[PATCH] sched/fair: Fix unused prototype warning

[PATCH] sched/fair: Fix unused prototype warning

[Valentin Schneider]

Building against the latest tip/sched/core

  a0f03b617c3b ("sched/numa: Stop an exhastive search if a reasonable swap candidate or idle CPU is found")

with the arm64 defconfig (which doesn't have CONFIG_SCHED_SMT set) leads
to:

  kernel/sched/fair.c:1525:20: warning: ‘test_idle_cores’ declared ‘static’ but never defined [-Wunused-function]
   static inline bool test_idle_cores(int cpu, bool def);
		      ^~~~~~~~~~~~~~~

Rather than define it in its own CONFIG_SCHED_SMT #define island, bunch it
up with test_idle_cores().

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
---
 kernel/sched/fair.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index fcc968669aea..fa048cba6077 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1520,9 +1520,6 @@ static inline bool is_core_idle(int cpu)
 	return true;
 }
 
-/* Forward declarations of select_idle_sibling helpers */
-static inline bool test_idle_cores(int cpu, bool def);
-
 struct task_numa_env {
 	struct task_struct *p;
 
@@ -1558,9 +1555,11 @@ numa_type numa_classify(unsigned int imbalance_pct,
 	return node_fully_busy;
 }
 
+#ifdef CONFIG_SCHED_SMT
+/* Forward declarations of select_idle_sibling helpers */
+static inline bool test_idle_cores(int cpu, bool def);
 static inline int numa_idle_core(int idle_core, int cpu)
 {
-#ifdef CONFIG_SCHED_SMT
 	if (!static_branch_likely(&sched_smt_present) ||
 	    idle_core >= 0 || !test_idle_cores(cpu, false))
 		return idle_core;
@@ -1571,10 +1570,12 @@ static inline int numa_idle_core(int idle_core, int cpu)
 	 */
 	if (is_core_idle(cpu))
 		idle_core = cpu;
-#endif
 
 	return idle_core;
 }
+#else
+static inline int numa_idle_core(int idle_core, int cpu) { return idle_core; }
+#endif
 
 /*
  * Gather all necessary information to make NUMA balancing placement
-- 
2.24.0

Re: [PATCH] sched/fair: Fix unused prototype warning

[Mel Gorman]

On Wed, Feb 26, 2020 at 12:12:44PM +0000, Valentin Schneider wrote:
> Building against the latest tip/sched/core
> 
>   a0f03b617c3b ("sched/numa: Stop an exhastive search if a reasonable swap candidate or idle CPU is found")
> 
> with the arm64 defconfig (which doesn't have CONFIG_SCHED_SMT set) leads
> to:
> 
>   kernel/sched/fair.c:1525:20: warning: ???test_idle_cores??? declared ???static??? but never defined [-Wunused-function]
>    static inline bool test_idle_cores(int cpu, bool def);
> 		      ^~~~~~~~~~~~~~~
> 
> Rather than define it in its own CONFIG_SCHED_SMT #define island, bunch it
> up with test_idle_cores().
> 
> Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>

Acked-by: Mel Gorman <mgorman@techsingularity.net>

Ingo, what is your preferred method for dealing with this situation
in tip? A resubmission of "sched/numa: Stop an exhastive search if a
reasonable swap candidate or idle CPU is found" with these folded together
or Valentin's patch on top?

-- 
Mel Gorman
SUSE Labs