linux-kernel - Re: [PATCH net-next v4 4/5] net: hdlc_fr: Do skb_reset_mac_header for skbs received on normal PVC devices

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Message-ID: <CAJht_EPscUkmcgidk5sGAO4K1iVeqDpBRDy75RQ+s0OKK3mB8Q@mail.gmail.com>
Date:   Fri, 30 Oct 2020 14:49:05 -0700
From:   Xie He <xie.he.0141@...il.com>
To:     Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc:     Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Network Development <netdev@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Krzysztof Halasa <khc@...waw.pl>
Subject: Re: [PATCH net-next v4 4/5] net: hdlc_fr: Do skb_reset_mac_header for
 skbs received on normal PVC devices

On Fri, Oct 30, 2020 at 2:28 PM Willem de Bruijn
<willemdebruijn.kernel@...il.com> wrote:
>
> Yes, it might require holding off the other patches until net is
> merged into net-next.
>
> Packet sockets are likely not the only way these packets are received?
> It changes mac_len as computed in __netif_receive_skb_core.

I looked at __netif_receive_skb_core. I didn't see it computing mac_len?

I thought only AF_PACKET/RAW sockets would need this information
because other upper layers would not care about what happened in L2.

I see mac_len is computed in netif_receive_generic_xdp. I'm not clear
about the reason why it calculates it. But it seems that it considers
the L2 header as an Ethernet header, which is incorrect for this
driver.

> If there is no real bug that is fixed, net-next is fine.