From 70fc085c5015c54a7b8742a45fc9ab05d6da90da Mon Sep 17 00:00:00 2001 From: zhengbin Date: Fri, 22 Mar 2019 10:56:46 +0800 Subject: [PATCH] scsi: core: Run queue when state is set to running after being blocked Use dd to test a SCSI device: 1. echo "blocked" >/sys/block/sda/device/state 2. dd if=/dev/sda of=/mnt/t.log bs=1M count=10 3. echo "running" >/sys/block/sda/device/state dd should finish this work after step 3, but it hangs. After step2, the call chain is this: blk_mq_dispatch_rq_list-->scsi_queue_rq-->prep_to_mq prep_to_mq will return BLK_STS_RESOURCE, and scsi_queue_rq will transition it to BLK_STS_DEV_RESOURCE which means that driver can guarantee that IO dispatch will be triggered in future when the resource is available. Need to follow the rule if we set the device state to running. [mkp: tweaked commit description and code comment as suggested by Bart] Signed-off-by: zhengbin Reviewed-by: Ming Lei Reviewed-by: Bart Van Assche Signed-off-by: Martin K. Petersen --- drivers/scsi/scsi_sysfs.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c index 6a9040faed00..3b119ca0cc0c 100644 --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -771,6 +771,12 @@ store_state_field(struct device *dev, struct device_attribute *attr, mutex_lock(&sdev->state_mutex); ret = scsi_device_set_state(sdev, state); + /* + * If the device state changes to SDEV_RUNNING, we need to run + * the queue to avoid I/O hang. + */ + if (ret == 0 && state == SDEV_RUNNING) + blk_mq_run_hw_queues(sdev->request_queue, true); mutex_unlock(&sdev->state_mutex); return ret == 0 ? count : -EINVAL; -- 2.30.2