ACPI / CPPC: Prevent cpc_desc_ptr points to the invalid data

BugLink: http://bugs.launchpad.net/bugs/1621113

commit 2324d154 upstream.

When CPPC fails to request a PCC channel, the CPC data is freed
and cpc_desc_ptr points to the invalid data.

Avoid this issue by moving the cpc_desc_ptr assignment after the PCC
channel request.
Signed-off-by: Hoan Tran <hotran@apm.com>
Acked-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

drivers/acpi/cppc_acpi.c

@@ -508,9 +508,6 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
 	/* Store CPU Logical ID */
 	cpc_ptr->cpu_id = pr->id;
 
-	/* Plug it into this CPUs CPC descriptor. */
-	per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr;
-
 	/* Parse PSD data for this CPU */
 	ret = acpi_get_psd(cpc_ptr, handle);
 	if (ret)
@@ -523,6 +520,9 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
 			goto out_free;
 	}
 
+	/* Plug PSD data into this CPUs CPC descriptor. */
+	per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr;
+
 	/* Everything looks okay */
 	pr_debug("Parsed CPC struct for CPU: %d\n", pr->id);