sched/smp: Always define is_percpu_thread() and scheduler_ipi()

Simplify the scheduler by making the CONFIG_SMP=y primitives
of is_percpu_thread() and scheduler_ipi() unconditional.

Signed-off-by: Ingo Molnar <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Cc: Dietmar Eggemann <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Shrikanth Hegde <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Valentin Schneider <[email protected]>
Cc: Vincent Guittot <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

include/linux/sched.h

@@ -1765,12 +1765,8 @@ extern struct pid *cad_pid;
 
 static __always_inline bool is_percpu_thread(void)
 {
-#ifdef CONFIG_SMP
 	return (current->flags & PF_NO_SETAFFINITY) &&
 		(current->nr_cpus_allowed  == 1);
-#else
-	return true;
-#endif
 }
 
 /* Per-process atomic flags. */
@@ -1967,7 +1963,6 @@ extern void __set_task_comm(struct task_struct *tsk, const char *from, bool exec
 	buf;						\
 })
 
-#ifdef CONFIG_SMP
 static __always_inline void scheduler_ipi(void)
 {
 	/*
@@ -1977,9 +1972,6 @@ static __always_inline void scheduler_ipi(void)
 	 */
 	preempt_fold_need_resched();
 }
-#else
-static inline void scheduler_ipi(void) { }
-#endif
 
 extern unsigned long wait_task_inactive(struct task_struct *, unsigned int match_state);