linux-kernel - Re: [PATCH v2 3/7] scsi: libsas: optimize the debug print of the revalidate process

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Date:   Wed, 30 Jan 2019 16:41:12 +0000
From:   John Garry <john.garry@...wei.com>
To:     Jason Yan <yanaijie@...wei.com>, <martin.petersen@...cle.com>,
        <jejb@...ux.vnet.ibm.com>
CC:     <linux-scsi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <zhaohongjiang@...wei.com>, <hare@...e.com>,
        <dan.j.williams@...el.com>, <jthumshirn@...e.de>, <hch@....de>,
        <huangdaode@...ilicon.com>, <chenxiang66@...ilicon.com>,
        <xiexiuqi@...wei.com>, <tj@...nel.org>, <miaoxie@...wei.com>,
        Ewan Milne <emilne@...hat.com>, Tomas Henzl <thenzl@...hat.com>
Subject: Re: [PATCH v2 3/7] scsi: libsas: optimize the debug print of the
 revalidate process

On 30/01/2019 08:24, Jason Yan wrote:
> sas_rediscover() returns error code if discover failed for a expander
> phy. And sas_ex_revalidate_domain() only returns the last phy's error
> code. So when sas_revalidate_domain() prints the return value of the
> discover process, we do not know if the revalidation for every phy is
> successful or not. We just know the last bcast phy revalidation
> succeeded or not.
>
> No need to return a error code for sas_ex_revalidate_domain() and
> sas_rediscover(), and just print the debug log for each bcast phy directly
> in sas_rediscover().

do we want to know about every PHY, or just the PHY where res != 0?

>

I don't see any optimisation here. Maybe an improvement.


> Signed-off-by: Jason Yan <yanaijie@...wei.com>
> CC: John Garry <john.garry@...wei.com>
> CC: Johannes Thumshirn <jthumshirn@...e.de>
> CC: Ewan Milne <emilne@...hat.com>
> CC: Christoph Hellwig <hch@....de>
> CC: Tomas Henzl <thenzl@...hat.com>
> CC: Dan Williams <dan.j.williams@...el.com>
> CC: Hannes Reinecke <hare@...e.com>
> ---
>  drivers/scsi/libsas/sas_discover.c |  7 +++----
>  drivers/scsi/libsas/sas_expander.c | 11 ++++++-----
>  include/scsi/libsas.h              |  2 +-
>  3 files changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
> index 726ada9b8c79..ffc571a12916 100644
> --- a/drivers/scsi/libsas/sas_discover.c
> +++ b/drivers/scsi/libsas/sas_discover.c
> @@ -500,7 +500,6 @@ static void sas_discover_domain(struct work_struct *work)
>
>  static void sas_revalidate_domain(struct work_struct *work)
>  {
> -	int res = 0;
>  	struct sas_discovery_event *ev = to_sas_discovery_event(work);
>  	struct asd_sas_port *port = ev->port;
>  	struct sas_ha_struct *ha = port->ha;
> @@ -521,10 +520,10 @@ static void sas_revalidate_domain(struct work_struct *work)
>
>  	if (ddev && (ddev->dev_type == SAS_FANOUT_EXPANDER_DEVICE ||
>  		     ddev->dev_type == SAS_EDGE_EXPANDER_DEVICE))
> -		res = sas_ex_revalidate_domain(ddev);
> +		sas_ex_revalidate_domain(ddev);
>
> -	pr_debug("done REVALIDATING DOMAIN on port %d, pid:%d, res 0x%x\n",
> -		 port->id, task_pid_nr(current), res);
> +	pr_debug("done REVALIDATING DOMAIN on port %d, pid:%d\n",
> +		 port->id, task_pid_nr(current));
>   out:
>  	mutex_unlock(&ha->disco_mutex);
>
> diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
> index 7b0e6dcef6e6..5cd720f93f96 100644
> --- a/drivers/scsi/libsas/sas_expander.c
> +++ b/drivers/scsi/libsas/sas_expander.c
> @@ -2062,7 +2062,7 @@ static int sas_rediscover_dev(struct domain_device *dev, int phy_id, bool last)
>   * first phy,for other phys in this port, we add it to the port to
>   * forming the wide-port.
>   */
> -static int sas_rediscover(struct domain_device *dev, const int phy_id)
> +static void sas_rediscover(struct domain_device *dev, const int phy_id)
>  {
>  	struct expander_device *ex = &dev->ex_dev;
>  	struct ex_phy *changed_phy = &ex->ex_phy[phy_id];
> @@ -2090,7 +2090,9 @@ static int sas_rediscover(struct domain_device *dev, const int phy_id)
>  		res = sas_rediscover_dev(dev, phy_id, last);
>  	} else
>  		res = sas_discover_new(dev, phy_id);
> -	return res;
> +
> +	pr_debug("ex %016llx phy%d discover returned 0x%x\n",

Hmmm.. this is not just discover, but also rediscover

> +		 SAS_ADDR(dev->sas_addr), phy_id, res);
>  }
>
>  /**
> @@ -2102,7 +2104,7 @@ static int sas_rediscover(struct domain_device *dev, const int phy_id)
>   * Discover process only interrogates devices in order to discover the
>   * domain.
>   */
> -int sas_ex_revalidate_domain(struct domain_device *port_dev)
> +void sas_ex_revalidate_domain(struct domain_device *port_dev)
>  {
>  	int res;
>  	struct domain_device *dev = NULL;
> @@ -2117,11 +2119,10 @@ int sas_ex_revalidate_domain(struct domain_device *port_dev)
>  			res = sas_find_bcast_phy(dev, &phy_id, i, true);

this was missed

>  			if (phy_id == -1)
>  				break;
> -			res = sas_rediscover(dev, phy_id);
> +			sas_rediscover(dev, phy_id);
>  			i = phy_id + 1;
>  		} while (i < ex->num_phys);
>  	}
> -	return res;
>  }
>
>  void sas_smp_handler(struct bsg_job *job, struct Scsi_Host *shost,
> diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
> index 420156cea3ee..e557bcb0c266 100644
> --- a/include/scsi/libsas.h
> +++ b/include/scsi/libsas.h
> @@ -692,7 +692,7 @@ int  sas_discover_root_expander(struct domain_device *);
>
>  void sas_init_ex_attr(void);
>
> -int  sas_ex_revalidate_domain(struct domain_device *);
> +void sas_ex_revalidate_domain(struct domain_device *);
>
>  void sas_unregister_domain_devices(struct asd_sas_port *port, int gone);
>  void sas_init_disc(struct sas_discovery *disc, struct asd_sas_port *);
>