linux-kernel - [PATCH 1/2] bitops.h: Improve sign

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Date:	Thu, 15 Oct 2015 18:18:28 +0200
From:	Martin Kepplinger <martink@...teo.de>
To:	mingo@...nel.org, akpm@...ux-foundation.org, linux@...izon.com,
	linux@...musvillemoes.dk, maxime.coquelin@...com,
	dvlasenk@...hat.com, yury.norov@...il.com,
	torvalds@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org,
	Martin Kepplinger <martink@...teo.de>,
	Martin Kepplinger <martin.kepplinger@...obroma-systems.com>
Subject: [PATCH 1/2] bitops.h: Improve sign_extend32()'s documentation

It is often overlooked that sign_extend32(), despite it's name, is safe
to use for 16 and 8 bit types aswell. This should help that sign extension
isn't done manually some other way.

Signed-off-by: Martin Kepplinger <martin.kepplinger@...obroma-systems.com>
---
 include/linux/bitops.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index e635533..2177c01 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -164,6 +164,8 @@ static inline __u8 ror8(__u8 word, unsigned int shift)
  * 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 aswell.
  */
 static inline __s32 sign_extend32(__u32 value, int index)
 {
-- 
2.1.4

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