lkml.org 
[lkml]   [2020]   [Oct]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.4 25/57] drivers/net/wan/hdlc: Set skb->protocol before transmitting
    Date
    From: Xie He <xie.he.0141@gmail.com>

    [ Upstream commit 9fb030a70431a2a2a1b292dbf0b2f399cc072c16 ]

    This patch sets skb->protocol before transmitting frames on the HDLC
    device, so that a user listening on the HDLC device with an AF_PACKET
    socket will see outgoing frames' sll_protocol field correctly set and
    consistent with that of incoming frames.

    1. Control frames in hdlc_cisco and hdlc_ppp

    When these drivers send control frames, skb->protocol is not set.

    This value should be set to htons(ETH_P_HDLC), because when receiving
    control frames, their skb->protocol is set to htons(ETH_P_HDLC).

    When receiving, hdlc_type_trans in hdlc.h is called, which then calls
    cisco_type_trans or ppp_type_trans. The skb->protocol of control frames
    is set to htons(ETH_P_HDLC) so that the control frames can be received
    by hdlc_rcv in hdlc.c, which calls cisco_rx or ppp_rx to process the
    control frames.

    2. hdlc_fr

    When this driver sends control frames, skb->protocol is set to internal
    values used in this driver.

    When this driver sends data frames (from upper stacked PVC devices),
    skb->protocol is the same as that of the user data packet being sent on
    the upper PVC device (for normal PVC devices), or is htons(ETH_P_802_3)
    (for Ethernet-emulating PVC devices).

    However, skb->protocol for both control frames and data frames should be
    set to htons(ETH_P_HDLC), because when receiving, all frames received on
    the HDLC device will have their skb->protocol set to htons(ETH_P_HDLC).

    When receiving, hdlc_type_trans in hdlc.h is called, and because this
    driver doesn't provide a type_trans function in struct hdlc_proto,
    all frames will have their skb->protocol set to htons(ETH_P_HDLC).
    The frames are then received by hdlc_rcv in hdlc.c, which calls fr_rx
    to process the frames (control frames are consumed and data frames
    are re-received on upper PVC devices).

    Cc: Krzysztof Halasa <khc@pm.waw.pl>
    Signed-off-by: Xie He <xie.he.0141@gmail.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/net/wan/hdlc_cisco.c | 1 +
    drivers/net/wan/hdlc_fr.c | 3 +++
    drivers/net/wan/hdlc_ppp.c | 1 +
    3 files changed, 5 insertions(+)

    diff --git a/drivers/net/wan/hdlc_cisco.c b/drivers/net/wan/hdlc_cisco.c
    index cc33441af4691..50804d0473083 100644
    --- a/drivers/net/wan/hdlc_cisco.c
    +++ b/drivers/net/wan/hdlc_cisco.c
    @@ -118,6 +118,7 @@ static void cisco_keepalive_send(struct net_device *dev, u32 type,
    skb_put(skb, sizeof(struct cisco_packet));
    skb->priority = TC_PRIO_CONTROL;
    skb->dev = dev;
    + skb->protocol = htons(ETH_P_HDLC);
    skb_reset_network_header(skb);

    dev_queue_xmit(skb);
    diff --git a/drivers/net/wan/hdlc_fr.c b/drivers/net/wan/hdlc_fr.c
    index 12b35404cd8e7..d6cfd51613ed8 100644
    --- a/drivers/net/wan/hdlc_fr.c
    +++ b/drivers/net/wan/hdlc_fr.c
    @@ -433,6 +433,8 @@ static netdev_tx_t pvc_xmit(struct sk_buff *skb, struct net_device *dev)
    if (pvc->state.fecn) /* TX Congestion counter */
    dev->stats.tx_compressed++;
    skb->dev = pvc->frad;
    + skb->protocol = htons(ETH_P_HDLC);
    + skb_reset_network_header(skb);
    dev_queue_xmit(skb);
    return NETDEV_TX_OK;
    }
    @@ -555,6 +557,7 @@ static void fr_lmi_send(struct net_device *dev, int fullrep)
    skb_put(skb, i);
    skb->priority = TC_PRIO_CONTROL;
    skb->dev = dev;
    + skb->protocol = htons(ETH_P_HDLC);
    skb_reset_network_header(skb);

    dev_queue_xmit(skb);
    diff --git a/drivers/net/wan/hdlc_ppp.c b/drivers/net/wan/hdlc_ppp.c
    index 16f33d1ffbfb9..64f8556513369 100644
    --- a/drivers/net/wan/hdlc_ppp.c
    +++ b/drivers/net/wan/hdlc_ppp.c
    @@ -251,6 +251,7 @@ static void ppp_tx_cp(struct net_device *dev, u16 pid, u8 code,

    skb->priority = TC_PRIO_CONTROL;
    skb->dev = dev;
    + skb->protocol = htons(ETH_P_HDLC);
    skb_reset_network_header(skb);
    skb_queue_tail(&tx_queue, skb);
    }
    --
    2.25.1


    \
     
     \ /
      Last update: 2020-10-05 17:30    [W:2.947 / U:0.108 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site