Date: Fri, 26 Oct 2007 12:37:33 -0700 From: Julian Elischer <julian@elischer.org> To: John Baldwin <jhb@freebsd.org> Cc: cvs-src@freebsd.org, src-committers@freebsd.org, Julian Elischer <julian@freebsd.org>, cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/sys kthread.h src/sys/kern kern_kthread.c Message-ID: <472241FD.1080502@elischer.org> In-Reply-To: <200710261524.51945.jhb@freebsd.org> References: <200710261703.l9QH3Nmt061137@repoman.freebsd.org> <200710261420.34168.jhb@freebsd.org> <4722399E.3090209@elischer.org> <200710261524.51945.jhb@freebsd.org>
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John Baldwin wrote:
> On Friday 26 October 2007 03:01:50 pm Julian Elischer wrote:
>> John Baldwin wrote:
>>> On Friday 26 October 2007 01:03:22 pm Julian Elischer wrote:
>>>> julian 2007-10-26 17:03:22 UTC
>>>>
>>>> FreeBSD src repository
>>>>
>>>> Modified files:
>>>> sys/sys kthread.h
>>>> sys/kern kern_kthread.c
>>>> Log:
>>>> kthread_exit needs no stinkin argument.
>>> So an important property of the old kthread_exit() (now kproc_exit()) was
> that
>>> a kernel module could safely ensure that a kthread it created was out of
> the
>>> kernel module's text segment before returning from a module unload hook to
>>> prevent kernel panics by sleeping on the proc pointer with the proc lock
> like
>>> so:
>>>
>>> mtx_lock(&mylock);
>>> PROC_LOCK(p);
>>> signal_death = 1;
>>> mtx_unlock(&mylock);
>>> msleep(p, &p->p_mtx, ...);
>>> PROC_UNLOCK(p);
>>>
>>> And have the main thread do this:
>>>
>>> ...
>>> mtx_lock(&mylock);
>>> while (!signal_death) {
>>> ... fetch work, may drop mylock...
>>> }
>>> mtx_unlock(&mylock);
>>> kthread_exit(0);
>> the kproc_exit still does..
>>
>> I didn't see any users of it in the code that I've switched to kthreads
>> so far so I haven't added it to the kthread_exit() yet.
>
> Ok. That needs to happen at some point so that more kprocs can be kthreads.
> For example, ipmi(4) creates a kthread/kproc, so does random(4), fdc(4), and
> I think ndis(4).
I'll check them out and see what the best solution is..
>
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