Hi Alex,
On ti, 2014-12-09 at 12:52 +0100, Alexander Aring wrote:
> Hi Jukka,
>
> On Tue, Dec 09, 2014 at 01:28:16PM +0200, Jukka Rissanen wrote:
> > Hi Alex,
> >
> > the module unloading caused some issues in the receiving end.
> >
> > I tried this:
> > * setup bluetooth 6lowpan connection
> > * transfer some UDP data
> > * unload the nhc_rfc6282_udp module (in one peer only, the other still
> > had udp nhc module loaded)
> > * try to send more data
> >
> > This caused kernel crash in peer that had udp module unloaded:
> >
> >
>
> mhh, okay. I don't know why this happens also the log gave me not much
> information, but thanks anyway.
>
> Maybe this is a global issue with bluetooth 6LoWPAN error handling.
>
> Can you simple do something like this:
>
> diff --git a/net/6lowpan/iphc.c b/net/6lowpan/iphc.c
> index 32ffec6..2228dce 100644
> --- a/net/6lowpan/iphc.c
> +++ b/net/6lowpan/iphc.c
> @@ -425,6 +425,8 @@ lowpan_header_decompress(struct sk_buff *skb, struct net_device *dev,
> return -EINVAL;
> }
>
> + return -EINVAL;
> +
> /* UDP data uncompression */
> if (iphc0 & LOWPAN_IPHC_NH_C) {
> struct udphdr uh;
>
>
> based on current bluetooth-next/master without the NHC framework.
>
> This should be working, maybe you never hit any error while calling
> lowpan_header_decompress function. It's simple testing the error
> handling not more.
Hmm, I get the same crash here also without this patchset. So something
goes wrong if <0 code is returned.
>
> Do this please on one node, the other node should send some 6LoWPAN IPHC
> packets to check if the error handling working there.
>
>
>
>
>
> Another issue is that I see that skb->dev isn't set before calling
> lowpan_header_decompress. Because inside your log is a "NULL":
>
> (NULL net_device): received unknown nhc id which was not found.
>
> Can you change that? That skb->dev is set to before calling
> lowpan_header_decompress.
I am setting the skb->dev after the call to lowpan_header_decompress().
And anyway the skb->dev is only used when printing the err.
Actually should we replace the skb->dev in lowpan_header_decompress()
with plain dev as that is given to the function as a parameter.
>
>
> btw: 802154 has also issues with that the dev is a wpan interface but
> should be a lowpan interface. It's a complicated issue because we
> support more than one lowpan interface at the same time for _one_ wpan
> interface. I will change that later because this has not any useful usecase
> at the moment. The new behaviour is then _one_ wpan interface -> _one_ lowpan
> interface.
>
> First we need to know if global error handling is working there. Another
> solution for the NULL string would be "don't using netdev_foo printouts,
> but then nobody knows which interface has this issue.
>
> - Alex
Cheers,
Jukka
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