Without this patch a Opteron test system here oopses at boot with currentg git. 
Calling to_pci_dev() on a NULL pointer gives a negative value so the following NULL

pointer check never triggers and then an illegal address is referenced. Check the

unadjusted original device pointer for NULL instead.
Signed-off-by: Andi Kleen <ak@suse.de>
Index: linux/include/linux/ide.h

===================================================================

--- linux.orig/include/linux/ide.h

+++ linux/include/linux/ide.h

@@ -1294,7 +1294,7 @@ static inline void ide_dump_identify(u8

 static inline int hwif_to_node(ide_hwif_t *hwif)

 {

 	struct pci_dev *dev = to_pci_dev(hwif->dev);

-	return dev ? pcibus_to_node(dev->bus) : -1;

+	return hwif->dev ? pcibus_to_node(dev->bus) : -1;

 }
 static inline ide_drive_t *ide_get_paired_drive(ide_drive_t *drive)

--

Thanks Andi!
This may explain+resolve ide_generic OOPS-es reported by Pavel/Kamalesh/Nish.
[ I also see that Linus has already merged the patch and you've followed

  up on pcibus_to_node() issue so there is nothing left for me to do...
--

Ok, I applied this, but it causes a *lot* of noise about "unused variable

'dev'" because pcibus_to_node() is defined to be -1 when you don't do any

strange NUMA thing (so that "dev->bus" usage thing is never even seen by

the compiler.
So we should probably make pcibus_to_node() be an inline function for that

case, or just make that thing be
	return hwif->dev ?

		pcibus_to_node(to_pci_dev(hwif->dev)->bus)

	       :

		-1;
or something. Because now things are really noisy.
Preferences, anybody? Bartlomiej?
		Linus

--

Yes sorry; I only checked NUMA builds before sending it off.

The easiest way is probably just the traditional (void) cast

I fixed most of the topology macros while I was at it.
-Andi
---
Make topology fallback macros reference their arguments.
This avoids warnings with unreferenced variables in the !NUMA case.
Signed-off-by: Andi Kleen <ak@suse.de>
Index: linux/include/asm-generic/topology.h

===================================================================

--- linux.orig/include/asm-generic/topology.h

+++ linux/include/asm-generic/topology.h

@@ -30,19 +30,19 @@

 /* Other architectures wishing to use this simple topology API should fill

    in the below functions as appropriate in their own <asm/topology.h> file. */

 #ifndef cpu_to_node

-#define cpu_to_node(cpu)	(0)

+#define cpu_to_node(cpu)	((void)(cpu),0)

 #endif

 #ifndef parent_node

-#define parent_node(node)	(0)

+#define parent_node(node)	((void)(node),0)

 #endif

 #ifndef node_to_cpumask

-#define node_to_cpumask(node)	(cpu_online_map)

+#define node_to_cpumask(node)	((void)node, cpu_online_map)

 #endif

 #ifndef node_to_first_cpu

-#define node_to_first_cpu(node)	(0)

+#define node_to_first_cpu(node)	((void)(node),0)

 #endif

 #ifndef pcibus_to_node

-#define pcibus_to_node(node)	(-1)

+#define pcibus_to_node(bus)	((void)(bus), -1)

 #endif
 #ifndef pcibus_to_cpumask

--

Or, we could just do the ugliest patch ever, namely
	-#define pcibus_to_node(node)   (-1)

	+#define pcibus_to_node(node)   ((int)(long)(node),-1)
Wow. It's so ugly it's almost wraps around and comes out the other sides

and looks pretty.
		Linus

--

(void)arg, ... is better. Trick originally from Jan Beulich I think

(his code is always a good source for useful new C tricks) 
-Andi
--