[PATCH 1/7] pid: Implement access helpers for a tacks various process groups.

["Eric W. Biederman" <ebiederm@xmission.com>]

task_session returns the struct pid of a tasks session.
task_pgrp    returns the struct pid of a tasks process group.
task_tgid    returns the struct pid of a tasks thread group.
task_pid     returns the struct pid of a tasks process id.

These can be used to avoid unnecessary hash table lookups,
and to implement safe pid comparisions in the face of a
pid namespace.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 include/linux/sched.h |   20 ++++++++++++++++++++
 1 files changed, 20 insertions(+), 0 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 03d96b9..6560dd3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1042,6 +1042,26 @@ static inline pid_t process_group(struct
 	return tsk->signal->pgrp;
 }
 
+static inline struct pid *task_pid(struct task_struct *task)
+{
+	return task->pids[PIDTYPE_PID].pid;
+}
+
+static inline struct pid *task_tgid(struct task_struct *task)
+{
+	return task->group_leader->pids[PIDTYPE_PID].pid;
+}
+
+static inline struct pid *task_pgrp(struct task_struct *task)
+{
+	return task->group_leader->pids[PIDTYPE_PGID].pid;
+}
+
+static inline struct pid *task_session(struct task_struct *task)
+{
+	return task->group_leader->pids[PIDTYPE_SID].pid;
+}
+
 /**
  * pid_alive - check that a task structure is not stale
  * @p: Task structure to be checked.
-- 
1.4.2.rc3.g7e18e-dirty