cvs commit: src/sys/dev/re if_re.c

[John Baldwin]

On Thursday 18 August 2005 03:58 pm, Maxim Sobolev wrote:
> John Baldwin wrote:
> >>Well, see kern/85005. IMO some generic approach should be worked out and
> >>implemented since I think many other network drivers may be affected by
> >>the same problem.
> >
> > I've still yet to see what the real panic is.  For one thing, if the
> > foo_stop method does its jobs, the ethernet hardware shouldn't be
> > generating interrupts.  The stop method should be shutting the card down
> > (i.e. turning off the receiver and transmitter for example).  Is your
> > ethernet driver sharing an interrupt with another device and the other
> > device is
>
> Yes, this is the case here. It shares interrupt with IDE controller.
> Panic happens in the re_rxeof() when the driver tries to dereference
> sc->rl_ldata.rl_rx_mbuf[i], which has already been deallocated in the
> re_stop().

Ok.

> > interrupting?  In that case, the ethernet driver would have the same
> > panic if you did an 'ifconfig foo0 down' and then the other device
> > interrupted.  So, I
>
> No, I don't think it would since 'ifconfig foo0 down' resets IFF_UPP.

Ah, yes.

> > think clearing IFF_UPP in foo_shutdown() is wrong.  foo_stop() should
> > really be sufficient, and foo_intr() should be able to handle a spurious
> > interrupt while the interface is stopped without panicing since it
> > already needs to do so to handle the shared interrupt case.
>
> Apparently it doesn't handle it, which has been probably masked by the
> IFF_UPP check in the re_intr(), so that this problem only happened at
> shutdown, when IFF_UPP isn't cleared after re_stop().

Right.  I think the better fix is for the driver to check the flag it manages 
and knows about (IFF_DRV_RUNNING) rather than IFF_UP in its interrupt handler 
and to revert the change to re_shutdown().  The vr(4) driver should probably 
be similarly fixed (check RUNNING in interrupt handler and just call stop in 
its shutdown method).

-- 
John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org