net/sock: Add kernel config SOCK_RX_QUEUE_MAPPING

Use a new config SOCK_RX_QUEUE_MAPPING to compile-in the socket
RX queue field and logic, instead of the XPS config.
This breaks dependency in XPS, and allows selecting it from non-XPS
use cases, as we do in the next patch.

In addition, use the new flag to wrap the logic in sk_rx_queue_get()
and protect access to the sk_rx_queue_mapping field, while keeping
the function exposed unconditionally, just like sk_rx_queue_set()
and sk_rx_queue_clear().

Signed-off-by: Tariq Toukan <[e-mail]>
Reviewed-by: Maxim Mikityanskiy <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/sock.h

···
 		struct hlist_nulls_node skc_nulls_node;
 	};
 	unsigned short		skc_tx_queue_mapping;
-#ifdef CONFIG_XPS
+#ifdef CONFIG_SOCK_RX_QUEUE_MAPPING
 	unsigned short		skc_rx_queue_mapping;
 #endif
 	union {
···
 #define sk_nulls_node		__sk_common.skc_nulls_node
 #define sk_refcnt		__sk_common.skc_refcnt
 #define sk_tx_queue_mapping	__sk_common.skc_tx_queue_mapping
-#ifdef CONFIG_XPS
+#ifdef CONFIG_SOCK_RX_QUEUE_MAPPING
 #define sk_rx_queue_mapping	__sk_common.skc_rx_queue_mapping
 #endif
 
···
 
 static inline void sk_rx_queue_set(struct sock *sk, const struct sk_buff *skb)
 {
-#ifdef CONFIG_XPS
+#ifdef CONFIG_SOCK_RX_QUEUE_MAPPING
 	if (skb_rx_queue_recorded(skb)) {
 		u16 rx_queue = skb_get_rx_queue(skb);
 
···
 
 static inline void sk_rx_queue_clear(struct sock *sk)
 {
-#ifdef CONFIG_XPS
+#ifdef CONFIG_SOCK_RX_QUEUE_MAPPING
 	sk->sk_rx_queue_mapping = NO_QUEUE_MAPPING;
 #endif
 }
 
-#ifdef CONFIG_XPS
 static inline int sk_rx_queue_get(const struct sock *sk)
 {
+#ifdef CONFIG_SOCK_RX_QUEUE_MAPPING
 	if (sk && sk->sk_rx_queue_mapping != NO_QUEUE_MAPPING)
 		return sk->sk_rx_queue_mapping;
+#endif
 
 	return -1;
 }
-#endif
 
 static inline void sk_set_socket(struct sock *sk, struct socket *sock)
 {

net/Kconfig

···
 	select CPU_RMAP
 	default y
 
+config SOCK_RX_QUEUE_MAPPING
+	bool
+
 config XPS
 	bool
 	depends on SMP
+	select SOCK_RX_QUEUE_MAPPING
 	default y
 
 config HWBM

net/core/filter.c

···
 				       target_size));
 		break;
 	case offsetof(struct bpf_sock, rx_queue_mapping):
-#ifdef CONFIG_XPS
+#ifdef CONFIG_SOCK_RX_QUEUE_MAPPING
 		*insn++ = BPF_LDX_MEM(
 			BPF_FIELD_SIZEOF(struct sock, sk_rx_queue_mapping),
 			si->dst_reg, si->src_reg,