changing EINVAL for SIOCSIFCAP to something else

[Gleb Smirnoff]

  Andre, Yar,

On Mon, Feb 27, 2006 at 10:04:28AM +0100, Andre Oppermann wrote:
A> > I prefer this variant:
A> > 
A> >                 if (ifp->if_ioctl == NULL)
A> >                         return (ENOTTY);
A> >                 if (ifr->ifr_reqcap & ~ifp->if_capabilities)
A> >                         return (ENODEV);
A> > 
A> > Any objections?
A> 
A> I don't think ENOTTY is appropriate here even though the comment to this
A> error code would fit.  But the define still says no TTY which is totally
A> unrelated and confusing.

It contains a confusing word "tty", but it means "Inappropriate ioctl for device".
This error code is used in many places throughout the kernel. We already have
some ENOTTY returns in src/sys/net.

Y> I'm afraid that this is a case when EINVAL is used properly: an
Y> argument to ioctl doesn't make sense to a particular device.  It's
Y> true that EINVAL may be abused in other places though.  I wish each
Y> EINVAL being returned to the userland were accompanied by log().

I don't agree. EINVAL can logically fit to almost any error condition. We
should fine error codes fitting better. If "ioctl doesn't make sense to a
particular device", then we should say "Operation not supported by device",
which is ENODEV.

-- 
Totus tuus, Glebius.
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