Clang warns:
arch/x86/lib/csum-partial_64.c:74:20: error: variable 'result' is uninitialized when used here [-Werror,-Wuninitialized]
return csum_tail(result, temp64, odd);
^~~~~~
arch/x86/lib/csum-partial_64.c:48:22: note: initialize the variable 'result' to silence this warning
unsigned odd, result;
^
= 0
1 error generated.
The only initialization and uses of result in csum_partial() were moved
into csum_tail() but result is still being passed by value to
csum_tail() (clang's -Wuninitialized does not do interprocedural
analysis to realize that result is always assigned in csum_tail()
however). Sink the declaration of result into csum_tail() to clear up
the warning.
Fixes: 688eb8191b47 ("x86/csum: Improve performance of `csum_partial`")
Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/[email protected]/
Signed-off-by: Nathan Chancellor <[email protected]>
---
arch/x86/lib/csum-partial_64.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/arch/x86/lib/csum-partial_64.c b/arch/x86/lib/csum-partial_64.c
index fe5861951b15..cea25ca8b8cf 100644
--- a/arch/x86/lib/csum-partial_64.c
+++ b/arch/x86/lib/csum-partial_64.c
@@ -21,8 +21,10 @@ static inline unsigned short from32to16(unsigned a)
return b;
}
-static inline __wsum csum_tail(unsigned int result, u64 temp64, int odd)
+static inline __wsum csum_tail(u64 temp64, int odd)
{
+ unsigned int result;
+
result = add32_with_carry(temp64 >> 32, temp64 & 0xffffffff);
if (unlikely(odd)) {
result = from32to16(result);
@@ -45,7 +47,7 @@ static inline __wsum csum_tail(unsigned int result, u64 temp64, int odd)
__wsum csum_partial(const void *buff, int len, __wsum sum)
{
u64 temp64 = (__force u64)sum;
- unsigned odd, result;
+ unsigned odd;
odd = 1 & (unsigned long) buff;
if (unlikely(odd)) {
@@ -71,7 +73,7 @@ __wsum csum_partial(const void *buff, int len, __wsum sum)
"adcq $0,%[res]"
: [res] "+r"(temp64)
: [src] "r"(buff), "m"(*(const char(*)[40])buff));
- return csum_tail(result, temp64, odd);
+ return csum_tail(temp64, odd);
}
if (unlikely(len >= 64)) {
/*
@@ -141,7 +143,7 @@ __wsum csum_partial(const void *buff, int len, __wsum sum)
: [res] "+r"(temp64)
: [trail] "r"(trail));
}
- return csum_tail(result, temp64, odd);
+ return csum_tail(temp64, odd);
}
EXPORT_SYMBOL(csum_partial);
---
base-commit: 688eb8191b475db5acfd48634600b04fd3dda9ad
change-id: 20230526-csum_partial-wuninitialized-08aa3d492f07
Best regards,
--
Nathan Chancellor <[email protected]>