Hi all:
  The kernel I use is 2.6.29-rc3 and among the timer_list function there is "add_timer_on". 
For smp, Is it possible for a timer to be run at the same time on different cpus? suppose the
following sequence:
1. a timer is being run on CPU 0, and the timer callback function use add_time_on to add itself on CPU 1;
  the expires is set to "jiffies + 0" to make it to be run as quickly as possible on CPU 1.
2. so there is chance that 2 cpus run the same timer at the same time?

I'm not sure whether the above can be true. Whether there is other way to make a time run at the same time
on different cpu?  If it can happen, the timer callback function must take smp safe into consideration.

Regards
Rednoah