Fix unnecessary tying of CLONE_THREAD and CLONE_PARENT

[Dave McCracken]

Code was added in about 2.4.7 that forced CLONE_PARENT behavior whenever
CLONE_THREAD was specified.  This was to work around a bug in exit that has
since been fixed.  It's unnecessary to force this behavior, and in fact
breaks some thread programming models.  Anyone who wants it can still
specify the flags separately.

Here's the patch to put it back the way it should be.

Dave McCracken

======================================================================
Dave McCracken          IBM Linux Base Kernel Team      1-512-838-3059
[e-mail]                                        T/L   678-3059

--------

--- linux-2.4.17/./kernel/fork.c	Wed Nov 21 12:18:42 2001
+++ linux-2.4.17-clone/./kernel/fork.c	Mon Jan 28 14:32:48 2002
@@ -700,10 +700,10 @@
 	/* Need tasklist lock for parent etc handling! */
 	write_lock_irq(&tasklist_lock);
 
-	/* CLONE_PARENT and CLONE_THREAD re-use the old parent */
+	/* CLONE_PARENT re-uses the old parent */
 	p->p_opptr = current->p_opptr;
 	p->p_pptr = current->p_pptr;
-	if (!(clone_flags & (CLONE_PARENT | CLONE_THREAD))) {
+	if (!(clone_flags & CLONE_PARENT)) {
 		p->p_opptr = current;
 		if (!(p->ptrace & PT_PTRACED))
 			p->p_pptr = current;