bonding: comparing a u8 with -1 is always false

slave->duplex is a u8 type so the in bond_info_show_slave() when we
check "if (slave->duplex == -1)", it's always false.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_main.c

@@ -560,8 +560,8 @@ static int bond_update_speed_duplex(struct slave *slave)
 	u32 slave_speed;
 	int res;
 
-	slave->speed = -1;
-	slave->duplex = -1;
+	slave->speed = SPEED_UNKNOWN;
+	slave->duplex = DUPLEX_UNKNOWN;
 
 	res = __ethtool_get_settings(slave_dev, &ecmd);
 	if (res < 0)

drivers/net/bonding/bond_procfs.c

@@ -157,12 +157,12 @@ static void bond_info_show_slave(struct seq_file *seq,
 	seq_printf(seq, "\nSlave Interface: %s\n", slave->dev->name);
 	seq_printf(seq, "MII Status: %s\n",
 		   (slave->link == BOND_LINK_UP) ?  "up" : "down");
-	if (slave->speed == -1)
+	if (slave->speed == SPEED_UNKNOWN)
 		seq_printf(seq, "Speed: %s\n", "Unknown");
 	else
 		seq_printf(seq, "Speed: %d Mbps\n", slave->speed);
 
-	if (slave->duplex == -1)
+	if (slave->duplex == DUPLEX_UNKNOWN)
 		seq_printf(seq, "Duplex: %s\n", "Unknown");
 	else
 		seq_printf(seq, "Duplex: %s\n", slave->duplex ? "full" : "half");

include/linux/ethtool.h

@@ -1097,10 +1097,12 @@ struct ethtool_ops {
 #define SPEED_1000		1000
 #define SPEED_2500		2500
 #define SPEED_10000		10000
+#define SPEED_UNKNOWN		-1
 
 /* Duplex, half or full. */
 #define DUPLEX_HALF		0x00
 #define DUPLEX_FULL		0x01
+#define DUPLEX_UNKNOWN		0xff
 
 /* Which connector port. */
 #define PORT_TP			0x00