[patch] natsemi: fix oops, link back netdevice from private-struct

[Ingo Molnar <mingo@elte.hu>]

* Andrew Nelless <andrew@nelless.net> wrote:

> Hi,
> 
> I booted up 2.6.24-rc1 this morning [Real early over a brew ;-)] and 
> was having a problems with multiple ~5 second hangs on SATA/drive init 
> (Something to do with "EH" something-or-other and resets but I'll 
> email in separately about it later unless its fixed by the time I get 
> the chance).
> 
> Anyway, I went to fire up netconsole to get a decent log dump and hit 
> across the following nasty. Netconsole works fine in 2.6.23.1 with a 
> similar config and the same kernel parameters.
> 
> A shot of the screen is the only method I could come up with to 
> capture the log, I hope that is OK, it is pretty readable.
> 
> 
> The nasty: 
> http://andotnet.nfshost.com/linux/2.6.24-rc1-netconsole-nullderef.jpg


the NULL dereference is here:

 (gdb) list *0xffffffff804a9504
 0xffffffff804a9504 is in natsemi_poll (drivers/net/natsemi.c:717).
 712             return count;
 713     }
 714
 715     static inline void __iomem *ns_ioaddr(struct net_device *dev)
 716     {
 717             return (void __iomem *) dev->base_addr;
 718     }
 719

which is this code from natsemi.c:

 2227            struct net_device *dev = np->dev;
 2228            void __iomem * ioaddr = ns_ioaddr(dev);
 2229            int work_done = 0;

seems like the NAPI changes in -rc1 added an np->dev field but forgot to 
initialize it ...

does the patch below fix the oops for you?

	Ingo

-------------------->
Subject: natsemi: fix oops, link back netdevice from private-struct
From: Ingo Molnar <mingo@elte.hu>

this commit:

  commit bea3348eef27e6044b6161fd04c3152215f96411
  Author: Stephen Hemminger <shemminger@linux-foundation.org>
  Date:   Wed Oct 3 16:41:36 2007 -0700

      [NET]: Make NAPI polling independent of struct net_device objects.

added np->dev to drivers/net/natsemi.c's struct netdev_private, but
forgot to initialize that new field upon driver init. The result was
a predictable NULL dereference oops the first time the hardware
generated an interrupt.

Reported-by: Andrew Nelless <andrew@nelless.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 drivers/net/natsemi.c |    1 +
 1 file changed, 1 insertion(+)

Index: linux/drivers/net/natsemi.c
===================================================================
--- linux.orig/drivers/net/natsemi.c
+++ linux/drivers/net/natsemi.c
@@ -864,6 +864,7 @@ static int __devinit natsemi_probe1 (str
 
 	np = netdev_priv(dev);
 	netif_napi_add(dev, &np->napi, natsemi_poll, 64);
+	np->dev = dev;
 
 	np->pci_dev = pdev;
 	pci_set_drvdata(pdev, dev);
-
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