Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755769Ab1FOPdM (ORCPT ); Wed, 15 Jun 2011 11:33:12 -0400 Received: from mta31.charter.net ([216.33.127.82]:33822 "EHLO mta31.charter.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755169Ab1FOPdJ (ORCPT ); Wed, 15 Jun 2011 11:33:09 -0400 X-Authority-Analysis: v=1.1 cv=G6Q69DB3AUoJKS2BpLRaz8MQ2NORN7h5HRzrJMPOhRw= c=1 sm=1 a=p9YancsnzTcA:10 a=xF9yuZ1V3iQA:10 a=HnXbG3lm2xYA:10 a=8nJEP1OIZ-IA:10 a=xzrYXqw+0zwiO4gHSXHcAg==:17 a=ijVwADQ8Gve17iG8bsYA:9 a=ovtdbYvR1d-wkxd7BrQA:7 a=wPNLvfGTeEIA:10 a=xzrYXqw+0zwiO4gHSXHcAg==:117 Message-ID: <4DF8D0B4.7020505@gregd.org> Date: Wed, 15 Jun 2011 10:33:08 -0500 From: Greg Dietsche User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.16) Gecko/20110505 Icedove/3.0.11 MIME-Version: 1.0 To: Julia Lawall CC: Greg Dietsche , linux-kernel@vger.kernel.org, cocci@diku.dk, Gilles.Muller@lip6.fr Subject: Re: [Cocci] Re: [PATCH v2] coccinelle: if (ret) return ret; return ret; semantic patch References: <1307989386-17666-1-git-send-email-Gregory.Dietsche@cuw.edu> <4DF67933.9080707@cuw.edu> <4DF7D197.5070205@cuw.edu> <4DF807B4.8010807@gregd.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3560 Lines: 98 On 06/15/2011 12:58 AM, Julia Lawall wrote: > On Tue, 14 Jun 2011, Greg Dietsche wrote: > >> >> >> 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; >>> } > > OK, but it is going to be hard for Coccinelle to know that, although the > programmer previously thought that return should be separated from the > rest of the function by a blank line, that is now no longer the case. > Perhaps it is due to the fact that there is now only one other line in the > body of the function, but it seems like an opinion as to how to draw the > line. > OK - I can see how that would be hard for Coccinelle to guess what we really want in this case. > So your - return ret; + return ret; is probably the appropriate solution. > You want to get rid of the whole pattern if (...) return ret; return ret; > and replace it with just return ret;, which will then be inserted at the > point of the beginning of the match to the pattern. ok > It would be nicer to put the - return ret; + return ret; inside the last > line of the ( | ). Then only those return ret's are rewritten rather than > every return ret in the program. It should improver performance and except that 4 of the 5 ORs are cases where we want to do the -return ret; + return ret; So I suppose for performance, I should actually add the +/- to each of the 4 cases that we want cocci to generate a patch for? thanks, Greg > reduce the risk of changing spacing. The other ifs in the ( | ) don't > need to be followed by return ret. They are just ifs that you want to > ignore completely. > > julia -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/