From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
"David S. Miller" <davem@davemloft.net>,
netdev@vger.kernel.org, Stephen Hemminger <shemminger@vyatta.com>
Subject: Re: [PATCH 6/13] bridge: Add core IGMP snooping support
Date: Wed, 10 Mar 2010 05:57:33 -0800 [thread overview]
Message-ID: <20100310135733.GH6267@linux.vnet.ibm.com> (raw)
In-Reply-To: <201003101430.06736.arnd@arndb.de>
On Wed, Mar 10, 2010 at 02:30:06PM +0100, Arnd Bergmann wrote:
> On Wednesday 10 March 2010, Paul E. McKenney wrote:
> > > When rt_hash_table[h].chain gets the __rcu_bh annotation, we'd have to
> > > turn first rcu_dereference into rcu_dereference_bh in order to have a clean
> > > build with sparse. Would that change be
> > > a) correct from RCU perspective,
> > > b) desirable for code inspection, and
> > > c) lockdep-clean?
> >
> > I have a patch queued up that will make rcu_dereference_bh() handle this
> > correctly -- current -tip and mainline would complain. Please see below
> > for a sneak preview.
> >
> > Thoughts?
>
> Ok, so that would mean we can convert it all to rcu_dereference_bh().
> I guess an alternative to this would be to also change the rcu_read_lock()
> inside local_bh_disable() sections to rcu_read_lock_bh(), which is not
> necessary but also not harmful, right?
It does impose additional overhead, which the networking guys are eager
to avoid, given that network links speeds are continuing to increase. ;-)
So moving to rcu_dereference_bh() seems better to me.
(Please note that rcu_dereference_bh() imposes checking overhead only
in the presence of both CONFIG_PROVE_LOCKING and CONFIG_PROVE_RCU.)
Thanx, Paul
next prev parent reply other threads:[~2010-03-10 13:57 UTC|newest]
Thread overview: 81+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-26 15:34 [RFC] [1/13] bridge: Add IGMP snooping support Herbert Xu
2010-02-26 15:35 ` [PATCH 1/13] bridge: Do br_pass_frame_up after other ports Herbert Xu
2010-02-26 15:35 ` [PATCH 2/13] bridge: Allow tail-call on br_pass_frame_up Herbert Xu
2010-02-27 11:14 ` David Miller
2010-02-27 15:36 ` Herbert Xu
2010-02-26 15:35 ` [PATCH 3/13] bridge: Avoid unnecessary clone on forward path Herbert Xu
2010-02-26 15:35 ` [PATCH 4/13] bridge: Use BR_INPUT_SKB_CB on xmit path Herbert Xu
2010-02-26 15:35 ` [PATCH 5/13] bridge: Split may_deliver/deliver_clone out of br_flood Herbert Xu
2010-02-26 15:35 ` [PATCH 6/13] bridge: Add core IGMP snooping support Herbert Xu
2010-02-26 15:35 ` [PATCH 7/13] bridge: Add multicast forwarding functions Herbert Xu
2010-02-26 15:35 ` [PATCH 8/13] bridge: Add multicast start/stop hooks Herbert Xu
2010-02-26 15:35 ` [PATCH 9/13] bridge: Add multicast data-path hooks Herbert Xu
2010-02-26 15:35 ` [PATCH 10/13] bridge: Add multicast_router sysfs entries Herbert Xu
2010-02-27 0:42 ` Stephen Hemminger
2010-02-27 11:29 ` David Miller
2010-02-27 15:53 ` Herbert Xu
2010-03-09 12:25 ` Herbert Xu
2010-03-09 12:26 ` Herbert Xu
2010-02-26 15:35 ` [PATCH 11/13] bridge: Add multicast_snooping sysfs toggle Herbert Xu
2010-02-26 15:35 ` [PATCH 12/13] bridge: Add hash elasticity/max sysfs entries Herbert Xu
2010-02-26 15:35 ` [PATCH 13/13] bridge: Add multicast count/interval " Herbert Xu
2010-02-28 5:40 ` [1/13] bridge: Add IGMP snooping support Herbert Xu
2010-02-28 5:41 ` [PATCH 1/13] bridge: Do br_pass_frame_up after other ports Herbert Xu
2010-02-28 5:41 ` [PATCH 2/13] bridge: Allow tail-call on br_pass_frame_up Herbert Xu
2010-02-28 5:41 ` [PATCH 3/13] bridge: Avoid unnecessary clone on forward path Herbert Xu
2010-02-28 5:41 ` [PATCH 4/13] bridge: Use BR_INPUT_SKB_CB on xmit path Herbert Xu
2010-02-28 5:41 ` [PATCH 5/13] bridge: Split may_deliver/deliver_clone out of br_flood Herbert Xu
2010-02-28 5:41 ` [PATCH 6/13] bridge: Add core IGMP snooping support Herbert Xu
2010-03-05 23:43 ` Paul E. McKenney
2010-03-06 1:17 ` Herbert Xu
2010-03-06 5:06 ` Paul E. McKenney
2010-03-06 6:56 ` Herbert Xu
2010-03-06 7:03 ` Herbert Xu
2010-03-07 23:31 ` David Miller
2010-03-06 7:07 ` Herbert Xu
2010-03-07 23:31 ` David Miller
2010-03-06 15:00 ` Paul E. McKenney
2010-03-06 15:19 ` Paul E. McKenney
2010-03-06 19:00 ` Paul E. McKenney
2010-03-07 2:45 ` Herbert Xu
2010-03-07 3:11 ` Paul E. McKenney
2010-03-08 18:50 ` Arnd Bergmann
2010-03-09 3:15 ` Paul E. McKenney
2010-03-11 18:49 ` Arnd Bergmann
2010-03-14 23:01 ` Paul E. McKenney
2010-03-09 21:12 ` Arnd Bergmann
2010-03-10 2:14 ` Paul E. McKenney
2010-03-10 9:41 ` Arnd Bergmann
2010-03-10 10:39 ` Eric Dumazet
2010-03-10 10:49 ` Herbert Xu
2010-03-10 13:13 ` Paul E. McKenney
2010-03-10 14:07 ` Herbert Xu
2010-03-10 16:26 ` Paul E. McKenney
2010-03-10 16:35 ` David Miller
2010-03-10 17:56 ` Arnd Bergmann
2010-03-10 21:25 ` Paul E. McKenney
2010-03-10 13:27 ` Arnd Bergmann
2010-03-10 13:39 ` Arnd Bergmann
2010-03-10 13:19 ` Paul E. McKenney
2010-03-10 13:30 ` Arnd Bergmann
2010-03-10 13:57 ` Paul E. McKenney [this message]
2010-02-28 5:41 ` [PATCH 7/13] bridge: Add multicast forwarding functions Herbert Xu
2010-02-28 5:41 ` [PATCH 8/13] bridge: Add multicast start/stop hooks Herbert Xu
2010-02-28 5:41 ` [PATCH 9/13] bridge: Add multicast data-path hooks Herbert Xu
2010-04-27 17:13 ` [PATCH net-next] bridge: use is_multicast_ether_addr Stephen Hemminger
2010-04-27 19:53 ` David Miller
2010-02-28 5:41 ` [PATCH 10/13] bridge: Add multicast_router sysfs entries Herbert Xu
2010-04-27 17:13 ` [PATCH net-next] bridge: multicast router list manipulation Stephen Hemminger
2010-04-27 19:54 ` David Miller
2010-04-27 23:11 ` Michał Mirosław
2010-04-27 23:25 ` Stephen Hemminger
2010-04-27 23:28 ` David Miller
2010-04-27 23:44 ` Stephen Hemminger
2010-04-27 23:51 ` David Miller
2010-04-27 23:27 ` David Miller
2010-04-28 1:51 ` Herbert Xu
2010-02-28 5:41 ` [PATCH 11/13] bridge: Add multicast_snooping sysfs toggle Herbert Xu
2010-02-28 5:41 ` [PATCH 12/13] bridge: Add hash elasticity/max sysfs entries Herbert Xu
2010-02-28 5:41 ` [PATCH 13/13] bridge: Add multicast count/interval " Herbert Xu
2010-02-28 8:52 ` [1/13] bridge: Add IGMP snooping support David Miller
2010-03-01 2:08 ` Herbert Xu
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