[RFC]Something wrong with my module

On Thu, Apr 12, 2012 at 7:18 PM, Kristof Provost [off-list ref] wrote:

Hi Kristof

On 2012-04-12 18:16:56 (+0800), harryxiyou [off-list ref] wrote:

quoted

Hi greg,

? ? I write a module for inserting a PCB or delete a PCB to kernel's
PCB tree, but when i run it something wrong happens to me like following.
My environment is "Linux 10 2.6.35-22-generic #33-Ubuntu SMP Sun Sep
19 20:34:50 UTC 2010 i686 GNU/Linux"


? ? ? printk("Search for insert task-------->\n");
? ? ? task = &init_task;
? ? ? list_for_each(pos, &task->tasks) {
? ? ? ? ? ? ? p = list_entry(pos, struct task_struct, tasks);
? ? ? ? ? ? ? count++;
? ? ? ? ? ? ? if (0 == p->pid) {
? ? ? ? ? ? ? ? ? ? ? rm_task(p);
? ? ? ? ? ? ? }
? ? ? ? ? ? ? printk("pid: %d, state: %ld, comm: %s\n", p->pid, p->state, p->comm);
? ? ? }

You're iterating over the tasks list without locking it.

What do you think happens if someone else comes along and modifies it
while you're reading it?

Hmmm, Yes, i should lock it.

Try to take the tasklist_lock.

I will try, thanks.


-- 
Thanks
Harry Wei