sched: Unify SMT active check via sched_smt_active()

There is a use of sched_smt_active() and explicit use of sched_smt_present.
Remove the explicit usage for better code maintenance and readability.

Note that this differs slightly for update_idle_core. It used to call
static_branch_unlikely earlier and now it will call static_branch_likely.

Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://patch.msgid.link/20260515172456.542799-5-sshegde@linux.ibm.com

kernel/sched/core_sched.c

@@ -136,7 +136,7 @@ int sched_core_share_pid(unsigned int cmd, pid_t pid, enum pid_type type,
 	struct pid *grp;
 	int err = 0;
 
-	if (!static_branch_likely(&sched_smt_present))
+	if (!sched_smt_active())
 		return -ENODEV;
 
 	BUILD_BUG_ON(PR_SCHED_CORE_SCOPE_THREAD != PIDTYPE_PID);

kernel/sched/fair.c

@@ -2247,7 +2247,7 @@ numa_type numa_classify(unsigned int imbalance_pct,
 static inline bool test_idle_cores(int cpu);
 static inline int numa_idle_core(int idle_core, int cpu)
 {
-	if (!static_branch_likely(&sched_smt_present) ||
+	if (!sched_smt_active() ||
 	    idle_core >= 0 || !test_idle_cores(cpu))
 		return idle_core;
 

kernel/sched/sched.h

@@ -1671,7 +1671,7 @@ extern void __update_idle_core(struct rq *rq);
 
 static inline void update_idle_core(struct rq *rq)
 {
-	if (static_branch_unlikely(&sched_smt_present))
+	if (sched_smt_active())
 		__update_idle_core(rq);
 }