[51/91] bridge: add rcu_read_lock on transmit

From: Greg KH
Date: Tue Aug 24 2010 - 19:32:39 EST


2.6.34-stable review patch. If anyone has any objections, please let us know.

------------------


From: Stephen Hemminger <shemminger@xxxxxxxxxx>

[ Upstream commit eeaf61d8891f9c9ed12c1a667e72bf83f0857954 ]

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@xxxxxxxxxx>
Tested-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
net/bridge/br_device.c | 4 +++-
net/bridge/br_fdb.c | 2 +-
net/bridge/br_input.c | 6 +++---
net/bridge/br_stp_bpdu.c | 2 +-
4 files changed, 8 insertions(+), 6 deletions(-)

--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -19,7 +19,7 @@
#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);
@@ -35,6 +35,7 @@ netdev_tx_t br_dev_xmit(struct sk_buff *
skb_reset_mac_header(skb);
skb_pull(skb, ETH_HLEN);

+ rcu_read_lock();
if (dest[0] & 1) {
if (br_multicast_rcv(br, NULL, skb))
goto out;
@@ -50,6 +51,7 @@ 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
+++ b/net/bridge/br_fdb.c
@@ -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
+++ b/net/bridge/br_input.c
@@ -35,7 +35,7 @@ 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;
@@ -106,7 +106,7 @@ 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 = rcu_dereference(skb->dev->br_port);
@@ -131,7 +131,7 @@ static inline int is_link_local(const un
/*
* Called via br_handle_frame_hook.
* Return NULL if skb is handled
- * note: already called with rcu_read_lock (preempt_disabled)
+ * note: already called with rcu_read_lock
*/
struct sk_buff *br_handle_frame(struct net_bridge_port *p, struct sk_buff *skb)
{
--- a/net/bridge/br_stp_bpdu.c
+++ b/net/bridge/br_stp_bpdu.c
@@ -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)


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/