netdev - [PATCH] Re: [PATCH v4] ethtool: Add direct access to ops->get_sset

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Date:	Thu, 04 Mar 2010 13:21:53 -0500
From:	Jeff Garzik <jeff@...zik.org>
To:	Ben Hutchings <bhutchings@...arflare.com>
CC:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>, davem@...emloft.net,
	netdev@...r.kernel.org, gospo@...hat.com
Subject: [PATCH] Re: [PATCH v4] ethtool: Add direct access to ops->get_sset_count

On 03/04/2010 09:26 AM, Ben Hutchings wrote:
> On Thu, 2010-03-04 at 00:51 -0800, Jeff Kirsher wrote:
>> From: Jeff Garzik<jgarzik@...hat.com>
>>
>> This patch is an alternative approach for accessing string
>> counts, vs. the drvinfo indirect approach.  This way the drvinfo
>> space doesn't run out, and we don't break ABI later.
> [...]
>> --- a/net/core/ethtool.c
>> +++ b/net/core/ethtool.c
>> @@ -214,6 +214,10 @@ static noinline int ethtool_get_drvinfo(struct net_device *dev, void __user *use
>>   	info.cmd = ETHTOOL_GDRVINFO;
>>   	ops->get_drvinfo(dev,&info);
>>
>> +	/*
>> +	 * this method of obtaining string set info is deprecated;
>> +	 * consider using ETHTOOL_GSSET_INFO instead
>> +	 */
>
> This comment belongs on the interface (ethtool.h) not the
> implementation.

Debatable -- the current comment is located at the callsite of 
ops->get_sset_count(), which is where an implementor might think to add 
a new call.  Not all the numeric fields in ethtool_drvinfo are obtained 
from ->get_sset_count().

Hence the "some" in the attached patch to include/linux/ethtool.h, 
addressing your comment.


> [...]
>> +static noinline int ethtool_get_sset_info(struct net_device *dev,
>> +                                          void __user *useraddr)
>> +{
> [...]
>> +	/* calculate size of return buffer */
>> +	for (i = 0; i<  64; i++)
>> +		if (sset_mask&  (1ULL<<  i))
>> +			n_bits++;
> [...]
>
> We have a function for this:
>
> 	n_bits = hweight64(sset_mask);

Agreed.

I've attached a follow-up patch, which should enable my/Jeff's kernel 
patch to be applied, followed by this one.

	Jeff




View attachment "patch" of type "text/plain" (1755 bytes)