Re: locking against myself panic (cprng_strongreseed, filt_rndread)

[Taylor R Campbell <campbell+netbsd-tech-kern%mumble.net@localhost>]

> Date: Tue, 7 Nov 2017 22:58:39 +0100
> From: Edgar Fuß <ef%math.uni-bonn.de@localhost>
> 
> I got the following panic on a mostly idle 6.1/amd64:
> 
> Mutex error: mutex_vector_enter: locking against myself
> 
> and then the machine got stuck. It's a development server, so I can
> leave it stuck until tomorrow in case someone wants me to examine
> anything in particular.

Also, no need to keep it around for diagnostics; it's clear what the
lock recursion is: cprng_strong_reseed acquires c->mtx and calls
selnotify, which calls filt_rndread, which calls cprng_strong_ready,
which tries to recursively acquire c->mtx.