[cpufreq] ondemand: make shutdown sequence more robust

Shutting down the ondemand policy was fraught with potential
problems, causing issues for SMP suspend (which wants to hot-
unplug) all but the last CPU.

This should fix at least the worst problems (divide-by-zero
and infinite wait for the workqueue to shut down).

Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 87299924e73508accd8961191cc4baf99832927b..178f0c547eb7ac928fcdce0d0f0edd3da73c4c70 100644 (file)
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -239,6 +239,8 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
        total_ticks = (unsigned int) cputime64_sub(cur_jiffies,
                        this_dbs_info->prev_cpu_wall);
        this_dbs_info->prev_cpu_wall = cur_jiffies;
+       if (!total_ticks)
+               return;
        /*
         * Every sampling_rate, we check, if current idle time is less
         * than 20% (default), then we try to increase frequency
@@ -304,6 +306,9 @@ static void do_dbs_timer(void *data)
        unsigned int cpu = smp_processor_id();
        struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, cpu);
 
+       if (!dbs_info->enable)
+               return;
+
        dbs_check_cpu(dbs_info);
        queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work,
                        usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
@@ -319,11 +324,11 @@ static inline void dbs_timer_init(unsigned int cpu)
        return;
 }
 
-static inline void dbs_timer_exit(unsigned int cpu)
+static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
 {
-       struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, cpu);
-
-       cancel_rearming_delayed_workqueue(kondemand_wq, &dbs_info->work);
+       dbs_info->enable = 0;
+       cancel_delayed_work(&dbs_info->work);
+       flush_workqueue(kondemand_wq);
 }
 
 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
@@ -396,8 +401,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 
        case CPUFREQ_GOV_STOP:
                mutex_lock(&dbs_mutex);
-               dbs_timer_exit(policy->cpu);
-               this_dbs_info->enable = 0;
+               dbs_timer_exit(this_dbs_info);
                sysfs_remove_group(&policy->kobj, &dbs_attr_group);
                dbs_enable--;
                if (dbs_enable == 0)