linux-kernel - [PATCH] asm-generic: bug: add unlikely() to BUG

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Message-Id: <20180907192119.4931-1-igor.stoppa@huawei.com>
Date:   Fri,  7 Sep 2018 22:21:19 +0300
From:   Igor Stoppa <igor.stoppa@...il.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     igor.stoppa@...il.com, Igor Stoppa <igor.stoppa@...wei.com>,
        linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] asm-generic: bug: add unlikely() to BUG_ON()

Add a hint to the compiler.
If BUG_ON() is used instead of BUG(), it means that probably the
preferred outcome is to not BUG().

The optimization is disabled, in case CONFIG_PROFILE_ANNOTATED_BRANCHES
is turned on.

Signed-off-by: Igor Stoppa <igor.stoppa@...wei.com>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: linux-arch@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
---
 include/asm-generic/bug.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index 20561a60db9c..bf47584eab2a 100644
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -183,7 +183,11 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
 #endif
 
 #ifndef HAVE_ARCH_BUG_ON
+#ifdef CONFIG_PROFILE_ANNOTATED_BRANCHES
 #define BUG_ON(condition) do { if (condition) BUG(); } while (0)
+#else
+#define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0)
+#endif
 #endif
 
 #ifndef HAVE_ARCH_WARN_ON
-- 
2.17.1