net: sock: Change tx_queue_mapping in sock_common to unsigned short

Change 'skc_tx_queue_mapping' field in sock_common structure from
'int' to 'unsigned short' type with ~0 indicating unset and
other positive queue values being set. This will accommodate adding
a new 'unsigned short' field in sock_common in the next patch for
rx_queue_mapping.

Signed-off-by: Amritha Nambiar <amritha.nambiar@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sock.h

@@ -214,7 +214,7 @@ struct sock_common {
 		struct hlist_node	skc_node;
 		struct hlist_nulls_node skc_nulls_node;
 	};
-	int			skc_tx_queue_mapping;
+	unsigned short		skc_tx_queue_mapping;
 	union {
 		int		skc_incoming_cpu;
 		u32		skc_rcv_wnd;
@@ -1681,17 +1681,25 @@ static inline int sk_receive_skb(struct sock *sk, struct sk_buff *skb,
 
 static inline void sk_tx_queue_set(struct sock *sk, int tx_queue)
 {
+	/* sk_tx_queue_mapping accept only upto a 16-bit value */
+	if (WARN_ON_ONCE((unsigned short)tx_queue >= USHRT_MAX))
+		return;
 	sk->sk_tx_queue_mapping = tx_queue;
 }
 
+#define NO_QUEUE_MAPPING	USHRT_MAX
+
 static inline void sk_tx_queue_clear(struct sock *sk)
 {
-	sk->sk_tx_queue_mapping = -1;
+	sk->sk_tx_queue_mapping = NO_QUEUE_MAPPING;
 }
 
 static inline int sk_tx_queue_get(const struct sock *sk)
 {
-	return sk ? sk->sk_tx_queue_mapping : -1;
+	if (sk && sk->sk_tx_queue_mapping != NO_QUEUE_MAPPING)
+		return sk->sk_tx_queue_mapping;
+
+	return -1;
 }
 
 static inline void sk_set_socket(struct sock *sk, struct socket *sock)