Commit 4b2b0315 authored by Yongpeng Yang's avatar Yongpeng Yang Committed by Jens Axboe
Browse files

zloop: use READ_ONCE() to read lo->lo_state in queue_rq path 



In the queue_rq path, zlo->state is accessed without locking, and direct
access may read stale data. This patch uses READ_ONCE() to read
zlo->state and data_race() to silence code checkers, and changes all
assignments to use WRITE_ONCE().

Reviewed-by: default avatarDamien Le Moal <dlemoal@kernel.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarYongpeng Yang <yangyongpeng@xiaomi.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 54891a96

drivers/block/zloop.c

+4 −4
Original line number Diff line number Diff line
@@ -697,7 +697,7 @@ static blk_status_t zloop_queue_rq(struct blk_mq_hw_ctx *hctx, 
	struct zloop_cmd *cmd = blk_mq_rq_to_pdu(rq);

	struct zloop_device *zlo = rq->q->queuedata;



	if (zlo->state == Zlo_deleting)

	if (data_race(READ_ONCE(zlo->state)) == Zlo_deleting)

		return BLK_STS_IOERR;



	/*
@@ -1002,7 +1002,7 @@ static int zloop_ctl_add(struct zloop_options *opts) 
		ret = -ENOMEM;

		goto out;

	}

	zlo->state = Zlo_creating;

	WRITE_ONCE(zlo->state, Zlo_creating);



	ret = mutex_lock_killable(&zloop_ctl_mutex);

	if (ret)
@@ -1113,7 +1113,7 @@ static int zloop_ctl_add(struct zloop_options *opts) 
	}



	mutex_lock(&zloop_ctl_mutex);

	zlo->state = Zlo_live;

	WRITE_ONCE(zlo->state, Zlo_live);

	mutex_unlock(&zloop_ctl_mutex);



	pr_info("zloop: device %d, %u zones of %llu MiB, %u B block size\n",
@@ -1177,7 +1177,7 @@ static int zloop_ctl_remove(struct zloop_options *opts) 
		ret = -EINVAL;

	} else {

		idr_remove(&zloop_index_idr, zlo->id);

		zlo->state = Zlo_deleting;

		WRITE_ONCE(zlo->state, Zlo_deleting);

	}



	mutex_unlock(&zloop_ctl_mutex);