Re: if_txtimer API to replace (*if_watchdog)()

[Jason Thorpe <thorpej%me.com@localhost>]

> On Jan 23, 2020, at 6:28 AM, Jason Thorpe <thorpej%me.com@localhost> wrote:
> 
>> We need to teach if_txtimer_tick not to call callout_schedule
>> somehow on destruction, otherwise if_txtimer_tick can continue
>> to run even after calling callout_halt.  wm avoids the flaw by
>> checking sc_core_stopping at the beginning of wm_tick.
> 
> This is a general problem in all drivers that use callouts, and if_txtimer_tick() doesn't really make it any worse than existing drivers that use tick callouts themselves.  I think even wm(4)'s approach has a problem in the detach case.  I have some thoughts on how to solve this problem generally, and will attack this problem at a future time.

Oh!  I just realized that I missed the point you were making here.  I see what you mean now, and I will address it.  But my other statements about callouts is also true :-)

-- thorpej