SIGKILL and a sleeping kernel module

[Srinivas Ganji]

On Wed, Feb 20, 2013 at 11:59 AM, Srinivas Ganji <
srinivasganji.kernel at gmail.com> wrote:

>
> On Tue, Feb 19, 2013 at 5:02 PM, Kevin Wilson <wkevils at gmail.com> wrote:
>
>> Hi,
>>
>> Thanks about the info about ps.
>> This raises two new questions:
>> 1)  The following code is a very basic kernel module (based on my
>> previous code, removing somethings).
>> I do not understand something:
>> I call
>>   /* sleep for a millisecond */
>>     msleep(1);
>>     printk("calling do_exit\n");
>>     msleep(60000);
>>
>> In my understanding, after 1 millisecond, it should have been
>> available to the scheduler, and after returning to the line after
>> msleep(1), it should print "calling do_exit". However,
>> I see no such log message. Any ideas why ? can something be
>> added to enable this ?
>>
>> 2)How can I create a kernel thread so that it will be in
>> TASK_INTERRUPTIBLE state ? there must be a way,
>> since I see many kernel threads where ps shows "S" in the
>> status coumn.
>>
>>
>> struct task_struct *task;
>>
>> int thread_function(void *data)
>> {
>>     int exit_sig = SIGKILL;
>>
>>     printk("in %s\n",__func__);
>>     /* sleep for a millisecond */
>>     msleep(1);
>>     printk("calling do_exit\n");
>>     msleep(60000);
>>     do_exit(exit_sig);
>>
>>     return 0;
>> }
>>
>> static int kernel_init(void)
>>     {
>>     printk("in kernel_init\n");
>>     task = kthread_create(thread_function,NULL,"MY_KERNEL_THREAD");
>>     return 0;
>> }
>>
>> static void kernel_exit(void)
>>     {
>>     printk("in kernel_exit\n");
>>     kthread_stop(task);
>>     }
>>
>>
>> module_init(kernel_init);
>> module_exit(kernel_exit);
>>
>>
>> rgs
>> Kevin
>>
>>
> After creating the kernel thread, you can use wake_up_process(task) call
> which will run your thread function.
>
> Generally, when we create a kernel thread using kthread_create,
>
the process is created in an unrunnable state. It will not start running
until explicitly woken up via wake_up_process(). The kthread_create()
followed by wake_up_process() is done by a single call kthread_run().

I hope this helps you.

Regards
Srinivas G.

>
>
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