pid namespaces: round up the API

The set of functions process_session, task_session, process_group and
task_pgrp is confusing, as the names can be mixed with each other when looking
at the code for a long time.

The proposals are to
* equip the functions that return the integer with _nr suffix to
  represent that fact,
* and to make all functions work with task (not process) by making
  the common prefix of the same name.

For monotony the routines signal_session() and set_signal_session() are
replaced with task_session_nr() and set_task_session(), especially since they
are only used with the explicit task->signal dereference.

Signed-off-by: Pavel Emelianov <xemul@openvz.org>
Acked-by: Serge E. Hallyn <serue@us.ibm.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/exit.c b/kernel/exit.c
index cf03a52..6e6ec30 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -299,12 +299,12 @@
 {
 	struct task_struct *curr = current->group_leader;
 
-	if (process_session(curr) != session) {
+	if (task_session_nr(curr) != session) {
 		detach_pid(curr, PIDTYPE_SID);
-		set_signal_session(curr->signal, session);
+		set_task_session(curr, session);
 		attach_pid(curr, PIDTYPE_SID, find_pid(session));
 	}
-	if (process_group(curr) != pgrp) {
+	if (task_pgrp_nr(curr) != pgrp) {
 		detach_pid(curr, PIDTYPE_PGID);
 		curr->signal->pgrp = pgrp;
 		attach_pid(curr, PIDTYPE_PGID, find_pid(pgrp));
@@ -1091,10 +1091,10 @@
 		if (p->pid != pid)
 			return 0;
 	} else if (!pid) {
-		if (process_group(p) != process_group(current))
+		if (task_pgrp_nr(p) != task_pgrp_nr(current))
 			return 0;
 	} else if (pid != -1) {
-		if (process_group(p) != -pid)
+		if (task_pgrp_nr(p) != -pid)
 			return 0;
 	}