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

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Message-ID: <6b06f81e-9ede-014d-b678-1996044106e3@huawei.com>
Date:   Wed, 30 Jan 2019 13:08:26 +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 1/7] scsi: libsas: reset the negotiated_linkrate when
 phy is down

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.

>  }
>
>  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.


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

Thanks,

>