perf core: Factor out __perf_sw_event_sched

In some cases, we need to check more than whether the software event
is enabled.  So split the condition check and the actual event
handling.  This is a preparation for the next change.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210210083327.22726-1-namhyung@kernel.org

include/linux/perf_event.h

@@ -1178,30 +1178,24 @@ DECLARE_PER_CPU(struct pt_regs, __perf_regs[4]);
  * which is guaranteed by us not actually scheduling inside other swevents
  * because those disable preemption.
  */
-static __always_inline void
-perf_sw_event_sched(u32 event_id, u64 nr, u64 addr)
+static __always_inline void __perf_sw_event_sched(u32 event_id, u64 nr, u64 addr)
 {
-	if (static_key_false(&perf_swevent_enabled[event_id])) {
-		struct pt_regs *regs = this_cpu_ptr(&__perf_regs[0]);
+	struct pt_regs *regs = this_cpu_ptr(&__perf_regs[0]);
 
-		perf_fetch_caller_regs(regs);
-		___perf_sw_event(event_id, nr, regs, addr);
-	}
+	perf_fetch_caller_regs(regs);
+	___perf_sw_event(event_id, nr, regs, addr);
 }
 
 extern struct static_key_false perf_sched_events;
 
-static __always_inline bool
-perf_sw_migrate_enabled(void)
+static __always_inline bool __perf_sw_enabled(int swevt)
 {
-	if (static_key_false(&perf_swevent_enabled[PERF_COUNT_SW_CPU_MIGRATIONS]))
-		return true;
-	return false;
+	return static_key_false(&perf_swevent_enabled[swevt]);
 }
 
 static inline void perf_event_task_migrate(struct task_struct *task)
 {
-	if (perf_sw_migrate_enabled())
+	if (__perf_sw_enabled(PERF_COUNT_SW_CPU_MIGRATIONS))
 		task->sched_migrated = 1;
 }
 
@@ -1211,19 +1205,18 @@ static inline void perf_event_task_sched_in(struct task_struct *prev,
 	if (static_branch_unlikely(&perf_sched_events))
 		__perf_event_task_sched_in(prev, task);
 
-	if (perf_sw_migrate_enabled() && task->sched_migrated) {
-		struct pt_regs *regs = this_cpu_ptr(&__perf_regs[0]);
-
-		perf_fetch_caller_regs(regs);
-		___perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, regs, 0);
+	if (__perf_sw_enabled(PERF_COUNT_SW_CPU_MIGRATIONS) &&
+	    task->sched_migrated) {
+		__perf_sw_event_sched(PERF_COUNT_SW_CPU_MIGRATIONS, 1, 0);
 		task->sched_migrated = 0;
 	}
 }
 
 static inline void perf_event_task_sched_out(struct task_struct *prev,
 					     struct task_struct *next)
 {
-	perf_sw_event_sched(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, 0);
+	if (__perf_sw_enabled(PERF_COUNT_SW_CONTEXT_SWITCHES))
+		__perf_sw_event_sched(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, 0);
 
 	if (static_branch_unlikely(&perf_sched_events))
 		__perf_event_task_sched_out(prev, next);
@@ -1480,8 +1473,6 @@ static inline int perf_event_refresh(struct perf_event *event, int refresh)
 static inline void
 perf_sw_event(u32 event_id, u64 nr, struct pt_regs *regs, u64 addr)	{ }
 static inline void
-perf_sw_event_sched(u32 event_id, u64 nr, u64 addr)			{ }
-static inline void
 perf_bp_event(struct perf_event *event, void *data)			{ }
 
 static inline int perf_register_guest_info_callbacks