ipv6: clean up cork setup/release

Clean up ip6_setup_cork() and ip6_cork_release() adding a local variable
for v6_cork->opt. It's a preparation patch for further changes.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/ipv6/ip6_output.c

@@ -1354,7 +1354,7 @@ static int ip6_setup_cork(struct sock *sk, struct inet_cork_full *cork,
 {
 	struct ipv6_pinfo *np = inet6_sk(sk);
 	unsigned int mtu;
-	struct ipv6_txoptions *opt = ipc6->opt;
+	struct ipv6_txoptions *nopt, *opt = ipc6->opt;
 
 	/*
 	 * setup for corking
@@ -1363,32 +1363,28 @@ static int ip6_setup_cork(struct sock *sk, struct inet_cork_full *cork,
 		if (WARN_ON(v6_cork->opt))
 			return -EINVAL;
 
-		v6_cork->opt = kzalloc(sizeof(*opt), sk->sk_allocation);
-		if (unlikely(!v6_cork->opt))
+		nopt = v6_cork->opt = kzalloc(sizeof(*opt), sk->sk_allocation);
+		if (unlikely(!nopt))
 			return -ENOBUFS;
 
-		v6_cork->opt->tot_len = sizeof(*opt);
-		v6_cork->opt->opt_flen = opt->opt_flen;
-		v6_cork->opt->opt_nflen = opt->opt_nflen;
+		nopt->tot_len = sizeof(*opt);
+		nopt->opt_flen = opt->opt_flen;
+		nopt->opt_nflen = opt->opt_nflen;
 
-		v6_cork->opt->dst0opt = ip6_opt_dup(opt->dst0opt,
-						    sk->sk_allocation);
-		if (opt->dst0opt && !v6_cork->opt->dst0opt)
+		nopt->dst0opt = ip6_opt_dup(opt->dst0opt, sk->sk_allocation);
+		if (opt->dst0opt && !nopt->dst0opt)
 			return -ENOBUFS;
 
-		v6_cork->opt->dst1opt = ip6_opt_dup(opt->dst1opt,
-						    sk->sk_allocation);
-		if (opt->dst1opt && !v6_cork->opt->dst1opt)
+		nopt->dst1opt = ip6_opt_dup(opt->dst1opt, sk->sk_allocation);
+		if (opt->dst1opt && !nopt->dst1opt)
 			return -ENOBUFS;
 
-		v6_cork->opt->hopopt = ip6_opt_dup(opt->hopopt,
-						   sk->sk_allocation);
-		if (opt->hopopt && !v6_cork->opt->hopopt)
+		nopt->hopopt = ip6_opt_dup(opt->hopopt, sk->sk_allocation);
+		if (opt->hopopt && !nopt->hopopt)
 			return -ENOBUFS;
 
-		v6_cork->opt->srcrt = ip6_rthdr_dup(opt->srcrt,
-						    sk->sk_allocation);
-		if (opt->srcrt && !v6_cork->opt->srcrt)
+		nopt->srcrt = ip6_rthdr_dup(opt->srcrt, sk->sk_allocation);
+		if (opt->srcrt && !nopt->srcrt)
 			return -ENOBUFS;
 
 		/* need source address above miyazawa*/
@@ -1820,11 +1816,13 @@ static void ip6_cork_release(struct inet_cork_full *cork,
 			     struct inet6_cork *v6_cork)
 {
 	if (v6_cork->opt) {
-		kfree(v6_cork->opt->dst0opt);
-		kfree(v6_cork->opt->dst1opt);
-		kfree(v6_cork->opt->hopopt);
-		kfree(v6_cork->opt->srcrt);
-		kfree(v6_cork->opt);
+		struct ipv6_txoptions *opt = v6_cork->opt;
+
+		kfree(opt->dst0opt);
+		kfree(opt->dst1opt);
+		kfree(opt->hopopt);
+		kfree(opt->srcrt);
+		kfree(opt);
 		v6_cork->opt = NULL;
 	}