net: Kill support for multiple hh_cache entries per neighbour

This never, ever, happens.

Neighbour entries are always tied to one address family, and therefore
one set of dst_ops, and therefore one dst_ops->protocol "hh_type"
value.

This capability was blindly imported by Alexey Kuznetsov when he wrote
the neighbour layer.

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 564d89f..7538237 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -252,7 +252,6 @@ struct netdev_hw_addr_list {
        netdev_hw_addr_list_for_each(ha, &(dev)->mc)
 
 struct hh_cache {
-       struct hh_cache *hh_next;       /* Next entry                        */
        atomic_t        hh_refcnt;      /* number of users                   */
 /*
  * We want hh_output, hh_len, hh_lock and hh_data be a in a separate
@@ -260,12 +259,8 @@ struct hh_cache {
  * They are mostly read, but hh_refcnt may be changed quite frequently,
  * incurring cache line ping pongs.
  */
-       __be16          hh_type ____cacheline_aligned_in_smp;
-                                       /* protocol identifier, f.e ETH_P_IP
-                                         *  NOTE:  For VLANs, this will be the
-                                         *  encapuslated type. --BLG
-                                         */
-       u16             hh_len;         /* length of header */
+       u16             hh_len ____cacheline_aligned_in_smp;
+       u16             __pad;
        int             (*hh_output)(struct sk_buff *skb);
        seqlock_t       hh_lock;
 

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 8f7e1d8..f879bb5 100644 (file)
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -702,9 +702,9 @@ void neigh_destroy(struct neighbour *neigh)
        if (neigh_del_timer(neigh))
                printk(KERN_WARNING "Impossible event.\n");
 
-       while ((hh = neigh->hh) != NULL) {
-               neigh->hh = hh->hh_next;
-               hh->hh_next = NULL;
+       hh = neigh->hh;
+       if (hh) {
+               neigh->hh = NULL;
 
                write_seqlock_bh(&hh->hh_lock);
                hh->hh_output = neigh_blackhole;
@@ -737,7 +737,8 @@ static void neigh_suspect(struct neighbour *neigh)
 
        neigh->output = neigh->ops->output;
 
-       for (hh = neigh->hh; hh; hh = hh->hh_next)
+       hh = neigh->hh;
+       if (hh)
                hh->hh_output = neigh->ops->output;
 }
 
@@ -754,7 +755,8 @@ static void neigh_connect(struct neighbour *neigh)
 
        neigh->output = neigh->ops->connected_output;
 
-       for (hh = neigh->hh; hh; hh = hh->hh_next)
+       hh = neigh->hh;
+       if (hh)
                hh->hh_output = neigh->ops->hh_output;
 }
 
@@ -1025,7 +1027,8 @@ static void neigh_update_hhs(const struct neighbour *neigh)
                update = neigh->dev->header_ops->cache_update;
 
        if (update) {
-               for (hh = neigh->hh; hh; hh = hh->hh_next) {
+               hh = neigh->hh;
+               if (hh) {
                        write_seqlock_bh(&hh->hh_lock);
                        update(hh, neigh->dev, neigh->ha);
                        write_sequnlock_bh(&hh->hh_lock);
@@ -1211,19 +1214,17 @@ struct neighbour *neigh_event_ns(struct neigh_table *tbl,
 }
 EXPORT_SYMBOL(neigh_event_ns);
 
-static inline bool neigh_hh_lookup(struct neighbour *n, struct dst_entry *dst,
-                                  __be16 protocol)
+static inline bool neigh_hh_lookup(struct neighbour *n, struct dst_entry *dst)
 {
        struct hh_cache *hh;
 
        smp_rmb(); /* paired with smp_wmb() in neigh_hh_init() */
-       for (hh = n->hh; hh; hh = hh->hh_next) {
-               if (hh->hh_type == protocol) {
-                       atomic_inc(&hh->hh_refcnt);
-                       if (unlikely(cmpxchg(&dst->hh, NULL, hh) != NULL))
-                               hh_cache_put(hh);
-                       return true;
-               }
+       hh = n->hh;
+       if (hh) {
+               atomic_inc(&hh->hh_refcnt);
+               if (unlikely(cmpxchg(&dst->hh, NULL, hh) != NULL))
+                       hh_cache_put(hh);
+               return true;
        }
        return false;
 }
@@ -1235,7 +1236,7 @@ static void neigh_hh_init(struct neighbour *n, struct dst_entry *dst,
        struct hh_cache *hh;
        struct net_device *dev = dst->dev;
 
-       if (likely(neigh_hh_lookup(n, dst, protocol)))
+       if (likely(neigh_hh_lookup(n, dst)))
                return;
 
        /* slow path */
@@ -1244,7 +1245,6 @@ static void neigh_hh_init(struct neighbour *n, struct dst_entry *dst,
                return;
 
        seqlock_init(&hh->hh_lock);
-       hh->hh_type = protocol;
        atomic_set(&hh->hh_refcnt, 2);
 
        if (dev->header_ops->cache(n, hh, protocol)) {
@@ -1255,7 +1255,7 @@ static void neigh_hh_init(struct neighbour *n, struct dst_entry *dst,
        write_lock_bh(&n->lock);
 
        /* must check if another thread already did the insert */
-       if (neigh_hh_lookup(n, dst, protocol)) {
+       if (neigh_hh_lookup(n, dst)) {
                kfree(hh);
                goto end;
        }
@@ -1265,7 +1265,6 @@ static void neigh_hh_init(struct neighbour *n, struct dst_entry *dst,
        else
                hh->hh_output = n->ops->output;
 
-       hh->hh_next = n->hh;
        smp_wmb(); /* paired with smp_rmb() in neigh_hh_lookup() */
        n->hh       = hh;