linux-kernel - [PATCH] linux/log2.h: enclose macro arg in parens

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Date:   Tue, 23 Jun 2020 10:07:39 -0700
From:   Jonathan Lemon <jonathan.lemon@...il.com>
To:     <linux-kernel@...r.kernel.org>
CC:     <netdev@...r.kernel.org>, <kernel-team@...com>
Subject: [PATCH] linux/log2.h: enclose macro arg in parens

From: Jonathan Lemon <bsd@...com>

roundup_pow_of_two uses its arg without enclosing it in parens.

A call of the form:

   roundup_pow_of_two(boolval ? PAGE_SIZE : frag_size)

resulted in an compile warning:

warning: ?: using integer constants in boolean context [-Wint-in-bool-context]
              PAGE_SIZE :
../include/linux/log2.h:176:4: note: in definition of macro ‘roundup_pow_of_two’
   (n == 1) ? 1 :  \
    ^
And the resulting code used '1' as the result of the operation.

Fixes: 312a0c170945 ("[PATCH] LOG2: Alter roundup_pow_of_two() so that it can use a ilog2() on a constant")

Signed-off-by: Jonathan Lemon <jonathan.lemon@...il.com>
---
 include/linux/log2.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/log2.h b/include/linux/log2.h
index 83a4a3ca3e8a..c619ec6eff4a 100644
--- a/include/linux/log2.h
+++ b/include/linux/log2.h
@@ -173,7 +173,7 @@ unsigned long __rounddown_pow_of_two(unsigned long n)
 #define roundup_pow_of_two(n)			\
 (						\
 	__builtin_constant_p(n) ? (		\
-		(n == 1) ? 1 :			\
+		((n) == 1) ? 1 :		\
 		(1UL << (ilog2((n) - 1) + 1))	\
 				   ) :		\
 	__roundup_pow_of_two(n)			\
-- 
2.24.1