cvs commit: src/sys/sys kthread.h src/sys/kern kern_kthread.c

[John Baldwin]

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).

-- 
John Baldwin