[patch] exit-fix-2.5.34-C0, BK-curr

[Ingo Molnar]

the attached patch (ontop of the previous exit.c patches), fixes one more
exit-time resource accounting issue - and it's also a speedup and a
thread-tree (to-be thread-aware pstree) visual improvement.

in the current code we reparent detached threads to the init thread. This
worked but was not very nice in ps output: threads showed up as being
related to init. There was also a resource-accounting issue, upon exit
they update their parent's (ie. init's) rusage fields - effectively losing
these statistics. Eg. 'time' under-reports CPU usage if the threaded app
is Ctrl-C-ed prematurely.

the solution is to reparent threads to the group leader - this is now very
easy since we have p->group_leader cached and it's also valid all the
time. It's also somewhat faster for applications that use CLONE_THREAD but
do not use the CLONE_DETACHED feature.

	Ingo

--- linux/kernel/exit.c.orig	Sun Sep 15 15:01:48 2002
+++ linux/kernel/exit.c	Sun Sep 15 16:23:49 2002
@@ -447,11 +447,7 @@
 	struct task_struct *p, *reaper = father;
 	struct list_head *_p;
 
-	if (father->exit_signal != -1)
-		reaper = prev_thread(reaper);
-	else
-		reaper = child_reaper;
-
+	reaper = father->group_leader;
 	if (reaper == father)
 		reaper = child_reaper;