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Subject: Re: [PATCH v2 6/7] scsi: libsas: reset the phy address if discover
 failed
To:     John Garry <john.garry@huawei.com>, <martin.petersen@oracle.com>,
        <jejb@linux.vnet.ibm.com>
References: <20190130082412.9357-1-yanaijie@huawei.com>
 <20190130082412.9357-7-yanaijie@huawei.com>
 <e6bb5696-b2ad-d546-5571-1e2fe39edb61@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:   Jason Yan <yanaijie@huawei.com>
Message-ID: <5C5259B4.10005@huawei.com>
Date:   Thu, 31 Jan 2019 10:13:08 +0800
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On 2019/1/31 1:36, John Garry wrote:
> 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.
>

The test guys have seen this for several times, especially after LLDD 
changed the logic of lldd_dev_found and may return error now.


>>
>> 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;
>>
>
>
>
> .
>