blk-mq: bitmap tag: use clear_bit_unlock in bt_clear_tag()
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>
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@ -236,7 +236,11 @@ static void bt_clear_tag(struct blk_mq_bitmap_tags *bt, unsigned int tag)
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const int index = TAG_TO_INDEX(bt, tag);
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struct bt_wait_state *bs;
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clear_bit(TAG_TO_BIT(bt, tag), &bt->map[index].word);
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/*
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* The unlock memory barrier need to order access to req in free
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* path and clearing tag bit
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*/
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clear_bit_unlock(TAG_TO_BIT(bt, tag), &bt->map[index].word);
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bs = bt_wake_ptr(bt);
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if (bs && atomic_dec_and_test(&bs->wait_cnt)) {
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