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Commit ed9f524a authored by Namhyung Kim's avatar Namhyung Kim Committed by Jiri Kosina
Browse files

ida: document IDA_BITMAP_LONGS calculation 



IDA_BITMAP_LONGS value is calculated take into account struct ida_bitmap
not to waste memory space. Comment it.

Signed-off-by: default avatarNamhyung Kim <namhyung@gmail.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent 72b43570

include/linux/idr.h

+5 −2
Original line number Diff line number Diff line
@@ -117,9 +117,12 @@ void idr_init(struct idr *idp); 
/*

 * IDA - IDR based id allocator, use when translation from id to

 * pointer isn't necessary.

 *

 * IDA_BITMAP_LONGS is calculated to be one less to accommodate

 * ida_bitmap->nr_busy so that the whole struct fits in 128 bytes.

 */

#define IDA_CHUNK_SIZE		128	/* 128 bytes per chunk */

#define IDA_BITMAP_LONGS	(128 / sizeof(long) - 1)

#define IDA_BITMAP_LONGS	(IDA_CHUNK_SIZE / sizeof(long) - 1)

#define IDA_BITMAP_BITS 	(IDA_BITMAP_LONGS * sizeof(long) * 8)



struct ida_bitmap {