* the timer it also makes sure the handler has finished executing on other
* CPUs.
*
- * Synchronization rules: callers must prevent restarting of the timer
- * (except restarting the timer from the timer function itself), otherwise
- * this function is meaningless. It must not be called from interrupt
- * contexts. Upon exit the timer is not queued and the handler is not
- * running on any CPU.
+ * Synchronization rules: callers must prevent restarting of the timer,
+ * otherwise this function is meaningless. It must not be called from
+ * interrupt contexts. Upon exit the timer is not queued and the handler
+ * is not running on any CPU.
*
- * The function returns the number of times it has deactivated a pending
- * timer.
+ * The function returns whether it has deactivated a pending timer or not.
*/
int del_timer_sync(struct timer_list *timer)
{
- int i, ret = 0, again;
- unsigned long flags;
tvec_base_t *base;
+ int i, ret = 0;
check_timer(timer);
del_again:
ret += del_timer(timer);
- /*
- * First do a lighter but racy check, whether the
- * timer is running on any other CPU:
- */
for (i = 0; i < NR_CPUS; i++) {
if (!cpu_online(i))
continue;
break;
}
}
-
- /*
- * Do a heavy but race-free re-check to make sure both that
- * the timer is neither running nor pending:
- */
- again = 0;
- local_irq_save(flags);
-
- for (i = 0; i < NR_CPUS; i++)
- if (cpu_online(i))
- spin_lock(&per_cpu(tvec_bases, i).lock);
-
+ smp_rmb();
if (timer_pending(timer))
- again = 1;
- else
- for (i = 0; i < NR_CPUS; i++)
- if (cpu_online(i) &&
- (per_cpu(tvec_bases, i).running_timer == timer))
- again = 1;
-
- for (i = 0; i < NR_CPUS; i++)
- if (cpu_online(i))
- spin_unlock(&per_cpu(tvec_bases, i).lock);
-
- local_irq_restore(flags);
-
- if (again)
goto del_again;
return ret;