macvlan: add multicast filter

Setting up IPv6 addresses on configurations with many macvlans
is not really working, as many multicast messages are dropped.

Add a multicast filter to macvlan to reduce the amount of cloned
skbs and overhead.

Successfully tested with 1024 macvlans on one ethernet device.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Ben Greear <greearb@candelatech.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 23 insertions, 0 deletions

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 7b44ebd7770e..f494da82c33f 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -29,6 +29,7 @@
 #include <linux/if_vlan.h>
 #include <linux/if_link.h>
 #include <linux/if_macvlan.h>
+#include <linux/hash.h>
 #include <net/rtnetlink.h>
 #include <net/xfrm.h>
 
@@ -126,6 +127,13 @@ static int macvlan_broadcast_one(struct sk_buff *skb,
         return vlan->receive(skb);
 }
 
+static unsigned int mc_hash(const unsigned char *addr)
+{
+        u32 val = __get_unaligned_cpu32(addr + 2);
+
+        return hash_32(val, MACVLAN_MC_FILTER_BITS);
+}
+
 static void macvlan_broadcast(struct sk_buff *skb,
                               const struct macvlan_port *port,
                               struct net_device *src,
@@ -137,6 +145,7 @@ static void macvlan_broadcast(struct sk_buff *skb,
         struct sk_buff *nskb;
         unsigned int i;
         int err;
+        unsigned int hash = mc_hash(eth->h_dest);
 
         if (skb->protocol == htons(ETH_P_PAUSE))
                 return;
@@ -146,6 +155,8 @@ static void macvlan_broadcast(struct sk_buff *skb,
                         if (vlan->dev == src || !(vlan->mode & mode))
                                 continue;
 
+                        if (!test_bit(hash, vlan->mc_filter))
+                                continue;
                         nskb = skb_clone(skb, GFP_ATOMIC);
                         err = macvlan_broadcast_one(nskb, vlan, eth,
                                          mode == MACVLAN_MODE_BRIDGE);
@@ -405,6 +416,18 @@ static void macvlan_set_mac_lists(struct net_device *dev)
 {
         struct macvlan_dev *vlan = netdev_priv(dev);
 
+        if (dev->flags & (IFF_PROMISC | IFF_ALLMULTI)) {
+                bitmap_fill(vlan->mc_filter, MACVLAN_MC_FILTER_SZ);
+        } else {
+                struct netdev_hw_addr *ha;
+                DECLARE_BITMAP(filter, MACVLAN_MC_FILTER_SZ);
+
+                bitmap_zero(filter, MACVLAN_MC_FILTER_SZ);
+                netdev_for_each_mc_addr(ha, dev) {
+                        __set_bit(mc_hash(ha->addr), filter);
+                }
+                bitmap_copy(vlan->mc_filter, filter, MACVLAN_MC_FILTER_SZ);
+        }
         dev_uc_sync(vlan->lowerdev, dev);
         dev_mc_sync(vlan->lowerdev, dev);
 }