The patch titled
Subject: lib/vsprintf.c: reduce stack use in number()
has been added to the -mm tree. Its filename is
lib-vsprintfc-reduce-stack-use-in-number.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/lib-vsprintfc-reduce-stack-use-in-number.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/lib-vsprintfc-reduce-stack-use-in-number.patch
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------------------------------------------------------
From: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Subject: lib/vsprintf.c: reduce stack use in number()
At least since the initial git commit, when base was passed as a separate
parameter, number() has only been called with bases 8, 10 and 16. I'm
guessing that 66 was to accommodate 64 0/1, a sign and a '\0', but the
buffer is only used for the actual digits. Octal digits carry 3 bits of
information, so 24 is enough. Spell that 3*sizeof(num) so one less place
needs to be changed should long long ever be 128 bits. Also remove the
commented-out code that would handle an arbitrary base.
Signed-off-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/vsprintf.c | 7 +------
1 file changed, 1 insertion(+), 6 deletions(-)
diff -puN lib/vsprintf.c~lib-vsprintfc-reduce-stack-use-in-number lib/vsprintf.c
--- a/lib/vsprintf.c~lib-vsprintfc-reduce-stack-use-in-number
+++ a/lib/vsprintf.c
@@ -386,7 +386,7 @@ char *number(char *buf, char *end, unsig
/* we are called with base 8, 10 or 16, only, thus don't need "G..." */
static const char digits[16] = "0123456789ABCDEF"; /* "GHIJKLMNOPQRSTUVWXYZ"; */
- char tmp[66];
+ char tmp[3 * sizeof(num)];
char sign;
char locase;
int need_pfx = ((spec.flags & SPECIAL) && spec.base != 10);
@@ -423,11 +423,6 @@ char *number(char *buf, char *end, unsig
i = 0;
if (num < spec.base)
tmp[i++] = digits[num] | locase;
- /* Generic code, for any base:
- else do {
- tmp[i++] = (digits[do_div(num,base)] | locase);
- } while (num != 0);
- */
else if (spec.base != 10) { /* 8 or 16 */
int mask = spec.base - 1;
int shift = 3;
_
Patches currently in -mm which might be from linux@xxxxxxxxxxxxxxxxxx are
lib-vsprintfc-eliminate-some-branches.patch
lib-vsprintfc-reduce-stack-use-in-number.patch
lib-vsprintfc-eliminate-duplicate-hex-string-array.patch
lib-vsprintfc-another-small-hack.patch
linux-bitmaph-improve-bitmap_lastfirst_word_mask.patch
rtc-mc13xxx-fix-obfuscated-and-wrong-format-string.patch
lib-lz4-pull-out-constant-tables.patch
linux-next.patch
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