linux-kernel - Re: [PATCH v1] driver core: Use list_del_init to replace list_del at device_links_purge()

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Date:   Wed, 8 Jan 2020 17:10:26 +0000
From:   John Garry <john.garry@...wei.com>
To:     James Bottomley <jejb@...ux.ibm.com>,
        Greg KH <gregkh@...uxfoundation.org>
CC:     "Martin K . Petersen" <martin.petersen@...cle.com>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        Linuxarm <linuxarm@...wei.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "saravanak@...gle.com" <saravanak@...gle.com>,
        Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH v1] driver core: Use list_del_init to replace list_del at
 device_links_purge()

On 08/01/2020 16:08, John Garry wrote:
> On 08/01/2020 16:01, James Bottomley wrote:
>>>>>     cdev->dev = NULL;
>>>>>             return device_add(&cdev->cdev);
>>>>>         }
>>>>>     }
>>>>>     return -ENODEV;
>>>>> }
>>>> The design of the code is simply to remove the link to the inserted
>>>> device which has been removed.
>>>>
>>>> I*think*  this means the calls to device_del and device_add are
>>>> unnecessary and should go.  enclosure_remove_links and the put of
>>>> the
>>>> enclosed device should be sufficient.
>>> That would make more sense than trying to "reuse" the device
>>> structure
>>> here by tearing it down and adding it back.
>> OK, let's try that.  This should be the patch if someone can try it
>> (I've compile tested it, but the enclosure system is under a heap of
>> stuff in the garage).
> 
> I can test it now.
> 

Yeah, that looks to have worked ok. SES disk locate was also fine after 
losing and rediscovering the disk.

Thanks,
John

> But it is a bit suspicious that we had the device_del() and device_add() 
> at all, especially since the code change makes it look a bit more like 
> pre-43d8eb9cfd0 ("ses: add support for enclosure component hot removal")
> 
> John
> 
>>
>> James
>>
>> ---
>>
>> diff --git a/drivers/misc/enclosure.c b/drivers/misc/enclosure.c
>> index 6d27ccfe0680..3c2d405bc79b 100644
>> --- a/drivers/misc/enclosure.c
>> +++ b/drivers/misc/enclosure.c
>> @@ -406,10 +406,9 @@ int enclosure_remove_device(struct 
>> enclosure_device *edev, struct device *dev)
>>           cdev = &edev->component[i];
>>           if (cdev->dev == dev) {
>>               enclosure_remove_links(cdev);
>> -            device_del(&cdev->cdev);
>>               put_device(dev);
>>               cdev->dev = NULL;
>> -            return device_add(&cdev->cdev);
>> +            return 0;
>>           }
>>       }
>>       return -ENODEV;
> 
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> Linuxarm@...wei.com
> http://hulk.huawei.com/mailman/listinfo/linuxarm
> .

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