Re: [PATCH 1/2] Allow rwlocks to re-enable interrupts

From: Peter Zijlstra
Date: Wed Oct 22 2008 - 13:24:45 EST


On Wed, 2008-10-22 at 10:58 +0200, Petr Tesarik wrote:
> On Wed, 2008-10-22 at 10:45 +0200, Peter Zijlstra wrote:
> > On Wed, 2008-10-22 at 10:34 +0200, Petr Tesarik wrote:
> > > c b/kernel/spinlock.c
> > > index 29ab207..f769d8a 100644
> > > --- a/kernel/spinlock.c
> > > +++ b/kernel/spinlock.c
> > > @@ -121,7 +121,11 @@ unsigned long __lockfunc _read_lock_irqsave(rwlock_t *lock)
> > > local_irq_save(flags);
> > > preempt_disable();
> > > rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
> > > +#ifdef CONFIG_LOCKDEP
> > > LOCK_CONTENDED(lock, _raw_read_trylock, _raw_read_lock);
> > > +#else
> > > + _raw_read_lock_flags(lock, &flags);
> > > +#endif
> > > return flags;
> > > }
> >
> > That should be CONFIG_LOCK_STAT.
>
> Ugh. Fine with me, but is CONFIG_LOCKDEP correct in _spin_lock_irqsave,
> or should it also read CONFIG_LOCK_STAT?

Yep.

> > But aside from that, I really don't like this change, I'd rather you'd
> > create a LOCK_CONTENDED_FLAGS() that can deal with this.
>
> No problem. I could then also use it for _spin_lock_irqsave, if the
> answer to the above question is use CONFIG_LOCK_STAT there as well.

If you create LOCK_CONTEDED_FLAGS() the whole issue goes away nicely.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/