On Mon, Sep 17, 2018 at 10:46:34AM +0800, jianchao.wang wrote: > Hi Ming > > On 09/14/2018 07:33 PM, Ming Lei wrote: > > On Fri, Sep 14, 2018 at 11:40 AM jianchao.wang > > <jianchao.w.wang@xxxxxxxxxx> wrote: > >> > >> Hi Ming > >> > >> On 09/13/2018 08:15 PM, Ming Lei wrote: > >>> EXPORT_SYMBOL(__scsi_execute); > >>> @@ -3246,6 +3251,7 @@ static int scsi_internal_device_block(struct scsi_device *sdev) > >>> else > >>> scsi_wait_for_queuecommand(sdev); > >>> } > >>> + wait_event(sdev->admin_wq, !atomic_read(&sdev->nr_admin_pending)); > >>> mutex_unlock(&sdev->state_mutex); > >>> > >>> return err; > >> ... > >>> diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c > >>> index 3aee9464a7bf..8bcb7ecc0c06 100644 > >>> --- a/drivers/scsi/scsi_sysfs.c > >>> +++ b/drivers/scsi/scsi_sysfs.c > >>> @@ -1393,6 +1393,7 @@ void __scsi_remove_device(struct scsi_device *sdev) > >>> > >>> blk_cleanup_queue(sdev->request_queue); > >>> cancel_work_sync(&sdev->requeue_work); > >>> + wait_event(sdev->admin_wq, !atomic_read(&sdev->nr_admin_pending)) > >> > >> This nr_admin_pending could drain the ongoing scsi_request_fn/scsi_queue_rq, > >> but I'm afraid it cannot stop new ones coming in, such as the ones that have passed > >> the sdev state checking and have not crossed the atomic_inc(&sdev->nr_admin_pending). > >> > > > > The counter of .nr_admin_pending is introduced for draining queued > > admin requests to this scsi device. > > > > Actually new requests have been prevented from entering scsi_queue_rq(), > > please see the two callers of wait_event(sdev->admin_wq, > > !atomic_read(&sdev->nr_admin_pending)). > > > For example > > _scsi_execute > ... > scsi_internal_device_block > scsi_internal_device_block_nowait > blk_mq_quiesce_queue > wait_event(sdev->admin_wq, !atomic_read(&sdev->nr_admin_pending)) > atomic_inc(&sdev->nr_admin_pending); > > blk_execute_rq（...） > > atomic_dec(&sdev->nr_admin_pending); > wake_up_all(&sdev->admin_wq); > > Or do you mean the scsi_queue_rq -> scsi_prep_state_check could gate out of ? I got it, then this issue can be fixed simply by moving atomic_inc/dec(&sdev->nr_admin_pending) and related wake_up_all(&sdev->admin_wq) into scsi_admin_queue_rq(). Thanks, Ming
