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 <[email protected]> --- block/blk-mq-tag.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index 8dc933b..b8b968d 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -235,7 +235,11 @@ static void bt_clear_tag(struct blk_mq_bitmap_tags *bt, unsigned int tag) const int index = TAG_TO_INDEX(tag); struct bt_wait_state *bs; - clear_bit(TAG_TO_BIT(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(tag), &bt->map[index].word); bs = bt_wake_ptr(bt); if (bs && atomic_dec_and_test(&bs->wait_cnt)) { -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
