linux-kernel - Re: [PATCH 0/2] usb: serial: handle -ENODEV and -EPROTO quietly

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Message-ID: <20141215125305.GA18251@hudson.localdomain>
Date:	Mon, 15 Dec 2014 04:53:05 -0800
From:	Jeremiah Mahler <jmmahler@...il.com>
To:	Johan Hovold <johan@...nel.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] usb: serial: handle -ENODEV and -EPROTO quietly

Johan,

On Mon, Dec 15, 2014 at 11:23:21AM +0100, Johan Hovold wrote:
> On Thu, Dec 11, 2014 at 03:29:52PM -0800, Jeremiah Mahler wrote:
> > If a USB serial device (e.g. /dev/ttyUSB0) with an active program is
> > unplugged, a bunch of -ENODEV and -EPROTO errors will be produced in the
> > logs.  This patch set quiets these messages without changing the
> > original behavior.
> 
> Don't unplug devices that are in use then. ;)
> 
I knew someone was going to say that :-)

> > This change is beneficial when using daemons such as slcand, which is
> > similar to pppd or slip, that cannot determine whether they should exit
> > until after the USB serial device is unplugged.  Producing these error
> > messages for a normal use case is not helpful.
> 
> Your patches would hide these errors when they occur during normal use
> (e.g. EPROTO).
> 
> Receiving an error message when unplugging an active device should not
> surprise anyone. And at least you know where it came from (and it's
> right there in the logs as well).
> 
> Johan

Hmm.  Yes, I can see why quieting -EPROTO would be bad because it would
hide protocol errors which we want to know about.

I need to re-think this patch.
Nack.

Thanks for the review,
-- 
- Jeremiah Mahler
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