From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: David Howells <dhowells@redhat.com>
Cc: linux-kernel@vger.kernel.org, mingo@elte.hu,
laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca,
josh@joshtriplett.org, dvhltc@us.ibm.com, niv@us.ibm.com,
tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org,
Valdis.Kletnieks@vt.edu, eric.dumazet@gmail.com
Subject: Re: [PATCH tip/urgent] rcu: add rcu_access_pointer and rcu_dereference_protected
Date: Thu, 8 Apr 2010 09:46:15 -0700 [thread overview]
Message-ID: <20100408164615.GA4836@linux.vnet.ibm.com> (raw)
In-Reply-To: <20100407230009.GK2481@linux.vnet.ibm.com>
On Wed, Apr 07, 2010 at 04:00:09PM -0700, Paul E. McKenney wrote:
> On Wed, Apr 07, 2010 at 06:20:48PM +0100, David Howells wrote:
> > Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote:
> >
> > > In other cases, there will be a reference counter or a "not yet fully
> > > initialized" flag that can (and should) be tested.
> >
> > Why would you be using rcu_access_pointer() there? Why wouldn't you be using
> > rcu_dereference_protected()?
>
> Excellent question. I am writing up the documentation now, and will
> either (1) have a good use case or (2) remove the condition.
And all of the examples I could come up with that had c!=1 were contorted,
even by my standards. So you were right, and I will drop the "c" on my
next set of patches.
Thanx, Paul
next prev parent reply other threads:[~2010-04-08 16:46 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-07 16:26 [PATCH tip/urgent] rcu: add rcu_access_pointer and rcu_dereference_protected Paul E. McKenney
2010-04-07 16:38 ` Eric Dumazet
2010-04-07 16:45 ` Mathieu Desnoyers
2010-04-07 17:00 ` David Howells
2010-04-07 17:13 ` Paul E. McKenney
2010-04-07 17:20 ` David Howells
2010-04-07 23:00 ` Paul E. McKenney
2010-04-08 16:46 ` Paul E. McKenney [this message]
2010-04-08 19:04 ` David Howells
2010-04-08 19:53 ` Paul E. McKenney
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