ACPI: avoid references to impossible processors.

ACPI uses NR_CPUS in various loops and in some it accesses per cpu data of
processors that are not present(!) and that will never be present.

The pointers to per cpu data are typically not initialized for processors
that are not present.  So we seem to be reading something here from offset
0 in memory.

Make ACPI use nr_cpu_ids instead. That stops at the end of the possible
processors.

Convert one loop to NR_CPUS to use the cpu_possible map instead.  That way
ranges of processor that can never be brought online are skipped during the
loop.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Len Brown <lenb@kernel.org>
Acked-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/acpi/processor_core.c

@@ -494,7 +494,7 @@ static int get_cpu_id(acpi_handle handle, u32 acpi_id)
 	if (apic_id == -1)
 		return apic_id;
 
-	for (i = 0; i < NR_CPUS; ++i) {
+	for_each_possible_cpu(i) {
 		if (cpu_physical_id(i) == apic_id)
 			return i;
 	}
@@ -632,7 +632,7 @@ static int __cpuinit acpi_processor_start(struct acpi_device *device)
 		return 0;
 	}
 
-	BUG_ON((pr->id >= NR_CPUS) || (pr->id < 0));
+	BUG_ON((pr->id >= nr_cpu_ids) || (pr->id < 0));
 
 	/*
 	 * Buggy BIOS check
@@ -774,7 +774,7 @@ static int acpi_processor_remove(struct acpi_device *device, int type)
 
 	pr = acpi_driver_data(device);
 
-	if (pr->id >= NR_CPUS) {
+	if (pr->id >= nr_cpu_ids) {
 		kfree(pr);
 		return 0;
 	}
@@ -845,7 +845,7 @@ int acpi_processor_device_add(acpi_handle handle, struct acpi_device **device)
 	if (!pr)
 		return -ENODEV;
 
-	if ((pr->id >= 0) && (pr->id < NR_CPUS)) {
+	if ((pr->id >= 0) && (pr->id < nr_cpu_ids)) {
 		kobject_uevent(&(*device)->dev.kobj, KOBJ_ONLINE);
 	}
 	return 0;
@@ -883,13 +883,13 @@ acpi_processor_hotplug_notify(acpi_handle handle, u32 event, void *data)
 			break;
 		}
 
-		if (pr->id >= 0 && (pr->id < NR_CPUS)) {
+		if (pr->id >= 0 && (pr->id < nr_cpu_ids)) {
 			kobject_uevent(&device->dev.kobj, KOBJ_OFFLINE);
 			break;
 		}
 
 		result = acpi_processor_start(device);
-		if ((!result) && ((pr->id >= 0) && (pr->id < NR_CPUS))) {
+		if ((!result) && ((pr->id >= 0) && (pr->id < nr_cpu_ids))) {
 			kobject_uevent(&device->dev.kobj, KOBJ_ONLINE);
 		} else {
 			printk(KERN_ERR PREFIX "Device [%s] failed to start\n",
@@ -912,7 +912,7 @@ acpi_processor_hotplug_notify(acpi_handle handle, u32 event, void *data)
 			return;
 		}
 
-		if ((pr->id < NR_CPUS) && (cpu_present(pr->id)))
+		if ((pr->id < nr_cpu_ids) && (cpu_present(pr->id)))
 			kobject_uevent(&device->dev.kobj, KOBJ_OFFLINE);
 		break;
 	default: