Re: smr inp breaks some jail use cases and panics with i915kms don't switch to the console anymore

On 12/13, Gleb Smirnoff wrote:
> On Mon, Dec 13, 2021 at 11:56:35AM -0800, John Baldwin wrote:
> J> > J> So there are two things here.  The root issue is that the devel/apr1 port
> J> > J> runs a configure test for TCP_NDELAY being inherited by accepted sockets.
> J> > J> This test panics because prison_check_ip4() tries to lock a prison mutex
> J> > J> to walk the IPs assigned to a jail, but the caller (in_pcblookup_hash()) has
> J> > J> done an smr_enter() which is a critical_enter():
> J> > 
> J> > The first one is known, and I got a patch to fix it:
> J> > 
> J> > https://reviews.freebsd.org/D33340
> J> > 
> J> > However, a pre-requisite to this simple patch is more complex:
> J> > 
> J> > https://reviews.freebsd.org/D33339
> J> > 
> J> > There is some discussion on how to improve that, and I decided to do that
> J> > rather than stick to original version. So I takes a few extra days.
> J> > 
> J> > We could push D33340 into main, if the negative effects (raciness of
> J> > the prison check) is considered lesser evil then potentially contested
> J> > mtx_lock in smr section.
> J> 
> J> I think raciness is probably better than always panicking as it does today.
> 
> AFAIK, today it will always panic only with WITNESS. Without WITNESS it would
> pass through mtx_lock as long as the mutex is not locked.
> 
> So, do you suggest to push D33340 before finalizing D33339?

It panics with GENERIC so I'd suggest to push D33340 or backout it
temprorary until D33339 is solved.