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| author | Matthew Wilcox <mawilcox@microsoft.com> | 2017-07-11 01:51:35 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-07-11 02:32:34 +0300 |
| commit | 2c6deb01525ac11cc03c44fe31e3f45ce2cadaf9 (patch) | |
| tree | 3ec33e9980028a7d01f54772b0a7ce60db55c39c | |
| parent | 2a98dc028f911a7c59c87d11d4eed6626be1605b (diff) | |
| download | linux-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>
| -rw-r--r-- | arch/arm/boot/compressed/decompress.c | 1 | ||||
| -rw-r--r-- | include/linux/bitmap.h | 4 |
2 files changed, 2 insertions, 3 deletions
diff --git a/arch/arm/boot/compressed/decompress.c b/arch/arm/boot/compressed/decompress.c index ea7832702a8f..f3a4bedd1afc 100644 --- a/arch/arm/boot/compressed/decompress.c +++ b/arch/arm/boot/compressed/decompress.c @@ -33,6 +33,7 @@ extern void error(char *); /* Not needed, but used in some headers pulled in by decompressors */ extern char * strstr(const char * s1, const char *s2); extern size_t strlen(const char *s); +extern int memcmp(const void *cs, const void *ct, size_t count); #ifdef CONFIG_KERNEL_GZIP #include "../../../../lib/decompress_inflate.c" 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); } |