Re: [PATCH RFC v3 29/41] snic: use reserved commands

From: Ming Lei <ming.lei@redhat.com>
To: Hannes Reinecke <hare@suse.de>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
	Christoph Hellwig <hch@lst.de>,
	James Bottomley <james.bottomley@hansenpartnership.com>,
	John Garry <john.garry@huawei.com>,
	Bart van Assche <bvanassche@acm.org>,
	linux-scsi@vger.kernel.org, Hannes Reinecke <hare@suse.com>
Subject: Re: [PATCH RFC v3 29/41] snic: use reserved commands
Date: Sat, 2 May 2020 11:19:16 +0800	[thread overview]
Message-ID: <20200502031916.GC1013372@T590> (raw)
In-Reply-To: <20200430131904.5847-30-hare@suse.de>

On Thu, Apr 30, 2020 at 03:18:52PM +0200, Hannes Reinecke wrote:
> From: Hannes Reinecke <hare@suse.com>
> 
> Use a reserved command for host and device reset.
> 
> Signed-off-by: Hannes Reinecke <hare@suse.com>
> ---
>  drivers/scsi/snic/snic.h      |   4 +-
>  drivers/scsi/snic/snic_main.c |   8 +++
>  drivers/scsi/snic/snic_scsi.c | 140 +++++++++++++++++-------------------------
>  3 files changed, 66 insertions(+), 86 deletions(-)
> 
> diff --git a/drivers/scsi/snic/snic.h b/drivers/scsi/snic/snic.h
> index de0ab5fc8474..7dc529ae8a90 100644
> --- a/drivers/scsi/snic/snic.h
> +++ b/drivers/scsi/snic/snic.h
> @@ -59,7 +59,6 @@
>   */
>  #define SNIC_TAG_ABORT		BIT(30)		/* Tag indicating abort */
>  #define SNIC_TAG_DEV_RST	BIT(29)		/* Tag for device reset */
> -#define SNIC_TAG_IOCTL_DEV_RST	BIT(28)		/* Tag for User Device Reset */
>  #define SNIC_TAG_MASK		(BIT(24) - 1)	/* Mask for lookup */
>  #define SNIC_NO_TAG		-1
>  
> @@ -278,6 +277,7 @@ struct snic {
>  
>  	/* Scsi Host info */
>  	struct Scsi_Host *shost;
> +	struct scsi_device *shost_dev;
>  
>  	/* vnic related structures */
>  	struct vnic_dev_bar bar0;
> @@ -380,7 +380,7 @@ int snic_queuecommand(struct Scsi_Host *, struct scsi_cmnd *);
>  int snic_abort_cmd(struct scsi_cmnd *);
>  int snic_device_reset(struct scsi_cmnd *);
>  int snic_host_reset(struct scsi_cmnd *);
> -int snic_reset(struct Scsi_Host *, struct scsi_cmnd *);
> +int snic_reset(struct Scsi_Host *);
>  void snic_shutdown_scsi_cleanup(struct snic *);
>  
>  
> diff --git a/drivers/scsi/snic/snic_main.c b/drivers/scsi/snic/snic_main.c
> index 14f4ce665e58..f520da64ec8e 100644
> --- a/drivers/scsi/snic/snic_main.c
> +++ b/drivers/scsi/snic/snic_main.c
> @@ -303,6 +303,7 @@ static int
>  snic_add_host(struct Scsi_Host *shost, struct pci_dev *pdev)
>  {
>  	int ret = 0;
> +	struct snic *snic = shost_priv(shost);
>  
>  	ret = scsi_add_host(shost, &pdev->dev);
>  	if (ret) {
> @@ -313,6 +314,12 @@ snic_add_host(struct Scsi_Host *shost, struct pci_dev *pdev)
>  		return ret;
>  	}
>  
> +	snic->shost_dev = scsi_get_virtual_dev(shost, 1, 0);
> +	if (!snic->shost_dev) {
> +		SNIC_HOST_ERR(shost,
> +			      "snic: scsi_get_virtual_dev failed\n");
> +		return -ENOMEM;
> +	}
>  	SNIC_BUG_ON(shost->work_q != NULL);
>  	snprintf(shost->work_q_name, sizeof(shost->work_q_name), "scsi_wq_%d",
>  		 shost->host_no);
> @@ -385,6 +392,7 @@ snic_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
>  
>  		goto prob_end;
>  	}
> +	shost->nr_reserved_cmds = 2;

Not see .can_queue is increased by 2 in this patch, please comment on
the reason. Otherwise, IO performance drop may be caused.

Thanks,
Ming