[PATCH v5 05/15] iommu/arm-smmu-v3: Flush in-flight fault work on domain detach

[Jason Gunthorpe]

> [ ... 54 lines skipped ... ]
> @@ -3422,8 +3423,38 @@ void arm_smmu_attach_release(struct arm_smmu_attach_state *state)
>  	 * which the IOMMU core might free once this returns. Drain the hardware
>  	 * eventq, so that a pending event cannot turn into new fault work.
>  	 */
> -	if (master_domain->using_iopf && master->stall_enabled)
> -		arm_smmu_wait_for_queue_drained(smmu, &smmu->evtq.q, false);
> +	if (master_domain->using_iopf && master->stall_enabled) {
> +		timed_out = arm_smmu_wait_for_queue_drained(smmu, &smmu->evtq.q,
> +							    false);
> +		/*
> +		 * Ensure pending events have reached the IOPF queue, unless
> +		 * the drain timed out: a stuck consumer would also block an
> +		 * unbounded wait_event() inside the synchronize_irq().
> +		 */
> +		if (!timed_out) {
> +			if (smmu->evtq.q.irq)
> +				synchronize_irq(smmu->evtq.q.irq);
> +			/* Pending events might be in the combined_irq handler */
> +			if (smmu->combined_irq)
> +				synchronize_irq(smmu->combined_irq);
> +		}

I think this logic is overkill. If we can't flush the queue we are
probably going to crash next. Chuck a warn on and hope for the
best. We don't need this fancy half attempt at recovery.

-- 
Jason