[PATCH] Extend next_timer_interrupt() to use a reference jiffie
For CONFIG_NO_HZ we need to calculate the next timer wheel event based on a
given jiffie value. Extend the existing code to allow the extra 'now'
argument. Provide a compability function for the existing implementations to
call the function with now == jiffies. (This also solves the racyness of the
original code vs. jiffies changing during the iteration.)
No functional changes to existing users of this infrastructure.
[ remove WARN_ON() that triggered on s390, by Carsten Otte <cotte@de.ibm.com> ]
[ made new helper static, Adrian Bunk <bunk@stusta.de> ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/timer.h b/include/linux/timer.h
index fb5edaa..bd0af32 100644
--- a/include/linux/timer.h
+++ b/include/linux/timer.h
@@ -61,7 +61,17 @@
extern int __mod_timer(struct timer_list *timer, unsigned long expires);
extern int mod_timer(struct timer_list *timer, unsigned long expires);
+/*
+ * Return when the next timer-wheel timeout occurs (in absolute jiffies),
+ * locks the timer base:
+ */
extern unsigned long next_timer_interrupt(void);
+/*
+ * Return when the next timer-wheel timeout occurs (in absolute jiffies),
+ * locks the timer base and does the comparison against the given
+ * jiffie.
+ */
+extern unsigned long get_next_timer_interrupt(unsigned long now);
/**
* add_timer - start a timer
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index c0fdb9b..bd57ef4 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -533,7 +533,7 @@
}
EXPORT_SYMBOL_GPL(hrtimer_get_remaining);
-#ifdef CONFIG_NO_IDLE_HZ
+#if defined(CONFIG_NO_IDLE_HZ) || defined(CONFIG_NO_HZ)
/**
* hrtimer_get_next_event - get the time until next expiry event
*
diff --git a/kernel/timer.c b/kernel/timer.c
index 201bee0..6d843e1 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -591,7 +591,7 @@
spin_unlock_irq(&base->lock);
}
-#ifdef CONFIG_NO_IDLE_HZ
+#if defined(CONFIG_NO_IDLE_HZ) || defined(CONFIG_NO_HZ)
/*
* Find out when the next timer event is due to happen. This
* is used on S/390 to stop all activity when a cpus is idle.
@@ -687,10 +687,10 @@
/**
* next_timer_interrupt - return the jiffy of the next pending timer
*/
-unsigned long next_timer_interrupt(void)
+unsigned long get_next_timer_interrupt(unsigned long now)
{
tvec_base_t *base = __get_cpu_var(tvec_bases);
- unsigned long expires, now = jiffies;
+ unsigned long expires;
spin_lock(&base->lock);
expires = __next_timer_interrupt(base);
@@ -701,6 +701,14 @@
return cmp_next_hrtimer_event(now, expires);
}
+
+#ifdef CONFIG_NO_IDLE_HZ
+unsigned long next_timer_interrupt(void)
+{
+ return get_next_timer_interrupt(jiffies);
+}
+#endif
+
#endif
/******************************************************************/