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authorXie He <xie.he.0141@gmail.com>2020-09-16 14:25:07 -0700
committerDavid S. Miller <davem@davemloft.net>2020-09-17 16:41:12 -0700
commit9fb030a70431a2a2a1b292dbf0b2f399cc072c16 (patch)
treefcf4a81b50210f9b8c3eb120b7ca84d7833f9706 /drivers/net/wan/hdlc_ppp.c
parent83f9a9c8c1edc222846dc1bde6e3479703e8e5a3 (diff)
drivers/net/wan/hdlc: Set skb->protocol before transmitting
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>
Diffstat (limited to 'drivers/net/wan/hdlc_ppp.c')
-rw-r--r--drivers/net/wan/hdlc_ppp.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/net/wan/hdlc_ppp.c b/drivers/net/wan/hdlc_ppp.c
index 16f33d1ffbfb..64f855651336 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);
}