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/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 9c867cf..9820f86 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -3528,7 +3528,7 @@
 	/* Kill the entire session */
 	do_each_pid_task(session, PIDTYPE_SID, p) {
 		printk(KERN_NOTICE "SAK: killed process %d"
-			" (%s): process_session(p)==tty->session\n",
+			" (%s): task_session_nr(p)==tty->session\n",
 			p->pid, p->comm);
 		send_sig(SIGKILL, p, 1);
 	} while_each_pid_task(session, PIDTYPE_SID, p);
@@ -3538,7 +3538,7 @@
 	do_each_thread(g, p) {
 		if (p->signal->tty == tty) {
 			printk(KERN_NOTICE "SAK: killed process %d"
-			    " (%s): process_session(p)==tty->session\n",
+			    " (%s): task_session_nr(p)==tty->session\n",
 			    p->pid, p->comm);
 			send_sig(SIGKILL, p, 1);
 			continue;