From: Matt Mackall <mpm@selenic.com>
To: Andi Kleen <ak@suse.de>
Cc: "David S. Miller" <davem@davemloft.net>,
Andrew Morton <akpm@osdl.org>,
colin@colino.net, netdev@oss.sgi.com
Subject: Re: [PATCH] Prevent netpoll hanging when link is down
Date: Mon, 11 Oct 2004 11:58:52 -0500 [thread overview]
Message-ID: <20041011165851.GN31237@waste.org> (raw)
In-Reply-To: <20041011164315.GH26350@wotan.suse.de>
On Mon, Oct 11, 2004 at 06:43:15PM +0200, Andi Kleen wrote:
> > It's not recursion on printk that's a problem, it's recursion on
> > ->poll() and attempting to take whatever internal driver locks.
>
> There is no recursion on poll because printk will never call into
> the low level console driver when the console sem is already taken.
Ergh, you deleted the context. Again, imagine we're originally in
->poll() for _a non-netpoll-related reason_. In other words, the
console sem is not taken, because we're just doing routine network
I/O. While in poll(), we take a private driver lock. Then for whatever
reason, we printk -> netconsole -> netpoll -> poll() again where we
attempt to retake the private driver lock.
> P.S.: I made the same mistake long ago, but akpm set me straight.
I'm pretty sure this case is different.
--
Mathematics is the supreme nostalgia of our time.
next prev parent reply other threads:[~2004-10-11 16:58 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20041006232544.53615761@jack.colino.net>
2004-10-06 21:43 ` [PATCH] Prevent netpoll hanging when link is down Matt Mackall
2004-10-07 5:53 ` Colin Leroy
2004-10-07 6:49 ` David S. Miller
2004-10-07 8:33 ` Colin Leroy
2004-10-07 8:45 ` Colin Leroy
2004-10-07 14:05 ` Colin Leroy
2004-10-07 18:28 ` David S. Miller
2004-10-07 18:41 ` Matt Mackall
2004-10-07 20:00 ` Colin Leroy
2004-10-07 18:43 ` Andi Kleen
2004-10-07 20:44 ` Colin Leroy
2004-10-07 21:45 ` Andi Kleen
2004-10-07 21:50 ` Matt Mackall
2004-10-07 22:07 ` David S. Miller
2004-10-07 23:43 ` Matt Mackall
2004-10-07 23:50 ` Andi Kleen
2004-10-08 6:46 ` Colin Leroy
2004-10-08 21:53 ` Matt Mackall
2004-10-08 7:06 ` Colin Leroy
2004-10-08 22:00 ` Matt Mackall
2004-10-08 22:18 ` Andrew Morton
2004-10-11 3:59 ` David S. Miller
2004-10-11 15:40 ` Andi Kleen
2004-10-11 16:22 ` Matt Mackall
2004-10-11 16:32 ` Andi Kleen
2004-10-11 16:36 ` Matt Mackall
2004-10-11 16:43 ` Andi Kleen
2004-10-11 16:58 ` Matt Mackall [this message]
2004-10-11 17:41 ` Andi Kleen
2004-10-11 20:45 ` Colin Leroy
[not found] ` <5cac192f0410181443303379e2@mail.gmail.com>
[not found] ` <5cac192f041018145824acce5a@mail.gmail.com>
[not found] ` <20041020161119.6e30efe5@pirandello>
[not found] ` <5cac192f0410200848179ccc81@mail.gmail.com>
2004-10-21 16:36 ` Colin Leroy
2004-10-24 15:22 ` Eric Lemoine
2004-10-07 22:08 ` David S. Miller
2004-10-08 6:54 ` Colin Leroy
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