[2/2] USB: usbdevfs: restore warning for nonsensical flags

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Wed, Sep 05, 2018 at 03:02:48PM +0200, Oliver Neukum wrote:
> On Mi, 2018-09-05 at 14:19 +0200, Greg KH wrote:
> > On Wed, Sep 05, 2018 at 12:07:03PM +0200, Oliver Neukum wrote:
> > > If we filter flags before they reach the core we need to generate our
> > > own warnings.
> > > 
> > > Signed-off-by: Oliver Neukum <oneukum@suse.com>
> > > Fixes: 0cb54a3e47cb ("USB: debugging code shouldn't alter control flow")
> > > ---
> > >  drivers/usb/core/devio.c | 5 +++++
> > >  1 file changed, 5 insertions(+)
> > > 
> > > diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
> > > index 263dd2f309fb..244417d0dfd1 100644
> > > --- a/drivers/usb/core/devio.c
> > > +++ b/drivers/usb/core/devio.c
> > > @@ -1697,6 +1697,11 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
> > >  		u |= URB_NO_INTERRUPT;
> > >  	as->urb->transfer_flags = u;
> > >  
> > > +	if (!allow_short && uurb->flags & USBDEVFS_URB_SHORT_NOT_OK)
> > > +		dev_warn(&ps->dev->dev, "Requested nonsensical USBDEVFS_URB_SHORT_NOT_OK.\n");
> > > +	if (!allow_zero && uurb->flags & USBDEVFS_URB_ZERO_PACKET)
> > > +		dev_warn(&ps->dev->dev, "Requested nonsensical USBDEVFS_URB_ZERO_PACKET.\n");
> > 
> > We should not make it trivial for userspace to spam the kernel log if at
> > all possible.  Returning an error is probably the better thing to do
> > here, not just silently fix it up or ignore it.
> 
> That means a change in the API in a way that makes orking systems fail.

Ah, good point.  I guess they were hitting the same dev_WARN() messages
today anyway, right?

> Do you want an extra version for stable?

No, but why was this patch not marked for stable?

thanks,

greg k-h