bonding: fail_over_mac should only affect AB mode at enslave and removal processing

According to bonding.txt, the fail_over_ma should only affect active-backup mode,
but I found that the fail_over_mac could be set to active or follow in all
modes, this will cause new slave could not be set to bond's MAC address at
enslave processing and restore its own MAC address at removal processing.

The correct way to fix the problem is that we should not add restrictions when
setting options, just need to modify the bond enslave and removal processing
to check the mode in addition to fail_over_mac when setting a slave's MAC during
enslavement. The change active slave processing already only calls the fail_over_mac
function when in active-backup mode.

Thanks for Jay's suggestion.

The patch also modify the pr_warning() to pr_warn().

Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Veaceslav Falico <vfalico@redhat.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_main.c

@@ -1270,9 +1270,13 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 
 	if (slave_ops->ndo_set_mac_address == NULL) {
 		if (!bond_has_slaves(bond)) {
-			pr_warning("%s: Warning: The first slave device specified does not support setting the MAC address. Setting fail_over_mac to active.",
-				   bond_dev->name);
-			bond->params.fail_over_mac = BOND_FOM_ACTIVE;
+			pr_warn("%s: Warning: The first slave device specified does not support setting the MAC address.\n",
+				bond_dev->name);
+			if (bond->params.mode == BOND_MODE_ACTIVEBACKUP) {
+				bond->params.fail_over_mac = BOND_FOM_ACTIVE;
+				pr_warn("%s: Setting fail_over_mac to active for active-backup mode.\n",
+					bond_dev->name);
+			}
 		} else if (bond->params.fail_over_mac != BOND_FOM_ACTIVE) {
 			pr_err("%s: Error: The slave device specified does not support setting the MAC address, but fail_over_mac is not set to active.\n",
 			       bond_dev->name);
@@ -1315,7 +1319,8 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 	 */
 	memcpy(new_slave->perm_hwaddr, slave_dev->dev_addr, ETH_ALEN);
 
-	if (!bond->params.fail_over_mac) {
+	if (!bond->params.fail_over_mac ||
+	    bond->params.mode != BOND_MODE_ACTIVEBACKUP) {
 		/*
 		 * Set slave to master's mac address.  The application already
 		 * set the master's mac address to that of the first slave
@@ -1579,7 +1584,8 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 	dev_close(slave_dev);
 
 err_restore_mac:
-	if (!bond->params.fail_over_mac) {
+	if (!bond->params.fail_over_mac ||
+	    bond->params.mode != BOND_MODE_ACTIVEBACKUP) {
 		/* XXX TODO - fom follow mode needs to change master's
 		 * MAC if this slave's MAC is in use by the bond, or at
 		 * least print a warning.
@@ -1672,7 +1678,8 @@ static int __bond_release_one(struct net_device *bond_dev,
 
 	bond->current_arp_slave = NULL;
 
-	if (!all && !bond->params.fail_over_mac) {
+	if (!all && (!bond->params.fail_over_mac ||
+		     bond->params.mode != BOND_MODE_ACTIVEBACKUP)) {
 		if (ether_addr_equal_64bits(bond_dev->dev_addr, slave->perm_hwaddr) &&
 		    bond_has_slaves(bond))
 			pr_warn("%s: Warning: the permanent HWaddr of %s - %pM - is still in use by %s. Set the HWaddr of %s to a different address to avoid conflicts.\n",
@@ -1769,7 +1776,8 @@ static int __bond_release_one(struct net_device *bond_dev,
 	/* close slave before restoring its mac address */
 	dev_close(slave_dev);
 
-	if (bond->params.fail_over_mac != BOND_FOM_ACTIVE) {
+	if (bond->params.fail_over_mac != BOND_FOM_ACTIVE ||
+	    bond->params.mode != BOND_MODE_ACTIVEBACKUP) {
 		/* restore original ("permanent") mac address */
 		memcpy(addr.sa_data, slave->perm_hwaddr, ETH_ALEN);
 		addr.sa_family = slave_dev->type;