linux-kernel - Re: [RFC PATCH] introduce sys_membarrier(): process-wide memory barrier (v5)

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Date:	Thu, 21 Jan 2010 11:22:49 -0500
From:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Oleg Nesterov <oleg@...hat.com>, Ingo Molnar <mingo@...e.hu>,
	akpm@...ux-foundation.org, josh@...htriplett.org,
	tglx@...utronix.de, Valdis.Kletnieks@...edu, dhowells@...hat.com,
	laijs@...fujitsu.com, dipankar@...ibm.com
Subject: Re: [RFC PATCH] introduce sys_membarrier(): process-wide memory
	barrier (v5)

* Steven Rostedt (rostedt@...dmis.org) wrote:
> On Thu, 2010-01-21 at 11:07 -0500, Mathieu Desnoyers wrote:
> > * Peter Zijlstra (peterz@...radead.org) wrote:
> 
> > We can even create a generic fallback with the following kind of code in
> > the meantime:
> > 
> > static inline void spin_lock_mb(spinlock_t *lock)
> > {
> > 	spin_lock(&lock);
> 
> That would be spin_lock(lock);
> 
> > 	smp_mb();
> > }
> > 
> > static inline void spin_unlock_mb(spinlock_t *lock)
> > {
> > 	smp_mb();
> > 	spin_unlock(&lock);
> 
> and spin_unlock(lock);
> 
> ;-)

Oh, right. I should think of integrating a compiler in my mail client ;)


> 
> > }
> > 
> > How does that sound ?
> 
> You may also need spin_lock_irqsave, et al. variants too.

Yep, or we simply use the local_irq_save/restore separately. That could
be a good idea given that only few specialized sites are affected.

Thanks,

Mathieu

> 
> -- Steve
> 
> 

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
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