The patch titled
Subject: bitops.h: improve sign_extend32()'s documentation
has been added to the -mm tree. Its filename is
bitopsh-improve-sign_extend32s-documentation.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/bitopsh-improve-sign_extend32s-documentation.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/bitopsh-improve-sign_extend32s-documentation.patch
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------------------------------------------------------
From: Martin Kepplinger <martink@xxxxxxxxx>
Subject: bitops.h: improve sign_extend32()'s documentation
It is often overlooked that sign_extend32(), despite its name, is safe to
use for 16 and 8 bit types as well. This should help prevent sign
extension being done manually some other way.
Signed-off-by: Martin Kepplinger <martin.kepplinger@xxxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: George Spelvin <linux@xxxxxxxxxxx>
Cc: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Cc: Maxime Coquelin <maxime.coquelin@xxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: Yury Norov <yury.norov@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/bitops.h | 2 ++
1 file changed, 2 insertions(+)
diff -puN include/linux/bitops.h~bitopsh-improve-sign_extend32s-documentation include/linux/bitops.h
--- a/include/linux/bitops.h~bitopsh-improve-sign_extend32s-documentation
+++ a/include/linux/bitops.h
@@ -164,6 +164,8 @@ static inline __u8 ror8(__u8 word, unsig
* sign_extend32 - sign extend a 32-bit value using specified bit as sign-bit
* @value: value to sign extend
* @index: 0 based bit index (0<=index<32) to sign bit
+ *
+ * This is safe to use for 16- and 8-bit types as well.
*/
static inline __s32 sign_extend32(__u32 value, int index)
{
_
Patches currently in -mm which might be from martink@xxxxxxxxx are
bitopsh-improve-sign_extend32s-documentation.patch
bitopsh-add-sign_extend64.patch
arch-sh-use-sign_extend64-for-sign-extension.patch
arch-sh-use-sign_extend64-for-sign-extension-2.patch
arch-x86-use-sign_extend64-for-sign-extension.patch
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