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Date: Thu, 3 Dec 2015 10:30:16 -0500
From: Sasha Levin <sasha.levin@...cle.com>
To: torvalds@...ux-foundation.org
Cc: linux-kernel@...r.kernel.org, Sasha Levin <sasha.levin@...cle.com>
Subject: [PATCH] linux/log2.h: Fix roundup_pow_of_two(0)
Passing 0 to roundup_pow_of_two would lead to wrapping around and trying to
find the last set bit on (unsigned long)(-1), which is obviously wrong.
Instead, deal with this case by rounding it up to the closest power of two
(2 ** 0).
Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
---
include/linux/log2.h | 3 +++
1 file changed, 3 insertions(+)
diff --git a/include/linux/log2.h b/include/linux/log2.h
index fd7ff3d..b6bdf0c 100644
--- a/include/linux/log2.h
+++ b/include/linux/log2.h
@@ -60,6 +60,9 @@ bool is_power_of_2(unsigned long n)
static inline __attribute__((const))
unsigned long __roundup_pow_of_two(unsigned long n)
{
+ if (n == 0)
+ return 1UL << 0;
+
return 1UL << fls_long(n - 1);
}
--
1.7.10.4
--
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