include/linux/kthread.h

   1 #ifndef _LINUX_KTHREAD_H
   2 #define _LINUX_KTHREAD_H
   3 /* Simple interface for creating and stopping kernel threads without mess. */
   4 #include <linux/err.h>
   5 #include <linux/sched.h>
   6
   7 /**
   8  * kthread_create: create a kthread.
   9  * @threadfn: the function to run until signal_pending(current).
  10  * @data: data ptr for @threadfn.
  11  * @namefmt: printf-style name for the thread.
  12  *
  13  * Description: This helper function creates and names a kernel
  14  * thread.  The thread will be stopped: use wake_up_process() to start
  15  * it.  See also kthread_run(), kthread_create_on_cpu().
  16  *
  17  * When woken, the thread will run @threadfn() with @data as its
  18  * argument. @threadfn can either call do_exit() directly if it is a
  19  * standalone thread for which noone will call kthread_stop(), or
  20  * return when 'kthread_should_stop()' is true (which means
  21  * kthread_stop() has been called).  The return value should be zero
  22  * or a negative error number: it will be passed to kthread_stop().
  23  *
  24  * Returns a task_struct or ERR_PTR(-ENOMEM).
  25  */
  26 struct task_struct *kthread_create(int (*threadfn)(void *data),
  27                                    void *data,
  28                                    const char namefmt[], ...);
  29
  30 /**
  31  * kthread_run: create and wake a thread.
  32  * @threadfn: the function to run until signal_pending(current).
  33  * @data: data ptr for @threadfn.
  34  * @namefmt: printf-style name for the thread.
  35  *
  36  * Description: Convenient wrapper for kthread_create() followed by
  37  * wake_up_process().  Returns the kthread, or ERR_PTR(-ENOMEM). */
  38 #define kthread_run(threadfn, data, namefmt, ...)                          \
  39 ({                                                                         \
  40         struct task_struct *__k                                            \
  41                 = kthread_create(threadfn, data, namefmt, ## __VA_ARGS__); \
  42         if (!IS_ERR(__k))                                                  \
  43                 wake_up_process(__k);                                      \
  44         __k;                                                               \
  45 })
  46
  47 /**
  48  * kthread_bind: bind a just-created kthread to a cpu.
  49  * @k: thread created by kthread_create().
  50  * @cpu: cpu (might not be online, must be possible) for @k to run on.
  51  *
  52  * Description: This function is equivalent to set_cpus_allowed(),
  53  * except that @cpu doesn't need to be online, and the thread must be
  54  * stopped (ie. just returned from kthread_create().
  55  */
  56 void kthread_bind(struct task_struct *k, unsigned int cpu);
  57
  58 /**
  59  * kthread_stop: stop a thread created by kthread_create().
  60  * @k: thread created by kthread_create().
  61  *
  62  * Sets kthread_should_stop() for @k to return true, wakes it, and
  63  * waits for it to exit.  Your threadfn() must not call do_exit()
  64  * itself if you use this function!  This can also be called after
  65  * kthread_create() instead of calling wake_up_process(): the thread
  66  * will exit without calling threadfn().
  67  *
  68  * Returns the result of threadfn(), or -EINTR if wake_up_process()
  69  * was never called. */
  70 int kthread_stop(struct task_struct *k);
  71
  72 /**
  73  * kthread_stop_sem: stop a thread created by kthread_create().
  74  * @k: thread created by kthread_create().
  75  * @s: semaphore that @k waits on while idle.
  76  *
  77  * Does essentially the same thing as kthread_stop() above, but wakes
  78  * @k by calling up(@s).
  79  *
  80  * Returns the result of threadfn(), or -EINTR if wake_up_process()
  81  * was never called. */
  82 int kthread_stop_sem(struct task_struct *k, struct semaphore *s);
  83
  84 /**
  85  * kthread_should_stop: should this kthread return now?
  86  *
  87  * When someone calls kthread_stop on your kthread, it will be woken
  88  * and this will return true.  You should then return, and your return
  89  * value will be passed through to kthread_stop().
  90  */
  91 int kthread_should_stop(void);
  92
  93 #endif /* _LINUX_KTHREAD_H */