* [PATCH] sched: Make sched_feat(x) boolean for !CONFIG_SCHED_DEBUG
@ 2018-10-23 0:41 Matthias Kaehlcke
2018-10-23 16:44 ` Nick Desaulniers
0 siblings, 1 reply; 2+ messages in thread
From: Matthias Kaehlcke @ 2018-10-23 0:41 UTC (permalink / raw)
To: Ingo Molnar, Peter Zijlstra
Cc: linux-kernel, Philipp Klocke, Guenter Roeck, Nick Desaulniers,
Matthias Kaehlcke
If scheduler debugging is disabled sched_feat() resolves to a constant
value that can be non-boolean. clang raises a warning when it detects
that a non-boolean constant is used as operand in logical expressions:
kernel/sched/core.c:208:26: warning: use of logical '&&' with constant
operand [-Wconstant-logical-operand]
if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Convert the original expression to boolean by means of a double not
operation.
Reported-by: Philipp Klocke <Phil_K97@gmx.de>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
---
kernel/sched/sched.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 4a2e8cae63c4..b9387d35e261 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1393,7 +1393,7 @@ static const_debug __maybe_unused unsigned int sysctl_sched_features =
0;
#undef SCHED_FEAT
-#define sched_feat(x) (sysctl_sched_features & (1UL << __SCHED_FEAT_##x))
+#define sched_feat(x) (!!(sysctl_sched_features & (1UL << __SCHED_FEAT_##x)))
#endif /* SCHED_DEBUG && HAVE_JUMP_LABEL */
--
2.19.1.568.g152ad8e336-goog
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] sched: Make sched_feat(x) boolean for !CONFIG_SCHED_DEBUG
2018-10-23 0:41 [PATCH] sched: Make sched_feat(x) boolean for !CONFIG_SCHED_DEBUG Matthias Kaehlcke
@ 2018-10-23 16:44 ` Nick Desaulniers
0 siblings, 0 replies; 2+ messages in thread
From: Nick Desaulniers @ 2018-10-23 16:44 UTC (permalink / raw)
To: Matthias Kaehlcke; +Cc: mingo, Peter Zijlstra, LKML, Phil_K97, groeck
On Mon, Oct 22, 2018 at 5:41 PM Matthias Kaehlcke <mka@chromium.org> wrote:
>
> If scheduler debugging is disabled sched_feat() resolves to a constant
> value that can be non-boolean. clang raises a warning when it detects
> that a non-boolean constant is used as operand in logical expressions:
>
> kernel/sched/core.c:208:26: warning: use of logical '&&' with constant
> operand [-Wconstant-logical-operand]
> if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
> ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Convert the original expression to boolean by means of a double not
> operation.
>
> Reported-by: Philipp Klocke <Phil_K97@gmx.de>
> Suggested-by: Peter Zijlstra <peterz@infradead.org>
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Thanks for resending, but I'm tracking this patch in -next:
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=7e6f4c5d600c1c8e2a1d900e65cab319d9b6782e
I just cloned -next yesterday and looks like it's still there.
> ---
> kernel/sched/sched.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index 4a2e8cae63c4..b9387d35e261 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -1393,7 +1393,7 @@ static const_debug __maybe_unused unsigned int sysctl_sched_features =
> 0;
> #undef SCHED_FEAT
>
> -#define sched_feat(x) (sysctl_sched_features & (1UL << __SCHED_FEAT_##x))
> +#define sched_feat(x) (!!(sysctl_sched_features & (1UL << __SCHED_FEAT_##x)))
>
> #endif /* SCHED_DEBUG && HAVE_JUMP_LABEL */
>
> --
> 2.19.1.568.g152ad8e336-goog
>
--
Thanks,
~Nick Desaulniers
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