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

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Date:	Mon, 6 Jun 2011 06:55:54 +0200 (CEST)
From:	Julia Lawall <julia@...u.dk>
To:	Greg Dietsche <Gregory.Dietsche@....edu>
Cc:	Gilles.Muller@...6.fr, npalix.work@...il.com, cocci@...u.dk,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] coccinelle: if(ret)return ret; return ret; semantic
 patch

Thanks.  I tried this too, but I wasn't sure about the results.  The 
question is why stop here.  For example, there are IS_ERR calls that one 
could consider as well.  Or ret < 0.  Or why not just:

@@
expression ret;
@@

- if (...) return ret;
  return ret;

Although there might be function calls that one doesn't want to touch, so:

@@
identifier f != IS_ERR;
expression ret;
statement S;
@@

(
if (<+...f(...)...+>) S
|
- if (...) return ret;
  return ret;
)

julia


On Sun, 5 Jun 2011, Greg Dietsche wrote:

> This semantic patch finds code matching this pattern:
> 	if(ret)
> 		return ret;
> 	return ret;
> 
> I will be submitting patches shortly against the mainline to cleanup all
> code matching this pattern.
> 
> Signed-off-by: Greg Dietsche <Gregory.Dietsche@....edu>
> ---
>  scripts/coccinelle/misc/doublereturn.cocci |   20 ++++++++++++++++++++
>  1 files changed, 20 insertions(+), 0 deletions(-)
>  create mode 100644 scripts/coccinelle/misc/doublereturn.cocci
> 
> diff --git a/scripts/coccinelle/misc/doublereturn.cocci b/scripts/coccinelle/misc/doublereturn.cocci
> new file mode 100644
> index 0000000..656a118
> --- /dev/null
> +++ b/scripts/coccinelle/misc/doublereturn.cocci
> @@ -0,0 +1,20 @@
> +/// Remove unecessary if/return in code that follows this pattern:
> +///	if(retval)
> +///		return retval;
> +///	return retval;
> +//
> +// Confidence: High
> +// Copyright: (C) 2011 Greg Dietsche GPLv2.
> +// URL: http://www.gregd.org
> +// Comments:
> +// Options: -no_includes
> +
> +virtual patch
> +
> +@@
> +identifier retval;
> +@@
> +-if (retval)
> +-	return retval;
> +-return retval;
> ++return retval;
> -- 
> 1.7.2.5
> 
> 
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