diff --git a/sys/fs/procfs/procfs.h b/sys/fs/procfs/procfs.h
index 69d88bdc2d07..b639980d95de 100644
--- a/sys/fs/procfs/procfs.h
+++ b/sys/fs/procfs/procfs.h
@@ -36,7 +36,7 @@
  *
  *	@(#)procfs.h	8.6 (Berkeley) 2/3/94
  *
- *	$Id: procfs.h,v 1.10 1996/06/17 22:43:35 dyson Exp $
+ *	$Id: procfs.h,v 1.11 1996/06/18 05:15:58 dyson Exp $
  */
 
 /*
@@ -68,6 +68,7 @@ struct pfsnode {
 	u_short		pfs_mode;	/* mode bits for stat() */
 	u_long		pfs_flags;	/* open flags */
 	u_long		pfs_fileno;	/* unique file id */
+	pid_t		pfs_lockowner;	/* pfs lock owner */
 };
 
 #define PROCFS_NOTELEN	64	/* max length of a note (/proc/$pid/note) */
diff --git a/sys/fs/procfs/procfs_subr.c b/sys/fs/procfs/procfs_subr.c
index 872a4e90c18e..7d0de04b4ec6 100644
--- a/sys/fs/procfs/procfs_subr.c
+++ b/sys/fs/procfs/procfs_subr.c
@@ -36,7 +36,7 @@
  *
  *	@(#)procfs_subr.c	8.4 (Berkeley) 1/27/94
  *
- *	$Id: procfs_subr.c,v 1.7 1996/06/17 22:43:35 dyson Exp $
+ *	$Id: procfs_subr.c,v 1.8 1996/06/18 05:15:59 dyson Exp $
  */
 
 #include <sys/param.h>
@@ -130,6 +130,7 @@ procfs_allocvp(mp, vpp, pid, pfs_type)
 	pfs->pfs_type = pfs_type;
 	pfs->pfs_vnode = *vpp;
 	pfs->pfs_flags = 0;
+	pfs->pfs_lockowner = 0;
 	pfs->pfs_fileno = PROCFS_FILENO(pid, pfs_type);
 
 	switch (pfs_type) {
@@ -230,40 +231,58 @@ procfs_rw(ap)
 	struct proc *curp = uio->uio_procp;
 	struct pfsnode *pfs = VTOPFS(vp);
 	struct proc *p;
+	int rtval;
 
 	p = PFIND(pfs->pfs_pid);
 	if (p == 0)
 		return (EINVAL);
 
+	while (pfs->pfs_lockowner) {
+		tsleep(&pfs->pfs_lockowner, PRIBIO, "pfslck", 0);
+	}
+	pfs->pfs_lockowner = curproc->p_pid;
+
 	switch (pfs->pfs_type) {
 	case Pnote:
 	case Pnotepg:
-		return (procfs_donote(curp, p, pfs, uio));
+		rtval = procfs_donote(curp, p, pfs, uio);
+		break;
 
 	case Pregs:
-		return (procfs_doregs(curp, p, pfs, uio));
+		rtval = procfs_doregs(curp, p, pfs, uio);
+		break;
 
 	case Pfpregs:
-		return (procfs_dofpregs(curp, p, pfs, uio));
+		rtval = procfs_dofpregs(curp, p, pfs, uio);
+		break;
 
 	case Pctl:
-		return (procfs_doctl(curp, p, pfs, uio));
+		rtval = procfs_doctl(curp, p, pfs, uio);
+		break;
 
 	case Pstatus:
-		return (procfs_dostatus(curp, p, pfs, uio));
+		rtval = procfs_dostatus(curp, p, pfs, uio);
+		break;
 
 	case Pmap:
-		return (procfs_domap(curp, p, pfs, uio));
+		rtval = procfs_domap(curp, p, pfs, uio);
+		break;
 
 	case Pmem:
-		return (procfs_domem(curp, p, pfs, uio));
+		rtval = procfs_domem(curp, p, pfs, uio);
+		break;
 
 	case Ptype:
-		return (procfs_dotype(curp, p, pfs, uio));
+		rtval = procfs_dotype(curp, p, pfs, uio);
+		break;
 
 	default:
-		return (EOPNOTSUPP);
+		rtval = EOPNOTSUPP;
+		break;
 	}
+	pfs->pfs_lockowner = 0;
+	wakeup(&pfs->pfs_lockowner);
+	return rtval;
 }
 
 /*
diff --git a/sys/miscfs/procfs/procfs.h b/sys/miscfs/procfs/procfs.h
index 69d88bdc2d07..b639980d95de 100644
--- a/sys/miscfs/procfs/procfs.h
+++ b/sys/miscfs/procfs/procfs.h
@@ -36,7 +36,7 @@
  *
  *	@(#)procfs.h	8.6 (Berkeley) 2/3/94
  *
- *	$Id: procfs.h,v 1.10 1996/06/17 22:43:35 dyson Exp $
+ *	$Id: procfs.h,v 1.11 1996/06/18 05:15:58 dyson Exp $
  */
 
 /*
@@ -68,6 +68,7 @@ struct pfsnode {
 	u_short		pfs_mode;	/* mode bits for stat() */
 	u_long		pfs_flags;	/* open flags */
 	u_long		pfs_fileno;	/* unique file id */
+	pid_t		pfs_lockowner;	/* pfs lock owner */
 };
 
 #define PROCFS_NOTELEN	64	/* max length of a note (/proc/$pid/note) */
diff --git a/sys/miscfs/procfs/procfs_subr.c b/sys/miscfs/procfs/procfs_subr.c
index 872a4e90c18e..7d0de04b4ec6 100644
--- a/sys/miscfs/procfs/procfs_subr.c
+++ b/sys/miscfs/procfs/procfs_subr.c
@@ -36,7 +36,7 @@
  *
  *	@(#)procfs_subr.c	8.4 (Berkeley) 1/27/94
  *
- *	$Id: procfs_subr.c,v 1.7 1996/06/17 22:43:35 dyson Exp $
+ *	$Id: procfs_subr.c,v 1.8 1996/06/18 05:15:59 dyson Exp $
  */
 
 #include <sys/param.h>
@@ -130,6 +130,7 @@ procfs_allocvp(mp, vpp, pid, pfs_type)
 	pfs->pfs_type = pfs_type;
 	pfs->pfs_vnode = *vpp;
 	pfs->pfs_flags = 0;
+	pfs->pfs_lockowner = 0;
 	pfs->pfs_fileno = PROCFS_FILENO(pid, pfs_type);
 
 	switch (pfs_type) {
@@ -230,40 +231,58 @@ procfs_rw(ap)
 	struct proc *curp = uio->uio_procp;
 	struct pfsnode *pfs = VTOPFS(vp);
 	struct proc *p;
+	int rtval;
 
 	p = PFIND(pfs->pfs_pid);
 	if (p == 0)
 		return (EINVAL);
 
+	while (pfs->pfs_lockowner) {
+		tsleep(&pfs->pfs_lockowner, PRIBIO, "pfslck", 0);
+	}
+	pfs->pfs_lockowner = curproc->p_pid;
+
 	switch (pfs->pfs_type) {
 	case Pnote:
 	case Pnotepg:
-		return (procfs_donote(curp, p, pfs, uio));
+		rtval = procfs_donote(curp, p, pfs, uio);
+		break;
 
 	case Pregs:
-		return (procfs_doregs(curp, p, pfs, uio));
+		rtval = procfs_doregs(curp, p, pfs, uio);
+		break;
 
 	case Pfpregs:
-		return (procfs_dofpregs(curp, p, pfs, uio));
+		rtval = procfs_dofpregs(curp, p, pfs, uio);
+		break;
 
 	case Pctl:
-		return (procfs_doctl(curp, p, pfs, uio));
+		rtval = procfs_doctl(curp, p, pfs, uio);
+		break;
 
 	case Pstatus:
-		return (procfs_dostatus(curp, p, pfs, uio));
+		rtval = procfs_dostatus(curp, p, pfs, uio);
+		break;
 
 	case Pmap:
-		return (procfs_domap(curp, p, pfs, uio));
+		rtval = procfs_domap(curp, p, pfs, uio);
+		break;
 
 	case Pmem:
-		return (procfs_domem(curp, p, pfs, uio));
+		rtval = procfs_domem(curp, p, pfs, uio);
+		break;
 
 	case Ptype:
-		return (procfs_dotype(curp, p, pfs, uio));
+		rtval = procfs_dotype(curp, p, pfs, uio);
+		break;
 
 	default:
-		return (EOPNOTSUPP);
+		rtval = EOPNOTSUPP;
+		break;
 	}
+	pfs->pfs_lockowner = 0;
+	wakeup(&pfs->pfs_lockowner);
+	return rtval;
 }
 
 /*