clang with W=1 reports
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);
^~~~~~
This is a false positive, but there is never an intermediate value
of result to pass into csum_trail, so move the parameter result to
a local variable.
Signed-off-by: Tom Rix <[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);
--
2.27.0
Hi Tom,
On Tue, May 30, 2023 at 09:59:53AM -0400, Tom Rix wrote:
> clang with W=1 reports
> 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);
> ^~~~~~
> This is a false positive, but there is never an intermediate value
> of result to pass into csum_trail, so move the parameter result to
> a local variable.
>
> Signed-off-by: Tom Rix <[email protected]>
Thanks for the patch. I sent the same one last Friday, which should be
in your inbox:
https://lore.kernel.org/20230526-csum_partial-wuninitialized-v1-1-ebc0108dcec1@kernel.org/
Dave picked it up yesterday, I guess -tip's auto-latest was not
refreshed for today's -next:
https://git.kernel.org/tip/2fe1e67e6987b6f05329740da79c8150a2205b0d
Cheers,
Nathan
> ---
> 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);
>
> --
> 2.27.0
>
On 5/30/23 08:20, Nathan Chancellor wrote:
> Dave picked it up yesterday, I guess -tip's auto-latest was not
> refreshed for today's -next:
>
> https://git.kernel.org/tip/2fe1e67e6987b6f05329740da79c8150a2205b0d
BTW, thank you _both_ for the patches!