From 2d6261583be005a91e4933aa53bbd678ef98e4c4 Mon Sep 17 00:00:00 2001
From: Yury Norov <yury.norov@gmail.com>
Date: Mon, 3 Feb 2020 17:37:34 -0800
Subject: lib: rework bitmap_parse()
bitmap_parse() is ineffective and full of opaque variables and opencoded
parts. It leads to hard understanding and usage of it. This rework
includes:
- remove bitmap_shift_left() call from the cycle. Now it makes the
complexity of the algorithm as O(nbits^2). In the suggested approach
the input string is parsed in reverse direction, so no shifts needed;
- relax requirement on a single comma and no white spaces between
chunks. It is considered useful in scripting, and it aligns with
bitmap_parselist();
- split bitmap_parse() to small readable helpers;
- make an explicit calculation of the end of input line at the
beginning, so users of the bitmap_parse() won't bother doing this.
Link: http://lkml.kernel.org/r/20200102043031.30357-6-yury.norov@gmail.com
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Cc: Amritha Nambiar <amritha.nambiar@intel.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: "Tobin C . Harding" <tobin@kernel.org>
Cc: Vineet Gupta <vineet.gupta1@synopsys.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/bitmap.h | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)
(limited to 'include')
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 80ad521116d7..e52ceb1a73d3 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -186,7 +186,7 @@ bitmap_find_next_zero_area(unsigned long *map,
align_mask, 0);
}
-extern int __bitmap_parse(const char *buf, unsigned int buflen, int is_user,
+extern int bitmap_parse(const char *buf, unsigned int buflen,
unsigned long *dst, int nbits);
extern int bitmap_parse_user(const char __user *ubuf, unsigned int ulen,
unsigned long *dst, int nbits);
@@ -454,12 +454,6 @@ static inline void bitmap_replace(unsigned long *dst,
__bitmap_replace(dst, old, new, mask, nbits);
}
-static inline int bitmap_parse(const char *buf, unsigned int buflen,
- unsigned long *maskp, int nmaskbits)
-{
- return __bitmap_parse(buf, buflen, 0, maskp, nmaskbits);
-}
-
static inline void bitmap_next_clear_region(unsigned long *bitmap,
unsigned int *rs, unsigned int *re,
unsigned int end)
--
cgit