From: Arnd Bergmann <arnd@arndb.de>
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: Networking <netdev@vger.kernel.org>,
David Miller <davem@davemloft.net>,
linux-arch <linux-arch@vger.kernel.org>,
y2038 Mailman List <y2038@lists.linaro.org>,
Eric Dumazet <edumazet@google.com>,
Willem de Bruijn <willemb@google.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-hams@vger.kernel.org,
Bluez mailing list <linux-bluetooth@vger.kernel.org>,
linux-can@vger.kernel.org, dccp@vger.kernel.org,
linux-wpan@vger.kernel.org, linux-sctp@vger.kernel.org,
linux-x25@vger.kernel.org
Subject: Re: [PATCH net-next 1/3] net: rework SIOCGSTAMP ioctl handling
Date: Fri, 31 Aug 2018 16:00:21 +0200 [thread overview]
Message-ID: <CAK8P3a00DLR9JyfKwbYXnKCpRf+YWuUyMbC+UfXZTfdnAJxRtg@mail.gmail.com> (raw)
In-Reply-To: <CAF=yD-+9yc838Y_DO1S4HsBpLrBk8iNt0oAj1ceO1S6sE+tCdg@mail.gmail.com>
On Fri, Aug 31, 2018 at 3:38 PM Willem de Bruijn
<willemdebruijn.kernel@gmail.com> wrote:
> On Fri, Aug 31, 2018 at 6:31 AM Arnd Bergmann <arnd@arndb.de> wrote:
> > On Thu, Aug 30, 2018 at 10:10 PM Willem de Bruijn
> > <willemdebruijn.kernel@gmail.com> wrote:
> > > On Wed, Aug 29, 2018 at 9:05 AM Arnd Bergmann <arnd@arndb.de> wrote:
> > > If this is the only valid implementation of .gettstamp, the indirect
> > > call could be avoided in favor of a simple branch.
> >
> > I thought about that as well, but I could not come up with a
> > good way to encode the difference between socket protocols
> > that allow timestamping and those that don't.
> >
> > I think ideally we would just call sock_gettstamp() unconditonally
> > on every socket, and have that function decide whether timestamps
> > make sense or not. The part I did not understand is which ones
> > actually want the timestamps or not. Most protocols that
> > implement the ioctls also assign skb->tstamp, but there are some
> > protocols in which I could not see skb->tstamp ever being set,
> > and some that set it but don't seem to have the ioctls.
>
> These probably only use cmsgs SCM_TIMESTAMP(NS|IMG)
> to read timestamps.
Good point. FWIW, I have discussed with Deepa how those should
be modified for y2038, but we don't have any current patches for
those.
> > Looking at it again, it seems that sock_gettstamp() should
> > actually deal with this gracefully: it will return a -EINVAL
> > error condition if the timestamp remains at the
> > SK_DEFAULT_STAMP initial value, which is probably
> > just as appropriate (or better) as the current -ENOTTY
> > default, and if we are actually recording timestamps, we
> > might just as well report them.
>
> Yes, that's a nice solution. There is always some risk in changing
> error codes. But ioctl callers should be able to support newly
> implemented functionality. Even if partially implemented and
> returning ENOENT instead of ENOIOCTLCMD.
Ok, so do you think we should stay with the current version
for now, and change the two points later, or should I rework
it to integrate the locking and removing the callback?
I suppose the series actually gets nicer without the
callback, since I can simply add the generic timestamping
implementation first, and then remove the dead ioctl
handlers.
Arnd
next prev parent reply other threads:[~2018-08-31 14:00 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-29 12:59 [PATCH net-next 1/3] net: rework SIOCGSTAMP ioctl handling Arnd Bergmann
2018-08-29 12:59 ` [PATCH net-next 2/3] asm-generic: generalize asm/sockios.h Arnd Bergmann
2018-08-29 13:11 ` [PATCH net-next 3/3] net: socket: implement 64-bit timestamps Arnd Bergmann
2018-08-30 20:09 ` [PATCH net-next 1/3] net: rework SIOCGSTAMP ioctl handling Willem de Bruijn
2018-08-31 10:31 ` Arnd Bergmann
2018-08-31 13:37 ` Willem de Bruijn
2018-08-31 14:00 ` Arnd Bergmann [this message]
2018-08-31 15:08 ` Willem de Bruijn
2018-09-13 12:28 ` Arnd Bergmann
2018-09-21 9:14 ` Stefan Schmidt
2019-04-16 20:32 Arnd Bergmann
2019-04-17 9:35 ` Neil Horman
2019-04-17 17:21 ` David Miller
2019-04-17 20:15 ` Neil Horman
2019-04-17 9:59 ` Marc Kleine-Budde
2019-04-17 14:46 ` Willem de Bruijn
2019-04-17 16:19 ` Arnd Bergmann
2019-04-17 18:16 ` Willem de Bruijn
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