net: Introduce sk_clone_lock() error path routine

When handling problems in cloning a socket with the sk_clone_locked()
function we need to perform several steps that were open coded in it and
its callers, so introduce a routine to avoid this duplication:
sk_free_unlock_clone().

Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/n/net-ui6laqkotycunhtmqryl9bfx@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dccp/minisocks.c

@@ -119,11 +119,7 @@ struct sock *dccp_create_openreq_child(const struct sock *sk,
 		 * Activate features: initialise CCIDs, sequence windows etc.
 		 */
 		if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
-			/* It is still raw copy of parent, so invalidate
-			 * destructor and make plain sk_free() */
-			newsk->sk_destruct = NULL;
-			bh_unlock_sock(newsk);
-			sk_free(newsk);
+			sk_free_unlock_clone(newsk);
 			return NULL;
 		}
 		dccp_init_xmit_timers(newsk);