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authorMatthew Wilcox <mawilcox@microsoft.com>2017-07-11 01:51:35 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-07-11 02:32:34 +0300
commit2c6deb01525ac11cc03c44fe31e3f45ce2cadaf9 (patch)
tree3ec33e9980028a7d01f54772b0a7ce60db55c39c /include/linux/bitmap.h
parent2a98dc028f911a7c59c87d11d4eed6626be1605b (diff)
downloadlinux-2c6deb01525ac11cc03c44fe31e3f45ce2cadaf9.tar.xz
bitmap: use memcmp optimisation in more situations
Commit 7dd968163f7c ("bitmap: bitmap_equal memcmp optimization") was rather more restrictive than necessary; we can use memcmp() to implement bitmap_equal() as long as the number of bits can be proved to be a multiple of 8. And architectures other than s390 may be able to make good use of this optimisation. [arnd@arndb.de: fix build: add a memcmp() declaration] Link: http://lkml.kernel.org/r/20170630153908.3439707-1-arnd@arndb.de Link: http://lkml.kernel.org/r/20170628153221.11322-5-willy@infradead.org Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/bitmap.h')
-rw-r--r--include/linux/bitmap.h4
1 files changed, 1 insertions, 3 deletions
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index c04c9d155e59..5797ca6fdfe2 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -266,10 +266,8 @@ static inline int bitmap_equal(const unsigned long *src1,
{
if (small_const_nbits(nbits))
return !((*src1 ^ *src2) & BITMAP_LAST_WORD_MASK(nbits));
-#ifdef CONFIG_S390
- if (__builtin_constant_p(nbits) && (nbits % BITS_PER_LONG) == 0)
+ if (__builtin_constant_p(nbits & 7) && IS_ALIGNED(nbits, 8))
return !memcmp(src1, src2, nbits / 8);
-#endif
return __bitmap_equal(src1, src2, nbits);
}