netdev - Re: [PATCH net-next 6/6] amd-xgbe: Resolve checkpatch warning about sscanf usage

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Date:	Tue, 24 Jun 2014 15:53:30 -0700
From:	Joe Perches <joe@...ches.com>
To:	Tom Lendacky <thomas.lendacky@....com>
Cc:	netdev@...r.kernel.org, davem@...emloft.net
Subject: Re: [PATCH net-next 6/6] amd-xgbe: Resolve checkpatch warning about
 sscanf usage

On Tue, 2014-06-24 at 17:44 -0500, Tom Lendacky wrote:
> On 06/24/2014 05:00 PM, Joe Perches wrote:
> > On Tue, 2014-06-24 at 16:19 -0500, Tom Lendacky wrote:
> >> Checkpatch issued a warning preferring to use kstrto<type> when
> >> using a single variable sscanf.  Change the sscanf invocation to
> >> a kstrtouint call.
> > []
> >> diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-debugfs.c b/drivers/net/ethernet/amd/xgbe/xgbe-debugfs.c
> > []
> >> @@ -165,10 +165,9 @@ static ssize_t xgbe_common_write(const char __user *buffer, size_t count,
> >>   		return len;
> >>
> >>   	workarea[len] = '\0';
> >> -	if (sscanf(workarea, "%x", &scan_value) == 1)
> >> -		*value = scan_value;
> >> -	else
> >> -		return -EIO;
> >> +	ret = kstrtouint(workarea, 0, value);
> >
> > Don't you need to use 16 for the base here?

> Using 0 allows for greater flexibility in the input format.

True, but there could be a change in behavior like reading a
previously hex value like 10 is now a decimal 10 not decimal 16.

> > Are there any issues with any of the various callers
> > getting a different error return?
> >
> > -EINVAL/-ERANGE vs -EIO ?
> There shouldn't be, but I can always return -EIO to be
> consistent with how it was previously.

Up to you Tom.  I just wanted you to think about it.

cheers, Joe

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