On Tue, Nov 19, 2013 at 02:57:41PM -0800, Tim Chen wrote:
> On Tue, 2013-11-19 at 11:13 -0800, Paul E. McKenney wrote:
> > On Fri, Nov 08, 2013 at 11:52:05AM -0800, Tim Chen wrote:
> > >
> > > +/*
> > > + * Releases the lock. The caller should pass in the corresponding node
> > > that
> > > + * was used to acquire the lock.
> > > + */
> > > static void mcs_spin_unlock(struct mcs_spinlock **lock, struct
> > > mcs_spinlock *node)
> > > {
> > > struct mcs_spinlock *next = ACCESS_ONCE(node->next);
> > > @@ -51,7 +60,7 @@ static void mcs_spin_unlock(struct mcs_spinlock **lock,
> > > struct mcs_spinlock *nod
> > > /*
> > > * Release the lock by setting it to NULL
> > > */
> > > - if (cmpxchg(lock, node, NULL) == node)
> > > + if (likely(cmpxchg(lock, node, NULL) == node))
> >
> > Agreed here as well. Takes a narrow race to hit this.
> >
> > So, did your testing exercise this path? If the answer is "yes",
>
>
> Paul,
>
> I did some instrumentation and confirmed that the path in question has
> been exercised. So this patch should be okay.
Very good!
Thanx, Paul
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