Subject: Re: [PATCHv5 2/2] memory barrier: adding smp_mb__after_lock

From: Peter Zijlstra <[email-masked]>
Date: Tue, 07 Jul 2009 17:50:15 +0200

On Tue, 2009-07-07 at 17:44 +0200, Oleg Nesterov wrote:
> On 07/07, Mathieu Desnoyers wrote:
> >
> > Actually, thinking about it more, to appropriately support x86, as well
> > as powerpc, arm and mips, we would need something like:
> >
> > read_lock_smp_mb()
> >
> > Which would be a read_lock with an included memory barrier.
> 
> Then we need read_lock_irq_smp_mb, read_lock_irqsave__smp_mb, write_lock_xxx,
> otherwise it is not clear why only read_lock() has _smp_mb() version.
> 
> The same for spin_lock_xxx...

At which time the smp_mb__{before,after}_{un,}lock become attractive
again.