linux-kernel - Re: [PATCH 4/8] scsi: libsas: trigger a new revalidation to discover the device

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Date:   Thu, 31 May 2018 16:42:29 +0100
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 4/8] scsi: libsas: trigger a new revalidation to discover
 the device

On 29/05/2018 03:23, Jason Yan wrote:
> Now if a new device replaced a old device, the sas address will change.
> We unregister the old device and discover the new device in one
> revalidation process. But after we deferred the sas_port_delete(), the
> sas port is not deleted when we registering the new port and device.
> This will make the sysfs complain of creating duplicate filename.
>
> Fix this by doing the replacement in two steps. The first revalidation
> only delete the old device and trigger a new revalidation. The second
> revalidation discover the new device.
>
> Signed-off-by: Jason Yan <yanaijie@...wei.com>
> CC: chenxiang <chenxiang66@...ilicon.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 | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
> index 629c580d906b..25ad9ef54e6c 100644
> --- a/drivers/scsi/libsas/sas_expander.c
> +++ b/drivers/scsi/libsas/sas_expander.c
> @@ -2013,6 +2013,8 @@ static int sas_rediscover_dev(struct domain_device *dev, int phy_id, bool last)
>  {
>  	struct expander_device *ex = &dev->ex_dev;
>  	struct ex_phy *phy = &ex->ex_phy[phy_id];
> +	struct asd_sas_port *port = dev->port;
> +	struct asd_sas_phy *sas_phy;
>  	enum sas_device_type type = SAS_PHY_UNUSED;
>  	u8 sas_addr[8];
>  	int res;
> @@ -2060,7 +2062,14 @@ static int sas_rediscover_dev(struct domain_device *dev, int phy_id, bool last)
>  		    SAS_ADDR(phy->attached_sas_addr));
>  	sas_unregister_devs_sas_addr(dev, phy_id, last);
>
> -	return sas_discover_new(dev, phy_id);
> +	/* force the next revalidation find this phy and bring it up */
> +	phy->phy_change_count = -1;
> +	ex->ex_change_count = -1;
> +	sas_phy = container_of(port->phy_list.next, struct asd_sas_phy,
> +			port_phy_el);
> +	port->ha->notify_port_event(sas_phy, PORTE_BROADCAST_RCVD);
> +

This is less than ideal: that is, restarting another discovery with this 
artifical broadcast event. We do something similar when re-enabling 
revalidation.

Can we do all the event processing synchronised to the original event?

> +	return 0;
>  }
>
>  /**
>