idr: reorder the fields (dcbff5d1) · Commits · 戴 / test

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>

include/linux/idr.h

+8 −5

Original line number	Diff line number	Diff line
		@@ -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 */
		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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