Re: [patch] O(1) sys_exit(), threading, scalable-exit-2.5.31-A6

[Ingo Molnar]

the attached patch ontop of BK-curr fixes the ptrace wait4() anomaly that
can be observed in any previous Linux kernel i could get my hands at. So
in fact ->ptrace_children, besides being a speedup, also fixed a bug that
couldnt be fixed in any satisfactory way before.

	Ingo

--- linux/kernel/exit.c.orig	Tue Aug 20 16:28:57 2002
+++ linux/kernel/exit.c	Tue Aug 20 16:30:13 2002
@@ -731,7 +731,7 @@
 		tsk = next_thread(tsk);
 	} while (tsk != current);
 	read_unlock(&tasklist_lock);
-	if (flag) {
+	if (flag || !list_empty(&current->ptrace_children)) {
 		retval = 0;
 		if (options & WNOHANG)
 			goto end_wait4;