From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Jiri Slaby <jirislaby@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Christophe Lermytte <christophe.lermytte@thomson.net>,
linux-kernel@vger.kernel.org
Subject: Re: mutex_lock_slowpath warning using mxser tty driver (input/output error)
Date: Thu, 2 Apr 2009 23:55:08 +0100 [thread overview]
Message-ID: <20090402235508.31c7f2b6@lxorguk.ukuu.org.uk> (raw)
In-Reply-To: <49D51EDD.4060902@gmail.com>
On Thu, 02 Apr 2009 22:23:57 +0200
Jiri Slaby <jirislaby@gmail.com> wrote:
> On 04/02/2009 08:44 PM, Alan Cox wrote:
> >> It appears to want to lock a mutex in interrupt context, something
> >> that's a definite no-no.
> >>
> >> CCed the folks who might know a thing or two about the driver.
> >
> > Moxa is not a USB driver so the USB trace at the end makes no sense at
> > all.
>
> Yes, unreliable stack entries, but echo_set_canon_col is called from irq
> context and locks mutex.
Which means that either the driver is calling the ldisc receive handlers
from an IRQ directly (not allowed) or calling the tty_flip_buffer_push
paths and set tty->low_latency
2.6.29 is the first kernel that catches this bug with warnings.
next prev parent reply other threads:[~2009-04-02 22:54 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-02 16:26 Christophe Lermytte
2009-04-02 18:19 ` Peter Zijlstra
2009-04-02 18:44 ` Alan Cox
2009-04-02 20:23 ` Jiri Slaby
2009-04-02 22:55 ` Alan Cox [this message]
2009-04-03 0:33 ` Johannes Weiner
2009-04-21 12:20 ` Jiri Slaby
2009-04-02 21:37 Christophe Lermytte
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