[PATCH] sched/fair: fix build warning about undefined test_idle_cores()

[PATCH] sched/fair: fix build warning about undefined test_idle_cores()

[qiwuchen55]

From: chenqiwu <chenqiwu@xiaomi.com>

The build with arm64's defconfig:
CONFIG_SCHED_MC=y
# CONFIG_SCHED_SMT is not set

Trigger the following warning due to test_idle_cores()'s definition
missing:
kernel/sched/fair.c:1524:20: warning: ‘test_idle_cores’ declared ‘static’
	but never defined [-Wunused-function]

Move the CONFIG_SCHED_SMT ifdeffery around test_idle_cores()'s declaration
to fix it.

Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
---
 kernel/sched/fair.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 84594f8..d11d965 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1520,8 +1520,10 @@ static inline bool is_core_idle(int cpu)
 	return true;
 }
 
+#ifdef CONFIG_SCHED_SMT
 /* Forward declarations of select_idle_sibling helpers */
 static inline bool test_idle_cores(int cpu, bool def);
+#endif
 
 struct task_numa_env {
 	struct task_struct *p;
-- 
1.9.1

Re: [PATCH] sched/fair: fix build warning about undefined test_idle_cores()

[Mel Gorman]

On Sun, Mar 08, 2020 at 11:53:12PM +0800, qiwuchen55@gmail.com wrote:
> From: chenqiwu <chenqiwu@xiaomi.com>
> 
> The build with arm64's defconfig:
> CONFIG_SCHED_MC=y
> # CONFIG_SCHED_SMT is not set
> 
> Trigger the following warning due to test_idle_cores()'s definition
> missing:
> kernel/sched/fair.c:1524:20: warning: ???test_idle_cores??? declared ???static???
> 	but never defined [-Wunused-function]
> 
> Move the CONFIG_SCHED_SMT ifdeffery around test_idle_cores()'s declaration
> to fix it.
> 
> Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>

Thanks. A fix has been merged to tip/sched/core as

commit 76c389ab2b5e300698eab87f9d4b7916f14117ba
Author: Valentin Schneider <valentin.schneider@arm.com>
Date:   Tue Mar 3 11:02:57 2020 +0000

    sched/fair: Fix kernel build warning in test_idle_cores() for !SMT NUMA


-- 
Mel Gorman
SUSE Labs