Re: [PATCH net] qmi_wwan: Clone the skb when in pass-through mode

[Kristian Evensen <kristian.evensen@gmail.com>]

Hi Bjørn,

On Mon, Jun 14, 2021 at 4:46 PM Bjørn Mork <bjorn@mork.no> wrote:
> Thanks for pointing this out.  But it still looks strange to me.  Why do
> we call netif_rx(skb) here instead of just returning 1 and leave that
> for usbnet_skb_return()?  With cloning we end up doing eth_type_trans()
> on the duplicate - is that wise?

Thanks for pointing this out. You are right and looking at the code
again, we should end up in usbnet_skb_return() if the call to netif_rx
is succesful. I do agree that calling netif_rx() is a bit strange,
considering that usbnet_skb_return() already calls this function.
Perhaps the issue is that we end up calling netif_rx() on the same skb
twice? rmnet also frees the skb when done with the de-aggregation.

I will do some more testing tomorrow and see if I can figure out
something. So far, the only thing I know is that if I try to perform a
more demanding transfer (like downloading a file) using qmi_wwan +
rmnet then I get a kernel oops immediatly.

Kristian