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From: John Garry <john.garry@huawei.com>
To: Jason Yan <yanaijie@huawei.com>, <martin.petersen@oracle.com>,
	<jejb@linux.vnet.ibm.com>
Cc: <linux-scsi@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<zhaohongjiang@huawei.com>, <hare@suse.com>,
	<dan.j.williams@intel.com>, <jthumshirn@suse.de>, <hch@lst.de>,
	<huangdaode@hisilicon.com>, <chenxiang66@hisilicon.com>,
	<xiexiuqi@huawei.com>, <tj@kernel.org>, <miaoxie@huawei.com>,
	Ewan Milne <emilne@redhat.com>, Tomas Henzl <thenzl@redhat.com>
Subject: Re: [PATCH 3/8] scsi: libsas: always unregister the old device if going to discover new
Date: Thu, 31 May 2018 16:09:56 +0100	[thread overview]
Message-ID: <8d3c7ee0-b76e-841f-b8e3-0346d22ae0b7@huawei.com> (raw)
In-Reply-To: <20180529022309.21071-4-yanaijie@huawei.com>

On 29/05/2018 03:23, Jason Yan wrote:
> If we went into sas_rediscover_dev() the attached_sas_addr was already
> insured not to be zero. So it's unnecessary to check if the
> attached_sas_addr is zero.
>
> And although if the sas address is not changed, we always have to
> unregister the old device when we are going to register a new one. We
> cannot just leave the device there and bring up the new.
>
> Signed-off-by: Jason Yan <yanaijie@huawei.com>
> CC: chenxiang <chenxiang66@hisilicon.com>
> CC: John Garry <john.garry@huawei.com>
> CC: Johannes Thumshirn <jthumshirn@suse.de>
> CC: Ewan Milne <emilne@redhat.com>
> CC: Christoph Hellwig <hch@lst.de>
> CC: Tomas Henzl <thenzl@redhat.com>
> CC: Dan Williams <dan.j.williams@intel.com>
> CC: Hannes Reinecke <hare@suse.com>
> ---
>  drivers/scsi/libsas/sas_expander.c | 13 +++++--------
>  1 file changed, 5 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
> index 8b7114348def..629c580d906b 100644
> --- a/drivers/scsi/libsas/sas_expander.c
> +++ b/drivers/scsi/libsas/sas_expander.c
> @@ -2054,14 +2054,11 @@ static int sas_rediscover_dev(struct domain_device *dev, int phy_id, bool last)
>  		return res;
>  	}
>
> -	/* delete the old link */
> -	if (SAS_ADDR(phy->attached_sas_addr) &&
> -	    SAS_ADDR(sas_addr) != SAS_ADDR(phy->attached_sas_addr)) {
> -		SAS_DPRINTK("ex %016llx phy 0x%x replace %016llx\n",
> -			    SAS_ADDR(dev->sas_addr), phy_id,
> -			    SAS_ADDR(phy->attached_sas_addr));
> -		sas_unregister_devs_sas_addr(dev, phy_id, last);
> -	}

The preceeding checks in code check for no device/comm fail or SATA flutter.

If we're rediscovering the device and the SAS address has not changed, 
then why previously still try to discover a new device? I'm guessing 
sas_discover_new() had no affect in this case, since maybe since the PHY 
was already discovered. But that would not make sense since you say "we 
are going to register a new one". Or, if we are always going to register 
a new one, how did we ensure we always unregistered the old device 
previously (when SAS address did not change)?

> +	/* we always have to delete the old device when we went here */
> +	SAS_DPRINTK("ex %016llx phy 0x%x replace %016llx\n",
> +		    SAS_ADDR(dev->sas_addr), phy_id,
> +		    SAS_ADDR(phy->attached_sas_addr));
> +	sas_unregister_devs_sas_addr(dev, phy_id, last);
>
>  	return sas_discover_new(dev, phy_id);
>  }
>

  parent reply	other threads:[~2018-05-31 15:10 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-29  2:23 [PATCH 0/8] libsas: Support swapping disks and SATA phy link rate matching the pathway Jason Yan
2018-05-29  2:23 ` [PATCH 1/8] scsi: libsas: delete dead code in scsi_transport_sas.c Jason Yan
2018-05-29  7:33   ` Johannes Thumshirn
2018-05-31 14:26   ` John Garry
2018-05-29  2:23 ` [PATCH 2/8] scsi: libsas: check the lldd callback correctly Jason Yan
2018-05-29  7:34   ` Johannes Thumshirn
2018-05-31 14:09   ` John Garry
2018-06-01  0:15     ` Jason Yan
2018-05-29  2:23 ` [PATCH 3/8] scsi: libsas: always unregister the old device if going to discover new Jason Yan
2018-05-29  7:37   ` Johannes Thumshirn
2018-05-31 15:09   ` John Garry [this message]
2018-06-01  0:28     ` Jason Yan
2018-05-29  2:23 ` [PATCH 4/8] scsi: libsas: trigger a new revalidation to discover the device Jason Yan
2018-05-29  7:43   ` Johannes Thumshirn
2018-05-31 15:42   ` John Garry
2018-06-01  0:59     ` Jason Yan
2018-06-01 10:02       ` John Garry
2018-06-04  1:01         ` Jason Yan
2018-05-29  2:23 ` [PATCH 5/8] scsi: libsas: check if the same sata device when flutter Jason Yan
2018-05-29  2:23 ` [PATCH 6/8] scsi: libsas: reset the phy state and address if discover failed Jason Yan
2018-05-29  2:23 ` [PATCH 7/8] scsi: libsas: fix issue of swapping two sas disks Jason Yan
2018-05-29  2:23 ` [PATCH 8/8] scsi: libsas: support SATA phy link rate unmatch the pathway Jason Yan
2018-05-31 16:05   ` John Garry
2018-06-01  1:21     ` Jason Yan
2018-06-01 10:13       ` John Garry

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