Isolate the explicit usage of signal->pgrp

The pgrp field is not used widely around the kernel so it is now marked as
deprecated with appropriate comment.

The initialization of INIT_SIGNALS is trimmed because
a) they are set to 0 automatically;
b) gcc cannot properly initialize two anonymous (the second one
   is the one with the session) unions. In this particular case
   to make it compile we'd have to add some field initialized
   right before the .pgrp.

This is the same patch as the 1ec320afdc9552c92191d5f89fcd1ebe588334ca one
(from Cedric), but for the pgrp field.

Some progress report:

We have to deprecate the pid, tgid, session and pgrp fields on struct
task_struct and struct signal_struct.  The session and pgrp are already
deprecated.  The tgid value is close to being such - the worst known usage
in in fs/locks.c and audit code.  The pid field deprecation is mainly
blocked by numerous printk-s around the kernel that print the tsk->pid to
log.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 4 insertions, 4 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 68d2703..6838d4d 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -306,7 +306,7 @@ void __set_special_pids(pid_t session, pid_t pgrp)
 	}
 	if (task_pgrp_nr(curr) != pgrp) {
 		detach_pid(curr, PIDTYPE_PGID);
-		curr->signal->pgrp = pgrp;
+		set_task_pgrp(curr, pgrp);
 		attach_pid(curr, PIDTYPE_PGID, find_pid(pgrp));
 	}
 }
diff --git a/kernel/fork.c b/kernel/fork.c
index 240aa66..9d40367 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1293,13 +1293,13 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 			if (clone_flags & CLONE_NEWPID) {
 				p->nsproxy->pid_ns->child_reaper = p;
 				p->signal->tty = NULL;
-				p->signal->pgrp = p->pid;
+				set_task_pgrp(p, p->pid);
 				set_task_session(p, p->pid);
 				attach_pid(p, PIDTYPE_PGID, pid);
 				attach_pid(p, PIDTYPE_SID, pid);
 			} else {
 				p->signal->tty = current->signal->tty;
-				p->signal->pgrp = task_pgrp_nr(current);
+				set_task_pgrp(p, task_pgrp_nr(current));
 				set_task_session(p, task_session_nr(current));
 				attach_pid(p, PIDTYPE_PGID,
 						task_pgrp(current));
diff --git a/kernel/sys.c b/kernel/sys.c
index 2befc29..304b541 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -977,7 +977,7 @@ asmlinkage long sys_setpgid(pid_t pid, pid_t pgid)
 		detach_pid(p, PIDTYPE_PGID);
 		pid = find_vpid(pgid);
 		attach_pid(p, PIDTYPE_PGID, pid);
-		p->signal->pgrp = pid_nr(pid);
+		set_task_pgrp(p, pid_nr(pid));
 	}
 
 	err = 0;