net: move sk_validate_xmit_skb() to net/core/dev.c

Move definition of sk_validate_xmit_skb() from net/core/sock.c to
net/core/dev.c.

This change is in preparation of the next patch, where
sk_validate_xmit_skb() will need to cast sk to a tcp_timewait_sock *,
and access member fields. Including linux/tcp.h from linux/sock.h
creates a circular dependency, and dev.c is the only current call site
of this function.

Reviewed-by: Willem de Bruijn <[e-mail]>
Signed-off-by: Daniel Zahka <[e-mail]>
Reviewed-by: Eric Dumazet <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Paolo Abeni <[e-mail]>

include/net/sock.h

···
 	return sk && sk_fullsock(sk) && sock_flag(sk, SOCK_WIFI_STATUS);
 }
 
-/* Checks if this SKB belongs to an HW offloaded socket
- * and whether any SW fallbacks are required based on dev.
- * Check decrypted mark in case skb_orphan() cleared socket.
- */
-static inline struct sk_buff *sk_validate_xmit_skb(struct sk_buff *skb,
-						   struct net_device *dev)
-{
-#ifdef CONFIG_SOCK_VALIDATE_XMIT
-	struct sock *sk = skb->sk;
-
-	if (sk && sk_fullsock(sk) && sk->sk_validate_xmit_skb) {
-		skb = sk->sk_validate_xmit_skb(sk, dev, skb);
-	} else if (unlikely(skb_is_decrypted(skb))) {
-		pr_warn_ratelimited("unencrypted skb with no associated socket - dropping\n");
-		kfree_skb(skb);
-		skb = NULL;
-	}
-#endif
-
-	return skb;
-}
-
 /* This helper checks if a socket is a LISTEN or NEW_SYN_RECV
  * SYNACK messages can be attached to either ones (depending on SYNCOOKIE)
  */

net/core/dev.c

···
 }
 EXPORT_SYMBOL(skb_csum_hwoffload_help);
 
+/* Checks if this SKB belongs to an HW offloaded socket
+ * and whether any SW fallbacks are required based on dev.
+ * Check decrypted mark in case skb_orphan() cleared socket.
+ */
+static struct sk_buff *sk_validate_xmit_skb(struct sk_buff *skb,
+					    struct net_device *dev)
+{
+#ifdef CONFIG_SOCK_VALIDATE_XMIT
+	struct sock *sk = skb->sk;
+
+	if (sk && sk_fullsock(sk) && sk->sk_validate_xmit_skb) {
+		skb = sk->sk_validate_xmit_skb(sk, dev, skb);
+	} else if (unlikely(skb_is_decrypted(skb))) {
+		pr_warn_ratelimited("unencrypted skb with no associated socket - dropping\n");
+		kfree_skb(skb);
+		skb = NULL;
+	}
+#endif
+
+	return skb;
+}
+
 static struct sk_buff *validate_xmit_unreadable_skb(struct sk_buff *skb,
 						    struct net_device *dev)
 {