From 7d930e85723d5b1b5f5e4fe6ce714ebd413c6402 Mon Sep 17 00:00:00 2001
From: christos <christos@NetBSD.org>
Date: Fri, 12 Apr 2002 17:02:33 +0000
Subject: [PATCH] Use SESSHOLD and SESSRELE consistently. Add SESSHOLD and
 SESSRELE to the t_session, so that we don't have dangling references
 [inspired by OpenBSD].

---
 sys/kern/kern_proc.c | 13 ++++---------
 sys/kern/tty.c       | 10 +++++++---
 2 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/sys/kern/kern_proc.c b/sys/kern/kern_proc.c
index 3c5c5198fa61..e0ee75f7bb84 100644
--- a/sys/kern/kern_proc.c
+++ b/sys/kern/kern_proc.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: kern_proc.c,v 1.46 2002/03/08 20:48:40 thorpej Exp $	*/
+/*	$NetBSD: kern_proc.c,v 1.47 2002/04/12 17:02:33 christos Exp $	*/
 
 /*-
  * Copyright (c) 1999 The NetBSD Foundation, Inc.
@@ -73,7 +73,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_proc.c,v 1.46 2002/03/08 20:48:40 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_proc.c,v 1.47 2002/04/12 17:02:33 christos Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -393,8 +393,8 @@ enterpgrp(p, pgid, mksess)
 				panic("enterpgrp: mksession and p != curproc");
 #endif
 		} else {
+			SESSHOLD(p->p_session);
 			pgrp->pg_session = p->p_session;
-			pgrp->pg_session->s_count++;
 		}
 		pgrp->pg_id = pgid;
 		LIST_INIT(&pgrp->pg_members);
@@ -447,12 +447,7 @@ pgdelete(pgrp)
 	    pgrp->pg_session->s_ttyp->t_pgrp == pgrp)
 		pgrp->pg_session->s_ttyp->t_pgrp = NULL;
 	LIST_REMOVE(pgrp, pg_hash);
-	if (--pgrp->pg_session->s_count == 0) {
-		/* Remove reference (if any) from tty to this session */
-		if (pgrp->pg_session->s_ttyp != NULL)
-			pgrp->pg_session->s_ttyp->t_session = NULL;
-		FREE(pgrp->pg_session, M_SESSION);
-	}
+	SESSRELE(pgrp->pg_session);
 	pool_put(&pgrp_pool, pgrp);
 }
 
diff --git a/sys/kern/tty.c b/sys/kern/tty.c
index 7c628256b603..449ecb734637 100644
--- a/sys/kern/tty.c
+++ b/sys/kern/tty.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: tty.c,v 1.135 2002/03/25 04:26:43 itohy Exp $	*/
+/*	$NetBSD: tty.c,v 1.136 2002/04/12 17:02:33 christos Exp $	*/
 
 /*-
  * Copyright (c) 1982, 1986, 1990, 1991, 1993
@@ -41,7 +41,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: tty.c,v 1.135 2002/03/25 04:26:43 itohy Exp $");
+__KERNEL_RCSID(0, "$NetBSD: tty.c,v 1.136 2002/04/12 17:02:33 christos Exp $");
 
 #include "opt_uconsole.h"
 
@@ -267,7 +267,10 @@ ttyclose(struct tty *tp)
 
 	tp->t_gen++;
 	tp->t_pgrp = NULL;
-	tp->t_session = NULL;
+	if (tp->t_session != NULL) {
+		SESSRELE(tp->t_session);
+		tp->t_session = NULL;
+	}
 	tp->t_state = 0;
 	return (0);
 }
@@ -988,6 +991,7 @@ ttioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct proc *p)
 		    ((p->p_session->s_ttyvp || tp->t_session) &&
 		     (tp->t_session != p->p_session)))
 			return (EPERM);
+		SESSHOLD(p->p_session);
 		tp->t_session = p->p_session;
 		tp->t_pgrp = p->p_pgrp;
 		p->p_session->s_ttyp = tp;