Re: [PATCH] ipv6: sr: fix useless rol32 call on hash
From: Joe Perches <joe@perches.com>
Date: 2018-07-17 17:08:51
Also in:
kernel-janitors, lkml
Subsystem:
bitops api, the rest · Maintainers:
Yury Norov, Linus Torvalds
On Tue, 2018-07-17 at 17:03 +0100, David Lebrun wrote:
On 07/17/2018 04:52 PM, Colin King wrote:quoted
From: Colin Ian King<redacted> The rol32 call is currently rotating hash but the rol'd value is being discarded. I believe the current code is incorrect and hash should be assigned the rotated value returned from rol32. Detected by CoverityScan, CID#1468411 ("Useless call") Fixes: b5facfdba14c ("ipv6: sr: Compute flowlabel for outer IPv6 header of seg6 encap mode") Signed-off-by: Colin Ian King<redacted>Acked-by: dlebrun@google.com Good catch, thanks ! In that case, the same issue is present in include/net/ipv6.h:ip6_make_flowlabel().
Perhaps all of the ror and rol definitions should add __must_check Something like the below and perhaps many more of the functions that return some value should have __must_chedk added as well. --- include/linux/bitops.h | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index af419012d77d..3cddde65c8bb 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h@@ -67,7 +67,7 @@ static inline __u64 rol64(__u64 word, unsigned int shift) * @word: value to rotate * @shift: bits to roll */ -static inline __u64 ror64(__u64 word, unsigned int shift) +static inline __must_check __u64 ror64(__u64 word, unsigned int shift) { return (word >> shift) | (word << (64 - shift)); }
@@ -77,7 +77,7 @@ static inline __u64 ror64(__u64 word, unsigned int shift) * @word: value to rotate * @shift: bits to roll */ -static inline __u32 rol32(__u32 word, unsigned int shift) +static inline __must_check __u32 rol32(__u32 word, unsigned int shift) { return (word << shift) | (word >> ((-shift) & 31)); }
@@ -87,7 +87,7 @@ static inline __u32 rol32(__u32 word, unsigned int shift) * @word: value to rotate * @shift: bits to roll */ -static inline __u32 ror32(__u32 word, unsigned int shift) +static inline __must_check __u32 ror32(__u32 word, unsigned int shift) { return (word >> shift) | (word << (32 - shift)); }
@@ -97,7 +97,7 @@ static inline __u32 ror32(__u32 word, unsigned int shift) * @word: value to rotate * @shift: bits to roll */ -static inline __u16 rol16(__u16 word, unsigned int shift) +static inline __must_check __u16 rol16(__u16 word, unsigned int shift) { return (word << shift) | (word >> (16 - shift)); }
@@ -107,7 +107,7 @@ static inline __u16 rol16(__u16 word, unsigned int shift) * @word: value to rotate * @shift: bits to roll */ -static inline __u16 ror16(__u16 word, unsigned int shift) +static inline __must_check __u16 ror16(__u16 word, unsigned int shift) { return (word >> shift) | (word << (16 - shift)); }
@@ -117,7 +117,7 @@ static inline __u16 ror16(__u16 word, unsigned int shift) * @word: value to rotate * @shift: bits to roll */ -static inline __u8 rol8(__u8 word, unsigned int shift) +static inline __must_check __u8 rol8(__u8 word, unsigned int shift) { return (word << shift) | (word >> (8 - shift)); }
@@ -127,7 +127,7 @@ static inline __u8 rol8(__u8 word, unsigned int shift) * @word: value to rotate * @shift: bits to roll */ -static inline __u8 ror8(__u8 word, unsigned int shift) +static inline __must_check __u8 ror8(__u8 word, unsigned int shift) { return (word >> shift) | (word << (8 - shift)); }
@@ -139,7 +139,7 @@ static inline __u8 ror8(__u8 word, unsigned int shift) * * This is safe to use for 16- and 8-bit types as well. */ -static inline __s32 sign_extend32(__u32 value, int index) +static inline __must_check __s32 sign_extend32(__u32 value, int index) { __u8 shift = 31 - index; return (__s32)(value << shift) >> shift;
@@ -150,7 +150,7 @@ static inline __s32 sign_extend32(__u32 value, int index) * @value: value to sign extend * @index: 0 based bit index (0<=index<64) to sign bit */ -static inline __s64 sign_extend64(__u64 value, int index) +static inline __must_check __s64 sign_extend64(__u64 value, int index) { __u8 shift = 63 - index; return (__s64)(value << shift) >> shift;