[Xen-changelog] [xen-unstable] cpufreq: P state stats aren't available if there is no cpufreq driver

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User David Vrabel <david.vrabel@xxxxxxxxxx>
# Date 1343980228 -7200
# Node ID 7fd5facb608427b7e5890ff10cee8ed0da6a7703
# Parent  983ea7521badb3e05d3379044fb283732ef558d6
cpufreq: P state stats aren't available if there is no cpufreq driver

If there is no cpufreq driver (e.g., with an AMD Opteron 8212) then
reading the P state statistics causes a deadlock as an uninitialized
spinlock is locked in do_get_pm_info(). The spinlock is initialized in
cpufreq_statistic_init() which is not called if cpufreq_driver == NULL.

Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
Committed-by: Jan Beulich <jbeulich@xxxxxxxx>
---


diff -r 983ea7521bad -r 7fd5facb6084 xen/drivers/acpi/pmstat.c
--- a/xen/drivers/acpi/pmstat.c Thu Aug 02 14:44:53 2012 +0100
+++ b/xen/drivers/acpi/pmstat.c Fri Aug 03 09:50:28 2012 +0200
@@ -66,6 +66,8 @@ int do_get_pm_info(struct xen_sysctl_get
     case PMSTAT_PX:
         if ( !(xen_processor_pmbits & XEN_PROCESSOR_PM_PX) )
             return -ENODEV;
+        if ( !cpufreq_driver )
+            return -ENODEV;
         if ( !pmpt || !(pmpt->perf.init & XEN_PX_INIT) )
             return -EINVAL;
         break;

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