[PATCH] net: Add etun driver

[Roland Dreier]

 > +/*
 > + * The higher levels take care of making this non-reentrant (it's
 > + * called with bh's disabled).
 > + */
 > +static int etun_xmit(struct sk_buff *skb, struct net_device *tx_dev)

You have this comment, but then...

 > +	dev->features		= NETIF_F_FRAGLIST
 > +				  | NETIF_F_HIGHDMA
 > +				  | NETIF_F_LLTX;

you set LLTX, which means that the upper layers _don't_ make sure that
your xmit routine is not reentrant.

It looks like the impact of multiple simultaneous xmit calls is just
the possibility of screwing up the statistics, but still I think you
want to drop the LLTX feature (since you have no lock of your own to
try and take).