From mboxrd@z Thu Jan 1 00:00:00 1970 From: mulyadi.santosa@gmail.com (Mulyadi Santosa) Date: Mon, 20 Dec 2010 16:08:22 +0700 Subject: add_timer crashes the kernel,Why? In-Reply-To: References: Message-ID: To: kernelnewbies@lists.kernelnewbies.org List-Id: kernelnewbies.lists.kernelnewbies.org Hi :) On Mon, Dec 20, 2010 at 15:27, lijin liu 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 -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com