From: Ivan Vecera <ivecera@redhat.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: "Jiri Pirko" <jpirko@redhat.com>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Andy Gospodarek" <andy@greyhouse.net>,
"David S. Miller" <davem@davemloft.net>,
LKML <linux-kernel@vger.kernel.org>,
netdev <netdev@vger.kernel.org>,
"Nicolas de Pesloüan" <nicolas.2p.debian@gmail.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Guy Streeter" <streeter@redhat.com>,
"Paul E. McKenney" <paulmck@us.ibm.com>,
stephen@networkplumber.org
Subject: Re: [PATCH] net: add a synchronize_net() in netdev_rx_handler_unregister()
Date: Fri, 29 Mar 2013 16:11:32 +0100 [thread overview]
Message-ID: <5155AF24.3090305@redhat.com> (raw)
In-Reply-To: <1364562082.5113.16.camel@edumazet-glaptop>
On 03/29/2013 02:01 PM, Eric Dumazet wrote:
>> CPU0 will see rx_handler set and yet, rx_handler_data nulled. Write
>> >barrier in rcu_assign_pointer() might prevent this reorder from happening.
>> >Therefore I suggest:
>> >
>> >diff --git a/net/core/dev.c b/net/core/dev.c
>> >index 0caa38e..c16b829 100644
>> >--- a/net/core/dev.c
>> >+++ b/net/core/dev.c
>> >@@ -3332,8 +3332,8 @@ void netdev_rx_handler_unregister(struct net_device *dev)
>> > {
>> >
>> > ASSERT_RTNL();
>> >- RCU_INIT_POINTER(dev->rx_handler, NULL);
>> >- RCU_INIT_POINTER(dev->rx_handler_data, NULL);
>> >+ rcu_assign_pointer(dev->rx_handler, NULL);
>> >+ rcu_assign_pointer(dev->rx_handler_data, NULL);
>> > }
>> > EXPORT_SYMBOL_GPL(netdev_rx_handler_unregister);
>> >
>> >
> Nope this changes nothing at all.
Erik, why doesn't help the write barrier between the assignments. It
should guarantee their orders... or not?
Thanks,
Ivan
next prev parent reply other threads:[~2013-03-29 15:12 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-28 17:16 [BUG] Crash with NULL pointer dereference in bond_handle_frame in -rt (possibly mainline) Steven Rostedt
2013-03-28 17:29 ` Eric Dumazet
2013-03-28 17:44 ` Steven Rostedt
2013-03-29 9:48 ` Jiri Pirko
2013-03-29 13:01 ` [PATCH] net: add a synchronize_net() in netdev_rx_handler_unregister() Eric Dumazet
2013-03-29 13:17 ` Steven Rostedt
2013-03-29 13:38 ` Eric Dumazet
2013-03-29 15:11 ` Ivan Vecera [this message]
2013-03-29 15:38 ` Eric Dumazet
2013-03-29 16:12 ` Jiri Pirko
2013-03-29 16:46 ` Eric Dumazet
2013-03-29 19:20 ` Paul E. McKenney
2013-03-29 19:26 ` Eric Dumazet
2013-03-29 19:39 ` David Miller
2013-03-29 15:46 ` [BUG] Crash with NULL pointer dereference in bond_handle_frame in -rt (possibly mainline) Stephen Hemminger
2013-03-29 18:36 ` Steven Rostedt
2013-03-29 19:55 ` Steven Rostedt
2013-03-30 9:19 ` Jiri Pirko
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