Patch "mtd: cfi: reduce stack size" has been added to the 3.18-stable tree

Patch "mtd: cfi: reduce stack size" has been added to the 3.18-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    mtd: cfi: reduce stack size

to the 3.18-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mtd-cfi-reduce-stack-size.patch
and it can be found in the queue-3.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From d09957fbb4d0b059b3176b510540df69048ad170 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@arndb.de>
Date: Tue, 10 Mar 2015 17:48:37 +0100
Subject: mtd: cfi: reduce stack size

From: Arnd Bergmann <arnd@arndb.de>

commit d09957fbb4d0b059b3176b510540df69048ad170 upstream.

The cfi_staa_write_buffers function uses a large amount of kernel stack
whenever CONFIG_MTD_MAP_BANK_WIDTH_32 is set, and that results in a
warning on ARM allmodconfig builds:

drivers/mtd/chips/cfi_cmdset_0020.c: In function 'cfi_staa_write_buffers':
drivers/mtd/chips/cfi_cmdset_0020.c:651:1: warning: the frame size of 1208 bytes is larger than 1024 bytes [-Wframe-larger-than=]

It turns out that this is largely a result of a suboptimal implementation
of map_word_andequal(). Replacing this function with a straightforward
one reduces the stack size in this function by exactly 200 bytes,
shrinks the .text segment for this file from 27648 bytes to 26608 bytes,
and makes the warning go away.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 include/linux/mtd/map.h |   12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

--- a/include/linux/mtd/map.h
+++ b/include/linux/mtd/map.h
@@ -309,7 +309,17 @@ static inline map_word map_word_or(struc
 	return r;
 }
 
-#define map_word_andequal(m, a, b, z) map_word_equal(m, z, map_word_and(m, a, b))
+static inline int map_word_andequal(struct map_info *map, map_word val1, map_word val2, map_word val3)
+{
+	int i;
+
+	for (i = 0; i < map_words(map); i++) {
+		if ((val1.x[i] & val2.x[i]) != val3.x[i])
+			return 0;
+	}
+
+	return 1;
+}
 
 static inline int map_word_bitsset(struct map_info *map, map_word val1, map_word val2)
 {


Patches currently in stable-queue which might be from arnd@arndb.de are

queue-3.18/mtd-cfi-reduce-stack-size.patch
queue-3.18/tty-remove-platform_sysrq_reset_seq.patch