From: David Laight <David.Laight@ACULAB.COM>
To: 'Stefano Garzarella' <sgarzare@redhat.com>
Cc: Colin King <colin.king@canonical.com>,
"David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"kernel-janitors@vger.kernel.org"
<kernel-janitors@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] vsock: ratelimit unknown ioctl error message
Date: Mon, 26 Oct 2020 09:46:17 +0000 [thread overview]
Message-ID: <3e34e4121f794355891fd7577c9dfbc0@AcuMS.aculab.com> (raw)
In-Reply-To: <20201026093917.5zgginii65pq6ezd@steredhat>
From: Stefano Garzarella
> Sent: 26 October 2020 09:39
>
> On Mon, Oct 26, 2020 at 09:13:23AM +0000, David Laight wrote:
> >From: Stefano Garzarella
> >> Sent: 26 October 2020 08:43
> >...
> >> >Isn't the canonical error for unknown ioctl codes -ENOTTY?
> >> >
> >>
> >> Oh, thanks for pointing that out!
> >>
> >> I had not paid attention to the error returned, but looking at it I
> >> noticed that perhaps the most appropriate would be -ENOIOCTLCMD.
> >> In the ioctl syscall we return -ENOTTY, if the callback returns
> >> -ENOIOCTLCMD.
> >>
> >> What do you think?
> >
> >It is 729 v 443 in favour of ENOTTY (based on grep).
>
> Under net/ it is 6 vs 83 in favour of ENOIOCTLCMD.
>
> >
> >No idea where ENOIOCTLCMD comes from, but ENOTTY probably
> >goes back to the early 1970s.
>
> Me too.
>
> >
> >The fact that the ioctl wrapper converts the value is a good
> >hint that userspace expects ENOTTY.
>
> Agree on that, but since we are not interfacing directly with userspace,
> I think it is better to return the more specific error (ENOIOCTLCMD).
I bet Linux thought it could use a different error code then
found that 'unknown ioctl' was spelt ENOTTY.
Back in the old days error values were probably almost unique.
strerror(EAGIAN) was "No more processes" for a long time!
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2020-10-26 9:46 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-23 12:21 [PATCH] vsock: ratelimit unknown ioctl error message Colin King
2020-10-23 14:09 ` Stefano Garzarella
2020-10-23 20:25 ` Jakub Kicinski
2020-10-23 21:30 ` David Laight
2020-10-26 8:43 ` Stefano Garzarella
2020-10-26 9:13 ` David Laight
2020-10-26 9:39 ` Stefano Garzarella
2020-10-26 9:46 ` David Laight [this message]
2020-10-26 10:01 ` Stefano Garzarella
2020-10-26 17:55 ` Jakub Kicinski
2020-10-26 18:24 ` Stefano Garzarella
2020-10-26 18:37 ` Jakub Kicinski
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