x86/fpu: Kill eager_fpu_init_bp()

Now that eager_fpu_init_bp() does setup_init_fpu_buf() only and
nothing else, we can remove it and move this code into its "caller",
eager_fpu_init().

This avoids the confusing games with "static __refdata void (*boot_func)":

init_xstate_buf can be NULL only during boot, so it is safe to call the
__init-annotated setup_init_fpu_buf() function in eager_fpu_init(), we
just need to mark it as __init_refok.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pekka Riikonen <priikone@iki.fi>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suresh Siddha <sbsiddha@gmail.com>
Link: http://lkml.kernel.org/r/20150314151334.GC13029@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/xsave.c

@@ -678,16 +678,12 @@ void xsave_init(void)
 	this_func();
 }
 
-static inline void __init eager_fpu_init_bp(void)
-{
-	if (!init_xstate_buf)
-		setup_init_fpu_buf();
-}
-
-void eager_fpu_init(void)
+/*
+ * setup_init_fpu_buf() is __init and it is OK to call it here because
+ * init_xstate_buf will be unset only once during boot.
+ */
+void __init_refok eager_fpu_init(void)
 {
-	static __refdata void (*boot_func)(void) = eager_fpu_init_bp;
-
 	WARN_ON(used_math());
 	current_thread_info()->status = 0;
 
@@ -699,10 +695,8 @@ void eager_fpu_init(void)
 		return;
 	}
 
-	if (boot_func) {
-		boot_func();
-		boot_func = NULL;
-	}
+	if (!init_xstate_buf)
+		setup_init_fpu_buf();
 }
 
 /*