Re: ndis(4) patch to replace obsolete if_watchdog interface

On Thu, 2008-05-29 at 23:01 -0700, Andrew Thompson wrote:
> On Thu, May 29, 2008 at 07:45:31PM -0400, Coleman Kane wrote:
> > On Thu, 2008-05-29 at 14:46 -0700, Andrew Thompson wrote:
> > > On Thu, May 29, 2008 at 04:41:32PM -0400, Coleman Kane wrote:
> > > > Hi,
> > > > 
> > > > I just replaced the obsoleted if_watchdog interface in ndis(4) with a
> > > > local implementation. This should remove the obnoxious warning message
> > > > on device init. Anyone using -CURRENT with an ndis card, could you send
> > > > me success/fails?
> > > > 
> > > > The patch is here:
> > > >   * http://people.freebsd.org/~cokane/patches/if_ndis-new_wd.patch
> > > 
> > > 
> > > This works different to the rest of the network drivers. The existing
> > > drivers use a callout tick that runs while the driver is up and an
> > > integer counter.
> > > 
> > >  if (x && --x == 0)
> > > 	 ...timeout...
> > > 
> > > You arm the callout and stop it after each Tx, does this have any
> > > perfornace impact?
> > > 
> > > 
> > > Andrew
> > > 
> > 
> > I am attaching a new patch, where I use the method that you suggested
> > and do away with the extra callout for the watchdog. A "tick" function
> > was already implemented for timeouts related to the NDIS systems.
> > 
> > I am not sure if the ndis-timeout code using ndis_stat_callout
> > duplicates the if_watchdog code (and what I replaced it with), but I
> > don't think so as both were implemented side-by-side before...
> > 
> 
> A few comments inline
> 
> >diff --git a/sys/dev/if_ndis/if_ndis.c b/sys/dev/if_ndis/if_ndis.c
> >+	NDIS_LOCK(sc);
> >+	if(sc->ndis_timer_countdown &&
> >+	    (sc->ndis_timer_countdown -=
> >+	    sc->ndis_block->nmb_checkforhangsecs) < 1) {
> >+		sc->ndis_timer_countdown = 0;
> >+		NDIS_UNLOCK(sc);
> >+		ndis_watchdog(xsc);
> >+	} else {
> >+		NDIS_UNLOCK(sc);
> >+	}
> 
> I think this is harder than it needs to be. It locks, unlocks, and then
> locks again in ndis_watchdog. I have attached a version of this diff
> that nukes ndis_watchdog() and just merges the code. Its also a pain to
> use nmb_checkforhangsecs for the timer period, the ndis driver blob can
> set this to whatever it desires and it could be far greater than the
> watchdog period of 5 secs.
> 
> I introduced two counters, ndis_tx_timer and ndis_hang_timer, that allow
> these events to be independent of each other.
> 
> > 	return;
> > }
> > 
> >_at__at_ -1888,7 +1904,9 _at__at_ ndis_start(ifp)
> > 	/*
> > 	 * Set a timeout in case the chip goes out to lunch.
> > 	 */
> >-	ifp->if_timer = 5;
> >+	if(sc->ndis_timer_countdown == 0) {
> >+		sc->ndis_timer_countdown = 5;
> >+	}
> 
> This isnt right. The timer doesnt need to expire in order to be reset,
> it should just set it each time. Otherwise if the timer is at 1 and the
> callout is _just_ about to fire then you will get a false watchdog
> timeout.
> 
> 
> 
> cheers,
> Andrew

Thanks this has all been very helpful. I'll test this out today and let
you know how it goes.

-- 
Coleman Kane