Messages in this thread | | | Date | Mon, 13 Jan 2020 05:44:21 -0800 | From | Jakub Kicinski <> | Subject | Re: [PATCH 2/2] wan/hdlc_x25: fix skb handling |
| |
On Mon, 13 Jan 2020 13:45:51 +0100, Martin Schiller wrote: > o call skb_reset_network_header() before hdlc->xmit() > o change skb proto to HDLC (0x0019) before hdlc->xmit() > o call dev_queue_xmit_nit() before hdlc->xmit() > > This changes make it possible to trace (tcpdump) outgoing layer2 > (ETH_P_HDLC) packets > > o use a copy of the skb for lapb_data_request() in x25_xmit()
It's not clear to me why
> This fixes the problem, that tracing layer3 (ETH_P_X25) packets > results in a malformed first byte of the packets. > > Signed-off-by: Martin Schiller <ms@dev.tdt.de> > --- > drivers/net/wan/hdlc_x25.c | 15 +++++++++++---- > 1 file changed, 11 insertions(+), 4 deletions(-) > > diff --git a/drivers/net/wan/hdlc_x25.c b/drivers/net/wan/hdlc_x25.c > index b28051eba736..434e5263eddf 100644 > --- a/drivers/net/wan/hdlc_x25.c > +++ b/drivers/net/wan/hdlc_x25.c > @@ -72,6 +72,7 @@ static int x25_data_indication(struct net_device *dev, struct sk_buff *skb) > unsigned char *ptr; > > skb_push(skb, 1); > + skb_reset_network_header(skb); > > if (skb_cow(skb, 1))
This skb_cow() here is for the next handler down to have a 1 byte of headroom guaranteed? It'd seem more natural to have skb_cow before the push.. not that it's related to your patch.
> return NET_RX_DROP; > @@ -88,6 +89,9 @@ static int x25_data_indication(struct net_device *dev, struct sk_buff *skb) > static void x25_data_transmit(struct net_device *dev, struct sk_buff *skb) > { > hdlc_device *hdlc = dev_to_hdlc(dev);
Please insert a new line after the variable declaration since you're touching this one.
> + skb_reset_network_header(skb); > + skb->protocol = hdlc_type_trans(skb, dev); > + dev_queue_xmit_nit(skb, dev); > hdlc->xmit(skb, dev); /* Ignore return value :-( */ > } >
| |