[PATCH] Time: Delay clocksource selection until later in boot

[john stultz <johnstul@us.ibm.com>]

	Delay installing new clocksources until later in boot. This avoids some
of the clocksource churn that can occur at boot, possibly allowing the
system to run for a brief time with a bad clocksource.

This patch resolves the boot time stalls seen by Mattia Dongili.

thanks
-john

Signed-off-by: John Stultz <johnstul@us.ibm.com>


diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -51,13 +51,27 @@ static LIST_HEAD(clocksource_list);
 static DEFINE_SPINLOCK(clocksource_lock);
 static char override_name[32];
 
+static int finished_booting;
+
+/* clocksource_done_booting - Called near the end of bootup
+ *
+ * Hack to avoid lots of clocksource churn at boot time 
+ */
+static int clocksource_done_booting(void)
+{
+	finished_booting = 1;
+	return 0;
+}
+
+late_initcall(clocksource_done_booting);
+
 /**
  * get_next_clocksource - Returns the selected clocksource
  */
 struct clocksource *get_next_clocksource(void)
 {
 	spin_lock(&clocksource_lock);
-	if (next_clocksource) {
+	if (next_clocksource && finished_booting) {
 		curr_clocksource = next_clocksource;
 		next_clocksource = NULL;
 	}