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Commit 05b79413 authored by Jens Axboe's avatar Jens Axboe
Browse files

Revert "blk-mq: don't handle TAG_SHARED in restart" 



This reverts commit 358a3a6b.

We have cases that aren't covered 100% in the drivers, so for now
we have to retain the shared tag restart loops.

Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent e10237cc

block/blk-mq-sched.c

+74 −4
Original line number Diff line number Diff line
@@ -68,17 +68,25 @@ static void blk_mq_sched_mark_restart_hctx(struct blk_mq_hw_ctx *hctx) 
		set_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);

}



void blk_mq_sched_restart(struct blk_mq_hw_ctx *hctx)

static bool blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)

{

	if (!test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))

		return;

		return false;



	if (hctx->flags & BLK_MQ_F_TAG_SHARED) {

		struct request_queue *q = hctx->queue;



		if (test_and_clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))

			atomic_dec(&q->shared_hctx_restart);

	} else

		clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);



	if (blk_mq_hctx_has_pending(hctx)) {

		blk_mq_run_hw_queue(hctx, true);

		return;

		return true;

	}



	return false;

}



/*
@@ -362,6 +370,68 @@ static bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx, 
	return false;

}



/**

 * list_for_each_entry_rcu_rr - iterate in a round-robin fashion over rcu list

 * @pos:    loop cursor.

 * @skip:   the list element that will not be examined. Iteration starts at

 *          @skip->next.

 * @head:   head of the list to examine. This list must have at least one

 *          element, namely @skip.

 * @member: name of the list_head structure within typeof(*pos).

 */

#define list_for_each_entry_rcu_rr(pos, skip, head, member)		\

	for ((pos) = (skip);						\

	     (pos = (pos)->member.next != (head) ? list_entry_rcu(	\

			(pos)->member.next, typeof(*pos), member) :	\

	      list_entry_rcu((pos)->member.next->next, typeof(*pos), member)), \

	     (pos) != (skip); )



/*

 * Called after a driver tag has been freed to check whether a hctx needs to

 * be restarted. Restarts @hctx if its tag set is not shared. Restarts hardware

 * queues in a round-robin fashion if the tag set of @hctx is shared with other

 * hardware queues.

 */

void blk_mq_sched_restart(struct blk_mq_hw_ctx *const hctx)

{

	struct blk_mq_tags *const tags = hctx->tags;

	struct blk_mq_tag_set *const set = hctx->queue->tag_set;

	struct request_queue *const queue = hctx->queue, *q;

	struct blk_mq_hw_ctx *hctx2;

	unsigned int i, j;



	if (set->flags & BLK_MQ_F_TAG_SHARED) {

		/*

		 * If this is 0, then we know that no hardware queues

		 * have RESTART marked. We're done.

		 */

		if (!atomic_read(&queue->shared_hctx_restart))

			return;



		rcu_read_lock();

		list_for_each_entry_rcu_rr(q, queue, &set->tag_list,

					   tag_set_list) {

			queue_for_each_hw_ctx(q, hctx2, i)

				if (hctx2->tags == tags &&

				    blk_mq_sched_restart_hctx(hctx2))

					goto done;

		}

		j = hctx->queue_num + 1;

		for (i = 0; i < queue->nr_hw_queues; i++, j++) {

			if (j == queue->nr_hw_queues)

				j = 0;

			hctx2 = queue->queue_hw_ctx[j];

			if (hctx2->tags == tags &&

			    blk_mq_sched_restart_hctx(hctx2))

				break;

		}

done:

		rcu_read_unlock();

	} else {

		blk_mq_sched_restart_hctx(hctx);

	}

}



void blk_mq_sched_insert_request(struct request *rq, bool at_head,

				 bool run_queue, bool async, bool can_block)

{