mm/sparse: refine usemap_size() a little
authorWei Yang <richard.weiyang@gmail.com>
Wed, 3 May 2017 21:53:51 +0000 (14:53 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 3 May 2017 22:52:09 +0000 (15:52 -0700)
The current implementation calculates usemap_size in two steps:
    * calculate number of bytes to cover these bits
    * calculate number of "unsigned long" to cover these bytes

It would be more clear by:
    * calculate number of "unsigned long" to cover these bits
    * multiple it with sizeof(unsigned long)

This patch refine usemap_size() a little to make it more easy to
understand.

Link: http://lkml.kernel.org/r/20170310043713.96871-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/sparse.c

index db6bf3c97ea2cd7e593922ab88840b84d67cdd88..6903c8fc308502eab4ca3570075cd6a881efa724 100644 (file)
@@ -248,10 +248,7 @@ static int __meminit sparse_init_one_section(struct mem_section *ms,
 
 unsigned long usemap_size(void)
 {
-       unsigned long size_bytes;
-       size_bytes = roundup(SECTION_BLOCKFLAGS_BITS, 8) / 8;
-       size_bytes = roundup(size_bytes, sizeof(unsigned long));
-       return size_bytes;
+       return BITS_TO_LONGS(SECTION_BLOCKFLAGS_BITS) * sizeof(unsigned long);
 }
 
 #ifdef CONFIG_MEMORY_HOTPLUG