From: Ilya Maximets <i.maximets@ovn.org>
To: Mina Almasry <almasrymina@google.com>,
Jakub Kicinski <kuba@kernel.org>,
Willem de Bruijn <willemb@google.com>,
Eric Dumazet <edumazet@google.com>,
Kaiyuan Zhang <kaiyuanz@google.com>,
Stanislav Fomichev <sdf@fomichev.me>,
Paolo Abeni <pabeni@redhat.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
dev@openvswitch.org
Cc: "David S. Miller" <davem@davemloft.net>,
Simon Horman <horms@kernel.org>,
Neal Cardwell <ncardwell@google.com>,
Kuniyuki Iwashima <kuniyu@google.com>,
Aaron Conole <aconole@redhat.com>,
Eelco Chaudron <echaudro@redhat.com>,
Ilya Maximets <i.maximets@ovn.org>,
Jason Xing <kerneljasonxing@gmail.com>,
Pavel Begunkov <asml.silence@gmail.com>,
Bobby Eshleman <bobbyeshleman@gmail.com>,
Florian Westphal <fw@strlen.de>
Subject: Re: [PATCH net v3 1/2] net: core: propagate unreadable flag in skb_zerocopy
Date: Wed, 12 Aug 2026 17:52:12 +0200 [thread overview]
Message-ID: <e532f313-447c-4ac5-806d-b686bc9181dd@ovn.org> (raw)
In-Reply-To: <20260811195405.3979177-1-almasrymina@google.com>
On 8/11/26 9:53 PM, Mina Almasry wrote:
> diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
> index ae69b2cabab9e..482893a5f67dc 100644
> --- a/net/openvswitch/datapath.c
> +++ b/net/openvswitch/datapath.c
> @@ -467,6 +467,9 @@ static int queue_userspace_packet(struct datapath *dp, struct sk_buff *skb,
> if (!dp_ifindex)
> return -ENODEV;
>
> + if (!skb_frags_readable(skb))
> + return -EFAULT;
> +
> if (skb_vlan_tag_present(skb)) {
> nskb = skb_clone(skb, GFP_ATOMIC);
> if (!nskb)
FWIW, the devmem integration doesn't seem well-designed. I understand
that it is for performance, but IMO there should be a way to copy the
data on a slow path to avoid dropping the packets. Clamping without
notifying the users that the packet is truncated is not a good solution.
Not for OVS, not for other parts of the kernel networking stack. It's
a uAPI breakage.
As it is, there is not much we can do here without extensive changes
in userspace applications, so for this OVS block:
Reviewed-by: Ilya Maximets <i.maximets@ovn.org>
prev parent reply other threads:[~2026-08-12 15:52 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-11 19:53 [PATCH net v3 1/2] net: core: propagate unreadable flag in skb_zerocopy Mina Almasry
2026-08-11 19:53 ` [PATCH net v3 2/2] net: tcp: block standard payload injection into devmem skbs Mina Almasry
2026-08-12 12:01 ` Eric Dumazet
2026-08-12 13:37 ` Pavel Begunkov
2026-08-12 15:52 ` Ilya Maximets [this message]
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