linux-kernel - Re: [PATCH v2] coccinelle: if (ret) return ret; return ret; semantic patch

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Date:	Tue, 14 Jun 2011 20:15:32 -0500
From:	Greg Dietsche <greg@...mergreg.com>
To:	Julia Lawall <julia@...u.dk>
CC:	Gilles.Muller@...6.fr, npalix.work@...il.com, cocci@...u.dk,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] coccinelle: if (ret) return ret; return ret; semantic
 patch



On 06/14/2011 04:24 PM, Greg Dietsche wrote:
> On 06/14/2011 12:50 AM, Julia Lawall wrote:
>> On Mon, 13 Jun 2011, Greg Dietsche wrote:
>>> just curious... i see you usually just write "return ret;" here when
>>> posting.
>>> I've assumed that's because it will 1) work and 2) is close enough.
>>>
>>> You'll notice I've been doing:
>>> -return ret;
>>> +return ret;
>>> because it seems to help coccinelle realize that it can get rid of
>>> extra line
>>> feeds - does this make sense - or should i just be doing a "return ret"?
>> I wondered why you were doing that :)
>>
>> Is the problem that the removed if is being replaced by a blank line? If
>> so, that is not intentional. I will look into it. If it doesn't happen
>> always, an example where it does happen could be helpful.
>>
>
> Some times it gets it right, so it's not always wrong. For example:
>
> diff -u -p a/arch/m68k/math-emu/fp_log.c b/arch/m68k/math-emu/fp_log.c
> --- a/arch/m68k/math-emu/fp_log.c 2011-06-13 14:06:37.943954469 -0500
> +++ b/arch/m68k/math-emu/fp_log.c 2011-06-14 16:07:22.394954040 -0500
> @@ -105,9 +105,6 @@ fp_fetoxm1(struct fp_ext *dest, struct f
>
> fp_monadic_check(dest, src);
>
> - if (IS_ZERO(dest))
> - return dest;
> -
> return dest;
> }
>
>
>
> Here's an example where it got it "wrong" - notice how the blank line is
> missing the - :
>
> diff -u -p a/arch/frv/mm/pgalloc.c b/arch/frv/mm/pgalloc.c
> --- a/arch/frv/mm/pgalloc.c 2011-06-13 14:06:37.855954391 -0500
> +++ b/arch/frv/mm/pgalloc.c 2011-06-14 16:07:16.714954008 -0500
> @@ -136,8 +136,6 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
> pgd_t *pgd;
>
> pgd = quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
> - if (!pgd)
> - return pgd;
>
> return pgd;
> }
>
>
> but when I do
> -return ret;
> +return ret;
>
> then both of the above examples are "correct"
>
>
> Greg
>
>
>> The disadvantage of removing something and then adding it back is that
>> then Coccinelle takes over the pretty printing of that thing. Since ret
>> is usually a variable, it doesn't matter, and since Coccinelle tries to
>> follow Linux spacing conventions it might not matter either. But eg
>> f(a,b,c,d) would become f(a, b, c, d).
>>
>> julia
>
>


here is another wierd one.. but this time it adds an extra blank line...:

diff -u -p a/drivers/staging/brcm80211/brcmsmac/phy/phy_cmn.c 
b/drivers/staging/brcm80211/brcmsmac/phy/phy_cmn.c
--- a/drivers/staging/brcm80211/brcmsmac/phy/phy_cmn.c 2011-06-13 
14:06:39.483954235 -0500
+++ b/drivers/staging/brcm80211/brcmsmac/phy/phy_cmn.c 2011-06-14 
19:20:38.915032203 -0500
@@ -3184,8 +3184,7 @@ wlc_user_txpwr_antport_to_rfport(phy_inf
  {
         s8 offset = 0;

-       if (!pi->user_txpwr_at_rfport)
-               return offset;
+
         return offset;
  }

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