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* [PATCH] ida: document IDA_BITMAP_LONGS calculation
@ 2010-09-03  9:38 Namhyung Kim
  2010-09-23 11:25 ` Jiri Kosina
  0 siblings, 1 reply; 4+ messages in thread
From: Namhyung Kim @ 2010-09-03  9:38 UTC (permalink / raw)
  To: trivial; +Cc: tj, linux-kernel

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

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
---
 include/linux/idr.h |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/include/linux/idr.h b/include/linux/idr.h
index e968db7..3f4b718 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -117,10 +117,13 @@ 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_BITS		(IDA_BITMAP_LONGS * sizeof(long) * 8)
+#define IDA_BITMAP_BITS 	(IDA_BITMAP_LONGS * sizeof(long) * 8)
 
 struct ida_bitmap {
 	long			nr_busy;
-- 
1.7.2.2


^ permalink raw reply related	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2010-09-23 11:53 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2010-09-03  9:38 [PATCH] ida: document IDA_BITMAP_LONGS calculation Namhyung Kim
2010-09-23 11:25 ` Jiri Kosina
2010-09-23 11:28   ` Tejun Heo
2010-09-23 11:52     ` Jiri Kosina

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