linux-kernel - [PATCH AUTOSEL 5.2 085/171] net/ipv4: fib_trie: Avoid cryptic ternary expressions

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Message-Id: <20190719035643.14300-85-sashal@kernel.org>
Date:   Thu, 18 Jul 2019 23:55:16 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Nathan Huckleberry <nhuck@...gle.com>,
        Matthias Kaehlcke <mka@...omium.org>,
        Douglas Anderson <dianders@...omium.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Alexander Duyck <alexander.h.duyck@...ux.intel.com>,
        "David S . Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>, linux-kbuild@...r.kernel.org,
        clang-built-linux@...glegroups.com
Subject: [PATCH AUTOSEL 5.2 085/171] net/ipv4: fib_trie: Avoid cryptic ternary expressions

From: Nathan Huckleberry <nhuck@...gle.com>

[ Upstream commit 25cec756891e8733433efea63b2254ddc93aa5cc ]

empty_child_inc/dec() use the ternary operator for conditional
operations. The conditions involve the post/pre in/decrement
operator and the operation is only performed when the condition
is *not* true. This is hard to parse for humans, use a regular
'if' construct instead and perform the in/decrement separately.

This also fixes two warnings that are emitted about the value
of the ternary expression being unused, when building the kernel
with clang + "kbuild: Remove unnecessary -Wno-unused-value"
(https://lore.kernel.org/patchwork/patch/1089869/):

CC      net/ipv4/fib_trie.o
net/ipv4/fib_trie.c:351:2: error: expression result unused [-Werror,-Wunused-value]
        ++tn_info(n)->empty_children ? : ++tn_info(n)->full_children;

Fixes: 95f60ea3e99a ("fib_trie: Add collapse() and should_collapse() to resize")
Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
Reviewed-by: Douglas Anderson <dianders@...omium.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>
Acked-by: Alexander Duyck <alexander.h.duyck@...ux.intel.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 scripts/Makefile.extrawarn | 1 -
 1 file changed, 1 deletion(-)

diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 3ab8d1a303cd..b293246e48fe 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -68,7 +68,6 @@ else
 
 ifdef CONFIG_CC_IS_CLANG
 KBUILD_CFLAGS += -Wno-initializer-overrides
-KBUILD_CFLAGS += -Wno-unused-value
 KBUILD_CFLAGS += -Wno-format
 KBUILD_CFLAGS += -Wno-sign-compare
 KBUILD_CFLAGS += -Wno-format-zero-length
-- 
2.20.1