Lock struct pgrp, session and sigio.

New locks are:

- pgrpsess_lock which locks the whole pgrps and sessions,
- pg_mtx which protects the pgrp members, and
- s_mtx which protects the session members.

Please refer to sys/proc.h for the coverage of these locks.

Changes on the pgrp/session interface:

- pgfind() needs the pgrpsess_lock held.

- The caller of enterpgrp() is responsible to allocate a new pgrp and
  session.

- Call enterthispgrp() in order to enter an existing pgrp.

- pgsignal() requires a pgrp lock held.

Reviewed by:	jhb, alfred
Tested on:	cvsup.jp.FreeBSD.org
		(which is a quad-CPU machine running -current)

1 files changed, 47 insertions, 9 deletions

diff --git a/sys/kern/tty_tty.c b/sys/kern/tty_tty.c
index 1c6635c..931da01 100644
--- a/sys/kern/tty_tty.c
+++ b/sys/kern/tty_tty.c
@@ -43,6 +43,8 @@
 #include <sys/conf.h>
 #include <sys/kernel.h>
 #include <sys/lock.h>
+#include <sys/mutex.h>
+#include <sys/sx.h>
 #include <sys/proc.h>
 #include <sys/ttycom.h>
 #include <sys/vnode.h>
@@ -80,9 +82,15 @@ cttyopen(dev, flag, mode, td)
 	int flag, mode;
 	struct thread *td;
 {
-	struct vnode *ttyvp = cttyvp(td);
+	struct vnode *ttyvp;
 	int error;
 
+	PROC_LOCK(td->td_proc);
+	SESS_LOCK(td->td_proc->p_session);
+	ttyvp = cttyvp(td);
+	SESS_UNLOCK(td->td_proc->p_session);
+	PROC_UNLOCK(td->td_proc);
+
 	if (ttyvp == NULL)
 		return (ENXIO);
 	vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY, td);
@@ -99,9 +107,15 @@ cttyread(dev, uio, flag)
 	int flag;
 {
 	struct thread *td = uio->uio_td;
-	register struct vnode *ttyvp = cttyvp(td);
+	register struct vnode *ttyvp;
 	int error;
 
+	PROC_LOCK(td->td_proc);
+	SESS_LOCK(td->td_proc->p_session);
+	ttyvp = cttyvp(td);
+	SESS_UNLOCK(td->td_proc->p_session);
+	PROC_UNLOCK(td->td_proc);
+
 	if (ttyvp == NULL)
 		return (EIO);
 	vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY, td);
@@ -118,10 +132,16 @@ cttywrite(dev, uio, flag)
 	int flag;
 {
 	struct thread *td = uio->uio_td;
-	struct vnode *ttyvp = cttyvp(uio->uio_td);
+	struct vnode *ttyvp;
 	struct mount *mp;
 	int error;
 
+	PROC_LOCK(td->td_proc);
+	SESS_LOCK(td->td_proc->p_session);
+	ttyvp = cttyvp(td);
+	SESS_UNLOCK(td->td_proc->p_session);
+	PROC_UNLOCK(td->td_proc);
+
 	if (ttyvp == NULL)
 		return (EIO);
 	mp = NULL;
@@ -144,18 +164,30 @@ cttyioctl(dev, cmd, addr, flag, td)
 	int flag;
 	struct thread *td;
 {
-	struct vnode *ttyvp = cttyvp(td);
+	struct vnode *ttyvp;
+	int error;
+
+	PROC_LOCK(td->td_proc);
+	SESS_LOCK(td->td_proc->p_session);
+	ttyvp = cttyvp(td);
+	SESS_UNLOCK(td->td_proc->p_session);
+	PROC_UNLOCK(td->td_proc);
 
 	if (ttyvp == NULL)
 		return (EIO);
 	if (cmd == TIOCSCTTY)  /* don't allow controlling tty to be set    */
 		return EINVAL; /* to controlling tty -- infinite recursion */
 	if (cmd == TIOCNOTTY) {
-		if (!SESS_LEADER(td->td_proc)) {
+		PROC_LOCK(td->td_proc);
+		SESS_LOCK(td->td_proc->p_session);
+		error = 0;
+		if (!SESS_LEADER(td->td_proc))
 			td->td_proc->p_flag &= ~P_CONTROLT;
-			return (0);
-		} else
-			return (EINVAL);
+		else
+			error = EINVAL;
+		SESS_UNLOCK(td->td_proc->p_session);
+		PROC_UNLOCK(td->td_proc);
+		return (error);
 	}
 	return (VOP_IOCTL(ttyvp, cmd, addr, flag, NOCRED, td));
 }
@@ -167,7 +199,13 @@ cttypoll(dev, events, td)
 	int events;
 	struct thread *td;
 {
-	struct vnode *ttyvp = cttyvp(td);
+	struct vnode *ttyvp;
+
+	PROC_LOCK(td->td_proc);
+	SESS_LOCK(td->td_proc->p_session);
+	ttyvp = cttyvp(td);
+	SESS_UNLOCK(td->td_proc->p_session);
+	PROC_UNLOCK(td->td_proc);
 
 	if (ttyvp == NULL)
 		/* try operation to get EOF/failure */