Re: Routing loops & TTL tracking with tunnel devices

[Jason A. Donenfeld]

On Mon, Nov 16, 2015 at 11:25 PM, Hannes Frederic Sowa
<hannes@xxxxxxxxxxxxxxxxxxx> wrote:
> Have a look at __dev_queue_xmit and the per_cpu recursion limits
> implemented there:
>
>                         if (__this_cpu_read(xmit_recursion) >
>                         RECURSION_LIMIT)
>                                 goto recursion_alert;

Ahh, thanks for pointing that out. So this works with virtual devices
with no queue. As of some recent changes, that now applies to what I'm
doing.

Unfortunately, I get a complete hard crash, with the blinking
keyboard. The only thing written to serial before it dies is:
[  171.347446] Dead loop on virtual device wg0, fix it urgently!
This means it did hit that recursion condition, which is good.
I assume the recursion limit is just too high, and this has something
to do with me overflowing the stack. I'll test this hypothesis and see
if I can add a similar check inside my driver to make it lower. If
this works, I'm satisfied.

Thanks a lot for the pointer here.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/