Re: timer problem
Hi, On Thu, Jul 7, 2011 at 2:48 PM, Daniel Baluta wrote: > On Wed, Jul 6, 2011 at 11:48 PM, Daniel Baluta > wrote: >> Hello Prashant, >> > is the one pointed below (schedule_timeout called in interrupt context). > Yes indeed ! the call to in_interrupt() returns 256 Thanks. ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: timer problem
On Wed, Jul 6, 2011 at 11:48 PM, Daniel Baluta wrote:
> Hello Prashant,
>
>> struct timer_list tim;
>>
>> void timfunc(unsigned long data)
>> {
> [..]
>> schedule_timeout(10 * HZ);
> [..]
>> }
>>
>> 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;
>> }
>
> You can find here ([1]) a good source for documenting
> on kernel timers API.
>
> Basically, the kernel has a list with registered timers and
> runs the associated handlers when timeout expires.
>
> Looking at your code, you've initialized the timer but you didn't
> added it to kernel timers list.
>
> You can find here a simple example of how to setup a timer ([2]).
Oh, so it seems you called add_timer :D, I just missed it. Then the problem
is the one pointed below (schedule_timeout called in interrupt context).
>
> Please read this [3], and figure out why even after you'll correctly
> setup the timer, your timer handler will cause you trouble.
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Re: timer problem
On Thu, Jul 7, 2011 at 13:58, Vishal Thanki wrote:
> On Thu, Jul 7, 2011 at 12:19 PM, Mulyadi Santosa
> wrote:
>> Hi..
>>
>> Trying to add another perspective, feel free to take or not :)
>>
>> On Wed, Jul 6, 2011 at 23:52, Prashant Shah 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
>
> 10*HZ is for 10 mins or for 10 seconds?
whoops sorry, it should be 10*HZ=10 seconds...thanks for noticing the error :)
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regards,
Mulyadi Santosa
Freelance Linux trainer and consultant
blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com
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Re: timer problem
On Thu, Jul 7, 2011 at 12:19 PM, Mulyadi Santosa
wrote:
> Hi..
>
> Trying to add another perspective, feel free to take or not :)
>
> On Wed, Jul 6, 2011 at 23:52, Prashant Shah 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
10*HZ is for 10 mins or for 10 seconds?
> 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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Re: timer problem
Hi..
Trying to add another perspective, feel free to take or not :)
On Wed, Jul 6, 2011 at 23:52, Prashant Shah 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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Re: timer problem
Hello Prashant,
> struct timer_list tim;
>
> void timfunc(unsigned long data)
> {
[..]
> schedule_timeout(10 * HZ);
[..]
> }
>
> 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;
> }
You can find here ([1]) a good source for documenting
on kernel timers API.
Basically, the kernel has a list with registered timers and
runs the associated handlers when timeout expires.
Looking at your code, you've initialized the timer but you didn't
added it to kernel timers list.
You can find here a simple example of how to setup a timer ([2]).
Please read this [3], and figure out why even after you'll correctly
setup the timer, your timer handler will cause you trouble.
thanks,
Daniel.
[1] http://www.ibm.com/developerworks/linux/library/l-timers-list/index.html
[2] http://lxr.linux.no/linux+v2.6.39/arch/blackfin/kernel/nmi.c#L176
[3] http://www.kernel.org/pub/linux/kernel/people/rusty/kernel-locking/c557.html
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timer problem
Hi,
I am test out a simple schedule_timeout() code. When I insert the
module kernel goes in a infinite loop printing this in the log :
Jul 6 22:04:35 ubuntupc kernel: [ 5738.281659] Pid: 0, comm: swapper
Not tainted 2.6.35-22-generic #33-Ubuntu
Jul 6 22:04:35 ubuntupc kernel: [ 5738.281663] Call Trace:
Jul 6 22:04:35 ubuntupc kernel: [ 5738.281671] []
dequeue_task_idle+0x3a/0x50
Jul 6 22:04:35 ubuntupc kernel: [ 5738.281679] []
dequeue_task+0x9a/0xb0
Jul 6 22:04:35 ubuntupc kernel: [ 5738.281687] []
deactivate_task+0x2e/0x40
Jul 6 22:04:35 ubuntupc kernel: [ 5738.281693] []
schedule+0x4a9/0x830
Jul 6 22:04:35 ubuntupc kernel: [ 5738.281702] []
cpu_idle+0xeb/0x110
Jul 6 22:04:35 ubuntupc kernel: [ 5738.281710] []
start_secondary+0x100/0x102
Any ideas on what is going on ?
--
--
#include
#include
#include
#include
#include
#include
struct timer_list tim;
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;
}
static void __exit exit_testmod(void)
{
printk("end of module\n");
return;
}
module_init(init_testmod);
module_exit(exit_testmod);
MODULE_LICENSE("GPL");
-- --
-- --
obj-m += testmod.o
KERNELDIR ?= /lib/modules/$(shell uname -r)/build
PWD := $(shell pwd)
default:
$(MAKE) -C $(KERNELDIR) M=$(PWD)
clean:
rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versions
depend .depend dep:
$(CC) $(CFLAGS) -M *.c > .depend
ifeq (.depend,$(wildcard .depend))
include .depend
endif
--
--
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