panic on invalid ifp pointer in iflib drivers

[Keller, Jacob E]

> -----Original Message-----
> From: John Baldwin <jhb at FreeBSD.org>
> Sent: Thursday, October 17, 2019 4:34 PM
> To: Keller, Jacob E <jacob.e.keller at intel.com>; freebsd-net at freebsd.org
> Cc: shurd at llnw.com; Joyner, Eric <eric.joyner at intel.com>
> Subject: Re: panic on invalid ifp pointer in iflib drivers
> 
> On 10/17/19 4:22 PM, Keller, Jacob E wrote:
> > Hmm.. now that I look at that more closely I think it's a separate issue.
> 
> This may just be the rcvif issue where we don't reference count the ifp we
> store in rcvif in mbufs?  That was my reaction to your first e-mail except
> that you said it wasn't reproducible on some other drivers.  I wonder if
> other drivers would also provoke this if you just ran them in a detach/attach
> loop long enough.
> 

This is almost certainly the rcvif issue based on where it panics.

I never saw this panic before. I 've also only reproduced it on a kernel with INVARIANTS and memguard set to ifnet.

Thanks,
Jake