[PATCH 1/6] staging: vt6655: Compress return logic

[PATCH 1/6] staging: vt6655: Compress return logic

[simran singhal]

Simplify function returns by merging assignment and return into
one command line.
Found with Coccinelle
@@
local idexpression ret;
expression e;
@@

-ret =
+return
     e;
-return ret;

Signed-off-by: simran singhal <singhalsimran0@gmail.com>
---
 drivers/staging/vt6655/card.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/vt6655/card.c b/drivers/staging/vt6655/card.c
index e0c9281..b513846 100644
--- a/drivers/staging/vt6655/card.c
+++ b/drivers/staging/vt6655/card.c
@@ -920,7 +920,7 @@ u64 CARDqGetTSFOffset(unsigned char byRxRate, u64 qwTSF1, u64 qwTSF2)
 
 	qwTSFOffset = qwTSF1 - qwTSF2;
 
-	return qwTSFOffset;
+	return qwTSF1 - qwTSF2;
 }
 
 /*
-- 
2.7.4

Re: [Outreachy kernel] [PATCH 1/6] staging: vt6655: Compress return logic

[Julia Lawall]

On Sun, 19 Feb 2017, simran singhal wrote:

> Simplify function returns by merging assignment and return into
> one command line.
> Found with Coccinelle
> @@
> local idexpression ret;
> expression e;
> @@
>
> -ret =
> +return
>      e;
> -return ret;
>
> Signed-off-by: simran singhal <singhalsimran0@gmail.com>
> ---
>  drivers/staging/vt6655/card.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/staging/vt6655/card.c b/drivers/staging/vt6655/card.c
> index e0c9281..b513846 100644
> --- a/drivers/staging/vt6655/card.c
> +++ b/drivers/staging/vt6655/card.c
> @@ -920,7 +920,7 @@ u64 CARDqGetTSFOffset(unsigned char byRxRate, u64 qwTSF1, u64 qwTSF2)
>
>  	qwTSFOffset = qwTSF1 - qwTSF2;
>
> -	return qwTSFOffset;
> +	return qwTSF1 - qwTSF2;

It looks like you can completely get rid of the variable qwTSFOffset as
well.

Actually, it seems that you didn't use the patch that Coccinelle gave you,
because that should have removed the assignment also.  By default
Coccinelle prints a patch on standard output.  You can redirect that into
a file, and if you like it, you can apply it to your code, using
patch -p1 < {file}.  Another option is the --in-place argument to spatch.
Then you would want to do git diff afterwards to see what Coccinelle did.

julia


>  }
>
>  /*
> --
> 2.7.4
>
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Re: [PATCH 1/6] staging: vt6655: Compress return logic

[Joe Perches]

On Sun, 2017-02-19 at 01:50 +0530, simran singhal wrote:
> Simplify function returns by merging assignment and return into
> one command line.
> Found with Coccinelle
> @@
> local idexpression ret;
> expression e;
> @@
> 
> -ret =
> +return
>      e;
> -return ret;
[]
> diff --git a/drivers/staging/vt6655/card.c b/drivers/staging/vt6655/card.c
[]
> @@ -920,7 +920,7 @@ u64 CARDqGetTSFOffset(unsigned char byRxRate, u64 qwTSF1, u64 qwTSF2)
>  
>  	qwTSFOffset = qwTSF1 - qwTSF2;
>  
> -	return qwTSFOffset;
> +	return qwTSF1 - qwTSF2;
>  }

It's not a problem here but generically, this transformation may
introduce defects when the local idexpression being assigned to
is a smaller type than the return type.  e.g.:

u64 foo(u64 a, u64 b)
{
	u8 bar = a - b;
	return bar;
}