When I use dd test a SCSI device which use blk-mq in the following steps: 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, unfortunately, still hung. After step2, the key code process is like 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 transter 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. Signed-off-by: zhengbin <zhengbin13@xxxxxxxxxx> --- drivers/scsi/scsi_sysfs.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c index 6a9040f..266e4c7 100644 --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -772,6 +772,11 @@ store_state_field(struct device *dev, struct device_attribute *attr, mutex_lock(&sdev->state_mutex); ret = scsi_device_set_state(sdev, state); mutex_unlock(&sdev->state_mutex); + /* If device state changes to SDEV_RUNNING, we need to run hw queue + * to avoid io hung. + */ + if (ret == 0 && state == SDEV_RUNNING) + blk_mq_run_hw_queues(sdev->request_queue, true); return ret == 0 ? count : -EINVAL; } -- 2.7.4
