On Tue, Jul 28, 2020 at 06:10:42PM +0800, Ming Lei wrote:
> + struct blk_mq_hw_ctx *hctx = (void *)srcu -
> + sizeof(struct blk_mq_hw_ctx);
I think this should use container_of.
> +{
> + struct blk_mq_hw_ctx *hctx;
> + unsigned int i;
> +
> + blk_mq_quiesce_queue_nowait(q);
> +
> + queue_for_each_hw_ctx(q, hctx, i) {
> + WARN_ON_ONCE(!(hctx->flags & BLK_MQ_F_BLOCKING));
> + init_rcu_head(&hctx->srcu->head);
We only need to initialize the rcu head once when we allocate the hctx.
> + mutex_lock(&set->tag_list_lock);
> + if (set->flags & BLK_MQ_F_BLOCKING) {
> + int count = 0;
> +
> + list_for_each_entry(q, &set->tag_list, tag_set_list)
> + count++;
> +
> + atomic_set(&set->quiesce_count, count);
> + init_completion(&set->quiesce_completion);
> +
> + list_for_each_entry(q, &set->tag_list, tag_set_list)
> + blk_mq_quiesce_blocking_queue_async(q);
> + wait_for_completion(&set->quiesce_completion);
> + } else {
> + list_for_each_entry(q, &set->tag_list, tag_set_list)
> + blk_mq_quiesce_queue_nowait(q);
> + synchronize_rcu();
> + }
> + mutex_unlock(&set->tag_list_lock);
It would be great to do the wait_for_completion and synchronize_rcu
outside the lock. Also I think the blocking case probably wants to be
split into a separate little helper.
