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. Knowing that a device is flakey (and should be replaced) might be of some worth? And wouldn't silencing such errors mean that we could be quietly dropping data? > > 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. The problem is that several errors may be returned from the host-controller driver as a consequence of disconnect (before the hub driver can process the disconnect). At least -EPROTO, -EILSEQ, -ETIME are -EPIPE explicitly listed in Documentation/usb/error-codes.txt for this, and of those, -EPROTO, -EILSEQ could also indicate hardware problems. I don't see how we can get around the trade-off between having a few error messages in the log in the short window prior to a processed (and also logged) disconnect, and not reporting potential hardware issues. Thanks, Johan -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
