[BRIDGE]: fix for RCU and deadlock on device removal
Change Bridge receive path to correctly handle RCU removal of device
from bridge. Also fixes deadlock between carrier_check and del_nbp.
This replaces the previous deleted flag fix.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/bridge/br_stp_bpdu.c b/net/bridge/br_stp_bpdu.c
index d071f1c..296f6a4 100644
--- a/net/bridge/br_stp_bpdu.c
+++ b/net/bridge/br_stp_bpdu.c
@@ -133,29 +133,35 @@
static const unsigned char header[6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00};
-/* NO locks */
+/* NO locks, but rcu_read_lock (preempt_disabled) */
int br_stp_handle_bpdu(struct sk_buff *skb)
{
- struct net_bridge_port *p = skb->dev->br_port;
- struct net_bridge *br = p->br;
+ struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
+ struct net_bridge *br;
unsigned char *buf;
+ if (!p)
+ goto err;
+
+ br = p->br;
+ spin_lock(&br->lock);
+
+ if (p->state == BR_STATE_DISABLED || !(br->dev->flags & IFF_UP))
+ goto out;
+
/* insert into forwarding database after filtering to avoid spoofing */
- br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
+ br_fdb_update(br, p, eth_hdr(skb)->h_source);
+
+ if (!br->stp_enabled)
+ goto out;
/* need at least the 802 and STP headers */
if (!pskb_may_pull(skb, sizeof(header)+1) ||
memcmp(skb->data, header, sizeof(header)))
- goto err;
+ goto out;
buf = skb_pull(skb, sizeof(header));
- spin_lock_bh(&br->lock);
- if (p->state == BR_STATE_DISABLED
- || !(br->dev->flags & IFF_UP)
- || !br->stp_enabled)
- goto out;
-
if (buf[0] == BPDU_TYPE_CONFIG) {
struct br_config_bpdu bpdu;
@@ -201,7 +207,7 @@
br_received_tcn_bpdu(p);
}
out:
- spin_unlock_bh(&br->lock);
+ spin_unlock(&br->lock);
err:
kfree_skb(skb);
return 0;