netdev - Re: [PATCH net-next v2 0/6] slight optimization of addr compare for some modules

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Date:	Wed, 18 Dec 2013 08:51:51 -0800
From:	Joe Perches <joe@...ches.com>
To:	Ding Tianhong <dingtianhong@...wei.com>
Cc:	Ding Tianhong <dthxman@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next v2 0/6] slight optimization of addr compare for
 some modules

On Wed, 2013-12-18 at 18:06 +0800, Ding Tianhong wrote:
> On 2013/12/18 17:17, Joe Perches wrote:
> > On Wed, 2013-12-18 at 16:47 +0800, Ding Tianhong wrote:
> >> On 2013/12/17 9:58, Ding Tianhong wrote:
> >>> On 2013/12/17 1:25, Joe Perches wrote:
> >>>> These should still be inspected for appropriate use of
> >>>> ether_addr_equal or ether_addr_equal_unaligned, but a
> >>>> better cocci input sp-file is:
> >>>>
> >>>> $ cat ether_addr_equal_unaligned.cocci 
> >>>> @@
> >>>> expression e1;
> >>>> expression e2;
> >>>> @@
> > []
> >> There are too many places need to be changed, should I make it in one patch or several pathset,
> >> pls give me some advise. thanks
> > 
> > Separate per-maintainer patches are generally good.
> > It can take several attempts to get these applied
> > in all the various trees.
> > 
> > So maybe 1 patch for each of most of these.  Maybe
> > some of these like drivers/media, drivers/mtd and
> > drivers/staging could probably be single patches.
> > 
> 
> Hi Joe:
> 
> I found there is a bug in spatch, it could not deal with 
> -       memcmp(e1, e2, \(6\|ETH_ALEN\)) != 0
> +       !ether_addr_equal_unaligned(e1, e2)

Not an spatch bug but a defect in the ordering of
transforms in the ether_addr_equal_unaligned.cocci file

This should be better:

$ cat ether_addr_equal_unaligned.cocci
@@
expression e1;
expression e2;
@@

-	memcmp(e1, e2, \(6\|ETH_ALEN\)) == 0
+	ether_addr_equal_unaligned(e1, e2)

@@
expression e1;
expression e2;
@@

-	memcmp(e1, e2, \(6\|ETH_ALEN\)) != 0
+	!ether_addr_equal_unaligned(e1, e2)

@@
expression e1;
expression e2;
@@

-	!memcmp(e1, e2, \(6\|ETH_ALEN\))
+	ether_addr_equal_unaligned(e1, e2)

@@
expression e1;
expression e2;
@@

-	memcmp(e1, e2, \(6\|ETH_ALEN\))
+	!ether_addr_equal_unaligned(e1, e2)



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