Subject: Re: [PATCH] pcmcia event thread. (fwd)
To: jgarzik@mandrakesoft.com (Jeff Garzik)
Date: Thu, 16 Nov 2000 13:39:05 +0000 (GMT)
Cc: dwmw2@infradead.org (David Woodhouse), torvalds@transmeta.com,
        dhinds@valinux.com, linux-kernel@vger.kernel.org
In-Reply-To: <3A1009DB.CC98CE06@mandrakesoft.com> from "Jeff Garzik" at Nov 13, 2000 10:33:47 AM
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Message-Id: <E13wPFs-0007og-00@the-village.bc.nu>
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
Sender: linux-kernel-owner@vger.kernel.org

> > up_and_exit() would do it. Or preferably passing the address of the
> > semaphore as an extra argument to kernel_thread() in the first place.
> 
> Any solution which involves a function being called from a kernel
> thread, and/or passing another arg to a kernel thread, is a non-starter
> ...  See the discussion about timer_exit() a while ago.  This sort of

timer_exit is a completely unrelated situation

> IMHO it is possible to solve this in a generic way without having to
> change the code for every single kernel thread.

It comes entirely down to one thing. The termination function of the thread
has to be code in the kernel code not a module. Thats it, nothing else. So
you just need some kind of sleep/wakeup proceedure for it.

As far as I can see all you need is


wait_and_die(sem)
{
	up(&sem);	/* In the kernel so can unload */
	sys_exit(0);	/* Never return to the unloaded module code */
}

in the main kernel. In fact if you were bored you could build this on the kernel
stack ;)

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