netdev-linux: "Down" tap devices before setting hw addr.

On Linux, it is not possible to set the mac address on "up" tap
interfaces.  This commit temporarily "down"s the interface so the
address can be set for the netdev_linux_set_etheraddr() call.

Signed-off-by: Justin Pettit <jpettit@nicira.com>

diff --git a/lib/netdev-linux.c b/lib/netdev-linux.c
index 0460c069cc3b8ef25b452dc7784d014abc44e1c5..b81396824a94cedd1c174383431afa4f1fa56374 100644 (file)
--- a/lib/netdev-linux.c
+++ b/lib/netdev-linux.c
@@ -1028,6 +1028,7 @@ netdev_linux_set_etheraddr(struct netdev *netdev_,
     struct netdev_dev_linux *netdev_dev =
                                 netdev_dev_linux_cast(netdev_get_dev(netdev_));
     int error;
+    bool up_again = false;
 
     if (netdev_dev->cache_valid & VALID_ETHERADDR) {
         if (netdev_dev->ether_addr_error) {
@@ -1039,6 +1040,15 @@ netdev_linux_set_etheraddr(struct netdev *netdev_,
         netdev_dev->cache_valid &= ~VALID_ETHERADDR;
     }
 
+    /* Tap devices must be brought down before setting the address. */
+    if (!strcmp(netdev_get_type(netdev_), "tap")) {
+        enum netdev_flags flags;
+
+        if (!netdev_get_flags(netdev_, &flags) && (flags & NETDEV_UP)) {
+            netdev_turn_flags_off(netdev_, NETDEV_UP, false);
+            up_again = true;
+        }
+    }
     error = set_etheraddr(netdev_get_name(netdev_), mac);
     if (!error || error == ENODEV) {
         netdev_dev->ether_addr_error = error;
@@ -1048,6 +1058,10 @@ netdev_linux_set_etheraddr(struct netdev *netdev_,
         }
     }
 
+    if (up_again) {
+        netdev_turn_flags_on(netdev_, NETDEV_UP, false);
+    }
+
     return error;
 }