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>

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 7b44ebd..f494da8 100644 (file)
--- 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);
 }

diff --git a/include/linux/if_macvlan.h b/include/linux/if_macvlan.h
index f65e8d2..84dde1d 100644 (file)
--- a/include/linux/if_macvlan.h
+++ b/include/linux/if_macvlan.h
@@ -52,6 +52,9 @@ struct macvlan_pcpu_stats {
  */
 #define MAX_MACVTAP_QUEUES     (NR_CPUS < 16 ? NR_CPUS : 16)
 
+#define MACVLAN_MC_FILTER_BITS 8
+#define MACVLAN_MC_FILTER_SZ   (1 << MACVLAN_MC_FILTER_BITS)
+
 struct macvlan_dev {
        struct net_device       *dev;
        struct list_head        list;
@@ -59,6 +62,9 @@ struct macvlan_dev {
        struct macvlan_port     *port;
        struct net_device       *lowerdev;
        struct macvlan_pcpu_stats __percpu *pcpu_stats;
+
+       DECLARE_BITMAP(mc_filter, MACVLAN_MC_FILTER_SZ);
+
        enum macvlan_mode       mode;
        u16                     flags;
        int (*receive)(struct sk_buff *skb);