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Commit adb4ddbb authored by Nick Piggin's avatar Nick Piggin Committed by Jens Axboe
Browse files

block: use lock bitops for the tag map. 



The block queue tag map can use lock bitops.

Signed-off-by: default avatarNick Piggin <npiggin@suse.de>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent bd4f36d6

block/ll_rw_blk.c

+9 −11
Original line number Diff line number Diff line
@@ -1057,18 +1057,16 @@ void blk_queue_end_tag(struct request_queue *q, struct request *rq) 


	bqt->tag_index[tag] = NULL;



	/*

	 * We use test_and_clear_bit's memory ordering properties here.

	 * The tag_map bit acts as a lock for tag_index[bit], so we need

	 * a barrer before clearing the bit (precisely: release semantics).

	 * Could use clear_bit_unlock when it is merged.

	 */

	if (unlikely(!test_and_clear_bit(tag, bqt->tag_map))) {

	if (unlikely(!test_bit(tag, bqt->tag_map))) {

		printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n",

		       __FUNCTION__, tag);

		return;

	}



	/*

	 * The tag_map bit acts as a lock for tag_index[bit], so we need

	 * unlock memory barrier semantics.

	 */

	clear_bit_unlock(tag, bqt->tag_map);

	bqt->busy--;

}
@@ -1114,10 +1112,10 @@ int blk_queue_start_tag(struct request_queue *q, struct request *rq) 
		if (tag >= bqt->max_depth)

			return 1;



	} while (test_and_set_bit(tag, bqt->tag_map));

	} while (test_and_set_bit_lock(tag, bqt->tag_map));

	/*

	 * We rely on test_and_set_bit providing lock memory ordering semantics

	 * (could use test_and_set_bit_lock when it is merged).

	 * We need lock ordering semantics given by test_and_set_bit_lock.

	 * See blk_queue_end_tag for details.

	 */



	rq->cmd_flags |= REQ_QUEUED;