[PATCH/RFC,net-next,v3] net: dec: tulip: de2104x: Add shutdown handler to stop NIC

The driver does not implement a shutdown handler which leads to issues
when using kexec in certain scenarios. The NIC keeps on fetching
descriptors which gets flagged by the IOMMU with errors like this:

DMAR: DMAR:[DMA read] Request device [5e:00.0]fault addr fffff000
DMAR: DMAR:[DMA read] Request device [5e:00.0]fault addr fffff000
DMAR: DMAR:[DMA read] Request device [5e:00.0]fault addr fffff000
DMAR: DMAR:[DMA read] Request device [5e:00.0]fault addr fffff000
DMAR: DMAR:[DMA read] Request device [5e:00.0]fault addr fffff000

Signed-off-by: Moritz Fischer <mdf@kernel.org>
---

I'd consider it a bug-fix but Jakub said it's a feature,
so net-next it is. I don't have a strong preference either way.

Changes from v2:
- Changed to net-next
- Removed extra whitespace

Changes from v1:
- Replace call to de_remove_one with de_shutdown() function
  as suggested by James.

---
 drivers/net/ethernet/dec/tulip/de2104x.c | 8 ++++++++
 1 file changed, 8 insertions(+)

On Fri, 23 Oct 2020 13:28:34 -0700 Moritz Fischer wrote:
> diff --git a/drivers/net/ethernet/dec/tulip/de2104x.c b/drivers/net/ethernet/dec/tulip/de2104x.c
> index d9f6c19940ef..ea7442cc8e75 100644
> --- a/drivers/net/ethernet/dec/tulip/de2104x.c
> +++ b/drivers/net/ethernet/dec/tulip/de2104x.c
> @@ -2175,11 +2175,19 @@ static int __maybe_unused de_resume(struct device *dev_d)
>  
>  static SIMPLE_DEV_PM_OPS(de_pm_ops, de_suspend, de_resume);
>  
> +static void de_shutdown(struct pci_dev *pdev)
> +{
> +	struct net_device *dev = pci_get_drvdata(pdev);
> +
> +	de_close(dev);

Apparently I get all the best ideas when I'm about to apply something..

I don't think you can just call de_close() like that, because 
(a) it may expect rtnl_lock() to be held, and (b) it may not be open.

Perhaps call unregister_netdev(dev) - that'll close the device.
Or rtnl_lock(); dev_close(dev); rtnl_unlock();

> +}
> +
>  static struct pci_driver de_driver = {
>  	.name		= DRV_NAME,
>  	.id_table	= de_pci_tbl,
>  	.probe		= de_init_one,
>  	.remove		= de_remove_one,
> +	.shutdown	= de_shutdown,
>  	.driver.pm	= &de_pm_ops,
>  };
>

Hi Jakub,

On Tue, Oct 27, 2020 at 04:16:06PM -0700, Jakub Kicinski wrote:
> On Fri, 23 Oct 2020 13:28:34 -0700 Moritz Fischer wrote:
> > diff --git a/drivers/net/ethernet/dec/tulip/de2104x.c b/drivers/net/ethernet/dec/tulip/de2104x.c
> > index d9f6c19940ef..ea7442cc8e75 100644
> > --- a/drivers/net/ethernet/dec/tulip/de2104x.c
> > +++ b/drivers/net/ethernet/dec/tulip/de2104x.c
> > @@ -2175,11 +2175,19 @@ static int __maybe_unused de_resume(struct device *dev_d)
> >  
> >  static SIMPLE_DEV_PM_OPS(de_pm_ops, de_suspend, de_resume);
> >  
> > +static void de_shutdown(struct pci_dev *pdev)
> > +{
> > +	struct net_device *dev = pci_get_drvdata(pdev);
> > +
> > +	de_close(dev);
> 
> Apparently I get all the best ideas when I'm about to apply something..

Better now than after =)

> I don't think you can just call de_close() like that, because 
> (a) it may expect rtnl_lock() to be held, and (b) it may not be open.

how about:

rtnl_lock();
if (netif_running(dev))
	dev_close(dev);
rtnl_unlock();

> 
> Perhaps call unregister_netdev(dev) - that'll close the device.
> Or rtnl_lock(); dev_close(dev); rtnl_unlock();
> 
> > +}
> > +
> >  static struct pci_driver de_driver = {
> >  	.name		= DRV_NAME,
> >  	.id_table	= de_pci_tbl,
> >  	.probe		= de_init_one,
> >  	.remove		= de_remove_one,
> > +	.shutdown	= de_shutdown,
> >  	.driver.pm	= &de_pm_ops,
> >  };
> >  
> 

Cheers,
Moritz

On Tue, 27 Oct 2020 18:59:09 -0700 Moritz Fischer wrote:
> Hi Jakub,
> 
> On Tue, Oct 27, 2020 at 04:16:06PM -0700, Jakub Kicinski wrote:
> > On Fri, 23 Oct 2020 13:28:34 -0700 Moritz Fischer wrote:  
> > > diff --git a/drivers/net/ethernet/dec/tulip/de2104x.c b/drivers/net/ethernet/dec/tulip/de2104x.c
> > > index d9f6c19940ef..ea7442cc8e75 100644
> > > --- a/drivers/net/ethernet/dec/tulip/de2104x.c
> > > +++ b/drivers/net/ethernet/dec/tulip/de2104x.c
> > > @@ -2175,11 +2175,19 @@ static int __maybe_unused de_resume(struct device *dev_d)
> > >  
> > >  static SIMPLE_DEV_PM_OPS(de_pm_ops, de_suspend, de_resume);
> > >  
> > > +static void de_shutdown(struct pci_dev *pdev)
> > > +{
> > > +	struct net_device *dev = pci_get_drvdata(pdev);
> > > +
> > > +	de_close(dev);  
> > 
> > Apparently I get all the best ideas when I'm about to apply something..  
> 
> Better now than after =)
> 
> > I don't think you can just call de_close() like that, because 
> > (a) it may expect rtnl_lock() to be held, and (b) it may not be open.  
> 
> how about:
> 
> rtnl_lock();
> if (netif_running(dev))
> 	dev_close(dev);
> rtnl_unlock();

That's fine as well, although dev_close() checks if the device is UP
AFAICT.