[NET]: dev_mcast: add multicast list synchronization helpers
The method drivers currently use to synchronize multicast lists is not
very pretty:
- walk the multicast list
- search each entry on a copy of the previous list
- if new add to lower device
- walk the copy of the previous list
- search each entry on the current list
- if removed delete from lower device
- copy entire list
This patch adds a new field to struct dev_addr_list to store the
synchronization state and adds two helper functions for synchronization
and cleanup.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index f193aba..e5af458 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -190,6 +190,7 @@
struct dev_addr_list *next;
u8 da_addr[MAX_ADDR_LEN];
u8 da_addrlen;
+ u8 da_synced;
int da_users;
int da_gusers;
};
@@ -1103,6 +1104,8 @@
extern int dev_unicast_add(struct net_device *dev, void *addr, int alen);
extern int dev_mc_delete(struct net_device *dev, void *addr, int alen, int all);
extern int dev_mc_add(struct net_device *dev, void *addr, int alen, int newonly);
+extern int dev_mc_sync(struct net_device *to, struct net_device *from);
+extern void dev_mc_unsync(struct net_device *to, struct net_device *from);
extern void dev_mc_discard(struct net_device *dev);
extern int __dev_addr_delete(struct dev_addr_list **list, int *count, void *addr, int alen, int all);
extern int __dev_addr_add(struct dev_addr_list **list, int *count, void *addr, int alen, int newonly);
diff --git a/net/core/dev_mcast.c b/net/core/dev_mcast.c
index aa381006..235a2a8 100644
--- a/net/core/dev_mcast.c
+++ b/net/core/dev_mcast.c
@@ -102,6 +102,81 @@
return err;
}
+/**
+ * dev_mc_sync - Synchronize device's multicast list to another device
+ * @to: destination device
+ * @from: source device
+ *
+ * Add newly added addresses to the destination device and release
+ * addresses that have no users left. The source device must be
+ * locked by netif_tx_lock_bh.
+ *
+ * This function is intended to be called from the dev->set_multicast_list
+ * function of layered software devices.
+ */
+int dev_mc_sync(struct net_device *to, struct net_device *from)
+{
+ struct dev_addr_list *da;
+ int err = 0;
+
+ netif_tx_lock_bh(to);
+ for (da = from->mc_list; da != NULL; da = da->next) {
+ if (!da->da_synced) {
+ err = __dev_addr_add(&to->mc_list, &to->mc_count,
+ da->da_addr, da->da_addrlen, 0);
+ if (err < 0)
+ break;
+ da->da_synced = 1;
+ da->da_users++;
+ } else if (da->da_users == 1) {
+ __dev_addr_delete(&to->mc_list, &to->mc_count,
+ da->da_addr, da->da_addrlen, 0);
+ __dev_addr_delete(&from->mc_list, &from->mc_count,
+ da->da_addr, da->da_addrlen, 0);
+ }
+ }
+ if (!err)
+ __dev_set_rx_mode(to);
+ netif_tx_unlock_bh(to);
+
+ return err;
+}
+EXPORT_SYMBOL(dev_mc_sync);
+
+
+/**
+ * dev_mc_unsync - Remove synchronized addresses from the destination
+ * device
+ * @to: destination device
+ * @from: source device
+ *
+ * Remove all addresses that were added to the destination device by
+ * dev_mc_sync(). This function is intended to be called from the
+ * dev->stop function of layered software devices.
+ */
+void dev_mc_unsync(struct net_device *to, struct net_device *from)
+{
+ struct dev_addr_list *da;
+
+ netif_tx_lock_bh(from);
+ netif_tx_lock_bh(to);
+
+ for (da = from->mc_list; da != NULL; da = da->next) {
+ if (!da->da_synced)
+ continue;
+ __dev_addr_delete(&to->mc_list, &to->mc_count,
+ da->da_addr, da->da_addrlen, 0);
+ da->da_synced = 0;
+ __dev_addr_delete(&from->mc_list, &from->mc_count,
+ da->da_addr, da->da_addrlen, 0);
+ }
+ __dev_set_rx_mode(to);
+
+ netif_tx_unlock_bh(to);
+ netif_tx_unlock_bh(from);
+}
+EXPORT_SYMBOL(dev_mc_unsync);
+
/*
* Discard multicast list when a device is downed
*/
