vlan: fix a race in egress prio management

[~andy/linux] / net / 8021q / vlan_dev.c

diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index 3a8c8fd63c88e2c204a8f1ac3b6dc4eb3f15cc63..1cd3d2a406f5a268113d0d802f03578f2a3cbe20 100644 (file)
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -73,6 +73,8 @@ vlan_dev_get_egress_qos_mask(struct net_device *dev, struct sk_buff *skb)
 {
        struct vlan_priority_tci_mapping *mp;
 
+       smp_rmb(); /* coupled with smp_wmb() in vlan_dev_set_egress_priority() */
+
        mp = vlan_dev_priv(dev)->egress_priority_map[(skb->priority & 0xF)];
        while (mp) {
                if (mp->priority == skb->priority) {
@@ -249,6 +251,11 @@ int vlan_dev_set_egress_priority(const struct net_device *dev,
        np->next = mp;
        np->priority = skb_prio;
        np->vlan_qos = vlan_qos;
+       /* Before inserting this element in hash table, make sure all its fields
+        * are committed to memory.
+        * coupled with smp_rmb() in vlan_dev_get_egress_qos_mask()
+        */
+       smp_wmb();
        vlan->egress_priority_map[skb_prio & 0xF] = np;
        if (vlan_qos)
                vlan->nr_egress_mappings++;