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/[email protected]
Signed-off-by: Yury Norov <[email protected]>
Cc: Amritha Nambiar <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Miklos Szeredi <[email protected]>
Cc: Rasmus Villemoes <[email protected]>
Cc: Steffen Klassert <[email protected]>
Cc: "Tobin C . Harding" <[email protected]>
Cc: Vineet Gupta <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Willem de Bruijn <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 1 insertions, 7 deletions

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)