linux-kernel - Re: [PATCH] scsi: libsas: Fix disk not being scanned in after being removed

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Message-ID: <a7eb46e3-997c-4746-b820-a09229e75581@oracle.com>
Date: Tue, 5 Mar 2024 10:15:11 +0000
From: John Garry <john.g.garry@...cle.com>
To: Jason Yan <yanaijie@...wei.com>, yangxingui <yangxingui@...wei.com>,
        jejb@...ux.ibm.com, martin.petersen@...cle.com,
        damien.lemoal@...nsource.wdc.com
Cc: linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        linuxarm@...wei.com, prime.zeng@...ilicon.com,
        chenxiang66@...ilicon.com, kangfenglong@...wei.com
Subject: Re: [PATCH] scsi: libsas: Fix disk not being scanned in after being
 removed

On 05/03/2024 02:56, Jason Yan wrote:
> On 2024/3/4 20:50, yangxingui wrote:
>> Hi Jason,
>>
>> On 2024/3/1 9:55, Jason Yan wrote:
>>> On 2024/2/29 2:13, John Garry wrote:
>>>> On 21/02/2024 07:31, Xingui Yang wrote:
>>>>> As of commit d8649fc1c5e4 ("scsi: libsas: Do discovery on empty PHY to
>>>>> update PHY info"), do discovery will send a new SMP_DISCOVER and 
>>>>> update
>>>>> phy->phy_change_count. We found that if the disk is reconnected and 
>>>>> phy
>>>>> change_count changes at this time, the disk scanning process will 
>>>>> not be
>>>>> triggered.
>>>>>
>>>>> So update the PHY info with the last query results.
>>>>>
>>>>> Fixes: d8649fc1c5e4 ("scsi: libsas: Do discovery on empty PHY to 
>>>>> update PHY info")
>>>>> Signed-off-by: Xingui Yang <yangxingui@...wei.com>
>>>>> ---
>>>>>   drivers/scsi/libsas/sas_expander.c | 9 ++++-----
>>>>>   1 file changed, 4 insertions(+), 5 deletions(-)
>>>>>
>>>>> diff --git a/drivers/scsi/libsas/sas_expander.c 
>>>>> b/drivers/scsi/libsas/sas_expander.c
>>>>> index a2204674b680..9563f5589948 100644
>>>>> --- a/drivers/scsi/libsas/sas_expander.c
>>>>> +++ b/drivers/scsi/libsas/sas_expander.c
>>>>> @@ -1681,6 +1681,10 @@ int sas_get_phy_attached_dev(struct 
>>>>> domain_device *dev, int phy_id,
>>>>>           if (*type == 0)
>>>>>               memset(sas_addr, 0, SAS_ADDR_SIZE);
>>>>>       }
>>>>> +
>>>>> +    if ((SAS_ADDR(sas_addr) == 0) || (res == -ECOMM))
>>>>
>>>> It's odd to call sas_set_ex_phy() if we got res == -ECOMM. I mean, 
>>>> in this this case disc_resp is not filled in as the command did not 
>>>> execute, right? I know that is what the current code does, but it is 
>>>> strange.
>>>
>>> The current code actually re-send the SMP command and update the PHY 
>>> status only when the the SMP command is responded correctly.
>>>
>>> Xinggui, can you please fix this and send v3?
>> The current location cannot directly update the phy information. The 
>> previous phy information will be used later, and the previous sas 
>> address will be compared with the currently queried sas address. At 
>> present, v2 is more suitable after many days of testing.

I don't understand this. Where is the previous SAS address compared to 
the current SAS address?

Could this work:

diff --git a/drivers/scsi/libsas/sas_expander.c 
b/drivers/scsi/libsas/sas_expander.c
index a2204674b680..e190038ba7bd 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -1675,11 +1675,13 @@ int sas_get_phy_attached_dev(struct 
domain_device *dev, int phy_id,

         res = sas_get_phy_discover(dev, phy_id, disc_resp);
         if (res == 0) {
-               memcpy(sas_addr, disc_resp->disc.attached_sas_addr,
-                      SAS_ADDR_SIZE);
                 *type = to_dev_type(&disc_resp->disc);
-               if (*type == 0)
+               if (*type == SAS_PHY_UNUSED)
                         memset(sas_addr, 0, SAS_ADDR_SIZE);
+               else
+                       memcpy(sas_addr, disc_resp->disc.attached_sas_addr,
+                      SAS_ADDR_SIZE);
+               sas_set_ex_phy(dev, phy_id, disc_resp);
         }
         kfree(disc_resp);
         return res;
lines 1-21/21 (END)

It's like the change in this patch.


> 
> OK, so let me have a closer look at v2.

I have to say that v2 is quite complicated...