From: "Michael S. Tsirkin" <mst@redhat.com>
To: David Ahern <dahern@digitalocean.com>
Cc: "Toke Høiland-Jørgensen" <toke@redhat.com>,
"Jason Wang" <jasowang@redhat.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Re: virtio_net: can change MTU after installing program
Date: Wed, 26 Feb 2020 12:02:03 -0500 [thread overview]
Message-ID: <20200226120142-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <ec1185ac-a2a1-e9d9-c116-ab42483c3b85@digitalocean.com>
On Wed, Feb 26, 2020 at 09:58:00AM -0700, David Ahern wrote:
> On 2/26/20 9:55 AM, Michael S. Tsirkin wrote:
> >
> > OK that seems to indicate an ndo callback as a reasonable way
> > to handle this. Right? The only problem is this might break
> > guests if they happen to reverse the order of
> > operations:
> > 1. set mtu
> > 2. detach xdp prog
> > would previously work fine, and would now give an error.
>
> That order should not work at all. You should not be allowed to change
> the MTU size that exceeds XDP limits while an XDP program is attached.
Right. But we didn't check it so blocking that now is a UAPI change.
Do we care?
> >
> > If we want to make it transparent for userspace,
> > I guess we can defer the actual update until xdp prog is detached.
> > Sound ugly and might still confuse some userspace ... worth it?
> >
next prev parent reply other threads:[~2020-02-26 17:02 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-26 9:33 Michael S. Tsirkin
2020-02-26 3:32 ` virtio_net: can change MTU after installing program David Ahern
2020-02-26 4:02 ` Jason Wang
2020-02-26 4:31 ` David Ahern
2020-02-26 5:53 ` Jason Wang
2020-02-26 16:04 ` David Ahern
2020-02-26 7:07 ` Michael S. Tsirkin
2020-02-26 7:37 ` Jason Wang
2020-02-26 8:39 ` Michael S. Tsirkin
2020-02-26 9:30 ` Jason Wang
2020-02-26 9:36 ` Michael S. Tsirkin
2020-02-26 16:08 ` David Ahern
2020-02-26 16:56 ` Michael S. Tsirkin
2020-02-26 9:51 ` Toke Høiland-Jørgensen
2020-02-26 16:03 ` David Ahern
2020-02-26 16:55 ` Michael S. Tsirkin
2020-02-26 16:58 ` David Ahern
2020-02-26 17:02 ` Michael S. Tsirkin [this message]
2020-02-27 1:37 ` Jakub Kicinski
2020-02-27 8:14 ` Michael S. Tsirkin
2020-02-27 17:16 ` Jakub Kicinski
2020-02-27 19:26 ` Michael Chan
2020-02-27 19:45 ` Jakub Kicinski
2020-02-27 21:37 ` David Ahern
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