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authorLai Jiangshan <laijs@cn.fujitsu.com>2014-06-06 14:37:15 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-06 16:08:13 -0700
commitdcbff5d1effbbd52be1ed9f2efb6c8d0445ad188 (patch)
tree461ec0551ce11d4fa387a7c93ed317e836697a34
parent15f3ec3f238a44181e1ae85b3cc2c27b9fece01b (diff)
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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>
-rw-r--r--include/linux/idr.h13
1 files changed, 8 insertions, 5 deletions
diff --git a/include/linux/idr.h b/include/linux/idr.h
index 6af3400b9b2f..013fd9bc4cb6 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) \
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