From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Balakumaran Kannan <kumaran.4353@gmail.com>,
yoshfuji@linux-ipv6.org, davem@davemloft.net,
Patrick McHardy <kaber@trash.net>,
Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
jmorris@namei.org, Balakumaran.Kannan@ap.sony.com,
maruthi.thotad@ap.sony.com, netdev@vger.kernel.org,
jamshed.a@ap.sony.com, amit.agarwal@ap.sony.com,
takuzo.ohara@jp.sony.com, aaditya.kumar@ap.sony.com
Subject: Re: [PATCH v2] net IPv6 : Fix broken IPv6 routing table after loopback down-up
Date: Thu, 28 Mar 2013 12:39:57 -0700 [thread overview]
Message-ID: <20130328193957.GH3337@linux.vnet.ibm.com> (raw)
In-Reply-To: <1364496577.15753.51.camel@edumazet-glaptop>
On Thu, Mar 28, 2013 at 11:49:37AM -0700, Eric Dumazet wrote:
> On Thu, 2013-03-28 at 11:23 -0700, Paul E. McKenney wrote:
>
> >
> > Agreed, there is no point in using RCU when it is not needed.
> >
> > That said...
> >
> > Since v3.1, in CONFIG_PREEMPT=y kernels, rcu_read_lock() does not
> > disable preemption. In CONFIG_PREEMPT=n kernels, rcu_read_lock() does
> > disable preemption, but to no effect because preemption is already
> > disabled anyway.
> >
> > The net effect is that rcu_read_lock() has no effect on preemption.
> >
>
> Good point, but this patch might be a stable candidate.
>
> Rule of thumb for networking is
>
> 1) Control path : RTNL mutex
>
> 2) Data path : RTNL cant be taken (from softirq), so use RCU if
> possible.
Stable candidate and rules of thumb sound good to me!
Thanx, Paul
prev parent reply other threads:[~2013-03-28 19:40 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-28 13:27 [PATCH v2] net IPv6 : Fix broken IPv6 routing table after loopback down-up Balakumaran Kannan
2013-03-28 13:44 ` Eric Dumazet
2013-03-28 13:45 ` Eric Dumazet
2013-03-28 14:04 ` Balakumaran Kannan
2013-03-28 14:47 ` Balakumaran Kannan
2013-03-28 15:14 ` Balakumaran Kannan
2013-03-29 19:17 ` David Miller
2013-03-31 6:38 ` Balakumaran Kannan
2013-04-01 11:59 ` Balakumaran Kannan
2013-04-01 14:16 ` YOSHIFUJI Hideaki
2013-04-02 10:45 ` Balakumaran Kannan
2013-04-02 18:37 ` David Miller
2013-03-28 18:23 ` Paul E. McKenney
2013-03-28 18:49 ` Eric Dumazet
2013-03-28 19:39 ` Paul E. McKenney [this message]
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