netdev - Re: [PATCH net-next] tg3: Prevent system hang during repeated EEH errors.

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Date:	Mon, 17 Jun 2013 11:59:12 -0700
From:	"Michael Chan" <mchan@...adcom.com>
To:	"Benjamin Poirier" <benjamin.poirier@...il.com>
cc:	"Nithin Nayak Sujir" <nsujir@...adcom.com>, davem@...emloft.net,
	netdev@...r.kernel.org
Subject: Re: [PATCH net-next] tg3: Prevent system hang during repeated
 EEH errors.

On Mon, 2013-06-17 at 14:28 -0400, Benjamin Poirier wrote: 
> On 2013/06/14 14:15, Nithin Nayak Sujir wrote:
> [...]
> > @@ -17796,6 +17799,10 @@ static pci_ers_result_t tg3_io_slot_reset(struct pci_dev *pdev)
> >  	rc = PCI_ERS_RESULT_RECOVERED;
> >  
> >  done:
> > +	if (rc != PCI_ERS_RESULT_RECOVERED && netif_running(netdev)) {
> > +		tg3_napi_enable(tp);
> > +		dev_close(netdev);
> > +	}
> >  	rtnl_unlock();
> >  
> >  	return rc;
> > @@ -17826,6 +17833,8 @@ static void tg3_io_resume(struct pci_dev *pdev)
> >  	if (err) {
> >  		tg3_full_unlock(tp);
> >  		netdev_err(netdev, "Cannot restart hardware after reset.\n");
> > +		tg3_napi_enable(tp);
> > +		dev_close(netdev);
> >  		goto done;
> >  	}
> 
> Are these two hunks needed?
> 1) These functions do not call tg3_netif_stop() or tg3_napi_disable()
> 2) an error in tg3_io_resume() does not trigger device removal in
> handle_eeh_events(). In fact the ->resume callback has no return value.
> 

The normal sequence is:

error_detected(), slot_reset(), resume()

In error_detected(), chip will be shutdown and NAPI will be disabled if
netif_running state is true.  When everything works correctly, the chip
will be re-enabled in resume() and NAPI re-enabled.  If we run into any
error in this sequence, the sequence will not complete normally.  In
this case, if netif_running state is true, we know that the NAPI state
has been disabled earlier in error_detected(), and we need to properly
close the device.




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