linux-kernel - [PATCH net-next] net/ipv6: resolve warning in ip6

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Date: Fri,  5 Jan 2024 09:39:20 -0800
From: Breno Leitao <leitao@...ian.org>
To: "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>
Cc: leit@...a.com,
	netdev@...r.kernel.org (open list:NETWORKING [IPv4/IPv6]),
	linux-kernel@...r.kernel.org (open list),
	llvm@...ts.linux.dev (open list:CLANG/LLVM BUILD SUPPORT:Keyword:\b(?i:clang|llvm)\b)
Subject: [PATCH net-next] net/ipv6: resolve warning in ip6_fib.c

In some configurations, the 'iter' variable in function
fib6_repair_tree() is unused, resulting the following warning when
compiled with W=1.

	net/ipv6/ip6_fib.c:1781:6: warning: variable 'iter' set but not used [-Wunused-but-set-variable]
	 1781 |         int iter = 0;
	      |             ^

Rewrite RT6_TRACE() macro to keep the variable in scope.

Clang 18 removes the trace completely from the binary when the trace is
disabled[1], so, no overhead is expected with this change.

[1] Link: https://paste.debian.net/1303162/

Signed-off-by: Breno Leitao <leitao@...ian.org>
---
 include/net/ip6_fib.h | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 9ba6413fd2e3..d2ef60ebeb25 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -30,11 +30,7 @@
 
 #define RT6_DEBUG 2
 
-#if RT6_DEBUG >= 3
-#define RT6_TRACE(x...) pr_debug(x)
-#else
-#define RT6_TRACE(x...) do { ; } while (0)
-#endif
+#define RT6_TRACE(x...) do { if (RT6_DEBUG > 3) pr_debug(x); } while (0)
 
 struct rt6_info;
 struct fib6_info;
-- 
2.39.3