time: Introduce new GENERIC_TIME_VSYSCALL

Now that we moved everyone over to GENERIC_TIME_VSYSCALL_OLD,
introduce the new declaration and config option for the new
update_vsyscall method.

Cc: Tony Luck <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Benjamin Herrenschmidt <[e-mail]>
Cc: Andy Lutomirski <[e-mail]>
Cc: Martin Schwidefsky <[e-mail]>
Cc: Paul Turner <[e-mail]>
Cc: Steven Rostedt <[e-mail]>
Cc: Richard Cochran <[e-mail]>
Cc: Prarit Bhargava <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Signed-off-by: John Stultz <[e-mail]>

include/linux/timekeeper_internal.h

···
 	seqlock_t		lock;
 };
 
+static inline struct timespec tk_xtime(struct timekeeper *tk)
+{
+	struct timespec ts;
 
-#ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
-extern void
-update_vsyscall_old(struct timespec *ts, struct timespec *wtm,
-			struct clocksource *c, u32 mult);
+	ts.tv_sec = tk->xtime_sec;
+	ts.tv_nsec = (long)(tk->xtime_nsec >> tk->shift);
+	return ts;
+}
+
+
+#ifdef CONFIG_GENERIC_TIME_VSYSCALL
+
+extern void update_vsyscall(struct timekeeper *tk);
 extern void update_vsyscall_tz(void);
+
+#elif defined(CONFIG_GENERIC_TIME_VSYSCALL_OLD)
+
+extern void update_vsyscall_old(struct timespec *ts, struct timespec *wtm,
+				struct clocksource *c, u32 mult);
+extern void update_vsyscall_tz(void);
+
+static inline void update_vsyscall(struct timekeeper *tk)
+{
+	struct timespec xt;
+
+	xt = tk_xtime(tk);
+	update_vsyscall_old(&xt, &tk->wall_to_monotonic, tk->clock, tk->mult);
+}
+
 #else
-static inline void
-update_vsyscall_old(struct timespec *ts, struct timespec *wtm,
-					struct clocksource *c, u32 mult)
+
+static inline void update_vsyscall(struct timekeeper *tk)
 {
 }
 static inline void update_vsyscall_tz(void)

kernel/time/Kconfig

···
 	bool
 
 # Timekeeping vsyscall support
+config GENERIC_TIME_VSYSCALL
+	bool
+
+# Timekeeping vsyscall support
 config GENERIC_TIME_VSYSCALL_OLD
 	bool
 

kernel/time/timekeeping.c

···
 	}
 }
 
-static struct timespec tk_xtime(struct timekeeper *tk)
-{
-	struct timespec ts;
-
-	ts.tv_sec = tk->xtime_sec;
-	ts.tv_nsec = (long)(tk->xtime_nsec >> tk->shift);
-	return ts;
-}
-
 static void tk_set_xtime(struct timekeeper *tk, const struct timespec *ts)
 {
 	tk->xtime_sec = ts->tv_sec;
···
 /* must hold write on timekeeper.lock */
 static void timekeeping_update(struct timekeeper *tk, bool clearntp)
 {
-	struct timespec xt;
-
 	if (clearntp) {
 		tk->ntp_error = 0;
 		ntp_clear();
 	}
-	xt = tk_xtime(tk);
-	update_vsyscall_old(&xt, &tk->wall_to_monotonic, tk->clock, tk->mult);
+	update_vsyscall(tk);
 }
 
 /**