vlan: Avoid hash table lookup to find group.

A struct net_device always maps to zero or one vlan groups and we
always know the device when we are looking up a group.  We currently
do a hash table lookup on the device to find the group but it is
much simpler to just store a pointer.

Signed-off-by: Jesse Gross <jesse@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 54 deletions

diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c
index 54f22d820ef5..f862dccf6bb0 100644
--- a/net/8021q/vlan.c
+++ b/net/8021q/vlan.c
@@ -44,9 +44,6 @@
 
 int vlan_net_id __read_mostly;
 
-/* Our listing of VLAN group(s) */
-static struct hlist_head vlan_group_hash[VLAN_GRP_HASH_SIZE];
-
 const char vlan_fullname[] = "802.1Q VLAN Support";
 const char vlan_version[] = DRV_VERSION;
 static const char vlan_copyright[] = "Ben Greear <greearb@candelatech.com>";
@@ -59,40 +56,6 @@ static struct packet_type vlan_packet_type __read_mostly = {
 
 /* End of global variables definitions. */
 
-static inline unsigned int vlan_grp_hashfn(unsigned int idx)
-{
-        return ((idx >> VLAN_GRP_HASH_SHIFT) ^ idx) & VLAN_GRP_HASH_MASK;
-}
-
-/* Must be invoked with RCU read lock (no preempt) */
-static struct vlan_group *__vlan_find_group(struct net_device *real_dev)
-{
-        struct vlan_group *grp;
-        struct hlist_node *n;
-        int hash = vlan_grp_hashfn(real_dev->ifindex);
-
-        hlist_for_each_entry_rcu(grp, n, &vlan_group_hash[hash], hlist) {
-                if (grp->real_dev == real_dev)
-                        return grp;
-        }
-
-        return NULL;
-}
-
-/*  Find the protocol handler.  Assumes VID < VLAN_VID_MASK.
- *
- * Must be invoked with RCU read lock (no preempt)
- */
-struct net_device *__find_vlan_dev(struct net_device *real_dev, u16 vlan_id)
-{
-        struct vlan_group *grp = __vlan_find_group(real_dev);
-
-        if (grp)
-                return vlan_group_get_device(grp, vlan_id);
-
-        return NULL;
-}
-
 static void vlan_group_free(struct vlan_group *grp)
 {
         int i;
@@ -111,8 +74,6 @@ static struct vlan_group *vlan_group_alloc(struct net_device *real_dev)
                 return NULL;
 
         grp->real_dev = real_dev;
-        hlist_add_head_rcu(&grp->hlist,
-                        &vlan_group_hash[vlan_grp_hashfn(real_dev->ifindex)]);
         return grp;
 }
 
@@ -151,7 +112,7 @@ void unregister_vlan_dev(struct net_device *dev, struct list_head *head)
 
         ASSERT_RTNL();
 
-        grp = __vlan_find_group(real_dev);
+        grp = real_dev->vlgrp;
         BUG_ON(!grp);
 
         /* Take it out of our own structures, but be sure to interlock with
@@ -173,11 +134,10 @@ void unregister_vlan_dev(struct net_device *dev, struct list_head *head)
         if (grp->nr_vlans == 0) {
                 vlan_gvrp_uninit_applicant(real_dev);
 
+                rcu_assign_pointer(real_dev->vlgrp, NULL);
                 if (real_dev->features & NETIF_F_HW_VLAN_RX)
                         ops->ndo_vlan_rx_register(real_dev, NULL);
 
-                hlist_del_rcu(&grp->hlist);
-
                 /* Free the group, after all cpu's are done. */
                 call_rcu(&grp->rcu, vlan_rcu_free);
         }
@@ -207,7 +167,7 @@ int vlan_check_real_dev(struct net_device *real_dev, u16 vlan_id)
                 return -EOPNOTSUPP;
         }
 
-        if (__find_vlan_dev(real_dev, vlan_id) != NULL)
+        if (vlan_find_dev(real_dev, vlan_id) != NULL)
                 return -EEXIST;
 
         return 0;
@@ -222,7 +182,7 @@ int register_vlan_dev(struct net_device *dev)
         struct vlan_group *grp, *ngrp = NULL;
         int err;
 
-        grp = __vlan_find_group(real_dev);
+        grp = real_dev->vlgrp;
         if (!grp) {
                 ngrp = grp = vlan_group_alloc(real_dev);
                 if (!grp)
@@ -252,8 +212,11 @@ int register_vlan_dev(struct net_device *dev)
         vlan_group_set_device(grp, vlan_id, dev);
         grp->nr_vlans++;
 
-        if (ngrp && real_dev->features & NETIF_F_HW_VLAN_RX)
-                ops->ndo_vlan_rx_register(real_dev, ngrp);
+        if (ngrp) {
+                if (real_dev->features & NETIF_F_HW_VLAN_RX)
+                        ops->ndo_vlan_rx_register(real_dev, ngrp);
+                rcu_assign_pointer(real_dev->vlgrp, ngrp);
+        }
         if (real_dev->features & NETIF_F_HW_VLAN_FILTER)
                 ops->ndo_vlan_rx_add_vid(real_dev, vlan_id);
 
@@ -264,7 +227,6 @@ out_uninit_applicant:
                 vlan_gvrp_uninit_applicant(real_dev);
 out_free_group:
         if (ngrp) {
-                hlist_del_rcu(&ngrp->hlist);
                 /* Free the group, after all cpu's are done. */
                 call_rcu(&ngrp->rcu, vlan_rcu_free);
         }
@@ -428,7 +390,7 @@ static int vlan_device_event(struct notifier_block *unused, unsigned long event,
                 dev->netdev_ops->ndo_vlan_rx_add_vid(dev, 0);
         }
 
-        grp = __vlan_find_group(dev);
+        grp = dev->vlgrp;
         if (!grp)
                 goto out;
 
@@ -746,8 +708,6 @@ err0:
 
 static void __exit vlan_cleanup_module(void)
 {
-        unsigned int i;
-
         vlan_ioctl_set(NULL);
         vlan_netlink_fini();
 
@@ -755,10 +715,6 @@ static void __exit vlan_cleanup_module(void)
 
         dev_remove_pack(&vlan_packet_type);
 
-        /* This table must be empty if there are no module references left. */
-        for (i = 0; i < VLAN_GRP_HASH_SIZE; i++)
-                BUG_ON(!hlist_empty(&vlan_group_hash[i]));
-
         unregister_pernet_subsys(&vlan_net_ops);
         rcu_barrier(); /* Wait for completion of call_rcu()'s */