[Xen-changelog] [xen-3.4-testing] cpufreq: fix statistic lock problem

["Xen patchbot-3.4-testing" <patchbot-3.4-testing@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1269952696 -3600
# Node ID 106fb323c803537762ad436991fb82aabfa2ca73
# Parent  a8d1c8013bb69a7f1740d4631ca6b8623d75d9d0
cpufreq: fix statistic lock problem

cpufreq_statistic_lock should not only protect the statistic memory
pointed by cpufreq_statistic_data[cpu], but also have to protect the
pointer in cpufreq_statistic_data[cpu] itself. So move the read
operation of cpufreq_statistic_data[cpu] after
spin_lock(cpufreq_statistic_lock).

Signed-off-by: Wei Gang <gang.wei@xxxxxxxxx>
xen-unstable changeset:   21071:415c0bf4ac7a
xen-unstable date:        Fri Mar 26 08:49:13 2010 +0000
---
 xen/drivers/cpufreq/utility.c |   12 ++++++++----
 1 files changed, 8 insertions(+), 4 deletions(-)

diff -r a8d1c8013bb6 -r 106fb323c803 xen/drivers/cpufreq/utility.c
--- a/xen/drivers/cpufreq/utility.c     Tue Mar 30 13:37:15 2010 +0100
+++ b/xen/drivers/cpufreq/utility.c     Tue Mar 30 13:38:16 2010 +0100
@@ -63,13 +63,14 @@ void cpufreq_residency_update(unsigned i
 
 void cpufreq_statistic_update(unsigned int cpu, uint8_t from, uint8_t to)
 {
-    struct pm_px *pxpt = cpufreq_statistic_data[cpu];
+    struct pm_px *pxpt;
     struct processor_pminfo *pmpt = processor_pminfo[cpu];
     spinlock_t *cpufreq_statistic_lock = 
                &per_cpu(cpufreq_statistic_lock, cpu);
 
     spin_lock(cpufreq_statistic_lock);
 
+    pxpt = cpufreq_statistic_data[cpu];
     if ( !pxpt || !pmpt ) {
         spin_unlock(cpufreq_statistic_lock);
         return;
@@ -89,7 +90,7 @@ int cpufreq_statistic_init(unsigned int 
 int cpufreq_statistic_init(unsigned int cpuid)
 {
     uint32_t i, count;
-    struct pm_px *pxpt = cpufreq_statistic_data[cpuid];
+    struct pm_px *pxpt;
     const struct processor_pminfo *pmpt = processor_pminfo[cpuid];
     spinlock_t *cpufreq_statistic_lock = 
                           &per_cpu(cpufreq_statistic_lock, cpuid);
@@ -99,6 +100,7 @@ int cpufreq_statistic_init(unsigned int 
 
     spin_lock(cpufreq_statistic_lock);
 
+    pxpt = cpufreq_statistic_data[cpuid];
     if ( pxpt ) {
         spin_unlock(cpufreq_statistic_lock);
         return 0;
@@ -148,12 +150,13 @@ int cpufreq_statistic_init(unsigned int 
 
 void cpufreq_statistic_exit(unsigned int cpuid)
 {
-    struct pm_px *pxpt = cpufreq_statistic_data[cpuid];
+    struct pm_px *pxpt;
     spinlock_t *cpufreq_statistic_lock = 
                &per_cpu(cpufreq_statistic_lock, cpuid);
 
     spin_lock(cpufreq_statistic_lock);
 
+    pxpt = cpufreq_statistic_data[cpuid];
     if (!pxpt) {
         spin_unlock(cpufreq_statistic_lock);
         return;
@@ -170,13 +173,14 @@ void cpufreq_statistic_reset(unsigned in
 void cpufreq_statistic_reset(unsigned int cpuid)
 {
     uint32_t i, j, count;
-    struct pm_px *pxpt = cpufreq_statistic_data[cpuid];
+    struct pm_px *pxpt;
     const struct processor_pminfo *pmpt = processor_pminfo[cpuid];
     spinlock_t *cpufreq_statistic_lock = 
                &per_cpu(cpufreq_statistic_lock, cpuid);
 
     spin_lock(cpufreq_statistic_lock);
 
+    pxpt = cpufreq_statistic_data[cpuid];
     if ( !pmpt || !pxpt || !pxpt->u.pt || !pxpt->u.trans_pt ) {
         spin_unlock(cpufreq_statistic_lock);
         return;

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