sched: Make scheduler_ipi inline

Now that the scheduler IPI is trivial and simple again there is no point to
have the little function out of line. This simplifies the effort of
constraining the instrumentation nicely.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200505134058.453581595@linutronix.de

include/linux/sched.h

@@ -1715,7 +1715,15 @@ extern char *__get_task_comm(char *to, size_t len, struct task_struct *tsk);
 })
 
 #ifdef CONFIG_SMP
-void scheduler_ipi(void);
+static __always_inline void scheduler_ipi(void)
+{
+	/*
+	 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
+	 * TIF_NEED_RESCHED remotely (for the first time) will also send
+	 * this IPI.
+	 */
+	preempt_fold_need_resched();
+}
 extern unsigned long wait_task_inactive(struct task_struct *, long match_state);
 #else
 static inline void scheduler_ipi(void) { }

kernel/sched/core.c

@@ -2312,16 +2312,6 @@ static void wake_csd_func(void *info)
 	sched_ttwu_pending();
 }
 
-void scheduler_ipi(void)
-{
-	/*
-	 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
-	 * TIF_NEED_RESCHED remotely (for the first time) will also send
-	 * this IPI.
-	 */
-	preempt_fold_need_resched();
-}
-
 static void ttwu_queue_remote(struct task_struct *p, int cpu, int wake_flags)
 {
 	struct rq *rq = cpu_rq(cpu);