Date: Fri, 8 Aug 2008 17:18:21 -0700
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: David Miller <davem@davemloft.net>
Cc: a.p.zijlstra@chello.nl, torvalds@linux-foundation.org,
       akpm@linux-foundation.org, mingo@elte.hu, tglx@linutronix.de,
       marcin.slusarz@gmail.com, linux-kernel@vger.kernel.org,
       rostedt@goodmis.org
Subject: Re: [PATCH] printk: robustify printk
Message-ID: <20080809001820.GS6760@linux.vnet.ibm.com>
Reply-To: paulmck@linux.vnet.ibm.com
References: <1218217257.29098.2.camel@lappy.programming.kicks-ass.net> <alpine.LFD.1.10.0808081043160.3462@nehalem.linux-foundation.org> <1218219269.29098.5.camel@lappy.programming.kicks-ass.net> <20080808.160254.223161300.davem@davemloft.net>
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On Fri, Aug 08, 2008 at 04:02:54PM -0700, David Miller wrote:
> From: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Date: Fri, 08 Aug 2008 20:14:28 +0200
> 
> > +struct klogd_wakeup_state {
> > +	struct rcu_head head;
> > +	int pending;
> > +};
> > +
> > +DEFINE_PER_CPU(struct klogd_wakeup_state, kws);
> 
> Since there is not RCU_HEAD_INIT() made on these per-cpu objects, this code
> is depending upon the fact that currently the RCU head is just initialized
> to all zeros.

RCU_HEAD_INIT() is only needed for debugging purposes, when you want
to be sure that any garbage in the rcu_head is due to corruption or
some such.  The call_rcu() function always completely initializes the
rcu_head structure.

							Thanx, Paul
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