From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: James Chapman <jchapman@katalix.com>
Cc: Stephen Hemminger <shemminger@vyatta.com>, netdev@vger.kernel.org
Subject: Re: [PATCH v3 10/12] l2tp: Add L2TP ethernet pseudowire support
Date: Wed, 31 Mar 2010 10:38:36 -0700 [thread overview]
Message-ID: <20100331173836.GG2461@linux.vnet.ibm.com> (raw)
In-Reply-To: <4BB31761.2090906@katalix.com>
On Wed, Mar 31, 2010 at 10:35:29AM +0100, James Chapman wrote:
> Stephen Hemminger wrote:
> > On Tue, 30 Mar 2010 17:18:19 +0100
> > James Chapman <jchapman@katalix.com> wrote:
> >
> >> +struct l2tp_eth_net {
> >> + struct list_head l2tp_eth_dev_list;
> >> + rwlock_t l2tp_eth_lock;
> >> +};
> >
> > Reader/write locks are discouraged because they are slower than
> > spin locks. If you have lots of readers use RCU, if reading
> > is infrequent just use a spin lock.
>
> Ok. In doing the conversion of the rwlocks in l2tp_core.c, I'm finding
> that some list access primitives don't have rcu equivalents, namely
> list_is_last(), list_for_each_entry_safe(). Is this intentional? Should
> I add the missing ones in a separate patch?
The list_is_last() is RCU-safe already, since the ->next pointer is
only compared, never dereferenced. I suggest adding a comment to its
header stating that it is RCU-safe.
Feel free to create a list_for_each_entry_safe_rcu(), and I will be
happy to review it.
Thanx, Paul
next prev parent reply other threads:[~2010-03-31 17:38 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-30 16:17 [PATCH v3 00/12] l2tp: Introduce L2TPv3 support James Chapman
2010-03-30 16:17 ` [PATCH v3 01/12] l2tp: Relocate pppol2tp driver to new net/l2tp directory James Chapman
2010-03-30 16:17 ` [PATCH v3 02/12] l2tp: Split pppol2tp patch into separate l2tp and ppp parts James Chapman
2010-03-30 16:17 ` [PATCH v3 03/12] ppp: Add ppp_dev_name() exported function James Chapman
2010-03-30 16:17 ` [PATCH v3 04/12] l2tp: Add ppp device name to L2TP ppp session data James Chapman
2010-03-30 16:29 ` Stephen Hemminger
2010-03-31 7:43 ` James Chapman
2010-03-31 8:46 ` David Miller
2010-03-31 23:08 ` Stephen Hemminger
2010-04-01 7:19 ` James Chapman
2010-04-01 7:30 ` Eric Dumazet
2010-04-01 8:55 ` James Chapman
2010-04-01 7:34 ` David Miller
2010-04-01 8:59 ` James Chapman
2010-04-01 9:04 ` David Miller
2010-03-30 16:17 ` [PATCH v3 05/12] l2tp: Add L2TPv3 protocol support James Chapman
2010-03-30 16:17 ` [PATCH v3 06/12] l2tp: Update PPP-over-L2TP driver to work over L2TPv3 James Chapman
2010-03-30 16:18 ` [PATCH v3 07/12] l2tp: Add L2TPv3 IP encapsulation (no UDP) support James Chapman
2010-03-30 16:18 ` [PATCH v3 08/12] netlink: Export genl_lock() API for use by modules James Chapman
2010-03-30 16:18 ` [PATCH v3 09/12] l2tp: Add netlink control API for L2TP James Chapman
2010-03-31 8:59 ` Patrick McHardy
2010-03-30 16:18 ` [PATCH v3 10/12] l2tp: Add L2TP ethernet pseudowire support James Chapman
2010-03-30 16:30 ` Stephen Hemminger
2010-03-30 16:30 ` Stephen Hemminger
2010-03-30 16:32 ` Stephen Hemminger
2010-03-31 9:35 ` James Chapman
2010-03-31 17:38 ` Paul E. McKenney [this message]
2010-04-02 15:24 ` Paul E. McKenney
2010-04-02 15:58 ` Eric Dumazet
2010-04-02 16:21 ` Paul E. McKenney
2010-03-30 16:18 ` [PATCH v3 11/12] l2tp: Add support for static unmanaged L2TPv3 tunnels James Chapman
2010-03-30 16:18 ` [PATCH v3 12/12] l2tp: Update documentation James Chapman
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