On Fri, Nov 04, 2011 at 02:00:11PM -0400, Nick Bowler wrote:
> On 2011-11-03 12:04 -0700, Greg KH wrote:
> > On Thu, Nov 03, 2011 at 02:40:56PM -0400, Nick Bowler wrote:
> > > Silently doing nothing when a break is requested but fails is not the
> > > most user-friendly behaviour. Convert the existing debug message to a
> > > proper error message.
> >
> > What we really need to do is propagate that error back to userspace,
> > unfortunately we forgot to do that, so we need to change the function
> > signature.
>
> OK, this actually looks pretty straightforward to do. I'll try to look
> into it over the weekend.
>
> > > if (result)
> > > - dbg("%s - error sending break = %d", __func__, result);
> > > + dev_err(&port->dev, "failed to send break: %d\n", result);
> >
> > If you do this, it's now trivial for userspace to spam your logs if you
> > have this type of hardware, so we should leave it at debug, and just fix
> > the ability to return the error properly to userspace, which can then
> > handle it correctly.
>
> Assuming userspace has sufficient privileges to access the serial port.
> But you're right, it's a problem.
>
> However, it seems that most existing userspace fails to actually check
> tcsendbreak for errors. :(
Ugh, well, that's userspace's fault :(
> What if we keep the debug message as-is, and instead add a new message
> that gets printed only once per device? That should avoid the log spam
> and allow people with old userspace to at least have some indication of
> what's going on. The message can be removed after wiring up the error
> returns and giving userspace some time to handle these new errors.
That sounds fine.
thanks,
greg k-h
--
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
