1 #ifndef __PERCPU_IDA_H__
2 #define __PERCPU_IDA_H__
3
4 #include <linux/types.h>
5 #include <linux/bitops.h>
6 #include <linux/init.h>
7 #include <linux/sched.h>
8 #include <linux/spinlock_types.h>
9 #include <linux/wait.h>
10 #include <linux/cpumask.h>
11
12 struct percpu_ida_cpu;
13
14 struct percpu_ida {
15 /*
16 * number of tags available to be allocated, as passed to
17 * percpu_ida_init()
18 */
19 unsigned nr_tags;
20 unsigned percpu_max_size;
21 unsigned percpu_batch_size;
22
23 struct percpu_ida_cpu __percpu *tag_cpu;
24
25 /*
26 * Bitmap of cpus that (may) have tags on their percpu freelists:
27 * steal_tags() uses this to decide when to steal tags, and which cpus
28 * to try stealing from.
29 *
30 * It's ok for a freelist to be empty when its bit is set - steal_tags()
31 * will just keep looking - but the bitmap _must_ be set whenever a
32 * percpu freelist does have tags.
33 */
34 cpumask_t cpus_have_tags;
35
36 struct {
37 spinlock_t lock;
38 /*
39 * When we go to steal tags from another cpu (see steal_tags()),
40 * we want to pick a cpu at random. Cycling through them every
41 * time we steal is a bit easier and more or less equivalent:
42 */
43 unsigned cpu_last_stolen;
44
45 /* For sleeping on allocation failure */
46 wait_queue_head_t wait;
47
48 /*
49 * Global freelist - it's a stack where nr_free points to the
50 * top
51 */
52 unsigned nr_free;
53 unsigned *freelist;
54 } ____cacheline_aligned_in_smp;
55 };
56
57 /*
58 * Number of tags we move between the percpu freelist and the global freelist at
59 * a time
60 */
61 #define IDA_DEFAULT_PCPU_BATCH_MOVE 32U
62 /* Max size of percpu freelist, */
63 #define IDA_DEFAULT_PCPU_SIZE ((IDA_DEFAULT_PCPU_BATCH_MOVE * 3) / 2)
64
65 int percpu_ida_alloc(struct percpu_ida *pool, int state);
66 void percpu_ida_free(struct percpu_ida *pool, unsigned tag);
67
68 void percpu_ida_destroy(struct percpu_ida *pool);
69 int __percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags,
70 unsigned long max_size, unsigned long batch_size);
percpu_ida_init(struct percpu_ida * pool,unsigned long nr_tags)71 static inline int percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags)
72 {
73 return __percpu_ida_init(pool, nr_tags, IDA_DEFAULT_PCPU_SIZE,
74 IDA_DEFAULT_PCPU_BATCH_MOVE);
75 }
76
77 typedef int (*percpu_ida_cb)(unsigned, void *);
78 int percpu_ida_for_each_free(struct percpu_ida *pool, percpu_ida_cb fn,
79 void *data);
80
81 unsigned percpu_ida_free_tags(struct percpu_ida *pool, int cpu);
82 #endif /* __PERCPU_IDA_H__ */
83