kthread.h

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#ifndef _LINUX_KTHREAD_H
#define _LINUX_KTHREAD_H
/* Simple interface for creating and stopping kernel threads without mess. */
#include <linux/err.h>
#include <linux/sched.h>

__printf(4, 5)
struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
                       void *data,
                       int node,
                       const char namefmt[], ...);

#define kthread_create(threadfn, data, namefmt, arg...) \
    kthread_create_on_node(threadfn, data, -1, namefmt, ##arg)


struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data),
                      void *data,
                      unsigned int cpu,
                      const char *namefmt);

#define kthread_run(threadfn, data, namefmt, ...)              \
({                                     \
    struct task_struct *__k                        \
        = kthread_create(threadfn, data, namefmt, ## __VA_ARGS__); \
    if (!IS_ERR(__k))                          \
        wake_up_process(__k);                      \
    __k;                                   \
})

void kthread_bind(struct task_struct *k, unsigned int cpu);
int kthread_stop(struct task_struct *k);
bool kthread_should_stop(void);
bool kthread_should_park(void);
bool kthread_freezable_should_stop(bool *was_frozen);
void *kthread_data(struct task_struct *k);
int kthread_park(struct task_struct *k);
void kthread_unpark(struct task_struct *k);
void kthread_parkme(void);

int kthreadd(void *unused);
extern struct task_struct *kthreadd_task;
extern int tsk_fork_get_node(struct task_struct *tsk);

/*
 * Simple work processor based on kthread.
 *
 * This provides easier way to make use of kthreads.  A kthread_work
 * can be queued and flushed using queue/flush_kthread_work()
 * respectively.  Queued kthread_works are processed by a kthread
 * running kthread_worker_fn().
 */
struct kthread_work;
typedef void (*kthread_work_func_t)(struct kthread_work *work);

struct kthread_worker {
    spinlock_t      lock;
    struct list_head    work_list;
    struct task_struct  *task;
    struct kthread_work *current_work;
};

struct kthread_work {
    struct list_head    node;
    kthread_work_func_t func;
    wait_queue_head_t   done;
    struct kthread_worker   *worker;
};

#define KTHREAD_WORKER_INIT(worker) {               \
    .lock = __SPIN_LOCK_UNLOCKED((worker).lock),            \
    .work_list = LIST_HEAD_INIT((worker).work_list),        \
    }

#define KTHREAD_WORK_INIT(work, fn) {               \
    .node = LIST_HEAD_INIT((work).node),                \
    .func = (fn),                           \
    .done = __WAIT_QUEUE_HEAD_INITIALIZER((work).done),     \
    }

#define DEFINE_KTHREAD_WORKER(worker)                   \
    struct kthread_worker worker = KTHREAD_WORKER_INIT(worker)

#define DEFINE_KTHREAD_WORK(work, fn)                   \
    struct kthread_work work = KTHREAD_WORK_INIT(work, fn)

/*
 * kthread_worker.lock and kthread_work.done need their own lockdep class
 * keys if they are defined on stack with lockdep enabled.  Use the
 * following macros when defining them on stack.
 */
#ifdef CONFIG_LOCKDEP
# define KTHREAD_WORKER_INIT_ONSTACK(worker)                \
    ({ init_kthread_worker(&worker); worker; })
# define DEFINE_KTHREAD_WORKER_ONSTACK(worker)              \
    struct kthread_worker worker = KTHREAD_WORKER_INIT_ONSTACK(worker)
# define KTHREAD_WORK_INIT_ONSTACK(work, fn)                \
    ({ init_kthread_work((&work), fn); work; })
# define DEFINE_KTHREAD_WORK_ONSTACK(work, fn)              \
    struct kthread_work work = KTHREAD_WORK_INIT_ONSTACK(work, fn)
#else
# define DEFINE_KTHREAD_WORKER_ONSTACK(worker) DEFINE_KTHREAD_WORKER(worker)
# define DEFINE_KTHREAD_WORK_ONSTACK(work, fn) DEFINE_KTHREAD_WORK(work, fn)
#endif

extern void __init_kthread_worker(struct kthread_worker *worker,
            const char *name, struct lock_class_key *key);

#define init_kthread_worker(worker)                 \
    do {                                \
        static struct lock_class_key __key;         \
        __init_kthread_worker((worker), "("#worker")->lock", &__key); \
    } while (0)

#define init_kthread_work(work, fn)                 \
    do {                                \
        memset((work), 0, sizeof(struct kthread_work));     \
        INIT_LIST_HEAD(&(work)->node);              \
        (work)->func = (fn);                    \
        init_waitqueue_head(&(work)->done);         \
    } while (0)

int kthread_worker_fn(void *worker_ptr);

bool queue_kthread_work(struct kthread_worker *worker,
            struct kthread_work *work);
void flush_kthread_work(struct kthread_work *work);
void flush_kthread_worker(struct kthread_worker *worker);

#endif /* _LINUX_KTHREAD_H */