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 <shemminger@vyatta.com>
Tested-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 1 deletions

diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index 753fc4221f3c..4cec8051164d 100644
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -22,7 +22,7 @@
 #include <asm/uaccess.h>
 #include "br_private.h"
 
-/* net device transmit always called with no BH (preempt_disabled) */
+/* net device transmit always called with BH disabled */
 netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
 {
         struct net_bridge *br = netdev_priv(dev);
@@ -46,6 +46,7 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
         skb_reset_mac_header(skb);
         skb_pull(skb, ETH_HLEN);
 
+        rcu_read_lock();
         if (is_multicast_ether_addr(dest)) {
                 if (br_multicast_rcv(br, NULL, skb))
                         goto out;
@@ -61,6 +62,7 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
                 br_flood_deliver(br, skb);
 
 out:
+        rcu_read_unlock();
         return NETDEV_TX_OK;
 }