[rfc 01/45] ACPI: Avoid references to impossible processors.

clameter
2007-11-20T01:14:07Z

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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.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

---
drivers/acpi/processor_core.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

Index: linux-2.6/drivers/acpi/processor_core.c
===================================================================
--- linux-2.6.orig/drivers/acpi/processor_core.c 2007-11-19 15:45:05.041140492 -0800
+++ linux-2.6/drivers/acpi/processor_core.c 2007-11-19 15:48:22.513639920 -0800
@@ -494,7 +494,7 @@ static int get_cpu_id(acpi_handle handle
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;
}
@@ -638,7 +638,7 @@ static int __cpuinit acpi_processor_star
return 0;
}

- BUG_ON((pr->id >= NR_CPUS) || (pr->id < 0));
+ BUG_ON((pr->id >= nr_cpu_ids) || (pr->id < 0));

/*
* Buggy BIOS check
@@ -771,7 +771,7 @@ static int acpi_processor_remove(struct

pr = acpi_driver_data(device);

- if (pr->id >= NR_CPUS) {
+ if (pr->id >= nr_cpu_ids) {
kfree(pr);
return 0;
}
@@ -842,7 +842,7 @@ int acpi_processor_device_add(acpi_handl
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;
@@ -880,13 +880,13 @@ acpi_processor_hotplug_notify(acpi_handl
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",
@@ -909,7 +909,7 @@ acpi_processor_hotplug_notify(acpi_handl
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:

--