Re: Bug: 2.4.0 w/ PCMCIA on ThinkPad: KERNEL: assertion(dev->ip_ptr==NULL)failed at dev.c(2422):netdev_finish_unregister

[Thomas Hood <jdthoodREMOVETHIS@yahoo.co.uk>]

Here is a patch which may not solve the underlying
problem but which does prevent the kernel from 
generating an infinite number of error messages
on "cardctl eject" and from hanging up on shutdown.

----------------------------------------------------
jdthood@thanatos:/usr/src/kernel-source-2.4.1-ac3/net/core# diff dev.c_ORIG dev.c
2558c2558
< 	while (atomic_read(&dev->refcnt) != 1) {
---
> 	while (atomic_read(&dev->refcnt) > 1) {
-----------------------------------------------------

The underlying problem is that refcnt is zero or less
at this point.  This is erroneous.  The error in 
maintaining the refcnt appears to occur only when 
I configure the eth0 interface using pump or dhclient.
Be that as it may, because of the erroneous refcnt,
this while loop loops forever in the original.  As
modified it falls through; and this makes the kernel
usable for me.

I hope the networking gurus can find the real bug.

Thomas Hood

> I have a bit more information about this bug now.
> The message "assertion(yadda) failed ..." occurs only
> if the eth0 interface has been configured using pump
> or dhclient.  If the card isn't connected to the network
> the message never occurs.  If eth0 is merely brought up
> and down using ifconfig the message doesn't occur.  Only
> if pump or dhclient has configured eth0 does the message
> occur.  Sometimes it occurs on "ifdown eth0", sometimes
> on "cardctl eject" and sometimes during the shutdown
> sequence.
> 
> Thomas
> 
> > Dear l-k. 
> > 
> > I'm still having this problem with kernel 2.4.0: 
> > 
> > Conditions: 
> > Linux 2.4.0 compiled on an IBM ThinkPad 600 51U (Pentium II) 
> > laptop with PCMCIA support. Same behavior with integral kernel 
> > PCMCIA, modular kernel PCMCIA and modular Hinds PCMCIA. System 
> > is Progeny Debian beta II. 
> > 
> > I have a Xircom modem/ethernet card which works correctly using 
> > the serial_cs, xirc2ps_cs, ds, i82365 and pcmcia_core modules; 
> > however when I try to "cardctl eject" or "reboot" I get first, 
> >    "KERNEL: assertion(dev->ip_ptr==NULL)failed at 
> >     dev.c(2422):netdev_finish_unregister" 
> > (not exact since I had to copy it down on paper ... doesn't 
> > show up in the logs) then a perpetual series of: 
> >    "unregister_netdevice: waiting for eth0 to become free. 
> >     Usage count = -1" 
> > messages every five seconds or so. "ps -A" reveals that 
> > modprobe is running; it can't be killed even with "kill -9". 
> > The "ifconfig" command locks up. Shutdown won't complete 
> > so I end up having to use SysRq-S-U-B to reboot. 
> > 
> > This problem only occurs if the Xircom card is connected to 
> > the Ethernet (in which case it is configured using DHCP). 
> > If the card is left unconnected to the network, the problem 
> > does not occur---the card can be ejected. 
> > 
> > Thomas Hood 
> > Please cc: your replies to me at jdthood_AT_yahoo.co.uk
>
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