From: Phil Sutter <phil@nwl.cc>
To: David Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Subject: Re: [PATCH 1/3] af_packet: when sending ethernet frames, parse header for skb->protocol
Date: Thu, 1 Aug 2013 12:35:09 +0200 [thread overview]
Message-ID: <20130801103509.GB27563@orbit.nwl.cc> (raw)
In-Reply-To: <20130731.173017.624144247713296239.davem@davemloft.net>
Hi,
On Wed, Jul 31, 2013 at 05:30:17PM -0700, David Miller wrote:
> From: Phil Sutter <phil@nwl.cc>
> Date: Wed, 31 Jul 2013 19:27:45 +0200
>
> > @@ -2324,6 +2328,13 @@ static int packet_snd(struct socket *sock,
> >
> > sock_tx_timestamp(sk, &skb_shinfo(skb)->tx_flags);
> >
> > + if (dev->type == ARPHRD_ETHER) {
> > + skb->protocol = eth_type_trans(skb, dev);
> > + } else {
> > + skb->protocol = proto;
> > + skb->dev = dev;
> > + }
> > +
> > if (!gso_type && (len > dev->mtu + reserve + extra_len)) {
> > /* Earlier code assumed this would be a VLAN pkt,
> > * double-check this now that we have the actual
> > @@ -2338,8 +2349,6 @@ static int packet_snd(struct socket *sock,
> > }
> > }
> >
> > - skb->protocol = proto;
> > - skb->dev = dev;
> > skb->priority = sk->sk_priority;
> > skb->mark = sk->sk_mark;
>
> I don't see anything explaining why you are avoiding setting skb->dev when
> you use eth_type_trans() to set the skb->protocol field.
Simply because eth_type_trans() sets skb->dev already. You're right, I
probably should have mentioned this explicitly. At least my introductory
mail elaborated on this.
> Also, why isn't the user setting the protocol field correctly? Isn't
> that the _real_ source of these problems?
Because the user specifies the value later used for skb->protocol at
either socket(), bind() or sendto() (i.e. flush) stage. Having both
"regular" and VLAN frames in the same TX ring is not possible at least.
> This patch series cannot be applied as is, it's either wrong, or
> explanations are missing from the commit messages.
Hmm. Is it OK to rely on eth_type_trans() setting skb->dev after all?
Depending on that, I would either add a comment or drop the change.
Best wishes, Phil
next prev parent reply other threads:[~2013-08-01 10:35 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-29 16:53 packet_mmap, 802.1Q and bridges Phil Sutter
2013-07-31 17:27 ` Parse ethernet headers in af_packet.c Phil Sutter
2013-07-31 17:27 ` [PATCH 1/3] af_packet: when sending ethernet frames, parse header for skb->protocol Phil Sutter
2013-07-31 17:27 ` [PATCH 2/3] af_packet: fix for sending VLAN frames via packet_mmap Phil Sutter
2013-07-31 17:27 ` [PATCH 3/3] af_packet: simplify VLAN frame check in packet_snd Phil Sutter
2013-08-01 0:30 ` [PATCH 1/3] af_packet: when sending ethernet frames, parse header for skb->protocol David Miller
2013-08-01 10:35 ` Phil Sutter [this message]
2013-08-02 1:12 ` David Miller
2013-08-02 9:37 ` [PATCH v2 " Phil Sutter
2013-08-02 9:37 ` [PATCH v2 2/3] af_packet: fix for sending VLAN frames via packet_mmap Phil Sutter
2013-08-02 9:37 ` [PATCH v2 3/3] af_packet: simplify VLAN frame check in packet_snd Phil Sutter
2013-08-02 21:59 ` David Miller
2013-08-02 21:58 ` [PATCH v2 2/3] af_packet: fix for sending VLAN frames via packet_mmap David Miller
2013-08-02 21:58 ` [PATCH v2 1/3] af_packet: when sending ethernet frames, parse header for skb->protocol David Miller
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