diff --git a/sys/compat/linux/linux_misc.c b/sys/compat/linux/linux_misc.c
index da1293cb86a5..76684546ba99 100644
--- a/sys/compat/linux/linux_misc.c
+++ b/sys/compat/linux/linux_misc.c
@@ -25,7 +25,7 @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
- *  $Id: linux_misc.c,v 1.51 1999/01/06 23:05:38 julian Exp $
+ *  $Id: linux_misc.c,v 1.52 1999/01/26 02:38:10 julian Exp $
  */
 
 #include <sys/param.h>
@@ -554,7 +554,7 @@ linux_fork(struct proc *p, struct linux_fork_args *args)
 #ifdef DEBUG
     printf("Linux-emul(%d): fork()\n", p->p_pid);
 #endif
-    if (error = fork(p, (struct fork_args *)args))
+    if ((error = fork(p, (struct fork_args *)args)) != 0)
 	return error;
     if (p->p_retval[1] == 1)
 	p->p_retval[0] = 0;
@@ -589,6 +589,7 @@ linux_clone(struct proc *p, struct linux_clone_args *args)
 
     if (!args->stack)
         return (EINVAL);
+
     exit_signal = args->flags & 0x000000ff;
     if (exit_signal >= LINUX_NSIG)
 	return EINVAL;
@@ -608,7 +609,7 @@ linux_clone(struct proc *p, struct linux_clone_args *args)
     start = 0;
 
     rf_args.flags = ff;
-    if (error = rfork(p, &rf_args))
+    if ((error = rfork(p, &rf_args)) != 0)
 	return error;
 
     p2 = pfind(p->p_retval[0]);
@@ -936,6 +937,8 @@ linux_utime(struct proc *p, struct linux_utime_args *args)
     return utimes(p, &bsdutimes);
 }
 
+#define __WCLONE 0x80000000
+
 int
 linux_waitpid(struct proc *p, struct linux_waitpid_args *args)
 {
@@ -953,20 +956,17 @@ linux_waitpid(struct proc *p, struct linux_waitpid_args *args)
 #endif
     tmp.pid = args->pid;
     tmp.status = args->status;
-    /* This filters out the linux option _WCLONE.  I don't
-     * think we need it, but I could be wrong.  If we need
-     * it, we need to fix wait4, since it will give us an
-     * error return of EINVAL if we pass in _WCLONE, and
-     * of course, it won't do anything with it.
-     */
     tmp.options = (args->options & (WNOHANG | WUNTRACED));
+    /* WLINUXCLONE should be equal to __WCLONE, but we make sure */
+    if (args->options & __WCLONE)
+	tmp.options |= WLINUXCLONE;
     tmp.rusage = NULL;
 
-    if (error = wait4(p, &tmp))
+    if ((error = wait4(p, &tmp)) != 0)
 	return error;
 
     if (args->status) {
-	if (error = copyin(args->status, &tmpstat, sizeof(int)))
+	if ((error = copyin(args->status, &tmpstat, sizeof(int))) != 0)
 	    return error;
 	if (WIFSIGNALED(tmpstat))
 	    tmpstat = (tmpstat & 0xffffff80) |
@@ -997,22 +997,19 @@ linux_wait4(struct proc *p, struct linux_wait4_args *args)
 #endif
     tmp.pid = args->pid;
     tmp.status = args->status;
-    /* This filters out the linux option _WCLONE.  I don't
-     * think we need it, but I could be wrong.  If we need
-     * it, we need to fix wait4, since it will give us an
-     * error return of EINVAL if we pass in _WCLONE, and
-     * of course, it won't do anything with it.
-     */
     tmp.options = (args->options & (WNOHANG | WUNTRACED));
+    /* WLINUXCLONE should be equal to __WCLONE, but we make sure */
+    if (args->options & __WCLONE)
+	tmp.options |= WLINUXCLONE;
     tmp.rusage = args->rusage;
 
-    if (error = wait4(p, &tmp))
+    if ((error = wait4(p, &tmp)) != 0)
 	return error;
 
     p->p_siglist &= ~sigmask(SIGCHLD);
 
     if (args->status) {
-	if (error = copyin(args->status, &tmpstat, sizeof(int)))
+	if ((error = copyin(args->status, &tmpstat, sizeof(int))) != 0)
 	    return error;
 	if (WIFSIGNALED(tmpstat))
 	    tmpstat = (tmpstat & 0xffffff80) |
diff --git a/sys/i386/linux/linux_misc.c b/sys/i386/linux/linux_misc.c
index da1293cb86a5..76684546ba99 100644
--- a/sys/i386/linux/linux_misc.c
+++ b/sys/i386/linux/linux_misc.c
@@ -25,7 +25,7 @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
- *  $Id: linux_misc.c,v 1.51 1999/01/06 23:05:38 julian Exp $
+ *  $Id: linux_misc.c,v 1.52 1999/01/26 02:38:10 julian Exp $
  */
 
 #include <sys/param.h>
@@ -554,7 +554,7 @@ linux_fork(struct proc *p, struct linux_fork_args *args)
 #ifdef DEBUG
     printf("Linux-emul(%d): fork()\n", p->p_pid);
 #endif
-    if (error = fork(p, (struct fork_args *)args))
+    if ((error = fork(p, (struct fork_args *)args)) != 0)
 	return error;
     if (p->p_retval[1] == 1)
 	p->p_retval[0] = 0;
@@ -589,6 +589,7 @@ linux_clone(struct proc *p, struct linux_clone_args *args)
 
     if (!args->stack)
         return (EINVAL);
+
     exit_signal = args->flags & 0x000000ff;
     if (exit_signal >= LINUX_NSIG)
 	return EINVAL;
@@ -608,7 +609,7 @@ linux_clone(struct proc *p, struct linux_clone_args *args)
     start = 0;
 
     rf_args.flags = ff;
-    if (error = rfork(p, &rf_args))
+    if ((error = rfork(p, &rf_args)) != 0)
 	return error;
 
     p2 = pfind(p->p_retval[0]);
@@ -936,6 +937,8 @@ linux_utime(struct proc *p, struct linux_utime_args *args)
     return utimes(p, &bsdutimes);
 }
 
+#define __WCLONE 0x80000000
+
 int
 linux_waitpid(struct proc *p, struct linux_waitpid_args *args)
 {
@@ -953,20 +956,17 @@ linux_waitpid(struct proc *p, struct linux_waitpid_args *args)
 #endif
     tmp.pid = args->pid;
     tmp.status = args->status;
-    /* This filters out the linux option _WCLONE.  I don't
-     * think we need it, but I could be wrong.  If we need
-     * it, we need to fix wait4, since it will give us an
-     * error return of EINVAL if we pass in _WCLONE, and
-     * of course, it won't do anything with it.
-     */
     tmp.options = (args->options & (WNOHANG | WUNTRACED));
+    /* WLINUXCLONE should be equal to __WCLONE, but we make sure */
+    if (args->options & __WCLONE)
+	tmp.options |= WLINUXCLONE;
     tmp.rusage = NULL;
 
-    if (error = wait4(p, &tmp))
+    if ((error = wait4(p, &tmp)) != 0)
 	return error;
 
     if (args->status) {
-	if (error = copyin(args->status, &tmpstat, sizeof(int)))
+	if ((error = copyin(args->status, &tmpstat, sizeof(int))) != 0)
 	    return error;
 	if (WIFSIGNALED(tmpstat))
 	    tmpstat = (tmpstat & 0xffffff80) |
@@ -997,22 +997,19 @@ linux_wait4(struct proc *p, struct linux_wait4_args *args)
 #endif
     tmp.pid = args->pid;
     tmp.status = args->status;
-    /* This filters out the linux option _WCLONE.  I don't
-     * think we need it, but I could be wrong.  If we need
-     * it, we need to fix wait4, since it will give us an
-     * error return of EINVAL if we pass in _WCLONE, and
-     * of course, it won't do anything with it.
-     */
     tmp.options = (args->options & (WNOHANG | WUNTRACED));
+    /* WLINUXCLONE should be equal to __WCLONE, but we make sure */
+    if (args->options & __WCLONE)
+	tmp.options |= WLINUXCLONE;
     tmp.rusage = args->rusage;
 
-    if (error = wait4(p, &tmp))
+    if ((error = wait4(p, &tmp)) != 0)
 	return error;
 
     p->p_siglist &= ~sigmask(SIGCHLD);
 
     if (args->status) {
-	if (error = copyin(args->status, &tmpstat, sizeof(int)))
+	if ((error = copyin(args->status, &tmpstat, sizeof(int))) != 0)
 	    return error;
 	if (WIFSIGNALED(tmpstat))
 	    tmpstat = (tmpstat & 0xffffff80) |
diff --git a/sys/kern/kern_exit.c b/sys/kern/kern_exit.c
index c80b3c8adb9d..297d9a7260ca 100644
--- a/sys/kern/kern_exit.c
+++ b/sys/kern/kern_exit.c
@@ -36,7 +36,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)kern_exit.c	8.7 (Berkeley) 2/12/94
- * $Id: kern_exit.c,v 1.74 1999/01/31 03:15:13 newton Exp $
+ * $Id: kern_exit.c,v 1.75 1999/02/19 14:25:34 luoqi Exp $
  */
 
 #include "opt_compat.h"
@@ -283,7 +283,7 @@ exit1(p, rv)
 		LIST_REMOVE(q, p_sibling);
 		LIST_INSERT_HEAD(&initproc->p_children, q, p_sibling);
 		q->p_pptr = initproc;
-		q->p_sigparent = 0;
+		q->p_sigparent = SIGCHLD;
 		/*
 		 * Traced processes are killed
 		 * since their existence means someone is screwing up.
@@ -420,7 +420,7 @@ wait1(q, uap, compat)
 
 	if (uap->pid == 0)
 		uap->pid = -q->p_pgid;
-	if (uap->options &~ (WUNTRACED|WNOHANG))
+	if (uap->options &~ (WUNTRACED|WNOHANG|WLINUXCLONE))
 		return (EINVAL);
 loop:
 	nfound = 0;
@@ -428,6 +428,17 @@ wait1(q, uap, compat)
 		if (uap->pid != WAIT_ANY &&
 		    p->p_pid != uap->pid && p->p_pgid != -uap->pid)
 			continue;
+
+		/* This special case handles a kthread spawned by linux_clone 
+		 * (see linux_misc.c).  The linux_wait4 and linux_waitpid functions
+		 * need to be able to distinguish between waiting on a process and
+		 * waiting on a thread.  It is a thread if p_sigparent is not SIGCHLD,
+		 * and the WLINUXCLONE option signifies we want to wait for threads
+		 * and not processes.
+		 */
+		if ((p->p_sigparent != SIGCHLD) ^ ((uap->options & WLINUXCLONE) != 0))
+			continue;
+
 		nfound++;
 		if (p->p_stat == SZOMB) {
 			/* charge childs scheduling cpu usage to parent */
diff --git a/sys/kern/kern_fork.c b/sys/kern/kern_fork.c
index 1ee86ae241e3..2877636e63d3 100644
--- a/sys/kern/kern_fork.c
+++ b/sys/kern/kern_fork.c
@@ -36,7 +36,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)kern_fork.c	8.6 (Berkeley) 4/8/94
- * $Id: kern_fork.c,v 1.54 1999/01/07 21:23:42 julian Exp $
+ * $Id: kern_fork.c,v 1.55 1999/01/26 02:38:10 julian Exp $
  */
 
 #include "opt_ktrace.h"
@@ -361,9 +361,10 @@ fork1(p1, flags)
 		/* Note that we fill in the values of sigacts in vm_fork */
 		p2->p_sigacts = NULL;
 	}
-	if (flags & RFLINUXTHPN) {
+	if (flags & RFLINUXTHPN) 
 	        p2->p_sigparent = SIGUSR1;
-	}
+	else
+	        p2->p_sigparent = SIGCHLD;
 
 	/* bump references to the text vnode (for procfs) */
 	p2->p_textvp = p1->p_textvp;
diff --git a/sys/sys/wait.h b/sys/sys/wait.h
index 0c8ea1b339fd..b0716d27fa7a 100644
--- a/sys/sys/wait.h
+++ b/sys/sys/wait.h
@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)wait.h	8.2 (Berkeley) 7/10/94
- * $Id$
+ * $Id: wait.h,v 1.8 1997/02/22 09:46:31 peter Exp $
  */
 
 #ifndef _SYS_WAIT_H_
@@ -79,6 +79,7 @@
  */
 #define WNOHANG		1	/* don't hang in wait */
 #define WUNTRACED	2	/* tell about stopped, untraced children */
+#define WLINUXCLONE     0x80000000       /* wait for kthread spawned from linux_clone */
 
 #ifndef _POSIX_SOURCE
 /* POSIX extensions and 4.2/4.3 compatibility: */