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SubjectRe: [PATCH] 8139too reparent_to_init() race
Robert Kuebel wrote:
>
> hello all,
>
> lately i noticed this message during boot-up (when the network
> interfaces were being configured) ...
>
> "task `ifconfig' exit_signal 17 in reparent_to_init"
>
> this happens only about 1/2 of the time.
>
> after some digging this is what i found...
> sometimes ifconfig's parent exits before ifconfig reaches
> rtl8139_thread(). when this happens, ifconfig's exit_signal is set to
> SIGCHLD (in forget_original_parent), because its new parent is init.
> then rlt8139_thread() is reached it calls reparent_to_init(), which
> complains that exit_signal is already non-zero.
>
> basically this patch stops rtl8139_thread() from calling
> reparent_to_init() when its parent is already init.
>

Thanks - that's a useful analysis.

The check in reparent_to_init() was to warn about the situation
where someone had deliberately set the exit signal to some
non-zero value and then the child calls reparent_to_init() - it's
telling you that we're about to stomp on your chosen exit signal.
I hadn't thought about the forget_original_parent() case.

So the fix should be to change the debug code in reparent_to_init()
so it doesn't complain if the exit signal is already SIGCHLD. Or
just kill it off altogether.


--- linux-2.4.14-pre3/kernel/sched.c Tue Oct 23 23:09:48 2001
+++ linux-akpm/kernel/sched.c Sun Oct 28 17:23:26 2001
@@ -1250,11 +1250,6 @@ void reparent_to_init(void)
SET_LINKS(this_task);

/* Set the exit signal to SIGCHLD so we signal init on exit */
- if (this_task->exit_signal != 0) {
- printk(KERN_ERR "task `%s' exit_signal %d in "
- __FUNCTION__ "\n",
- this_task->comm, this_task->exit_signal);
- }
this_task->exit_signal = SIGCHLD;

/* We also take the runqueue_lock while altering task fields
-
-
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