linux-kernel - [PATCH v2 06/12] tools/kernel.h: add BUILD_BUG_ON_NOT_POWER_OF

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Message-Id: <20200419015754.24456-7-sashal@kernel.org>
Date:   Sat, 18 Apr 2020 21:57:48 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     mingo@...nel.org, peterz@...radead.org
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de, jolsa@...hat.com,
        alexey.budankov@...ux.intel.com, songliubraving@...com,
        acme@...hat.com, allison@...utok.net,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH v2 06/12] tools/kernel.h: add BUILD_BUG_ON_NOT_POWER_OF_2 macro

This is now needed as a result of 12593b7467f9 ("locking/lockdep: Reduce
space occupied by stack traces").

Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 tools/include/linux/kernel.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/include/linux/kernel.h b/tools/include/linux/kernel.h
index d2b3e1cc0218e..cc3d60623ca47 100644
--- a/tools/include/linux/kernel.h
+++ b/tools/include/linux/kernel.h
@@ -38,6 +38,12 @@
 #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
 #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
 
+/* Force a compilation error if a constant expression is not a power of 2 */
+#define __BUILD_BUG_ON_NOT_POWER_OF_2(n)        \
+	BUILD_BUG_ON(((n) & ((n) - 1)) != 0)
+#define BUILD_BUG_ON_NOT_POWER_OF_2(n)                  \
+	BUILD_BUG_ON((n) == 0 || (((n) & ((n) - 1)) != 0))
+
 #ifndef max
 #define max(x, y) ({				\
 	typeof(x) _max1 = (x);			\
-- 
2.20.1