On 12/20/2010 2:08 AM, Mulyadi Santosa wrote: > Hi :) > > On Mon, Dec 20, 2010 at 15:27, lijin liu<llj098@xxxxxxxxx> wrote: >> Hello everyone! >> >> I want to use the timer in my kernel module. I read the book _Linux >> kernel development 3rd version_ and LDD 3rd version. >> >> Both the two books tell me write the code like this: >> >> struct timer_list my_timer; >> init_timer(&my_timer); >> >> my_timer.expires = jiffies + wait; >> my_timer.data = 0; >> my_timer.function=my_function; >> >> //active the timer: >> add_timer(&timer); >> >> >> When I insmod the module, the kernel crashed, and when I change my >> code to *mod_timer* rather than add_timer. > > Hmmm, from http://lxr.linux.no/linux+v2.6.36/kernel/timer.c#L864, it reads: > void add_timer(struct timer_list *timer) > { > BUG_ON(timer_pending(timer)); > mod_timer(timer, timer->expires); > } > > thus, IMHO the error happened because there is other timer pending... > somehow it is forbidden to add timer when other are still in queue in > latest kernel > I believe add_timer just prevents creating duplicate timers from the same struct. I was actually thinking I had the same problem with timer code (following essential linux device drivers). But the issue was removing a module with an active timer will cause a crash. Here is what I ended up with, a silly sample timer that chains itself 3 times. It might be useful to OP: http://pastebin.com/v4rr3t50 -- -Dexter Haslem _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
