From: Keir Fraser <keir.fraser@citrix.com>
Date: Mon, 12 Apr 2010 16:33:47 +0000 (+0100)
Subject: cpufreq: fix racing issue for cpu hotplug
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~12411
X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/success//%22http:/www.example.com/cgi/success/?a=commitdiff_plain;h=7cc4840cb2ec55f784800543d7ec49655f049654;p=xen.git

cpufreq: fix racing issue for cpu hotplug

To eliminate racing between dbs timer handler and cpufreq_del_cpu,
using kill_timer instead of stop_timer to make sure timer handler
execution finished before other stuff in cpufreq_del_cpu.

BTW, fix a lost point of cpufreq_statistic_lock taking sequence.

Signed-off-by: Wei Gang <gang.wei@intel.com>
---

diff --git a/xen/drivers/acpi/pmstat.c b/xen/drivers/acpi/pmstat.c
index c88d000f63..c93f98f70a 100644
--- a/xen/drivers/acpi/pmstat.c
+++ b/xen/drivers/acpi/pmstat.c
@@ -86,12 +86,13 @@ int do_get_pm_info(struct xen_sysctl_get_pmstat *op)
     case PMSTAT_get_pxstat:
     {
         uint32_t ct;
-        struct pm_px *pxpt = cpufreq_statistic_data[op->cpuid];
+        struct pm_px *pxpt;
         spinlock_t *cpufreq_statistic_lock = 
                    &per_cpu(cpufreq_statistic_lock, op->cpuid);
 
         spin_lock(cpufreq_statistic_lock);
 
+        pxpt = cpufreq_statistic_data[op->cpuid];
         if ( !pxpt || !pxpt->u.pt || !pxpt->u.trans_pt )
         {
             spin_unlock(cpufreq_statistic_lock);
diff --git a/xen/drivers/cpufreq/cpufreq_ondemand.c b/xen/drivers/cpufreq/cpufreq_ondemand.c
index dd4f6c45c1..f69dd7a19c 100644
--- a/xen/drivers/cpufreq/cpufreq_ondemand.c
+++ b/xen/drivers/cpufreq/cpufreq_ondemand.c
@@ -189,9 +189,8 @@ static void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
 {
     dbs_info->enable = 1;
 
-    if ( !dbs_timer[dbs_info->cpu].function )
-        init_timer(&dbs_timer[dbs_info->cpu], do_dbs_timer, 
-            (void *)dbs_info, dbs_info->cpu);
+    init_timer(&dbs_timer[dbs_info->cpu], do_dbs_timer, 
+        (void *)dbs_info, dbs_info->cpu);
 
     set_timer(&dbs_timer[dbs_info->cpu], NOW()+dbs_tuners_ins.sampling_rate);
 
@@ -206,7 +205,7 @@ static void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
 {
     dbs_info->enable = 0;
     dbs_info->stoppable = 0;
-    stop_timer(&dbs_timer[dbs_info->cpu]);
+    kill_timer(&dbs_timer[dbs_info->cpu]);
 }
 
 int cpufreq_governor_dbs(struct cpufreq_policy *policy, unsigned int event)