Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH v2 3/7] scsi: libsas: optimize the debug print of the
 revalidate process
To:     Jason Yan <yanaijie@huawei.com>, <martin.petersen@oracle.com>,
        <jejb@linux.vnet.ibm.com>
References: <20190130082412.9357-1-yanaijie@huawei.com>
 <20190130082412.9357-4-yanaijie@huawei.com>
 <2ffa6821-93d4-7925-d435-e34338f323ec@huawei.com>
 <5C524FE2.9070801@huawei.com>
CC:     <linux-scsi@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <zhaohongjiang@huawei.com>, <hare@suse.com>,
        <dan.j.williams@intel.com>, <jthumshirn@suse.de>, <hch@lst.de>,
        <huangdaode@hisilicon.com>, <chenxiang66@hisilicon.com>,
        <xiexiuqi@huawei.com>, <tj@kernel.org>, <miaoxie@huawei.com>,
        Ewan Milne <emilne@redhat.com>, Tomas Henzl <thenzl@redhat.com>
From:   John Garry <john.garry@huawei.com>
Message-ID: <50358ca3-5350-2f82-b94e-02e27a64873f@huawei.com>
Date:   Thu, 31 Jan 2019 10:25:11 +0000
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101
 Thunderbird/45.3.0
MIME-Version: 1.0
In-Reply-To: <5C524FE2.9070801@huawei.com>
Content-Type: text/plain; charset="windows-1252"; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 31/01/2019 01:31, Jason Yan wrote:
>
>
> On 2019/1/31 0:41, John Garry wrote:
>> 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?
>>
>
> Here I mean every PHY that raises bcast.


This may be better added at the sas_rediscover() callsite. And do you 
feel adding this for every bcast phy is useful, or just those whose 
rediscover error'ed?

>
>>>
>>
>> I don't see any optimisation here. Maybe an improvement.
>>
>
> Thanks, I will change the wording.
>
>>
>>> Signed-off-by: Jason Yan <yanaijie@huawei.com>
>>> CC: John Garry <john.garry@huawei.com>
>>> CC: Johannes Thumshirn <jthumshirn@suse.de>
>>> CC: Ewan Milne <emilne@redhat.com>
>>> CC: Christoph Hellwig <hch@lst.de>
>>> CC: Tomas Henzl <thenzl@redhat.com>
>>> CC: Dan Williams <dan.j.williams@intel.com>
>>> CC: Hannes Reinecke <hare@suse.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
>>
>
> Yes, will fix.
>
>>> +         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
>
> Yes, the return value of sas_find_bcast_phy() is actually unused, and
> inside the function debug info has been printed. So we can directly
> make it a void function.

ok, but how about add a comment like:

-if (phy_id == -1)
+if (phy_id == -1) /* no remaining broadcast phy found */

>
>>
>>>              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 *);
>>>
>>
>>
>>
>> .
>>
>
>
> .
>