blk-mq: bitmap tag: use clear_bit_unlock in bt_clear_tag() (0289b2e1) · Commits · 戴 / test

The unlock memory barrier need to order access to req in free path and clearing tag bit, otherwise either request free path may see a allocated request, or initialized request in allocate path might be modified by the ongoing free path. Signed-off-by:

Ming Lei <tom.leiming@gmail.com> Signed-off-by:

Jens Axboe <axboe@fb.com>

block/blk-mq-tag.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -236,7 +236,11 @@ static void bt_clear_tag(struct blk_mq_bitmap_tags *bt, unsigned int tag)
		const int index = TAG_TO_INDEX(bt, tag);
		struct bt_wait_state *bs;

		clear_bit(TAG_TO_BIT(bt, tag), &bt->map[index].word);
		/*
		* The unlock memory barrier need to order access to req in free
		* path and clearing tag bit
		*/
		clear_bit_unlock(TAG_TO_BIT(bt, tag), &bt->map[index].word);

		bs = bt_wake_ptr(bt);
		if (bs && atomic_dec_and_test(&bs->wait_cnt)) {

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