iflib: Prevent watchdog from resetting idle queues

[piotr.pietruszewski_intel.com]

Summary

While changing link state in iflib_link_state_change(), queues are
marked as IFLIB_QUEUE_IDLE to disable watchdog. Currently, iflib_timer()
watchdog does not check for previous queue status before marking it as
IFLIB_QUEUE_HUNG.

This patch adds check of queue status before marking it as hung.

Signed-off-by: Piotr Pietruszewski <[e-mail]>

[gallatin]

I'm not sure, but I think the only way this can happen is when the link is down. Is that the caee here?

[krzysztof.galazka_intel.com]

In D21712#473977, @gallatin wrote:

I'm not sure, but I think the only way this can happen is when the link is down. Is that the caee here?

Yes. We discovered that while investigating this PR: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=239240

[gallatin]

Would it make sense then to assert that the link is down?

[erj]

In D21712#474097, @gallatin wrote:

Would it make sense then to assert that the link is down?

Could you clarify on what you mean by that? Did you mean have a check for when the link is down, or an actual kernel assert? I think some of us internally were confused about what you meant.

[gallatin]

Yes, I meant adding a KASSERT or at least a comment.

[egypcio]

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=236724#c20 + https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=236724#c21

[piotr.pietruszewski_intel.com]

Add KASSERT check

[egypcio]

In D21712#500570, @piotr.pietruszewski_intel.com wrote:

Add KASSERT check

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=236724#c32