Issue with epoch_drain_callbacks and unloading iavf(4) [using iflib]

[Eric Joyner]

On Mon, Apr 6, 2020 at 2:29 PM Mark Johnston <markj at freebsd.org> wrote:

> On Mon, Apr 06, 2020 at 02:19:25PM -0700, Eric Joyner wrote:
> > Mark,
> >
> > I think I was mistaken about the backtrace looking the same. I was
> looking
> > at it from within ddb, and I think I focused on the
> > epoch_block_handler_preempt line and didn't notice that it only stopped
> > there this time. Here's the new one I've got from kgdb:
>
> Thanks.  Could you try to print "td->td_name" from frame 4?  It should
> also be available as er->er_blockedtd.  Basically, I'm trying to verify
> that the interrupt thread itself isn't the one that we're waiting for,
> else there is another bug to be fixed.
>
> If you can provide kernel symbols and vmcore, I'd be happy to look at it
> myself.
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Here's what I get:

(kgdb) frame 4
#4  epoch_block_handler_preempt (global=0xfffff80003de0100,
cr=0xfffffe00dee85900, arg=0x0) at /usr/src/sys/kern/subr_epoch.c:507
507     }
(kgdb) print td->td_name
$1 = "if_io_tqg_31\000\000\000\000\000\000\000"
(kgdb) print er->er_blockedtd
$2 = (struct thread *) 0x0

- Eric