net: split eth_mac_addr for better error handling

When we set mac address, software mac address in system and hardware mac
address all need to be updated. Current eth_mac_addr() doesn't allow
callers to implement error handling nicely.

This patch split eth_mac_addr() to prepare part and real commit part,
then we can prepare first, and try to change hardware address, then do
the real commit if hardware address is set successfully.

Signed-off-by: Stefan Hajnoczi <stefanha@gmail.com>
Signed-off-by: Amos Kong <akong@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 37 insertions, 6 deletions

diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h
index 1a43e1b4f7ad..c623861964e4 100644
--- a/include/linux/etherdevice.h
+++ b/include/linux/etherdevice.h
@@ -40,6 +40,8 @@ extern int eth_header_cache(const struct neighbour *neigh, struct hh_cache *hh,
 extern void eth_header_cache_update(struct hh_cache *hh,
                                     const struct net_device *dev,
                                     const unsigned char *haddr);
+extern int eth_prepare_mac_addr_change(struct net_device *dev, void *p);
+extern void eth_commit_mac_addr_change(struct net_device *dev, void *p);
 extern int eth_mac_addr(struct net_device *dev, void *p);
 extern int eth_change_mtu(struct net_device *dev, int new_mtu);
 extern int eth_validate_addr(struct net_device *dev);
diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
index bc39c8c8f589..a36c85eab5b4 100644
--- a/net/ethernet/eth.c
+++ b/net/ethernet/eth.c
@@ -272,6 +272,36 @@ void eth_header_cache_update(struct hh_cache *hh,
 EXPORT_SYMBOL(eth_header_cache_update);
 
 /**
+ * eth_prepare_mac_addr_change - prepare for mac change
+ * @dev: network device
+ * @p: socket address
+ */
+int eth_prepare_mac_addr_change(struct net_device *dev, void *p)
+{
+        struct sockaddr *addr = p;
+
+        if (!(dev->priv_flags & IFF_LIVE_ADDR_CHANGE) && netif_running(dev))
+                return -EBUSY;
+        if (!is_valid_ether_addr(addr->sa_data))
+                return -EADDRNOTAVAIL;
+        return 0;
+}
+EXPORT_SYMBOL(eth_prepare_mac_addr_change);
+
+/**
+ * eth_commit_mac_addr_change - commit mac change
+ * @dev: network device
+ * @p: socket address
+ */
+void eth_commit_mac_addr_change(struct net_device *dev, void *p)
+{
+        struct sockaddr *addr = p;
+
+        memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
+}
+EXPORT_SYMBOL(eth_commit_mac_addr_change);
+
+/**
  * eth_mac_addr - set new Ethernet hardware address
  * @dev: network device
  * @p: socket address
@@ -283,13 +313,12 @@ EXPORT_SYMBOL(eth_header_cache_update);
  */
 int eth_mac_addr(struct net_device *dev, void *p)
 {
-        struct sockaddr *addr = p;
+        int ret;
 
-        if (!(dev->priv_flags & IFF_LIVE_ADDR_CHANGE) && netif_running(dev))
-                return -EBUSY;
-        if (!is_valid_ether_addr(addr->sa_data))
-                return -EADDRNOTAVAIL;
-        memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
+        ret = eth_prepare_mac_addr_change(dev, p);
+        if (ret < 0)
+                return ret;
+        eth_commit_mac_addr_change(dev, p);
         return 0;
 }
 EXPORT_SYMBOL(eth_mac_addr);