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