include/linux/pid.h

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