Re: call for bge(4) testers

On Wed, Aug 23, 2006 at 04:40:35PM +0400, Oleg Bulyzhin wrote:
> On Wed, Aug 23, 2006 at 09:55:54AM +0900, Pyun YongHyeon wrote:
> > On Wed, Aug 23, 2006 at 12:43:42AM +0400, Oleg Bulyzhin wrote:
> >  > On Tue, Aug 22, 2006 at 02:44:34PM +0200, Michael Reifenberger wrote:
> >  > > On Tue, 22 Aug 2006, Pyun YongHyeon wrote:
> >  > > ...
> >  > > >I'm not familiar with vge(4) and don't have hardwares supported by
> >  > > >vge(4). Because vge(4) supports a kind of interrupt moderation, there
> >  > > >is a possiblity to have the same issue seen on em(4).
> >  > > >If you want my blind patch I can send a patch for you.
> >  > > >
> >  > > Yes, please!
> >  > > I can test it (on RELENG_6 though).
> >  > 
> >  > I have an idea why those timeouts can happen. Could you please test
> >  > attached patch? It may help (or may not). Anyway would be fine
> >  > to know results.
> >  > 
> > 
> > Since vge(4) uses MTX_RECURSE mutex and miibus(4) handler is
> > protected with the mutex I guess it wouldn't help much.
> > I guess it needs a seperate mutex to protect miibus(4) handler
> > and should remove the use of MTX_RECURSE.
> 
> Hmm.
> 1) _ifmedia_upd() & _ifmedia_sts() functions are not called from mii layer.
> 2) As i can see MII layer is not protected by anything, unless you
> specially acquire driver lock prior to calling mii_ function.
> Locking ifmedia callbacks should be done (though, it may not help
> with watchdogs timeout), otherwise we have race on accessing PHY registers.
> (kern/98738).
> 
> As i can see, random watchdog timeouts was reported for em, bge, vge, sk
> (and maybe others, those ones which i remember) drivers.
> All of them has unlocked _ifmedia_ functions.
> 
> My idea was: perhaps, under certain condition, concurrent access to PHY could
> lead to hardware deadlock.
> 
> 
> > vge(4) also has a bug
> > if mbuf chain is too long(7 or higher) and defragmentation with
> > m_defrag(9) fails it would access an invalid mbuf chain.
> > All these requires lots of work and need a real hardware.
> > Oleg, if you have hardware, would you fix it?
> 
> Unfortunately i don't have vge hardware.
> > 
> > -- 
> > Regards,
> > Pyun YongHyeon
> 
> -- 
> Oleg.
> 

Forgot one thing: i think we need no dedicated mutex for mii layer if we lock
ifmedia callbacks.

-- 
Oleg.