linux-kernel - Re: [PATCH v2 1/7] scsi: libsas: reset the negotiated

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Message-ID: <5C524B3B.5030007@huawei.com>
Date:   Thu, 31 Jan 2019 09:11:23 +0800
From:   Jason Yan <yanaijie@...wei.com>
To:     John Garry <john.garry@...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 1/7] scsi: libsas: reset the negotiated_linkrate when
 phy is down



On 2019/1/30 21:08, John Garry wrote:
> On 30/01/2019 08:24, Jason Yan wrote:
>> If the device is unplugged or disconnected, the negotiated_linkrate
>> still can be seen from the userspace by sysfs. This makes people
>> confused and leaks information of the device last used. So let's reset
>> the negotiated_linkrate after the phy is down.
>>
>> 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_expander.c | 2 ++
>>  include/scsi/libsas.h              | 3 +++
>>  2 files changed, 5 insertions(+)
>>
>> diff --git a/drivers/scsi/libsas/sas_expander.c
>> b/drivers/scsi/libsas/sas_expander.c
>> index 17eb4185f29d..7b0e6dcef6e6 100644
>> --- a/drivers/scsi/libsas/sas_expander.c
>> +++ b/drivers/scsi/libsas/sas_expander.c
>> @@ -1904,6 +1904,8 @@ static void sas_unregister_devs_sas_addr(struct
>> domain_device *parent,
>>                  &parent->port->sas_port_del_list);
>>          phy->port = NULL;
>>      }
>> +    if (phy->phy)
>> +        phy->phy->negotiated_linkrate = SAS_LINK_RATE_UNKNOWN;
>
> Does this work for both PHYs which were either directly attached or just
> forming part of a wideport?
>
> Please also note that the expander PHY which was previously attached may
> also show the incorrect value.

Good catch, all PHYs need to do this, not only the last PHY of the wideport.

>
>>  }
>>
>>  static int sas_discover_bfs_by_root_level(struct domain_device *root,
>> diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
>> index 3de3b10da19a..420156cea3ee 100644
>> --- a/include/scsi/libsas.h
>> +++ b/include/scsi/libsas.h
>> @@ -448,6 +448,9 @@ static inline void sas_phy_disconnected(struct
>> asd_sas_phy *phy)
>>  {
>>      phy->oob_mode = OOB_NOT_CONNECTED;
>>      phy->linkrate = SAS_LINK_RATE_UNKNOWN;
>> +
>
> Then idea behind sas_phy_disconnected() was to set root PHY values only:
>
> /* Before calling a notify event, LLDD should use this function
>   * when the link is severed (possibly from its tasklet).
>   * The idea is that the Class only reads those, while the LLDD,
>   * can R/W these (thus avoiding a race)
>
> libsas does set sas_phy negotiated_linkrate (but only for expander
> PHYs), so not the perfect place to set this. I'm nitpicking a bit here.
>

I don't want to put it here. I asked chenxiang to fix this in LLDD, but 
he insist libsas to do this. Would you please discuss with chenxiang and 
come to an agreement?

>
>> +    if (phy->phy)
>> +        phy->phy->negotiated_linkrate = SAS_LINK_RATE_UNKNOWN;
>>  }
>>
>>  static inline unsigned int to_sas_gpio_od(int device, int bit)
>
> Thanks,
>
>>
>
>
>
>
>
> .
>