bonding: allow carrier and link status to determine link state

In a mixed environment it may be difficult to tell if your hardware
support carrier, if it does not it can always report true. With a new
use_carrier option of 2, we can check both carrier and link status
sequentially, instead of one or the other
Signed-off-by: Debabrata Banerjee <dbanerje@akamai.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/bonding.txt

@@ -828,8 +828,8 @@ use_carrier
 	MII / ETHTOOL ioctl method to determine the link state.
 
 	A value of 1 enables the use of netif_carrier_ok(), a value of
-	0 will use the deprecated MII / ETHTOOL ioctls.  The default
-	value is 1.
+	0 will use the deprecated MII / ETHTOOL ioctls. A value of 2
+	will check both.  The default value is 1.
 
 xmit_hash_policy
 

drivers/net/bonding/bond_main.c

@@ -132,7 +132,7 @@ MODULE_PARM_DESC(downdelay, "Delay before considering link down, "
 			    "in milliseconds");
 module_param(use_carrier, int, 0);
 MODULE_PARM_DESC(use_carrier, "Use netif_carrier_ok (vs MII ioctls) in miimon; "
-			      "0 for off, 1 for on (default)");
+			      "0 for off, 1 for on (default), 2 for carrier then legacy checks");
 module_param(mode, charp, 0);
 MODULE_PARM_DESC(mode, "Mode of operation; 0 for balance-rr, "
 		       "1 for active-backup, 2 for balance-xor, "
@@ -434,12 +434,16 @@ static int bond_check_dev_link(struct bonding *bond,
 	int (*ioctl)(struct net_device *, struct ifreq *, int);
 	struct ifreq ifr;
 	struct mii_ioctl_data *mii;
+	bool carrier = true;
 
 	if (!reporting && !netif_running(slave_dev))
 		return 0;
 
 	if (bond->params.use_carrier)
-		return netif_carrier_ok(slave_dev) ? BMSR_LSTATUS : 0;
+		carrier = netif_carrier_ok(slave_dev) ? BMSR_LSTATUS : 0;
+
+	if (!carrier)
+		return carrier;
 
 	/* Try to get link status using Ethtool first. */
 	if (slave_dev->ethtool_ops->get_link)
@@ -4403,8 +4407,8 @@ static int bond_check_params(struct bond_params *params)
 		downdelay = 0;
 	}
 
-	if ((use_carrier != 0) && (use_carrier != 1)) {
-		pr_warn("Warning: use_carrier module parameter (%d), not of valid value (0/1), so it was set to 1\n",
+	if (use_carrier < 0 || use_carrier > 2) {
+		pr_warn("Warning: use_carrier module parameter (%d), not of valid value (0-2), so it was set to 1\n",
 			use_carrier);
 		use_carrier = 1;
 	}

drivers/net/bonding/bond_options.c

@@ -164,9 +164,10 @@ static const struct bond_opt_value bond_primary_reselect_tbl[] = {
 };
 
 static const struct bond_opt_value bond_use_carrier_tbl[] = {
-	{ "off", 0,  0},
-	{ "on",  1,  BOND_VALFLAG_DEFAULT},
-	{ NULL,  -1, 0}
+	{ "off",  0,  0},
+	{ "on",   1,  BOND_VALFLAG_DEFAULT},
+	{ "both", 2,  0},
+	{ NULL,  -1,  0}
 };
 
 static const struct bond_opt_value bond_all_slaves_active_tbl[] = {