From: Doug Chapman <dchapman@redhat.com>
Date: Thu, 6 Dec 2007 16:14:34 -0500
Subject: [cpufreq] ondemand governor restructure the work cb
Message-id: 1196975674.1083.5.camel@athlon
O-Subject: [RHEL 5.2 PATCH 2/5] hang at 'Disabling ondemand cpu frequency scaling'
Bugzilla: 253416

Patch 2/5 for BZ 253416

Somewhat loose backport from upstream.  There were other changes
in the upstream commit that were not applicable to this issue
or even to the description given for the commit.  I just ported
the bit about removing smp_processor_id.

commit 529af7a14f04f92213bac371931a2b2b060c63fa
Author: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Date:   Mon Feb 5 16:12:44 2007 -0800

    [CPUFREQ] ondemand governor restructure the work callback

    Restructure the delayed_work callback in ondemand.

    This eliminates the need for smp_processor_id in the callback function and
    also helps in proper locking and avoiding flush_workqueue when stopping the
    governor (done in subsequent patch).

diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 52cf1f0..7ce7ca9 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -47,15 +47,17 @@ static unsigned int def_sampling_rate;
 #define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER	(1000)
 #define TRANSITION_LATENCY_LIMIT		(10 * 1000)
 
-static void do_dbs_timer(void *data);
-
 struct cpu_dbs_info_s {
 	cputime64_t prev_cpu_idle;
 	cputime64_t prev_cpu_wall;
 	struct cpufreq_policy *cur_policy;
  	struct work_struct work;
+	int cpu;
 	unsigned int enable;
 };
+
+static void do_dbs_timer(struct cpu_dbs_info_s *dbs_info);
+
 static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
 
 static unsigned int dbs_enable;	/* number of CPUs using this policy */
@@ -301,10 +303,9 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
 	}
 }
 
-static void do_dbs_timer(void *data)
+static void do_dbs_timer(struct cpu_dbs_info_s *dbs_info)
 {
-	unsigned int cpu = smp_processor_id();
-	struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, cpu);
+	unsigned int cpu = dbs_info->cpu;
 
 	if (!dbs_info->enable)
 		return;
@@ -316,12 +317,10 @@ static void do_dbs_timer(void *data)
 			usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
 }
 
-static inline void dbs_timer_init(unsigned int cpu)
+static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
 {
-	struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, cpu);
-
-	INIT_WORK(&dbs_info->work, do_dbs_timer, 0);
-	queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work,
+	INIT_WORK(&dbs_info->work, do_dbs_timer, dbs_info);
+	queue_delayed_work_on(dbs_info->cpu, kondemand_wq, &dbs_info->work,
 			usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
 	return;
 }
@@ -375,6 +374,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 			j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j);
 			j_dbs_info->prev_cpu_wall = get_jiffies_64();
 		}
+		this_dbs_info->cpu = cpu;
 		this_dbs_info->enable = 1;
 		sysfs_create_group(&policy->kobj, &dbs_attr_group);
 		/*
@@ -396,7 +396,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 
 			dbs_tuners_ins.sampling_rate = def_sampling_rate;
 		}
-		dbs_timer_init(policy->cpu);
+		dbs_timer_init(this_dbs_info);
 
 		mutex_unlock(&dbs_mutex);
 		break;