mtd: cfi: reduce stack size

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=d09957fbb4d0b059b3176b510540df69048ad170
Commit:     d09957fbb4d0b059b3176b510540df69048ad170
Parent:     0ec56dc4a1489d5b1d23d1c019b76a69ce153805
Author:     Arnd Bergmann <arnd at arndb.de>
AuthorDate: Tue Mar 10 17:48:37 2015 +0100
Committer:  Brian Norris <computersforpeace at gmail.com>
CommitDate: Wed Mar 11 15:25:51 2015 -0700

    mtd: cfi: reduce stack size
    
    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 at arndb.de>
    Signed-off-by: Brian Norris <computersforpeace at gmail.com>
---
 include/linux/mtd/map.h | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/include/linux/mtd/map.h b/include/linux/mtd/map.h
index 5f487d7..a872157 100644
--- a/include/linux/mtd/map.h
+++ b/include/linux/mtd/map.h
@@ -314,7 +314,17 @@ static inline map_word map_word_or(struct map_info *map, map_word val1, map_word
 	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)
 {