linux-kernel - [PATCH 3/7] lib: bitmap: Remove redundant code from __bitmap_shift

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Date:	Fri, 28 Nov 2014 17:01:06 +0100
From:	Rasmus Villemoes <linux@...musvillemoes.dk>
To:	Andrew Morton <akpm@...ux-foundation.org>, Jan Kara <jack@...e.cz>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH 3/7] lib: bitmap: Remove redundant code from __bitmap_shift_right

If the condition k==lim-1 is true, we must have off == 0 (otherwise, k
could never become that big). But in that case we have upper == 0 and
hence dst[k] == (src[k] & mask) >> rem. Since mask consists of a
consecutive range of bits starting from the LSB, anding dst[k] with
mask is a no-op.

Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
---
 lib/bitmap.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/lib/bitmap.c b/lib/bitmap.c
index 9250c3f..20bb314 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -134,8 +134,6 @@ void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
 			lower &= mask;
 		lower >>= rem;
 		dst[k] = lower | upper;
-		if (left && k == lim - 1)
-			dst[k] &= mask;
 	}
 	if (off)
 		memset(&dst[lim - off], 0, off*sizeof(unsigned long));
-- 
2.0.4

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