sched/debug: Remove obsolete init_schedstats()

Revert commit 4698f88 ("sched/debug: Fix 'schedstats=enable'
cmdline option").

After commit 6041186 ("init: initialize jump labels before
command line option parsing") we can rely on jump label infra being
ready for use when setup_schedstats() is called.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20210602112108.1709635-1-eric.dumazet@gmail.com

kernel/sched/core.c

@@ -4009,7 +4009,6 @@ int sysctl_numa_balancing(struct ctl_table *table, int write,
 #ifdef CONFIG_SCHEDSTATS
 
 DEFINE_STATIC_KEY_FALSE(sched_schedstats);
-static bool __initdata __sched_schedstats = false;
 
 static void set_schedstats(bool enabled)
 {
@@ -4033,16 +4032,11 @@ static int __init setup_schedstats(char *str)
 	if (!str)
 		goto out;
 
-	/*
-	 * This code is called before jump labels have been set up, so we can't
-	 * change the static branch directly just yet.  Instead set a temporary
-	 * variable so init_schedstats() can do it later.
-	 */
 	if (!strcmp(str, "enable")) {
-		__sched_schedstats = true;
+		set_schedstats(true);
 		ret = 1;
 	} else if (!strcmp(str, "disable")) {
-		__sched_schedstats = false;
+		set_schedstats(false);
 		ret = 1;
 	}
 out:
@@ -4053,11 +4047,6 @@ static int __init setup_schedstats(char *str)
 }
 __setup("schedstats=", setup_schedstats);
 
-static void __init init_schedstats(void)
-{
-	set_schedstats(__sched_schedstats);
-}
-
 #ifdef CONFIG_PROC_SYSCTL
 int sysctl_schedstats(struct ctl_table *table, int write, void *buffer,
 		size_t *lenp, loff_t *ppos)
@@ -4079,8 +4068,6 @@ int sysctl_schedstats(struct ctl_table *table, int write, void *buffer,
 	return err;
 }
 #endif /* CONFIG_PROC_SYSCTL */
-#else  /* !CONFIG_SCHEDSTATS */
-static inline void init_schedstats(void) {}
 #endif /* CONFIG_SCHEDSTATS */
 
 /*
@@ -9089,8 +9076,6 @@ void __init sched_init(void)
 #endif
 	init_sched_fair_class();
 
-	init_schedstats();
-
 	psi_init();
 
 	init_uclamp();