Merge branch 'locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[linux-2.6-omap-h63xx.git] / kernel / timer.c

diff --git a/kernel/timer.c b/kernel/timer.c
index ef1c385bc5726ee6185575d4fcb3c3cab987f3ed..b4555568b4e4ad16f34a887eabed6f21e05abfba 100644 (file)
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -600,11 +600,14 @@ static struct tvec_base *lock_timer_base(struct timer_list *timer,
        }
 }
 
-int __mod_timer(struct timer_list *timer, unsigned long expires)
+static inline int
+__mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only)
 {
        struct tvec_base *base, *new_base;
        unsigned long flags;
-       int ret = 0;
+       int ret;
+
+       ret = 0;
 
        timer_stats_timer_set_start_info(timer);
        BUG_ON(!timer->function);
@@ -614,6 +617,9 @@ int __mod_timer(struct timer_list *timer, unsigned long expires)
        if (timer_pending(timer)) {
                detach_timer(timer, 0);
                ret = 1;
+       } else {
+               if (pending_only)
+                       goto out_unlock;
        }
 
        debug_timer_activate(timer);
@@ -640,42 +646,28 @@ int __mod_timer(struct timer_list *timer, unsigned long expires)
 
        timer->expires = expires;
        internal_add_timer(base, timer);
+
+out_unlock:
        spin_unlock_irqrestore(&base->lock, flags);
 
        return ret;
 }
 
-EXPORT_SYMBOL(__mod_timer);
-
 /**
- * add_timer_on - start a timer on a particular CPU
- * @timer: the timer to be added
- * @cpu: the CPU to start it on
+ * mod_timer_pending - modify a pending timer's timeout
+ * @timer: the pending timer to be modified
+ * @expires: new timeout in jiffies
  *
- * This is not very scalable on SMP. Double adds are not possible.
+ * mod_timer_pending() is the same for pending timers as mod_timer(),
+ * but will not re-activate and modify already deleted timers.
+ *
+ * It is useful for unserialized use of timers.
  */
-void add_timer_on(struct timer_list *timer, int cpu)
+int mod_timer_pending(struct timer_list *timer, unsigned long expires)
 {
-       struct tvec_base *base = per_cpu(tvec_bases, cpu);
-       unsigned long flags;
-
-       timer_stats_timer_set_start_info(timer);
-       BUG_ON(timer_pending(timer) || !timer->function);
-       spin_lock_irqsave(&base->lock, flags);
-       timer_set_base(timer, base);
-       debug_timer_activate(timer);
-       internal_add_timer(base, timer);
-       /*
-        * Check whether the other CPU is idle and needs to be
-        * triggered to reevaluate the timer wheel when nohz is
-        * active. We are protected against the other CPU fiddling
-        * with the timer by holding the timer base lock. This also
-        * makes sure that a CPU on the way to idle can not evaluate
-        * the timer wheel.
-        */
-       wake_up_idle_cpu(cpu);
-       spin_unlock_irqrestore(&base->lock, flags);
+       return __mod_timer(timer, expires, true);
 }
+EXPORT_SYMBOL(mod_timer_pending);
 
 /**
  * mod_timer - modify a timer's timeout
@@ -699,9 +691,6 @@ void add_timer_on(struct timer_list *timer, int cpu)
  */
 int mod_timer(struct timer_list *timer, unsigned long expires)
 {
-       BUG_ON(!timer->function);
-
-       timer_stats_timer_set_start_info(timer);
        /*
         * This is a common optimization triggered by the
         * networking code - if the timer is re-modified
@@ -710,11 +699,61 @@ int mod_timer(struct timer_list *timer, unsigned long expires)
        if (timer->expires == expires && timer_pending(timer))
                return 1;
 
-       return __mod_timer(timer, expires);
+       return __mod_timer(timer, expires, false);
 }
-
 EXPORT_SYMBOL(mod_timer);
 
+/**
+ * add_timer - start a timer
+ * @timer: the timer to be added
+ *
+ * The kernel will do a ->function(->data) callback from the
+ * timer interrupt at the ->expires point in the future. The
+ * current time is 'jiffies'.
+ *
+ * The timer's ->expires, ->function (and if the handler uses it, ->data)
+ * fields must be set prior calling this function.
+ *
+ * Timers with an ->expires field in the past will be executed in the next
+ * timer tick.
+ */
+void add_timer(struct timer_list *timer)
+{
+       BUG_ON(timer_pending(timer));
+       mod_timer(timer, timer->expires);
+}
+EXPORT_SYMBOL(add_timer);
+
+/**
+ * add_timer_on - start a timer on a particular CPU
+ * @timer: the timer to be added
+ * @cpu: the CPU to start it on
+ *
+ * This is not very scalable on SMP. Double adds are not possible.
+ */
+void add_timer_on(struct timer_list *timer, int cpu)
+{
+       struct tvec_base *base = per_cpu(tvec_bases, cpu);
+       unsigned long flags;
+
+       timer_stats_timer_set_start_info(timer);
+       BUG_ON(timer_pending(timer) || !timer->function);
+       spin_lock_irqsave(&base->lock, flags);
+       timer_set_base(timer, base);
+       debug_timer_activate(timer);
+       internal_add_timer(base, timer);
+       /*
+        * Check whether the other CPU is idle and needs to be
+        * triggered to reevaluate the timer wheel when nohz is
+        * active. We are protected against the other CPU fiddling
+        * with the timer by holding the timer base lock. This also
+        * makes sure that a CPU on the way to idle can not evaluate
+        * the timer wheel.
+        */
+       wake_up_idle_cpu(cpu);
+       spin_unlock_irqrestore(&base->lock, flags);
+}
+
 /**
  * del_timer - deactive a timer.
  * @timer: the timer to be deactivated
@@ -744,7 +783,6 @@ int del_timer(struct timer_list *timer)
 
        return ret;
 }
-
 EXPORT_SYMBOL(del_timer);
 
 #ifdef CONFIG_SMP
@@ -778,7 +816,6 @@ out:
 
        return ret;
 }
-
 EXPORT_SYMBOL(try_to_del_timer_sync);
 
 /**
@@ -816,7 +853,6 @@ int del_timer_sync(struct timer_list *timer)
                cpu_relax();
        }
 }
-
 EXPORT_SYMBOL(del_timer_sync);
 #endif
 
@@ -1314,7 +1350,7 @@ signed long __sched schedule_timeout(signed long timeout)
        expire = timeout + jiffies;
 
        setup_timer_on_stack(&timer, process_timeout, (unsigned long)current);
-       __mod_timer(&timer, expire);
+       __mod_timer(&timer, expire, false);
        schedule();
        del_singleshot_timer_sync(&timer);