From: Konstantin Khlebnikov <khlebnikov@openvz.org>
To: Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org
Cc: linux-arch@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH 1/4] compiler.h: introduce unused_expression() macro
Date: Wed, 25 Apr 2012 15:26:23 +0400 [thread overview]
Message-ID: <20120425112623.26927.43229.stgit@zurg> (raw)
Sometimes we want to check some expressions correctness in compile-time without
generating extra code. "(void)(e)" does not work if expression has side-effects.
This patch introduces macro unused_expression() which helps in this situation.
Cast to "long" required because sizeof does not work for bit-fields.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
---
include/linux/compiler.h | 2 ++
1 file changed, 2 insertions(+)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 923d093..46fbda3 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -310,4 +310,6 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
*/
#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
+#define unused_expression(e) ((void)(sizeof((__force long)(e))))
+
#endif /* __LINUX_COMPILER_H */
next reply other threads:[~2012-04-25 11:26 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-25 11:26 Konstantin Khlebnikov [this message]
2012-04-25 11:26 ` [PATCH 2/4] bug: completely remove code of disabled VM_BUG_ON() Konstantin Khlebnikov
2012-04-25 14:40 ` Geert Uytterhoeven
2012-04-26 22:32 ` Andrew Morton
2012-04-27 5:17 ` Geert Uytterhoeven
2012-04-27 7:07 ` Andrew Morton
2012-04-25 11:26 ` [PATCH 3/4] bug: completely remove code of disabled BUG_ON() Konstantin Khlebnikov
2012-04-25 11:26 ` Konstantin Khlebnikov
2012-04-25 11:26 ` [PATCH 4/4] bug: mark disabled BUG() as unreachable() code Konstantin Khlebnikov
2012-04-25 11:26 ` Konstantin Khlebnikov
2012-04-28 5:10 ` Konstantin Khlebnikov
2012-04-28 5:21 ` Linus Torvalds
2012-04-28 5:21 ` Linus Torvalds
2012-04-28 6:14 ` Andrew Morton
2012-04-25 11:51 ` [PATCH 1/4] compiler.h: introduce unused_expression() macro Cong Wang
2012-04-25 11:54 ` Konstantin Khlebnikov
2012-04-25 11:54 ` Konstantin Khlebnikov
2012-04-26 22:29 ` Andrew Morton
2012-04-27 9:55 ` Konstantin Khlebnikov
2012-04-27 21:53 ` Andrew Morton
2012-04-26 22:34 ` Andrew Morton
2012-04-26 22:34 ` Andrew Morton
2012-04-27 7:54 ` Konstantin Khlebnikov
2012-04-27 8:16 ` H. Peter Anvin
2012-04-28 3:50 ` Konstantin Khlebnikov
2012-04-28 3:50 ` Konstantin Khlebnikov
2012-04-28 7:06 ` [PATCH v2 1/2] bug: introduce BUILD_BUG_ON_INVALID() macro Konstantin Khlebnikov
2012-04-28 7:06 ` Konstantin Khlebnikov
2012-04-28 7:06 ` [PATCH v2 2/2] bug: completely remove code of disabled VM_BUG_ON() Konstantin Khlebnikov
2012-04-28 7:06 ` Konstantin Khlebnikov
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