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>

1 files changed, 18 insertions, 19 deletions

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 8f7e1d8d92a..f879bb55299 100644
--- 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;