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: Namhyung Kim <namhyung@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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@ -117,10 +117,13 @@ void idr_init(struct idr *idp);
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/*
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* IDA - IDR based id allocator, use when translation from id to
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* pointer isn't necessary.
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*
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* IDA_BITMAP_LONGS is calculated to be one less to accommodate
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* ida_bitmap->nr_busy so that the whole struct fits in 128 bytes.
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*/
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#define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */
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#define IDA_BITMAP_LONGS (128 / sizeof(long) - 1)
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#define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
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#define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long) - 1)
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#define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
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struct ida_bitmap {
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long nr_busy;
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