From a09da298590e8c11ebafa37f79e0046814665237 Mon Sep 17 00:00:00 2001
From: tanimura <tanimura@FreeBSD.org>
Date: Sat, 23 Feb 2002 11:12:57 +0000
Subject: 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)
---
 sys/kern/tty_pty.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

(limited to 'sys/kern/tty_pty.c')

diff --git a/sys/kern/tty_pty.c b/sys/kern/tty_pty.c
index 6f1c0db..b3fcc8d 100644
--- a/sys/kern/tty_pty.c
+++ b/sys/kern/tty_pty.c
@@ -41,6 +41,9 @@
 #include "opt_compat.h"
 #include <sys/param.h>
 #include <sys/systm.h>
+#include <sys/lock.h>
+#include <sys/mutex.h>
+#include <sys/sx.h>
 #if defined(COMPAT_43) || defined(COMPAT_SUNOS)
 #include <sys/ioctl_compat.h>
 #endif
@@ -237,11 +240,19 @@ ptsread(dev, uio, flag)
 again:
 	if (pti->pt_flags & PF_REMOTE) {
 		while (isbackground(p, tp)) {
+			PGRPSESS_SLOCK();
+			PROC_LOCK(p);
 			if (SIGISMEMBER(p->p_sigignore, SIGTTIN) ||
 			    SIGISMEMBER(p->p_sigmask, SIGTTIN) ||
-			    p->p_pgrp->pg_jobc == 0 || p->p_flag & P_PPWAIT)
+			    p->p_pgrp->pg_jobc == 0 || p->p_flag & P_PPWAIT) {
+				PROC_UNLOCK(p);
 				return (EIO);
+			}
+			PROC_UNLOCK(p);
+			PGRP_LOCK(p->p_pgrp);
+			PGRPSESS_SUNLOCK();
 			pgsignal(p->p_pgrp, SIGTTIN, 1);
+			PGRP_UNLOCK(p->p_pgrp);
 			error = ttysleep(tp, &lbolt, TTIPRI | PCATCH, "ptsbg",
 					 0);
 			if (error)
@@ -715,7 +726,11 @@ ptyioctl(dev, cmd, data, flag, td)
 				return(EINVAL);
 			if ((tp->t_lflag&NOFLSH) == 0)
 				ttyflush(tp, FREAD|FWRITE);
-			pgsignal(tp->t_pgrp, *(unsigned int *)data, 1);
+			if (tp->t_pgrp != NULL) {
+				PGRP_LOCK(tp->t_pgrp);
+				pgsignal(tp->t_pgrp, *(unsigned int *)data, 1);
+				PGRP_UNLOCK(tp->t_pgrp);
+			}
 			if ((*(unsigned int *)data == SIGINFO) &&
 			    ((tp->t_lflag&NOKERNINFO) == 0))
 				ttyinfo(tp);
-- 
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