[PATCH v5 1/2] blk-mq: add tagset quiesce interface

[Keith Busch]

On Mon, Jul 27, 2020 at 04:10:21PM -0700, Sagi Grimberg wrote:
> +static void blk_mq_quiesce_blocking_queue_async_wait(struct request_queue *q)
> +{
> +	struct blk_mq_hw_ctx *hctx;
> +	unsigned int i;
> +
> +	queue_for_each_hw_ctx(q, hctx, i) {
> +		WARN_ON_ONCE(!(hctx->flags & BLK_MQ_F_BLOCKING));
> +		if (!hctx->rcu_sync) {
> +			synchronize_srcu(hctx->srcu);
> +			continue;
> +		}
> +		wait_for_completion(&hctx->rcu_sync->completion);
> +		destroy_rcu_head(&hctx->rcu_sync->head);

Leaking rcu_sync, and not clearing it across quiesce contexts. Needs:

		kfree(hctx->rcu_sync);
		hctx->rcu_sync = NULL;