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authorOleg Nesterov <oleg@tv-sign.ru>2005-06-23 00:08:59 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-23 09:45:16 -0700
commitfd450b7318b75343fd76b3d95416853e34e72c95 (patch)
treee747348f7d3c9f1615963dde4f2c8baaf842415f /kernel
parent55c888d6d09a0df236adfaf8ccf06ff5d0646775 (diff)
[PATCH] timers: introduce try_to_del_timer_sync()
This patch splits del_timer_sync() into 2 functions. The new one, try_to_del_timer_sync(), returns -1 when it hits executing timer. It can be used in interrupt context, or when the caller hold locks which can prevent completion of the timer's handler. NOTE. Currently it can't be used in interrupt context in UP case, because ->running_timer is used only with CONFIG_SMP. Should the need arise, it is possible to kill #ifdef CONFIG_SMP in set_running_timer(), it is cheap. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/timer.c53
1 files changed, 33 insertions, 20 deletions
diff --git a/kernel/timer.c b/kernel/timer.c
index 8aadc62efd65..1f986c16d89f 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -365,6 +365,34 @@ int del_timer(struct timer_list *timer)
EXPORT_SYMBOL(del_timer);
#ifdef CONFIG_SMP
+/*
+ * This function tries to deactivate a timer. Upon successful (ret >= 0)
+ * exit the timer is not queued and the handler is not running on any CPU.
+ *
+ * It must not be called from interrupt contexts.
+ */
+int try_to_del_timer_sync(struct timer_list *timer)
+{
+ timer_base_t *base;
+ unsigned long flags;
+ int ret = -1;
+
+ base = lock_timer_base(timer, &flags);
+
+ if (base->running_timer == timer)
+ goto out;
+
+ ret = 0;
+ if (timer_pending(timer)) {
+ detach_timer(timer, 1);
+ ret = 1;
+ }
+out:
+ spin_unlock_irqrestore(&base->lock, flags);
+
+ return ret;
+}
+
/***
* del_timer_sync - deactivate a timer and wait for the handler to finish.
* @timer: the timer to be deactivated
@@ -384,28 +412,13 @@ EXPORT_SYMBOL(del_timer);
*/
int del_timer_sync(struct timer_list *timer)
{
- timer_base_t *base;
- unsigned long flags;
- int ret = -1;
-
check_timer(timer);
- do {
- base = lock_timer_base(timer, &flags);
-
- if (base->running_timer == timer)
- goto unlock;
-
- ret = 0;
- if (timer_pending(timer)) {
- detach_timer(timer, 1);
- ret = 1;
- }
-unlock:
- spin_unlock_irqrestore(&base->lock, flags);
- } while (ret < 0);
-
- return ret;
+ for (;;) {
+ int ret = try_to_del_timer_sync(timer);
+ if (ret >= 0)
+ return ret;
+ }
}
EXPORT_SYMBOL(del_timer_sync);