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Subject: Re: [PATCH v2 6/7] scsi: libsas: reset the phy address if discover
 failed
To:     Jason Yan <yanaijie@huawei.com>, <martin.petersen@oracle.com>,
        <jejb@linux.vnet.ibm.com>
References: <20190130082412.9357-1-yanaijie@huawei.com>
 <20190130082412.9357-7-yanaijie@huawei.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>,
        Xiaofei Tan <tanxiaofei@huawei.com>,
        Ewan Milne <emilne@redhat.com>, Tomas Henzl <thenzl@redhat.com>
From:   John Garry <john.garry@huawei.com>
Message-ID: <e6bb5696-b2ad-d546-5571-1e2fe39edb61@huawei.com>
Date:   Wed, 30 Jan 2019 17:36:20 +0000
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On 30/01/2019 08:24, Jason Yan wrote:
> When we failed to discover the device, the phy address is still kept
> in ex_phy. So when the next time we revalidate this phy the
> address and device type is the same, it will be considered as flutter
> and will not be discovered again. So the device will not be brought up.
>
> Fix this by reset the phy address to the initial value. Then
> in the next revalidation the device will be discovered agian.

Why fail to discover the device? I wonder in which scenario you have 
seen this, such that it is worth rediscovery.

>
> Tested-by: Chen Liangfei <chenliangfei1@huawei.com>
> Signed-off-by: Jason Yan <yanaijie@huawei.com>
> CC: Xiaofei Tan <tanxiaofei@huawei.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 | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
> index 6e56ebdc2148..e781941a7088 100644
> --- a/drivers/scsi/libsas/sas_expander.c
> +++ b/drivers/scsi/libsas/sas_expander.c
> @@ -1100,6 +1100,13 @@ static int sas_ex_discover_dev(struct domain_device *dev, int phy_id)
>  						 i, SAS_ADDR(ex->ex_phy[i].attached_sas_addr));
>  			}
>  		}
> +	} else {
> +		/* if we failed to discover this device, we have to
> +		 * reset the expander phy attached address so that we
> +		 * will not treat the phy as flutter in the next
> +		 * revalidation
> +		 */
> +		memset(ex_phy->attached_sas_addr, 0, SAS_ADDR_SIZE);
>  	}
>
>  	return res;
>