Re: [PATCH][RESEND] scsi_sysfs: add 'is_bin_visible' callback

[Hannes Reinecke <hare@suse.com>]

On 03/02/2016 05:19 PM, Christoph Hellwig wrote:
> On Wed, Mar 02, 2016 at 03:33:14PM +0800, Hannes Reinecke wrote:
>>>> +	rcu_read_lock();
>>>> +	if (attr == &dev_attr_vpd_pg80 &&
>>>> +	    !rcu_dereference(sdev->vpd_pg80)) {
>>>> +		rcu_read_unlock();
>>>> +		return 0;
>>>> +	}
>>>> +	if (attr == &dev_attr_vpd_pg83 &&
>>>> +	    !rcu_dereference(sdev->vpd_pg83)) {
>>>> +		rcu_read_unlock();
>>>> +		return 0;
>>>> +	}
>>>> +	rcu_read_unlock();
>>>
>>> We are only checking the pointers for being non-zero.  No need for the
>>> rcu_read_lock() or rcu_dereference() here.
>>>
>> Better to be same than sorry; some overly clever code analysis tool
>> might trip over it otherwise.
> 
> It shouldn't.  There is no dereference going on here.
> 
Ok.

>>
>>> Otherwise this looks fine to me.
>>
>> Reviewed-by: ?
> 
> Only without the cargo culted rcu magic.
> 
Okay, will be resending it.

Cheers,

Hannes