Subject: Re: [RFC PATCH] introduce sys_membarrier(): process-wide memory
 barrier (v5)
From: Steven Rostedt <rostedt@goodmis.org>
Reply-To: rostedt@goodmis.org
To: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Peter Zijlstra <peterz@infradead.org>, linux-kernel@vger.kernel.org,
       "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
       Oleg Nesterov <oleg@redhat.com>, Ingo Molnar <mingo@elte.hu>,
       akpm@linux-foundation.org, josh@joshtriplett.org, tglx@linutronix.de,
       Valdis.Kletnieks@vt.edu, dhowells@redhat.com, laijs@cn.fujitsu.com,
       dipankar@in.ibm.com
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Organization: Kihon Technologies Inc.
Date: Thu, 21 Jan 2010 11:12:11 -0500
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On Thu, 2010-01-21 at 11:07 -0500, Mathieu Desnoyers wrote:
> * Peter Zijlstra (peterz@infradead.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);

;-)

> }
> 
> How does that sound ?

You may also need spin_lock_irqsave, et al. variants too.

-- Steve


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