From: Oleg Nesterov <oleg@tv-sign.ru>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "linux-os (Dick Johnson)" <linux-os@analogic.com>,
Roland McGrath <roland@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: Kernel threads
Date: Thu, 8 Mar 2007 19:38:44 +0300 [thread overview]
Message-ID: <20070308163844.GA6638@tv-sign.ru> (raw)
Andrew Morton wrote:
>
> > On Tue, 6 Mar 2007 11:03:48 -0500 "linux-os \(Dick Johnson\)" <linux-os@analogic.com> wrote:
> >
> > In linux-2.6.16.24, there is a problem with kernel threads
> > and the aic79xx.c driver.
> >
> > When nash is executing /initrd/linuxrc in the initial RAM disk
> > during boot, it will be installing drivers. One driver, aic79xx.c
> > creates some kernel threads that will exit after the initialization
> > procedure. Actually the number of tasks depends upon the number
> > of disks found as the driver spawns these tasks so initialization
> > can occur in the background. The kernel tasks have been 'parented'
> > to init. This may be fine for the real init, but nash and other
> > shells receive the SIGCHLD signal and think that the fork()/exec()
> > they have executed is complete. This makes nash insert drivers
> > when the needed previous ones have not yet initialized. Also, when
> > booting a shell, the signals from the exiting kernel tasks confuse
> > it.
>
> ug. I've always disliked the kernel's dependence upon init to reap exitted
> kernel threads. It Just Seems Wrong.
Yes. It is ugly to kick init to reap the kernel thread. I was going to
do this change a long ago, but I don't have time to do even a minimal
testing now.
reparent_to_init() expects that thread_group_empty() == true anyway,
we can set ->exit_signal = -1 and make this thread invisible to init.
Roland, what do you think?
Oleg.
--- WQ/kernel/exit.c~rti 2007-02-18 22:56:49.000000000 +0300
+++ WQ/kernel/exit.c 2007-03-08 19:26:39.000000000 +0300
@@ -276,8 +276,8 @@ static void reparent_to_init(void)
current->parent = child_reaper(current);
add_parent(current);
- /* Set the exit signal to SIGCHLD so we signal init on exit */
- current->exit_signal = SIGCHLD;
+ /* make the task autoreap */
+ current->exit_signal = -1;
if (!has_rt_policy(current) && (task_nice(current) < 0))
set_user_nice(current, 0);
next reply other threads:[~2007-03-08 16:38 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-08 16:38 Oleg Nesterov [this message]
2007-03-09 0:31 ` Kernel threads Roland McGrath
2007-03-09 20:52 ` Oleg Nesterov
2007-03-09 21:38 ` Roland McGrath
2007-03-09 23:46 ` Oleg Nesterov
-- strict thread matches above, loose matches on Subject: below --
2007-03-06 16:03 linux-os (Dick Johnson)
2007-03-08 9:00 ` Andrew Morton
2002-11-20 9:36 kernel threads Madhavi
2002-04-12 17:07 Vahid Fereydunkolahi
2002-04-12 17:45 ` Masoud Sharbiani
2001-12-13 7:05 blesson paul
[not found] <no.id>
2001-08-16 22:37 ` Alan Cox
2001-08-21 12:15 ` Christian Widmer
2001-08-16 22:23 Christian Widmer
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