mtd: cfi: reduce stack size

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>

diff --git a/include/linux/mtd/map.h b/include/linux/mtd/map.h
index 78957a9de6237f3f332bf0f0b47063e504227c6e..ff53f24fa8f059a07dba959521e75ff1b58f62ad 100644 (file)
--- a/include/linux/mtd/map.h
+++ b/include/linux/mtd/map.h
@@ -309,7 +309,17 @@ 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)
 {