[PATCH V5 1/6] cpufreq: Merge cpufreq_offline_prepare/finish routines

From: Viresh Kumar
Date: Thu Feb 11 2016 - 07:01:33 EST


Governor sysfs attributes are still removed in
__cpufreq_governor(_EXIT), though, so had store() been used for them,
the deadlock described in the changelog of commit 1aee40ac9c86 would
have been possible.

Fortunately, we don't use store() (which still does get_online_cpus())
for those attributes now. We use governor_store() for them and that
doesn't call get_online_cpus().

And so we don't need to split cpufreq-offline functionality into
DOWN_PREPARE and POST_DEAD hotplug notifiers anymore.

Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
[ rjw: Changelog ]
Tested-by: Juri Lelli <juri.lelli@xxxxxxx>
Tested-by: Shilpasri G Bhat <shilpa.bhat@xxxxxxxxxxxxxxxxxx>
---
drivers/cpufreq/cpufreq.c | 36 ++++++++++--------------------------
1 file changed, 10 insertions(+), 26 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 9c62bf35b9dc..863ac26c4ecf 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1361,9 +1361,10 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
return ret;
}

-static void cpufreq_offline_prepare(unsigned int cpu)
+static void cpufreq_offline(unsigned int cpu)
{
struct cpufreq_policy *policy;
+ int ret;

pr_debug("%s: unregistering CPU %u\n", __func__, cpu);

@@ -1374,7 +1375,7 @@ static void cpufreq_offline_prepare(unsigned int cpu)
}

if (has_target()) {
- int ret = __cpufreq_governor(policy, CPUFREQ_GOV_STOP);
+ ret = __cpufreq_governor(policy, CPUFREQ_GOV_STOP);
if (ret)
pr_err("%s: Failed to stop governor\n", __func__);
}
@@ -1397,34 +1398,23 @@ static void cpufreq_offline_prepare(unsigned int cpu)
/* Start governor again for active policy */
if (!policy_is_inactive(policy)) {
if (has_target()) {
- int ret = __cpufreq_governor(policy, CPUFREQ_GOV_START);
+ ret = __cpufreq_governor(policy, CPUFREQ_GOV_START);
if (!ret)
ret = __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS);

if (ret)
pr_err("%s: Failed to start governor\n", __func__);
}
- } else if (cpufreq_driver->stop_cpu) {
- cpufreq_driver->stop_cpu(policy);
- }
-}

-static void cpufreq_offline_finish(unsigned int cpu)
-{
- struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
-
- if (!policy) {
- pr_debug("%s: No cpu_data found\n", __func__);
return;
}

- /* Only proceed for inactive policies */
- if (!policy_is_inactive(policy))
- return;
+ if (cpufreq_driver->stop_cpu)
+ cpufreq_driver->stop_cpu(policy);

/* If cpu is last user of policy, free policy */
if (has_target()) {
- int ret = __cpufreq_governor(policy, CPUFREQ_GOV_POLICY_EXIT);
+ ret = __cpufreq_governor(policy, CPUFREQ_GOV_POLICY_EXIT);
if (ret)
pr_err("%s: Failed to exit governor\n", __func__);
}
@@ -1453,10 +1443,8 @@ static void cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif)
if (!policy)
return;

- if (cpu_online(cpu)) {
- cpufreq_offline_prepare(cpu);
- cpufreq_offline_finish(cpu);
- }
+ if (cpu_online(cpu))
+ cpufreq_offline(cpu);

cpumask_clear_cpu(cpu, policy->real_cpus);
remove_cpu_dev_symlink(policy, cpu);
@@ -2304,11 +2292,7 @@ static int cpufreq_cpu_callback(struct notifier_block *nfb,
break;

case CPU_DOWN_PREPARE:
- cpufreq_offline_prepare(cpu);
- break;
-
- case CPU_POST_DEAD:
- cpufreq_offline_finish(cpu);
+ cpufreq_offline(cpu);
break;

case CPU_DOWN_FAILED:
--
2.7.1.370.gb2aa7f8