3 files changed, 134 insertions, 11 deletions

diff --git a/include/linux/pid.h b/include/linux/pid.h
index 67470ad..c5fee61 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -114,11 +114,33 @@ extern struct pid *find_ge_pid(int nr);
 extern struct pid *alloc_pid(struct pid_namespace *ns);
 extern void FASTCALL(free_pid(struct pid *pid));
 
+/*
+ * 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;
 }
 
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 47cf81d..77e8cad 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1188,16 +1188,6 @@ static inline int rt_task(struct task_struct *p)
 	return rt_prio(p->prio);
 }
 
-static inline pid_t task_pgrp_nr(struct task_struct *tsk)
-{
-	return tsk->signal->pgrp;
-}
-
-static inline pid_t task_session_nr(struct task_struct *tsk)
-{
-	return tsk->signal->__session;
-}
-
 static inline void set_task_session(struct task_struct *tsk, pid_t session)
 {
 	tsk->signal->__session = session;
@@ -1223,6 +1213,104 @@ static inline struct pid *task_session(struct task_struct *task)
 	return task->group_leader->pids[PIDTYPE_SID].pid;
 }
 
+struct pid_namespace;
+
+/*
+ * the helpers to get the task's different pids as they are seen
+ * from various namespaces
+ *
+ * task_xid_nr()     : global id, i.e. the id seen from the init namespace;
+ * task_xid_vnr()    : virtual id, i.e. the id seen from the namespace the task
+ *                     belongs to. this only makes sence when called in the
+ *                     context of the task that belongs to the same namespace;
+ * task_xid_nr_ns()  : id seen from the ns specified;
+ *
+ * set_task_vxid()   : assigns a virtual id to a task;
+ *
+ * task_ppid_nr_ns() : the parent's id as seen from the namespace specified.
+ *                     the result depends on the namespace and whether the
+ *                     task in question is the namespace's init. e.g. for the
+ *                     namespace's init this will return 0 when called from
+ *                     the namespace of this init, or appropriate id otherwise.
+ *
+ *
+ * see also pid_nr() etc in include/linux/pid.h
+ */
+
+static inline pid_t task_pid_nr(struct task_struct *tsk)
+{
+	return tsk->pid;
+}
+
+static inline pid_t task_pid_nr_ns(struct task_struct *tsk,
+		struct pid_namespace *ns)
+{
+	return pid_nr_ns(task_pid(tsk), ns);
+}
+
+static inline pid_t task_pid_vnr(struct task_struct *tsk)
+{
+	return pid_vnr(task_pid(tsk));
+}
+
+
+static inline pid_t task_tgid_nr(struct task_struct *tsk)
+{
+	return tsk->tgid;
+}
+
+static inline pid_t task_tgid_nr_ns(struct task_struct *tsk,
+		struct pid_namespace *ns)
+{
+	return pid_nr_ns(task_tgid(tsk), ns);
+}
+
+static inline pid_t task_tgid_vnr(struct task_struct *tsk)
+{
+	return pid_vnr(task_tgid(tsk));
+}
+
+
+static inline pid_t task_pgrp_nr(struct task_struct *tsk)
+{
+	return tsk->signal->pgrp;
+}
+
+static inline pid_t task_pgrp_nr_ns(struct task_struct *tsk,
+		struct pid_namespace *ns)
+{
+	return pid_nr_ns(task_pgrp(tsk), ns);
+}
+
+static inline pid_t task_pgrp_vnr(struct task_struct *tsk)
+{
+	return pid_vnr(task_pgrp(tsk));
+}
+
+
+static inline pid_t task_session_nr(struct task_struct *tsk)
+{
+	return tsk->signal->__session;
+}
+
+static inline pid_t task_session_nr_ns(struct task_struct *tsk,
+		struct pid_namespace *ns)
+{
+	return pid_nr_ns(task_session(tsk), ns);
+}
+
+static inline pid_t task_session_vnr(struct task_struct *tsk)
+{
+	return pid_vnr(task_session(tsk));
+}
+
+
+static inline pid_t task_ppid_nr_ns(struct task_struct *tsk,
+		struct pid_namespace *ns)
+{
+	return pid_nr_ns(task_pid(rcu_dereference(tsk->real_parent)), ns);
+}
+
 /**
  * pid_alive - check that a task structure is not stale
  * @p: Task structure to be checked.
diff --git a/kernel/pid.c b/kernel/pid.c
index 8132a6d..6eb1484 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -376,6 +376,19 @@ struct pid *find_get_pid(pid_t nr)
 	return pid;
 }
 
+pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns)
+{
+	struct upid *upid;
+	pid_t nr = 0;
+
+	if (pid && ns->level <= pid->level) {
+		upid = &pid->numbers[ns->level];
+		if (upid->ns == ns)
+			nr = upid->nr;
+	}
+	return nr;
+}
+
 /*
  * Used by proc to find the first pid that is greater then or equal to nr.
  *