cvs commit: src/sys/kern kern_mutex.c

[John Baldwin]

On Tuesday 05 June 2007 03:20:42 pm Jeff Roberson wrote:
> On Tue, 5 Jun 2007, John Baldwin wrote:
> 
> > On Tuesday 05 June 2007 02:57:09 pm Attilio Rao wrote:
> >> attilio     2007-06-05 18:57:09 UTC
> >>
> >>   FreeBSD src repository
> >>
> >>   Modified files:
> >>     sys/kern             kern_mutex.c
> >>   Log:
> >>   Fix a problem with not-preemptive kernels caming from mis-merging of
> >>   existing code with the new thread_lock patch.
> >>   This also cleans up a bit unlock operation for mutexes.
> >>
> >>   Approved by: jhb, jeff(mentor)
> >
> > Specifically, this retires the explicit preemption code in mtx_unlock()
> > (inherited from BSD/OS) in the #ifndef PREEMPTION case.  We now only do
> > preemptions as a scheduling decision in the scheduler and only
> > #ifdef PREEMPTION.
> 
> I believe we also should replace thread_lock() and thread_unlock() with 
> calls to spinlock_enter()/exit() on !SMP and make thread_set_lock() a 
> no-op for this case.  Does that sounds right to everyone?

Probably.  spinlocks in general already do that.

-- 
John Baldwin