net: introduce rx_handler results and logic around that

This patch allows rx_handlers to better signalize what to do next to
it's caller. That makes skb->deliver_no_wcard no longer needed.

kernel-doc for rx_handler_result is taken from Nicolas' patch.

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Reviewed-by: Nicolas de Pesloüan <nicolas.2p.debian@free.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 30 insertions, 19 deletions

diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 88e4aa9cb1f9..e2160792e1bc 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -139,21 +139,22 @@ static inline int is_link_local(const unsigned char *dest)
  * Return NULL if skb is handled
  * note: already called with rcu_read_lock
  */
-struct sk_buff *br_handle_frame(struct sk_buff *skb)
+rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
 {
         struct net_bridge_port *p;
+        struct sk_buff *skb = *pskb;
         const unsigned char *dest = eth_hdr(skb)->h_dest;
         br_should_route_hook_t *rhook;
 
         if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
-                return skb;
+                return RX_HANDLER_PASS;
 
         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
                 goto drop;
 
         skb = skb_share_check(skb, GFP_ATOMIC);
         if (!skb)
-                return NULL;
+                return RX_HANDLER_CONSUMED;
 
         p = br_port_get_rcu(skb->dev);
 
@@ -167,10 +168,12 @@ struct sk_buff *br_handle_frame(struct sk_buff *skb)
                         goto forward;
 
                 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
-                            NULL, br_handle_local_finish))
-                        return NULL;    /* frame consumed by filter */
-                else
-                        return skb;     /* continue processing */
+                            NULL, br_handle_local_finish)) {
+                        return RX_HANDLER_CONSUMED; /* consumed by filter */
+                } else {
+                        *pskb = skb;
+                        return RX_HANDLER_PASS; /* continue processing */
+                }
         }
 
 forward:
@@ -178,8 +181,10 @@ forward:
         case BR_STATE_FORWARDING:
                 rhook = rcu_dereference(br_should_route_hook);
                 if (rhook) {
-                        if ((*rhook)(skb))
-                                return skb;
+                        if ((*rhook)(skb)) {
+                                *pskb = skb;
+                                return RX_HANDLER_PASS;
+                        }
                         dest = eth_hdr(skb)->h_dest;
                 }
                 /* fall through */
@@ -194,5 +199,5 @@ forward:
 drop:
                 kfree_skb(skb);
         }
-        return NULL;
+        return RX_HANDLER_CONSUMED;
 }
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index f7afc364d777..19e2f46ed086 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -379,7 +379,7 @@ extern void br_features_recompute(struct net_bridge *br);
 
 /* br_input.c */
 extern int br_handle_frame_finish(struct sk_buff *skb);
-extern struct sk_buff *br_handle_frame(struct sk_buff *skb);
+extern rx_handler_result_t br_handle_frame(struct sk_buff **pskb);
 
 /* br_ioctl.c */
 extern int br_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
diff --git a/net/core/dev.c b/net/core/dev.c
index 0d39032e9621..0b88eba97dab 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3070,6 +3070,8 @@ out:
  *      on a failure.
  *
  *      The caller must hold the rtnl_mutex.
+ *
+ *      For a general description of rx_handler, see enum rx_handler_result.
  */
 int netdev_rx_handler_register(struct net_device *dev,
                                rx_handler_func_t *rx_handler,
@@ -3129,6 +3131,7 @@ static int __netif_receive_skb(struct sk_buff *skb)
         rx_handler_func_t *rx_handler;
         struct net_device *orig_dev;
         struct net_device *null_or_dev;
+        bool deliver_exact = false;
         int ret = NET_RX_DROP;
         __be16 type;
 
@@ -3181,18 +3184,22 @@ ncls:
 
         rx_handler = rcu_dereference(skb->dev->rx_handler);
         if (rx_handler) {
-                struct net_device *prev_dev;
-
                 if (pt_prev) {
                         ret = deliver_skb(skb, pt_prev, orig_dev);
                         pt_prev = NULL;
                 }
-                prev_dev = skb->dev;
-                skb = rx_handler(skb);
-                if (!skb)
+                switch (rx_handler(&skb)) {
+                case RX_HANDLER_CONSUMED:
                         goto out;
-                if (skb->dev != prev_dev)
+                case RX_HANDLER_ANOTHER:
                         goto another_round;
+                case RX_HANDLER_EXACT:
+                        deliver_exact = true;
+                case RX_HANDLER_PASS:
+                        break;
+                default:
+                        BUG();
+                }
         }
 
         if (vlan_tx_tag_present(skb)) {
@@ -3210,7 +3217,7 @@ ncls:
         vlan_on_bond_hook(skb);
 
         /* deliver only exact match when indicated */
-        null_or_dev = skb->deliver_no_wcard ? skb->dev : NULL;
+        null_or_dev = deliver_exact ? skb->dev : NULL;
 
         type = skb->protocol;
         list_for_each_entry_rcu(ptype,
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 1eb526a848ff..801dd08908f9 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -523,7 +523,6 @@ static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
         new->ip_summed          = old->ip_summed;
         skb_copy_queue_mapping(new, old);
         new->priority           = old->priority;
-        new->deliver_no_wcard   = old->deliver_no_wcard;
 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
         new->ipvs_property      = old->ipvs_property;
 #endif