From: Andrew Morton <akpm@osdl.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: rmk+lkml@arm.linux.org.uk, e9925248@student.tuwien.ac.at,
linux-kernel@vger.kernel.org
Subject: Re: Deadlock in serial driver 2.6.x
Date: Thu, 3 Feb 2005 10:21:12 -0800 [thread overview]
Message-ID: <20050203102112.06c06fe7.akpm@osdl.org> (raw)
In-Reply-To: <1107332396.14847.112.camel@localhost.localdomain>
Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
>
> On Llu, 2005-01-31 at 08:48, Andrew Morton wrote:
> > > The tty layer cannot fix this for now, and I don't intend to fix it. Fix
> > > the serial driver: the fix is quite simple since you can keep a field in
> > > the driver for now to detect recursive calling into the echo case and
> > > don't relock.
> >
> > Are we sure that the serial driver is the only one which will hit this
> > deadlock?
>
> Yes fairly sure. The feature has been a well known but non-documented
> property of the tty layer since about 1.0. There are two ways I see to
> clean it up - we
> can have the serial driver behave like other drivers and if need be
> known about
> recursive entries or we could extend the driver interface with an "echo"
> method used by line disciplines when calling back to the tty driver from
> a data
> receive event.
The "echo method" method sounds good. Do we think that's feasible for
2.6.11, or would it be safer to disable low-latency mode for that driver?
next prev parent reply other threads:[~2005-02-03 18:25 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-01-26 13:20 Martin Kögler
2005-01-27 7:13 ` Andrew Morton
2005-01-30 15:39 ` Alan Cox
2005-01-30 16:48 ` Russell King
2005-01-31 7:37 ` Alan Cox
2005-01-31 8:48 ` Andrew Morton
2005-02-03 10:02 ` Alan Cox
2005-02-03 18:21 ` Andrew Morton [this message]
2005-02-04 11:07 ` Martin Kögler
2005-02-04 13:50 ` Paul Fulghum
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