potential set_child_tid/clear_child_tid bug

[David Mosberger]

At the moment, if you don't set CLONE_CHILD_SETTID/CLONE_CHILD_CLEARTID,
the {set,clear}_child_tid values get inherited from the parent task.
I may be missing something, but I suspect that's not the intended behavior.
The patch below instead clears the respective members.

	--david

diff -Nru a/kernel/fork.c b/kernel/fork.c
--- a/kernel/fork.c	Thu Jun 19 12:20:17 2003
+++ b/kernel/fork.c	Thu Jun 19 12:20:17 2003
@@ -889,11 +889,15 @@
 
 	if (clone_flags & CLONE_CHILD_SETTID)
 		p->set_child_tid = child_tidptr;
+	else
+		p->set_child_tid = NULL;
 	/*
 	 * Clear TID on mm_release()?
 	 */
 	if (clone_flags & CLONE_CHILD_CLEARTID)
 		p->clear_child_tid = child_tidptr;
+	else
+		p->clear_child_tid = NULL;
 
 	/*
 	 * Syscall tracing should be turned off in the child regardless