netdev - [PATCH] net: wireguard: avoid unused variable warning

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Date:   Tue,  5 May 2020 16:13:17 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     "Jason A. Donenfeld" <Jason@...c4.com>,
        "David S. Miller" <davem@...emloft.net>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Greg KH <gregkh@...uxfoundation.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, wireguard@...ts.zx2c4.com,
        clang-built-linux@...glegroups.com
Subject: [PATCH] net: wireguard: avoid unused variable warning

clang points out a harmless use of uninitialized variables that
get passed into a local function but are ignored there:

In file included from drivers/net/wireguard/ratelimiter.c:223:
drivers/net/wireguard/selftest/ratelimiter.c:173:34: error: variable 'skb6' is uninitialized when used here [-Werror,-Wuninitialized]
                ret = timings_test(skb4, hdr4, skb6, hdr6, &test_count);
                                               ^~~~
drivers/net/wireguard/selftest/ratelimiter.c:123:29: note: initialize the variable 'skb6' to silence this warning
        struct sk_buff *skb4, *skb6;
                                   ^
                                    = NULL
drivers/net/wireguard/selftest/ratelimiter.c:173:40: error: variable 'hdr6' is uninitialized when used here [-Werror,-Wuninitialized]
                ret = timings_test(skb4, hdr4, skb6, hdr6, &test_count);
                                                     ^~~~
drivers/net/wireguard/selftest/ratelimiter.c:125:22: note: initialize the variable 'hdr6' to silence this warning
        struct ipv6hdr *hdr6;
                            ^

Shut up the warning by ensuring the variables are always initialized,
and make up for the loss of readability by changing the "#if IS_ENABLED()"
checks to regular "if (IS_ENABLED())".

Fixes: e7096c131e51 ("net: WireGuard secure network tunnel")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/net/wireguard/selftest/ratelimiter.c | 32 +++++++++++---------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/drivers/net/wireguard/selftest/ratelimiter.c b/drivers/net/wireguard/selftest/ratelimiter.c
index bcd6462e4540..f408b936e224 100644
--- a/drivers/net/wireguard/selftest/ratelimiter.c
+++ b/drivers/net/wireguard/selftest/ratelimiter.c
@@ -153,19 +153,22 @@ bool __init wg_ratelimiter_selftest(void)
 	skb_reset_network_header(skb4);
 	++test;
 
-#if IS_ENABLED(CONFIG_IPV6)
-	skb6 = alloc_skb(sizeof(struct ipv6hdr), GFP_KERNEL);
-	if (unlikely(!skb6)) {
-		kfree_skb(skb4);
-		goto err_nofree;
+	if (IS_ENABLED(CONFIG_IPV6)) {
+		skb6 = alloc_skb(sizeof(struct ipv6hdr), GFP_KERNEL);
+		if (unlikely(!skb6)) {
+			kfree_skb(skb4);
+			goto err_nofree;
+		}
+		skb6->protocol = htons(ETH_P_IPV6);
+		hdr6 = (struct ipv6hdr *)skb_put(skb6, sizeof(*hdr6));
+		hdr6->saddr.in6_u.u6_addr32[0] = htonl(1212);
+		hdr6->saddr.in6_u.u6_addr32[1] = htonl(289188);
+		skb_reset_network_header(skb6);
+		++test;
+	} else {
+		skb6 = NULL;
+		hdr6 = NULL;
 	}
-	skb6->protocol = htons(ETH_P_IPV6);
-	hdr6 = (struct ipv6hdr *)skb_put(skb6, sizeof(*hdr6));
-	hdr6->saddr.in6_u.u6_addr32[0] = htonl(1212);
-	hdr6->saddr.in6_u.u6_addr32[1] = htonl(289188);
-	skb_reset_network_header(skb6);
-	++test;
-#endif
 
 	for (trials = TRIALS_BEFORE_GIVING_UP;;) {
 		int test_count = 0, ret;
@@ -206,9 +209,8 @@ bool __init wg_ratelimiter_selftest(void)
 
 err:
 	kfree_skb(skb4);
-#if IS_ENABLED(CONFIG_IPV6)
-	kfree_skb(skb6);
-#endif
+	if (IS_ENABLED(CONFIG_IPV6))
+		kfree_skb(skb6);
 err_nofree:
 	wg_ratelimiter_uninit();
 	wg_ratelimiter_uninit();
-- 
2.26.0