Date: Mon, 20 Jul 2009 23:58:41 +0200
From: Daniel Mack <daniel@caiaq.de>
To: Alan Cox <alan@linux.intel.com>
Cc: linux-kernel@vger.kernel.org, Greg Kroah-Hartman <gregkh@suse.de>,
       Alan Cox <alan@redhat.com>, Alan Stern <stern@rowland.harvard.edu>,
       Oliver Neukum <oneukum@suse.de>, linux-usb@vger.kernel.org
Subject: Re: [PATCH] [usb-serial] fix Ooops on uplug
Message-ID: <20090720215841.GJ19257@buzzloop.caiaq.de>
References: <20090720155502.50b84ae9@lxorguk.ukuu.org.uk> <1248112313-7842-1-git-send-email-daniel@caiaq.de> <20090720234829.1b32b2c0@t61.ukuu.org.uk>
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On Mon, Jul 20, 2009 at 11:48:29PM +0100, Alan Cox wrote:
> > The reason is that the serial port's resources are freed upon
> > disconnect (in serial_hangup()) but the tty device layer is not made
> > aware of that. Hence, the close callback will later access the
> > resources again.
> 
> tty_port_hangup() is part of the hangup path and the physical resources
> should not be touched after the hangup completes. It's a good
> indication of where the bug might be but its not I suspect the fix as
> we now leak the resources.

Depends on how you define the time of removal. The user space connection
stays open after the device was removed. And it is closed once the tty
layer finds out that it can't write to the hardware anymore. Once you
try to bring the tty to life, all resources are freed.

At least, this patch fixes a serious oops.

Daniel

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