linux-kernel - [PATCH net v1 1/1] netfilter: nf_reject: Fix build error when CONFIG_BRIDGE

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Message-ID: <20240906145513.567781-1-andriy.shevchenko@linux.intel.com>
Date: Fri,  6 Sep 2024 17:55:13 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Pablo Neira Ayuso <pablo@...filter.org>,
	Pavel Tikhomirov <ptikhomirov@...tuozzo.com>,
	netfilter-devel@...r.kernel.org,
	coreteam@...filter.org,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	llvm@...ts.linux.dev
Cc: Jozsef Kadlecsik <kadlec@...filter.org>,
	"David S. Miller" <davem@...emloft.net>,
	David Ahern <dsahern@...nel.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Nathan Chancellor <nathan@...nel.org>,
	Nick Desaulniers <ndesaulniers@...gle.com>,
	Bill Wendling <morbo@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [PATCH net v1 1/1] netfilter: nf_reject: Fix build error when CONFIG_BRIDGE_NETFILTER=n

In some cases (CONFIG_BRIDGE_NETFILTER=n) the pointer to IP header
is set but not used, it prevents kernel builds with clang, `make W=1`
and CONFIG_WERROR=y:

ipv6: split nf_send_reset6() in smaller functions
netfilter: nf_reject_ipv4: split nf_send_reset() in smaller functions

net/ipv4/netfilter/nf_reject_ipv4.c:243:16: error: variable 'niph' set but not used [-Werror,-Wunused-but-set-variable]
  243 |         struct iphdr *niph;
      |                       ^
net/ipv6/netfilter/nf_reject_ipv6.c:286:18: error: variable 'ip6h' set but not used [-Werror,-Wunused-but-set-variable]
  286 |         struct ipv6hdr *ip6h;
      |                         ^

Fix these by marking respective variables with __maybe_unused as it
seems more complicated to address that in a better way due to ifdeffery.

Fixes: 8bfcdf6671b1 ("netfilter: nf_reject_ipv6: split nf_send_reset6() in smaller functions")
Fixes: 052b9498eea5 ("netfilter: nf_reject_ipv4: split nf_send_reset() in smaller functions")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 net/ipv4/netfilter/nf_reject_ipv4.c | 2 +-
 net/ipv6/netfilter/nf_reject_ipv6.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/netfilter/nf_reject_ipv4.c b/net/ipv4/netfilter/nf_reject_ipv4.c
index 04504b2b51df..0af42494ac66 100644
--- a/net/ipv4/netfilter/nf_reject_ipv4.c
+++ b/net/ipv4/netfilter/nf_reject_ipv4.c
@@ -240,7 +240,7 @@ void nf_send_reset(struct net *net, struct sock *sk, struct sk_buff *oldskb,
 		   int hook)
 {
 	struct sk_buff *nskb;
-	struct iphdr *niph;
+	struct iphdr *niph __maybe_unused;
 	const struct tcphdr *oth;
 	struct tcphdr _oth;
 
diff --git a/net/ipv6/netfilter/nf_reject_ipv6.c b/net/ipv6/netfilter/nf_reject_ipv6.c
index dedee264b8f6..f5ed4e779b72 100644
--- a/net/ipv6/netfilter/nf_reject_ipv6.c
+++ b/net/ipv6/netfilter/nf_reject_ipv6.c
@@ -283,7 +283,7 @@ void nf_send_reset6(struct net *net, struct sock *sk, struct sk_buff *oldskb,
 	const struct tcphdr *otcph;
 	unsigned int otcplen, hh_len;
 	const struct ipv6hdr *oip6h = ipv6_hdr(oldskb);
-	struct ipv6hdr *ip6h;
+	struct ipv6hdr *ip6h __maybe_unused;
 	struct dst_entry *dst = NULL;
 	struct flowi6 fl6;
 
-- 
2.43.0.rc1.1336.g36b5255a03ac