From: ZiyangZhang Date: Fri, 23 Sep 2022 15:39:13 +0000 (+0800) Subject: ublk_drv: check 'current' instead of 'ubq_daemon' X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=ae3f719300816865489abd44c91c821859daa26f;p=linux.git 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: ZiyangZhang Reviewed-by: Ming Lei Link: https://lore.kernel.org/r/20220923153919.44078-2-ZiyangZhang@linux.alibaba.com Signed-off-by: Jens Axboe --- diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 6a4a94b4cdf42..c39b67d7133d5 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -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;