linux-kernel - [PATCH 1/9] mtd: cfi_cmdset_0020: Drop unnecessary static

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Date:   Thu,  4 May 2017 22:10:46 +0200
From:   Julia Lawall <Julia.Lawall@...6.fr>
To:     David Woodhouse <dwmw2@...radead.org>
Cc:     keescook@...omium.org, kernel-janitors@...r.kernel.org,
        Brian Norris <computersforpeace@...il.com>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Richard Weinberger <richard@....at>,
        Cyrille Pitchen <cyrille.pitchen@...ev4u.fr>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/9] mtd: cfi_cmdset_0020: Drop unnecessary static

Drop static on a local variable, when the variable is initialized before
any use on every possible execution path through the function.  The static
has no benefit, and dropping it reduces the code size.

The semantic patch that fixes this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@bad exists@
position p;
identifier x;
type T;
@@

static T x@p;
...
x = <+...x...+>

@@
identifier x;
expression e;
type T;
position p != bad.p;
@@

-static
 T x@p;
 ... when != x
     when strict
?x = e;
// </smpl>

The change in code size is indicates by the following output from the size
command.

before:
   text    data     bss     dec     hex filename
  16671      48      16   16735    415f drivers/mtd/chips/cfi_cmdset_0020.o

after:
   text    data     bss     dec     hex filename
  16639      48       8   16695    4137 drivers/mtd/chips/cfi_cmdset_0020.o

Signed-off-by: Julia Lawall <Julia.Lawall@...6.fr>

---
 drivers/mtd/chips/cfi_cmdset_0020.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/chips/cfi_cmdset_0020.c b/drivers/mtd/chips/cfi_cmdset_0020.c
index 94d3eb4..7d34296 100644
--- a/drivers/mtd/chips/cfi_cmdset_0020.c
+++ b/drivers/mtd/chips/cfi_cmdset_0020.c
@@ -666,7 +666,7 @@ static int cfi_staa_write_buffers (struct mtd_info *mtd, loff_t to,
 	size_t	 totlen = 0, thislen;
 	int	 ret = 0;
 	size_t	 buflen = 0;
-	static char *buffer;
+	char *buffer;
 
 	if (!ECCBUF_SIZE) {
 		/* We should fall back to a general writev implementation.