Hello.

[CC David Palma and Rabi Narayan Sahoo]

On 02.07.2018 22:32, Alexander Aring wrote:
> This patch fixes patch add handling to take care tail and headroom for
> single 6lowpan frames. We need to be sure we have a skb with the right
> head and tailroom for single frames. This patch do it by using
> skb_copy_expand() if head and tailroom is not enough allocated by upper
> layer.
> 
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=195059
> Reported-by: David Palma <david.pa...@ntnu.no>
> Reported-by: Rabi Narayan Sahoo <rabinarayans0...@gmail.com>
> Signed-off-by: Alexander Aring <ar...@mojatatu.com>

David, Rabi and you please test these two patches and verify that it
fixes the problems you have?

regards
Stefan Schmidt

> ---
>  net/ieee802154/6lowpan/tx.c | 21 ++++++++++++++++++---
>  1 file changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/net/ieee802154/6lowpan/tx.c b/net/ieee802154/6lowpan/tx.c
> index e6ff5128e61a..d0c4d220de08 100644
> --- a/net/ieee802154/6lowpan/tx.c
> +++ b/net/ieee802154/6lowpan/tx.c
> @@ -265,9 +265,24 @@ netdev_tx_t lowpan_xmit(struct sk_buff *skb, struct 
> net_device *ldev)
>       /* We must take a copy of the skb before we modify/replace the ipv6
>        * header as the header could be used elsewhere
>        */
> -     skb = skb_unshare(skb, GFP_ATOMIC);
> -     if (!skb)
> -             return NET_XMIT_DROP;
> +     if (unlikely(skb_headroom(skb) < ldev->needed_headroom ||
> +                  skb_tailroom(skb) < ldev->needed_tailroom)) {
> +             struct sk_buff *nskb;
> +
> +             nskb = skb_copy_expand(skb, ldev->needed_headroom,
> +                                    ldev->needed_tailroom, GFP_ATOMIC);
> +             if (likely(skb)) {
> +                     consume_skb(skb);
> +                     skb = nskb;
> +             } else {
> +                     kfree_skb(skb);
> +                     return NET_XMIT_DROP;
> +             }
> +     } else {
> +             skb = skb_unshare(skb, GFP_ATOMIC);
> +             if (!skb)
> +                     return NET_XMIT_DROP;
> +     }
>  
>       ret = lowpan_header(skb, ldev, &dgram_size, &dgram_offset);
>       if (ret < 0) {
> 

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