On Tue, Aug 07, 2018 at 11:33:15PM +0000, Bart Van Assche wrote: > On Wed, 2018-08-08 at 01:44 +0800, Ming Lei wrote: > > --- a/drivers/scsi/scsi_lib.c > > +++ b/drivers/scsi/scsi_lib.c > > @@ -278,16 +278,16 @@ int __scsi_execute(struct scsi_device *sdev, const unsigned char *cmd, > > struct request *req; > > struct scsi_request *rq; > > int ret = DRIVER_ERROR << 24; > > + struct request_queue *q = sdev->host->admin_q; > > > > - req = blk_get_request(sdev->request_queue, > > + req = blk_get_request(q, > > data_direction == DMA_TO_DEVICE ? > > REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, BLK_MQ_REQ_PREEMPT); > > The above looks weird to me. Why are all RQF_PREEMPT requests sent to the admin > queue instead of only RQF_PM requests? The motivation is to use the dedicated admin queue for sending any admin request, and that is why it isn't named as pm_queue, :-) Also usually RQF_PREEMPT request is allowed when queue is quiesced, which can be used in both system suspend and sending domain validation. > > > @@ -299,6 +299,8 @@ int __scsi_execute(struct scsi_device *sdev, const unsigned char *cmd, > > req->cmd_flags |= flags; > > req->rq_flags |= rq_flags | RQF_QUIET; > > > > + atomic_inc(&sdev->nr_admin_pending); > > Why has a new counter been introduced to keep track of admin requests instead of > using q_usage_counter? Just for making sure all admin requests sent to this scsi_device can be completed before removing this scsi_device, given this patch switches to use per-host admin queue to send admin requests to all scsi_devices in this host. So we can't use the q_usage_counter of scsi_device's queue or the per-host admin queue. It won't be one big deal since scsi_execute() won't be run in fast path. Thanks, Ming
