1 files changed, 54 insertions, 7 deletions

diff --git a/include/linux/pid.h b/include/linux/pid.h
index 1e0e4e3423a6..e29a900a8499 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -40,15 +40,28 @@ enum pid_type
  * processes.
  */
 
-struct pid
-{
-        atomic_t count;
+
+/*
+ * struct upid is used to get the id of the struct pid, as it is
+ * seen in particular namespace. Later the struct pid is found with
+ * find_pid_ns() using the int nr and struct pid_namespace *ns.
+ */
+
+struct upid {
         /* Try to keep pid_chain in the same cacheline as nr for find_pid */
         int nr;
+        struct pid_namespace *ns;
         struct hlist_node pid_chain;
+};
+
+struct pid
+{
+        atomic_t count;
         /* lists of tasks that use this pid */
         struct hlist_head tasks[PIDTYPE_MAX];
         struct rcu_head rcu;
+        int level;
+        struct upid numbers[1];
 };
 
 extern struct pid init_struct_pid;
@@ -83,26 +96,60 @@ 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));
+extern struct pid *find_vpid(int nr);
+extern struct pid *find_pid(int nr);
 
 /*
  * 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(void);
+extern struct pid *alloc_pid(struct pid_namespace *ns);
 extern void FASTCALL(free_pid(struct pid *pid));
+extern void zap_pid_ns_processes(struct pid_namespace *pid_ns);
+
+/*
+ * the helpers to get the pid's id seen from different namespaces
+ *
+ * pid_nr()    : global id, i.e. the id seen from the init namespace;
+ * pid_vnr()   : virtual id, i.e. the id seen from the namespace this pid
+ *               belongs to. this only makes sence when called in the
+ *               context of the task that belongs to the same namespace;
+ * pid_nr_ns() : id seen from the ns specified.
+ *
+ * see also task_xid_nr() etc in include/linux/sched.h
+ */
 
 static inline pid_t pid_nr(struct pid *pid)
 {
         pid_t nr = 0;
         if (pid)
-                nr = pid->nr;
+                nr = pid->numbers[0].nr;
+        return nr;
+}
+
+pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns);
+
+static inline pid_t pid_vnr(struct pid *pid)
+{
+        pid_t nr = 0;
+        if (pid)
+                nr = pid->numbers[pid->level].nr;
         return nr;
 }