PCI: Check the node argument passed to cpumask_of_node

Commit e0cd516 "PCI: derive nearby CPUs from device's instead of bus'
NUMA information" causes an null pointer dereference when reading from
the sysfs attributes local_cpu* on Intel machines with no ACPI NUMA
proximity info, since dev->numa_node gets set to -1 for all PCI devices,
which then gets passed to cpumask_of_node.

Add a check to prevent this.

Signed-off-by: David John <davidjon@xenontk.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/pci-sysfs.c

@@ -75,7 +75,8 @@ static ssize_t local_cpus_show(struct device *dev,
 	int len;
 
 #ifdef CONFIG_NUMA
-	mask = cpumask_of_node(dev_to_node(dev));
+	mask = (dev_to_node(dev) == -1) ? cpu_online_mask :
+					  cpumask_of_node(dev_to_node(dev));
 #else
 	mask = cpumask_of_pcibus(to_pci_dev(dev)->bus);
 #endif
@@ -93,7 +94,8 @@ static ssize_t local_cpulist_show(struct device *dev,
 	int len;
 
 #ifdef CONFIG_NUMA
-	mask = cpumask_of_node(dev_to_node(dev));
+	mask = (dev_to_node(dev) == -1) ? cpu_online_mask :
+					  cpumask_of_node(dev_to_node(dev));
 #else
 	mask = cpumask_of_pcibus(to_pci_dev(dev)->bus);
 #endif