kitten/include/lwk/waitq.h

   1 #ifndef _LWK_WAITQ_H
   2 #define _LWK_WAITQ_H
   3
   4 #include <lwk/spinlock.h>
   5 #include <lwk/list.h>
   6 #include <lwk/task.h>
   7
   8 typedef struct waitq {
   9         spinlock_t           lock;
  10         struct list_head     waitq;
  11 } waitq_t;
  12
  13 typedef struct waitq_entry {
  14         struct task_struct * task;
  15         struct list_head     link;
  16 } waitq_entry_t;
  17
  18 #define DECLARE_WAITQ(name)                             \
  19         waitq_t name = {                                \
  20             .lock  = SPIN_LOCK_UNLOCKED,                \
  21             .waitq = { &(name).waitq, &(name).waitq }   \
  22         }
  23
  24 #define DECLARE_WAITQ_ENTRY(name, tsk)                  \
  25         waitq_entry_t name = {                          \
  26             .task  = tsk,                               \
  27             .link  = { &(name).link, &(name).link }     \
  28         }
  29
  30 extern void waitq_init(waitq_t *waitq);
  31 extern void waitq_init_entry(waitq_entry_t *entry, struct task_struct *task);
  32 extern bool waitq_active(waitq_t *waitq);
  33 extern void waitq_add_entry(waitq_t *waitq, waitq_entry_t *entry);
  34 extern void waitq_prepare_to_wait(waitq_t *waitq, waitq_entry_t *entry,
  35                                   taskstate_t state);
  36 extern void waitq_finish_wait(waitq_t *waitq, waitq_entry_t *entry);
  37 extern void waitq_wakeup(waitq_t *waitq);
  38
  39 /**
  40  * This puts the task to sleep until condition becomes true.
  41  * This must be a macro because condition is tested repeatedly, not just
  42  * when wait_event() is first called.
  43  */
  44 #define wait_event(waitq, condition)                               \
  45 do {                                                               \
  46         DECLARE_WAITQ_ENTRY(__entry, current);                     \
  47         for (;;) {                                                 \
  48                 waitq_prepare_to_wait(&waitq, &__entry,            \
  49                                       TASKSTATE_UNINTERRUPTIBLE);  \
  50                 if (condition)                                     \
  51                         break;                                     \
  52                 schedule();                                        \
  53         }                                                          \
  54         waitq_finish_wait(&waitq, &__entry);                       \
  55 } while (0)
  56
  57 #endif