From: Matthew Wilcox <mawilcox@microsoft.com>
Date: Mon, 10 Jul 2017 22:51:32 +0000 (-0700)
Subject: include/linux/bitmap.h: turn bitmap_set and bitmap_clear into memset when possible
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=2a98dc028f911a7c59c87d11d4eed6626be1605b;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

include/linux/bitmap.h: turn bitmap_set and bitmap_clear into memset when possible

Several callers have constant 'start' and an 'nbits' that is a multiple
of 8, so we can turn them into calls to memset.  We don't need the
entirety of 'start' and 'nbits' to be constant, we just need to know
whether they're divisible by 8.

Link: http://lkml.kernel.org/r/20170628153221.11322-4-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 4e0f0c8167af..c04c9d155e59 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -319,6 +319,9 @@ static __always_inline void bitmap_set(unsigned long *map, unsigned int start,
 {
 	if (__builtin_constant_p(nbits) && nbits == 1)
 		__set_bit(start, map);
+	else if (__builtin_constant_p(start & 7) && IS_ALIGNED(start, 8) &&
+		 __builtin_constant_p(nbits & 7) && IS_ALIGNED(nbits, 8))
+		memset((char *)map + start / 8, 0xff, nbits / 8);
 	else
 		__bitmap_set(map, start, nbits);
 }
@@ -328,6 +331,9 @@ static __always_inline void bitmap_clear(unsigned long *map, unsigned int start,
 {
 	if (__builtin_constant_p(nbits) && nbits == 1)
 		__clear_bit(start, map);
+	else if (__builtin_constant_p(start & 7) && IS_ALIGNED(start, 8) &&
+		 __builtin_constant_p(nbits & 7) && IS_ALIGNED(nbits, 8))
+		memset((char *)map + start / 8, 0, nbits / 8);
 	else
 		__bitmap_clear(map, start, nbits);
 }