[PATCH] sched: Make sched_feat(x) boolean for !CONFIG_SCHED_DEBUG

From: Matthias Kaehlcke <mka@chromium.org>
To: Ingo Molnar <mingo@redhat.com>, Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, Philipp Klocke <Phil_K97@gmx.de>,
	Guenter Roeck <groeck@chromium.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Matthias Kaehlcke <mka@chromium.org>
Subject: [PATCH] sched: Make sched_feat(x) boolean for !CONFIG_SCHED_DEBUG
Date: Mon, 22 Oct 2018 17:41:16 -0700	[thread overview]
Message-ID: <20181023004116.77465-1-mka@chromium.org> (raw)

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

