callout_stop; callout_destroy

[coypu%sdf.org@localhost]

Hi,

callout(9) says:

callout_destroy() destroys the callout, preventing further use.
...   The callout should be stopped before callout_destroy() is
called by calling callout_halt().  Note that callout_stop()
shouldn't be used for this purpose.

Some users use callout_stop:

./dev/usb/if_run.c

Also, some code does this:
./netbt/hci_link.c:     callout_stop(&link->hl_expire);
./netbt/hci_link.c-     if (callout_invoking(&link->hl_expire))
./netbt/hci_link.c-             return;
./netbt/hci_link.c-
./netbt/hci_link.c-     callout_destroy(&link->hl_expire);

I am not sure this is wrong.

Other code seems odd, e.g. agr does:

agrtimer_stop(sc); (callout_stop)
(*sc->sc_iftop->iftop_dtor)(sc);

carp:

    887 	if_detach(ifp); (carpdetach -> callout_stop)
    888 	callout_destroy(&sc->sc_ad_tmo);

So, this is common and non-obvious.
(Maybe not a big deal with few things being MPSAFE?)

- Can I blindly change run(4) to callout_halt?
- If it's a big deal, maybe add a flag CALLOUT_UNHALTED*
  remove on _halt, and assert it's removed on _destroy?

* with better name