Commit ae3f7193 authored by ZiyangZhang's avatar ZiyangZhang Committed by Jens Axboe
Browse files

ublk_drv: check 'current' instead of 'ubq_daemon' 



This check is not atomic. So with recovery feature, ubq_daemon may be
modified simultaneously by recovery task. Instead, check 'current' is
safe here because 'current' never changes.

Also add comment explaining this check, which is really important for
understanding recovery feature.

Signed-off-by: default avatarZiyangZhang <ZiyangZhang@linux.alibaba.com>
Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20220923153919.44078-2-ZiyangZhang@linux.alibaba.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 4324796e

drivers/block/ublk_drv.c

+10 −2
Original line number Diff line number Diff line
@@ -645,14 +645,22 @@ static inline void __ublk_rq_task_work(struct request *req) 
	struct ublk_device *ub = ubq->dev;

	int tag = req->tag;

	struct ublk_io *io = &ubq->ios[tag];

	bool task_exiting = current != ubq->ubq_daemon || ubq_daemon_is_dying(ubq);

	unsigned int mapped_bytes;



	pr_devel("%s: complete: op %d, qid %d tag %d io_flags %x addr %llx\n",

			__func__, io->cmd->cmd_op, ubq->q_id, req->tag, io->flags,

			ublk_get_iod(ubq, req->tag)->addr);



	if (unlikely(task_exiting)) {

	/*

	 * Task is exiting if either:

	 *

	 * (1) current != ubq_daemon.

	 * io_uring_cmd_complete_in_task() tries to run task_work

	 * in a workqueue if ubq_daemon(cmd's task) is PF_EXITING.

	 *

	 * (2) current->flags & PF_EXITING.

	 */

	if (unlikely(current != ubq->ubq_daemon || current->flags & PF_EXITING)) {

		blk_mq_end_request(req, BLK_STS_IOERR);

		mod_delayed_work(system_wq, &ub->monitor_work, 0);

		return;