Re: netconsole system freeze when cable unplugged

[Simon Arlott]

On 10/03/07 13:38, Andi Kleen wrote:
> Simon Arlott <simon@xxxxxxxxxxx> writes:
>
> > On 09/03/07 20:42, Francois Romieu wrote:
> > > Simon Arlott <simon@xxxxxxxxxxx> :
> > > > When I unplug the cable the system just stops responding to
> > > > anything, at all. No message is printed to the console when the
> > > > cable is plugged back in.
> > > rtl8139_interrupt (spin_lock(&tp->lock))
> > > -> rtl8139_weird_interrupt
> > >    -> rtl_check_media
> > >       -> mii_check_media (printk(KERN_INFO "%s: link down\n", ...))
> > >          [netpoll stuff here]
> > >          -> rtl8139_poll_controller
> > >             -> rtl8139_interrupt
> > >                *deadlock*
> > > See below for my random stuff of the day. Feel free to open a PR at
> > > bugzilla.kernel.org if the issue does not go away.
> > The patch doesn't fix it, nothing changes. I'm not sure how this can
> > be debugged if printk won't work...
>
> earlyprintk can be called directly (early_printk()) and should
> work. It won't log over the network of course.

It also won't log over the serial console either :(
(but that's probably a good thing, it's slow enough to boot with tons 
of messages to the display because of netconsole and nfs).

rtl8139_interrupt
-> spin_lock(&tp->lock)
-> rtl8139_weird_interrupt
  -> rtl_check_media
     -> mii_check_media
        -> printk(KERN_INFO "%s: link down\n", ...)
           -> wite_msg
              -> local_irq_save
              -> netpoll_send_udp
                 -> netpoll_send_skb
                    -> local_irq_save
                    -> dev->hard_start_xmit(..., ...)
rtl8139_start_xmit
-> spin_lock_irqsave
  *deadlock*

--
Simon Arlott
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