Re: Stopping Kernel Threads at module unload time

[Aritz Bastida <aritzbastida@gmail.com>]

Thank you very much Arnd!
You solved my problem. hehe

I began to write a test module for showing you this and have just
realized about the problem. As I create as many threads as CPUs, I
have to delete them all when finishing.

I killed them like this:

        /* We don't need the distraction of CPUs appearing and vanishing. */
        lock_cpu_hotplug();
        for_each_online_cpu(cpu) {
                p = per_cpu(ksensord_info, cpu);
                kthread_stop(p);
        }
        unlock_cpu_hotplug();

I locked the cpu hotplug lock to protect the for_each_online_cpu()
code in case a cpu appears/vanishes, so I am actually calling
kthread_stop() in an atomic context, so it wakes up the process, but
dont let it run!

This is quite a subtle error, but of course it's my complete fault :P
May be a BUG_ON(in_atomic()) within kthread_stop() would let this kind of
errors be acknowledged more easily.

Thank you for your help
Regards

Aritz Bastida

PS:  Sorry Arnd, I forgot adding the linux-kernel address to the message