2 files changed, 43 insertions, 4 deletions

diff --git a/include/linux/pid.h b/include/linux/pid.h
index c5fee61bfb4f..0dc940f4be46 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -99,17 +99,29 @@ extern void FASTCALL(detach_pid(struct task_struct *task, enum pid_type));
 extern void FASTCALL(transfer_pid(struct task_struct *old,
                                   struct task_struct *new, enum pid_type));
 
+struct pid_namespace;
+extern struct pid_namespace init_pid_ns;
+
 /*
  * look up a PID in the hash table. Must be called with the tasklist_lock
  * or rcu_read_lock() held.
+ *
+ * find_pid_ns() finds the pid in the namespace specified
+ * find_pid() find the pid by its global id, i.e. in the init namespace
+ * find_vpid() finr the pid by its virtual id, i.e. in the current namespace
+ *
+ * see also find_task_by_pid() set in include/linux/sched.h
  */
-extern struct pid *FASTCALL(find_pid(int nr));
+extern struct pid *FASTCALL(find_pid_ns(int nr, struct pid_namespace *ns));
+
+#define find_vpid(pid)  find_pid_ns(pid, current->nsproxy->pid_ns)
+#define find_pid(pid)   find_pid_ns(pid, &init_pid_ns)
 
 /*
  * Lookup a PID in the hash table, and return with it's count elevated.
  */
 extern struct pid *find_get_pid(int nr);
-extern struct pid *find_ge_pid(int nr);
+extern struct pid *find_ge_pid(int nr, struct pid_namespace *);
 
 extern struct pid *alloc_pid(struct pid_namespace *ns);
 extern void FASTCALL(free_pid(struct pid *pid));
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 77e8cad3b17a..511cc4549f58 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1514,8 +1514,35 @@ extern struct task_struct init_task;
 
 extern struct   mm_struct init_mm;
 
-#define find_task_by_pid(nr)    find_task_by_pid_type(PIDTYPE_PID, nr)
-extern struct task_struct *find_task_by_pid_type(int type, int pid);
+extern struct pid_namespace init_pid_ns;
+
+/*
+ * find a task by one of its numerical ids
+ *
+ * find_task_by_pid_type_ns():
+ *      it is the most generic call - it finds a task by all id,
+ *      type and namespace specified
+ * find_task_by_pid_ns():
+ *      finds a task by its pid in the specified namespace
+ * find_task_by_pid_type():
+ *      finds a task by its global id with the specified type, e.g.
+ *      by global session id
+ * find_task_by_pid():
+ *      finds a task by its global pid
+ *
+ * see also find_pid() etc in include/linux/pid.h
+ */
+
+extern struct task_struct *find_task_by_pid_type_ns(int type, int pid,
+                struct pid_namespace *ns);
+
+#define find_task_by_pid_ns(nr, ns)     \
+                find_task_by_pid_type_ns(PIDTYPE_PID, nr, ns)
+#define find_task_by_pid_type(type, nr) \
+                find_task_by_pid_type_ns(type, nr, &init_pid_ns)
+#define find_task_by_pid(nr)            \
+                find_task_by_pid_type(PIDTYPE_PID, nr)
+
 extern void __set_special_pids(pid_t session, pid_t pgrp);
 
 /* per-UID process charging. */