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Message-ID: <8138ab55-1c43-8df1-dafd-95b16b7b3ce4@huawei.com>
Date: Tue, 27 Feb 2024 15:16:58 +0800
From: Jason Yan <yanaijie@...wei.com>
To: yangxingui <yangxingui@...wei.com>, John Garry <john.g.garry@...cle.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 2024/2/27 11:06, yangxingui wrote:
> Hi Jason,
>
> On 2024/2/23 15:04, Jason Yan wrote:
>> On 2024/2/23 12:04, yangxingui wrote:
>>> Hi, John
>>>
>>> On 2024/2/22 20:41, 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))
>>>>> + sas_set_ex_phy(dev, phy_id, disc_resp);
>>>>> +
>>>>> kfree(disc_resp);
>>>>> return res;
>>>>> }
>>>>> @@ -1972,11 +1976,6 @@ static int sas_rediscover_dev(struct
>>>>> domain_device *dev, int phy_id,
>>>>> if ((SAS_ADDR(sas_addr) == 0) || (res == -ECOMM)) {
>>>>> phy->phy_state = PHY_EMPTY;
>>>>> sas_unregister_devs_sas_addr(dev, phy_id, last);
>>>>> - /*
>>>>> - * Even though the PHY is empty, for convenience we discover
>>>>> - * the PHY to update the PHY info, like negotiated linkrate.
>>>>> - */
>>>>> - sas_ex_phy_discover(dev, phy_id);
>>>>
>>>> It would be nice to be able to call sas_set_ex_phy() here (instead
>>>> of sas_get_phy_attached_dev()), but I assume that you can't do that
>>>> as the disc_resp memory is not available.
>>>>
>>>> If we were to manually set the PHY info here instead, how would that
>>>> look?
>>> Yes, I think it is indeed better to use sas_set_ex_phy, as you said,
>>> disc_resp memory is not available. Maybe we can use
>>> sas_get_phy_discover instead of sas_get_phy_attached_dev so we can
>>> use disc_resp?
>>
>> Can we directly set phy->negotiated_linkrate = SAS_PHY_DISABLED here?
>> For an empty PHY the other variables means nothing, so why bother get
>> and update them?
> The value of the negotiated link rate has two possible values in the
> current processing branch: SAS_LINK_RATE_UNKNOWN and SAS_PHY_DISABLED,
> and both come from disc_resp. If we do not use disc_resp, but set a
> fixed value SAS_PHY_DISABLED for it, it may not be appropriate.
OK, makes sense.
>
> Thanks,
> Xingui
>
> .
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