Thread (7 messages) 7 messages, 4 authors, 2011-07-10

timer problem

From: Mulyadi Santosa <hidden>
Date: 2011-07-07 06:49:29

Hi..

Trying to add another perspective, feel free to take or not  :)

On Wed, Jul 6, 2011 at 23:52, Prashant Shah [off-list ref] wrote:
void timfunc(unsigned long data)
{
? ? ? ?printk("hi this is a timer %lu\n", data);
? ? ? ?set_current_state(TASK_INTERRUPTIBLE);
? ? ? ?schedule_timeout(10 * HZ);
? ? ? ?printk("hi again this is a timer after timeout %lu\n", data);
}

static int __init init_testmod(void)
{
? ? ? ?init_timer(&tim);
? ? ? ?tim.expires = jiffies + HZ*5;
? ? ? ?tim.data = 1000;
? ? ? ?tim.function = timfunc;
? ? ? ?add_timer(&tim);
? ? ? ?return 0;
}
If my brain still works correctly, then I think the core of the
problem is that you're doing schedule() inside timer function. The
thing is, timer function is running in bottom halves...or in other
word, you are not supposed to do that in interrupt-handler alike
function.

What you need to do in order to wake up ten minutes later (10*HZ) is
to reinsert the function and make it expire 10*HZ later.

Just my 2 cents :)


-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com
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