: Arvind Yadav <arvind.yadav@intel.com>
>> ---
>>   drivers/gpu/drm/xe/xe_guc_submit.c | 42 +++++++++++++++++-------------
>>   1 file changed, 24 insertions(+), 18 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
>> index f3ba8abfc228..ca24a77dfb26 100644
>> --- a/drivers/gpu/drm/xe/xe_guc_submit.c
>> +++ b/drivers/gpu/drm/xe/xe_guc_submit.c
>> @@ -3265,26 +3265,32 @@ static void handle_sched_done(struct xe_guc *guc, struct xe_exec_queue *q,
>>   		if (q->guc->suspend_pending) {
>>   			clear_exec_queue_pending_disable(q);
>>   			suspend_fence_signal(q);
>> +
>> +			/*
>> +			 * Publish the cleared state before waking waiters.
>> +			 */
>> +			smp_wmb();
>> +			wake_up_all(&guc->ct.wq);
>>   		} else {
>> -			if (exec_queue_banned(q)) {
>> -				smp_wmb();
>> -				wake_up_all(&guc->ct.wq);
>> -			}
>> -			if (exec_queue_destroyed(q)) {
>> -				/*
>> -				 * Make sure to clear the pending_disable only
>> -				 * after sampling the destroyed state. We want
>> -				 * to ensure we don't trigger the unregister too
>> -				 * early with something intending to only
>> -				 * disable scheduling. The caller doing the
>> -				 * destroy must wait for an ongoing
>> -				 * pending_disable before marking as destroyed.
>> -				 */
>> -				clear_exec_queue_pending_disable(q);
>> +			bool destroyed = exec_queue_destroyed(q);
>> +
>> +			/*
>> +			 * Make sure to clear pending_disable only after sampling
>> +			 * the destroyed state. The caller doing the destroy must
>> +			 * wait for an ongoing disable before marking the queue
>> +			 * destroyed.
>> +			 */
>> +			clear_exec_queue_pending_disable(q);
>> +
>> +			/*
>> +			 * Publish the cleared state before waking waiters.
>> +			 */
>> +			smp_wmb();
>> +			wake_up_all(&guc->ct.wq);
>> +
>> +			/* The queue remains alive until DEREGISTER_DONE. */
>> +			if (destroyed)
>>   				deregister_exec_queue(guc, q);
>> -			} else {
>> -				clear_exec_queue_pending_disable(q);
>> -			}
>>   		}
>>   	}
>>   }
>> -- 
>> 2.43.0
>>