[PATCH] Validate ACPI CPU frequency values

This is a simple fix for some of the problems with bad ACPI frequency values:

  Abort if the frequency field in _PSS is zero, as we're having a
  completely broken ACPI table then.

A more complete overhaul of the acpi-cpufreq driver (where the cause of
the problem lies) is in the latest acpi-test tree, but that's definitely
something to be delayed for 2.6.3 -- and the same is true for the
yet-to-be-written do_div64 conversion.

arch/i386/kernel/cpu/cpufreq/acpi.c

@@ -208,6 +208,12 @@ acpi_processor_get_performance_states (
 			goto end;
 		}
 
+		if (!px->core_frequency) {
+			ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Invalid _PSS data: freq is zero\n"));
+			result = -EFAULT;
+			goto end;
+		}
+
 		ACPI_DEBUG_PRINT((ACPI_DB_INFO, 
 			"State [%d]: core_frequency[%d] power[%d] transition_latency[%d] bus_master_latency[%d] control[0x%x] status[0x%x]\n",
 			i,