From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: br_forward.c - rcu dereference warning Date: Tue, 27 Jul 2010 11:26:30 -0700 Message-ID: <20100727112630.5a5ce84b@nehalam> References: <1280227553.3755.2.camel@jlt3.sipsolutions.net> <20100727123859.GF3766@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Johannes Berg , netdev To: paulmck@linux.vnet.ibm.com Return-path: Received: from mail.vyatta.com ([76.74.103.46]:45765 "EHLO mail.vyatta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751879Ab0G0S0g (ORCPT ); Tue, 27 Jul 2010 14:26:36 -0400 In-Reply-To: <20100727123859.GF3766@linux.vnet.ibm.com> Sender: netdev-owner@vger.kernel.org List-ID: I think this is needed (untested)... ----- Subject: bridge: add rcu_read_lock on transmit Long ago, when bridge was converted to RCU, rcu lock was equivalent to having preempt disabled. RCU has changed a lot since then and bridge code was still assuming the since transmit was called with bottom half disabled, it was RCU safe. Signed-off-by: Stephen Hemminger --- net/bridge/br_device.c | 4 +++- net/bridge/br_fdb.c | 2 +- net/bridge/br_input.c | 7 +++---- net/bridge/br_stp_bpdu.c | 2 +- 4 files changed, 8 insertions(+), 7 deletions(-) --- a/net/bridge/br_device.c 2010-07-27 08:57:43.169399349 -0700 +++ b/net/bridge/br_device.c 2010-07-27 11:18:51.677053426 -0700 @@ -22,7 +22,7 @@ #include #include "br_private.h" -/* net device transmit always called with no BH (preempt_disabled) */ +/* net device transmit always called with no BH disabled */ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev) { struct net_bridge *br = netdev_priv(dev); @@ -48,6 +48,7 @@ netdev_tx_t br_dev_xmit(struct sk_buff * skb_reset_mac_header(skb); skb_pull(skb, ETH_HLEN); + rcu_read_lock(); if (is_multicast_ether_addr(dest)) { if (unlikely(netpoll_tx_running(dev))) { br_flood_deliver(br, skb); @@ -67,6 +68,7 @@ netdev_tx_t br_dev_xmit(struct sk_buff * br_flood_deliver(br, skb); out: + rcu_read_unlock(); return NETDEV_TX_OK; } --- a/net/bridge/br_fdb.c 2010-07-27 11:18:30.815320981 -0700 +++ b/net/bridge/br_fdb.c 2010-07-27 11:18:59.597710975 -0700 @@ -214,7 +214,7 @@ void br_fdb_delete_by_port(struct net_br spin_unlock_bh(&br->hash_lock); } -/* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */ +/* No locking or refcounting, assumes caller has rcu_read_lock */ struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br, const unsigned char *addr) { --- a/net/bridge/br_input.c 2010-07-27 11:19:05.266181492 -0700 +++ b/net/bridge/br_input.c 2010-07-27 11:19:29.148163149 -0700 @@ -39,7 +39,7 @@ static int br_pass_frame_up(struct sk_bu netif_receive_skb); } -/* note: already called with rcu_read_lock (preempt_disabled) */ +/* note: already called with rcu_read_lock */ int br_handle_frame_finish(struct sk_buff *skb) { const unsigned char *dest = eth_hdr(skb)->h_dest; @@ -110,7 +110,7 @@ drop: goto out; } -/* note: already called with rcu_read_lock (preempt_disabled) */ +/* note: already called with rcu_read_lock */ static int br_handle_local_finish(struct sk_buff *skb) { struct net_bridge_port *p = br_port_get_rcu(skb->dev); @@ -133,8 +133,7 @@ static inline int is_link_local(const un /* * Return NULL if skb is handled - * note: already called with rcu_read_lock (preempt_disabled) from - * netif_receive_skb + * note: already called with rcu_read_lock from netif_receive_skb */ struct sk_buff *br_handle_frame(struct sk_buff *skb) { --- a/net/bridge/br_stp_bpdu.c 2010-07-27 11:19:34.092573294 -0700 +++ b/net/bridge/br_stp_bpdu.c 2010-07-27 11:19:40.725123403 -0700 @@ -131,7 +131,7 @@ void br_send_tcn_bpdu(struct net_bridge_ /* * Called from llc. * - * NO locks, but rcu_read_lock (preempt_disabled) + * NO locks, but rcu_read_lock */ void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb, struct net_device *dev)