percpu_ida.h
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#ifndef __PERCPU_IDA_H__
#define __PERCPU_IDA_H__
#include <linux/types.h>
#include <linux/bitops.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/spinlock_types.h>
#include <linux/wait.h>
#include <linux/cpumask.h>
struct percpu_ida_cpu;
struct percpu_ida {
/*
* number of tags available to be allocated, as passed to
* percpu_ida_init()
*/
unsigned nr_tags;
unsigned percpu_max_size;
unsigned percpu_batch_size;
struct percpu_ida_cpu __percpu *tag_cpu;
/*
* Bitmap of cpus that (may) have tags on their percpu freelists:
* steal_tags() uses this to decide when to steal tags, and which cpus
* to try stealing from.
*
* It's ok for a freelist to be empty when its bit is set - steal_tags()
* will just keep looking - but the bitmap _must_ be set whenever a
* percpu freelist does have tags.
*/
cpumask_t cpus_have_tags;
struct {
spinlock_t lock;
/*
* When we go to steal tags from another cpu (see steal_tags()),
* we want to pick a cpu at random. Cycling through them every
* time we steal is a bit easier and more or less equivalent:
*/
unsigned cpu_last_stolen;
/* For sleeping on allocation failure */
wait_queue_head_t wait;
/*
* Global freelist - it's a stack where nr_free points to the
* top
*/
unsigned nr_free;
unsigned *freelist;
} ____cacheline_aligned_in_smp;
};
/*
* Number of tags we move between the percpu freelist and the global freelist at
* a time
*/
#define IDA_DEFAULT_PCPU_BATCH_MOVE 32U
/* Max size of percpu freelist, */
#define IDA_DEFAULT_PCPU_SIZE ((IDA_DEFAULT_PCPU_BATCH_MOVE * 3) / 2)
int percpu_ida_alloc(struct percpu_ida *pool, int state);
void percpu_ida_free(struct percpu_ida *pool, unsigned tag);
void percpu_ida_destroy(struct percpu_ida *pool);
int __percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags,
unsigned long max_size, unsigned long batch_size);
static inline int percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags)
{
return __percpu_ida_init(pool, nr_tags, IDA_DEFAULT_PCPU_SIZE,
IDA_DEFAULT_PCPU_BATCH_MOVE);
}
typedef int (*percpu_ida_cb)(unsigned, void *);
int percpu_ida_for_each_free(struct percpu_ida *pool, percpu_ida_cb fn,
void *data);
unsigned percpu_ida_free_tags(struct percpu_ida *pool, int cpu);
#endif /* __PERCPU_IDA_H__ */