idr: reorder the fields
idr_layer->layer is always accessed in read path, move it in the front.
idr_layer->bitmap is moved on the bottom. And rcu_head shares with
bitmap due to they do not be accessed at the same time.
idr->id_free/id_free_cnt/lock are free list fields, and moved to the
bottom. They will be removed in near future.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.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>
diff --git a/include/linux/idr.h b/include/linux/idr.h
index 6af3400..013fd9b 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -29,21 +29,24 @@
struct idr_layer {
int prefix; /* the ID prefix of this idr_layer */
- DECLARE_BITMAP(bitmap, IDR_SIZE); /* A zero bit means "space here" */
+ int layer; /* distance from leaf */
struct idr_layer __rcu *ary[1<<IDR_BITS];
int count; /* When zero, we can release it */
- int layer; /* distance from leaf */
- struct rcu_head rcu_head;
+ union {
+ /* A zero bit means "space here" */
+ DECLARE_BITMAP(bitmap, IDR_SIZE);
+ struct rcu_head rcu_head;
+ };
};
struct idr {
struct idr_layer __rcu *hint; /* the last layer allocated from */
struct idr_layer __rcu *top;
- struct idr_layer *id_free;
int layers; /* only valid w/o concurrent changes */
- int id_free_cnt;
int cur; /* current pos for cyclic allocation */
spinlock_t lock;
+ int id_free_cnt;
+ struct idr_layer *id_free;
};
#define IDR_INIT(name) \