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   1 #ifndef _LINUX_PID_H
   2 #define _LINUX_PID_H
   3
   4 enum pid_type
   5 {
   6         PIDTYPE_PID,
   7         PIDTYPE_TGID,
   8         PIDTYPE_PGID,
   9         PIDTYPE_SID,
  10         PIDTYPE_MAX
  11 };
  12
  13 struct pid
  14 {
  15         /* Try to keep pid_chain in the same cacheline as nr for find_pid */
  16         int nr;
  17         struct hlist_node pid_chain;
  18         /* list of pids with the same nr, only one of them is in the hash */
  19         struct list_head pid_list;
  20 };
  21
  22 #define pid_task(elem, type) \
  23         list_entry(elem, struct task_struct, pids[type].pid_list)
  24
  25 /*
  26  * attach_pid() and detach_pid() must be called with the tasklist_lock
  27  * write-held.
  28  */
  29 extern int FASTCALL(attach_pid(struct task_struct *task, enum pid_type type, int nr));
  30
  31 extern void FASTCALL(detach_pid(struct task_struct *task, enum pid_type));
  32
  33 /*
  34  * look up a PID in the hash table. Must be called with the tasklist_lock
  35  * held.
  36  */
  37 extern struct pid *FASTCALL(find_pid(enum pid_type, int));
  38
  39 extern int alloc_pidmap(void);
  40 extern void FASTCALL(free_pidmap(int));
  41 extern void switch_exec_pids(struct task_struct *leader, struct task_struct *thread);
  42
  43 #define do_each_task_pid(who, type, task)                               \
  44         if ((task = find_task_by_pid_type(type, who))) {                \
  45                 prefetch((task)->pids[type].pid_list.next);             \
  46                 do {
  47
  48 #define while_each_task_pid(who, type, task)                            \
  49                 } while (task = pid_task((task)->pids[type].pid_list.next,\
  50                                                 type),                  \
  51                         prefetch((task)->pids[type].pid_list.next),     \
  52                         hlist_unhashed(&(task)->pids[type].pid_chain)); \
  53         }                                                               \
  54
  55 #endif /* _LINUX_PID_H */