2020-10-06 20:00:05

by Nathan Chancellor

Subject: [PATCH] crypto: xor - Remove unused variable count in do_xor_speed

Clang warns:

crypto/xor.c:101:4: warning: variable 'count' is uninitialized when used
here [-Wuninitialized]
count++;
^~~~~
crypto/xor.c:86:17: note: initialize the variable 'count' to silence
this warning
int i, j, count;
^
= 0
1 warning generated.

After the refactoring to use ktime that happened in this function, count
is only assigned, never read. Just remove the variable to get rid of the
warning.

Fixes: c055e3eae0f1 ("crypto: xor - use ktime for template benchmarking")
Link: https://github.com/ClangBuiltLinux/linux/issues/1171
Signed-off-by: Nathan Chancellor <[email protected]>
---
crypto/xor.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/crypto/xor.c b/crypto/xor.c
index a0badbc03577..eacbf4f93990 100644
--- a/crypto/xor.c
+++ b/crypto/xor.c
@@ -83,7 +83,7 @@ static void __init
do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)
{
int speed;
- int i, j, count;
+ int i, j;
ktime_t min, start, diff;

tmpl->next = template_list;
@@ -98,8 +98,6 @@ do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)
mb(); /* prevent loop optimzation */
tmpl->do_2(BENCH_SIZE, b1, b2);
mb();
- count++;
- mb();
}
diff = ktime_sub(ktime_get(), start);
if (diff < min)

base-commit: ed4424f2fb02497b0ea92bf58c533c598c0da1d3
--
2.29.0.rc0

2020-10-06 23:11:10

by Doug Anderson

Subject: Re: [PATCH] crypto: xor - Remove unused variable count in do_xor_speed

Hi,

On Tue, Oct 6, 2020 at 12:59 PM Nathan Chancellor
<[email protected]> wrote:
>
> Clang warns:
>
> crypto/xor.c:101:4: warning: variable 'count' is uninitialized when used
> here [-Wuninitialized]
> count++;
> ^~~~~
> crypto/xor.c:86:17: note: initialize the variable 'count' to silence
> this warning
> int i, j, count;
> ^
> = 0
> 1 warning generated.
>
> After the refactoring to use ktime that happened in this function, count
> is only assigned, never read. Just remove the variable to get rid of the
> warning.
>
> Fixes: c055e3eae0f1 ("crypto: xor - use ktime for template benchmarking")
> Link: https://github.com/ClangBuiltLinux/linux/issues/1171
> Signed-off-by: Nathan Chancellor <[email protected]>
> ---
> crypto/xor.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)

Whoops! Sorry for missing this in my review.

Reviewed-by: Douglas Anderson <[email protected]>

2020-10-07 06:41:07

by Ard Biesheuvel

Subject: Re: [PATCH] crypto: xor - Remove unused variable count in do_xor_speed

On Tue, 6 Oct 2020 at 21:59, Nathan Chancellor <[email protected]> wrote:
>
> Clang warns:
>
> crypto/xor.c:101:4: warning: variable 'count' is uninitialized when used
> here [-Wuninitialized]
> count++;
> ^~~~~
> crypto/xor.c:86:17: note: initialize the variable 'count' to silence
> this warning
> int i, j, count;
> ^
> = 0
> 1 warning generated.
>
> After the refactoring to use ktime that happened in this function, count
> is only assigned, never read. Just remove the variable to get rid of the
> warning.
>
> Fixes: c055e3eae0f1 ("crypto: xor - use ktime for template benchmarking")
> Link: https://github.com/ClangBuiltLinux/linux/issues/1171
> Signed-off-by: Nathan Chancellor <[email protected]>

Acked-by: Ard Biesheuvel <[email protected]>

> ---
> crypto/xor.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/crypto/xor.c b/crypto/xor.c
> index a0badbc03577..eacbf4f93990 100644
> --- a/crypto/xor.c
> +++ b/crypto/xor.c
> @@ -83,7 +83,7 @@ static void __init
> do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)
> {
> int speed;
> - int i, j, count;
> + int i, j;
> ktime_t min, start, diff;
>
> tmpl->next = template_list;
> @@ -98,8 +98,6 @@ do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)
> mb(); /* prevent loop optimzation */
> tmpl->do_2(BENCH_SIZE, b1, b2);
> mb();
> - count++;
> - mb();
> }
> diff = ktime_sub(ktime_get(), start);
> if (diff < min)
>
> base-commit: ed4424f2fb02497b0ea92bf58c533c598c0da1d3
> --
> 2.29.0.rc0
>