[PATCH v2 3/3] sched/fair: Add compile time check in fastpaths for CONFIG_SCHED_SMT=n

[Shrikanth Hegde <sshegde@linux.ibm.com>]

For fastpaths such as wakeup, load balance even a minimal code additons
can pop up. Add IS_ENABLED checks there to ensure there is no overhead.

Other places are either have sched_smt_active() check or they are not in
fast paths.

Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
---
 kernel/sched/fair.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 353e31ecaadc..b6f9592b31fd 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1586,6 +1586,9 @@ static inline bool is_core_idle(int cpu)
 {
 	int sibling;
 
+	if (!IS_ENABLED(CONFIG_SCHED_SMT))
+		return true;
+
 	for_each_cpu(sibling, cpu_smt_mask(cpu)) {
 		if (cpu == sibling)
 			continue;
@@ -12003,7 +12006,8 @@ static int should_we_balance(struct lb_env *env)
 			 * idle has been found, then its not needed to check other
 			 * SMT siblings for idleness:
 			 */
-			cpumask_andnot(swb_cpus, swb_cpus, cpu_smt_mask(cpu));
+			if (IS_ENABLED(CONFIG_SCHED_SMT))
+				cpumask_andnot(swb_cpus, swb_cpus, cpu_smt_mask(cpu));
 			continue;
 		}
 
-- 
2.47.3