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    SubjectRe: [PATCH 0/2] usb: serial: handle -ENODEV and -EPROTO quietly
    Greg,

    On Mon, Dec 15, 2014 at 08:38:01AM -0800, Greg Kroah-Hartman wrote:
    > On Mon, Dec 15, 2014 at 04:53:05AM -0800, Jeremiah Mahler wrote:
    > > 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.
    >
    > Do you really want to "know about" them? What can a user do with them?
    > Nothing, so just resubmit and you should be fine.
    >
    > > I need to re-think this patch.
    > > Nack.
    >
    > I like this patch, putting crud in the kernel log that no one can do
    > anything with for a "normal" operation like yanking a USB device out
    > while it is open should not happen.
    >
    > thanks,
    >
    > greg k-h

    Perhaps something at a lower level could return a more apt error number
    such as -ENODEV. Then there would be no conflict with -EPROTO.

    I will look in to it again and re-submit the patches.

    --
    - Jeremiah Mahler


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