[PATCH 0/2] CPUFreq core fixes for v3.10-rc2

[PATCH 0/2] CPUFreq core fixes for v3.10-rc2

[Viresh Kumar]

I just saw your pull request and so these should go in rc2 now.

These are fixes for cpufreq core and common governor part. They mostly impact
systems which have set have_governor_per_policy to true. i.e. big LITTLE cpufreq
driver.

Viresh Kumar (2):
  cpufreq: governors: Fix CPUFREQ_GOV_POLICY_{INIT|EXIT} notifiers
  cpufreq: Issue CPUFREQ_GOV_POLICY_EXIT notifier before dropping
    policy refcount

 drivers/cpufreq/cpufreq.c          |  6 +++---
 drivers/cpufreq/cpufreq_governor.c | 11 +++++++----
 drivers/cpufreq/cpufreq_governor.h |  1 +
 3 files changed, 11 insertions(+), 7 deletions(-)

-- 
1.7.12.rc2.18.g61b472e

[PATCH 1/2] cpufreq: governors: Fix CPUFREQ_GOV_POLICY_{INIT|EXIT} notifiers

[Viresh Kumar]

There are two types of INIT/EXIT activities that we need to do for governors:
- Done only once per governor (doesn't depend how many instances of governor
  were there). eg: cpufreq_register_notifier() for conservative governor.
- Done per instance of governor, eg: sysfs_{create|remove}_group().

There were some corner cases where current code isn't able to handle them
separately and so failing for some test cases.

We use two separate variables now for keeping track of above two requirements.
- governor->initialized for first one
- dbs_data->usage_count for per governor instance

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/cpufreq_governor.c | 11 +++++++----
 drivers/cpufreq/cpufreq_governor.h |  1 +
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index 443442d..5af40ad 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -255,6 +255,7 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 		if (have_governor_per_policy()) {
 			WARN_ON(dbs_data);
 		} else if (dbs_data) {
+			dbs_data->usage_count++;
 			policy->governor_data = dbs_data;
 			return 0;
 		}
@@ -266,6 +267,7 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 		}
 
 		dbs_data->cdata = cdata;
+		dbs_data->usage_count = 1;
 		rc = cdata->init(dbs_data);
 		if (rc) {
 			pr_err("%s: POLICY_INIT: init() failed\n", __func__);
@@ -294,7 +296,8 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 		set_sampling_rate(dbs_data, max(dbs_data->min_sampling_rate,
 					latency * LATENCY_MULTIPLIER));
 
-		if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
+		if ((cdata->governor == GOV_CONSERVATIVE) &&
+				(!policy->governor->initialized)) {
 			struct cs_ops *cs_ops = dbs_data->cdata->gov_ops;
 
 			cpufreq_register_notifier(cs_ops->notifier_block,
@@ -306,12 +309,12 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 
 		return 0;
 	case CPUFREQ_GOV_POLICY_EXIT:
-		if ((policy->governor->initialized == 1) ||
-				have_governor_per_policy()) {
+		if (!--dbs_data->usage_count) {
 			sysfs_remove_group(get_governor_parent_kobj(policy),
 					get_sysfs_attr(dbs_data));
 
-			if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
+			if ((dbs_data->cdata->governor == GOV_CONSERVATIVE) &&
+				(policy->governor->initialized == 1)) {
 				struct cs_ops *cs_ops = dbs_data->cdata->gov_ops;
 
 				cpufreq_unregister_notifier(cs_ops->notifier_block,
diff --git a/drivers/cpufreq/cpufreq_governor.h b/drivers/cpufreq/cpufreq_governor.h
index 8ac3353..e16a961 100644
--- a/drivers/cpufreq/cpufreq_governor.h
+++ b/drivers/cpufreq/cpufreq_governor.h
@@ -211,6 +211,7 @@ struct common_dbs_data {
 struct dbs_data {
 	struct common_dbs_data *cdata;
 	unsigned int min_sampling_rate;
+	int usage_count;
 	void *tuners;
 
 	/* dbs_mutex protects dbs_enable in governor start/stop */
-- 
1.7.12.rc2.18.g61b472e

[PATCH 2/2] cpufreq: Issue CPUFREQ_GOV_POLICY_EXIT notifier before dropping policy refcount

[Viresh Kumar]

We must call __cpufreq_governor(data, CPUFREQ_GOV_POLICY_EXIT) before calling
cpufreq_cpu_put(data), so that policy kobject have valid fields. Otherwise,
removing last online cpu of policy->cpus causes this crash for
ondemand/conservative governor.

[  146.386064] [<c00fb076>] (sysfs_find_dirent+0xe/0xa8) from [<c00fb1bd>] (sysfs_get_dirent+0x21/0x58)
[  146.413440] [<c00fb1bd>] (sysfs_get_dirent+0x21/0x58) from [<c00fc259>] (sysfs_remove_group+0x85/0xbc)
[  146.441338] [<c00fc259>] (sysfs_remove_group+0x85/0xbc) from [<c02faad9>] (cpufreq_governor_dbs+0x369/0x4a0)
[  146.470795] [<c02faad9>] (cpufreq_governor_dbs+0x369/0x4a0) from [<c02f66d7>] (__cpufreq_governor+0x2b/0x8c)
[  146.500254] [<c02f66d7>] (__cpufreq_governor+0x2b/0x8c) from [<c02f6893>] (__cpufreq_remove_dev.isra.12+0x15b/0x250)
[  146.531799] [<c02f6893>] (__cpufreq_remove_dev.isra.12+0x15b/0x250) from [<c03e91c7>] (cpufreq_cpu_callback+0x2f/0x3c)
[  146.563860] [<c03e91c7>] (cpufreq_cpu_callback+0x2f/0x3c) from [<c0036fe1>] (notifier_call_chain+0x45/0x54)
[  146.593059] [<c0036fe1>] (notifier_call_chain+0x45/0x54) from [<c001e611>] (__cpu_notify+0x1d/0x34)
[  146.620177] [<c001e611>] (__cpu_notify+0x1d/0x34) from [<c03e5833>] (_cpu_down+0x63/0x1ac)
[  146.644948] [<c03e5833>] (_cpu_down+0x63/0x1ac) from [<c03e5997>] (cpu_down+0x1b/0x30)
[  146.668675] [<c03e5997>] (cpu_down+0x1b/0x30) from [<c03e60eb>] (store_online+0x27/0x54)
[  146.692922] [<c03e60eb>] (store_online+0x27/0x54) from [<c0295629>] (dev_attr_store+0x11/0x18)
[  146.718733] [<c0295629>] (dev_attr_store+0x11/0x18) from [<c00f9edd>] (sysfs_write_file+0xed/0x114)
[  146.745847] [<c00f9edd>] (sysfs_write_file+0xed/0x114) from [<c00b42a9>] (vfs_write+0x65/0xd8)
[  146.771656] [<c00b42a9>] (vfs_write+0x65/0xd8) from [<c00b4523>] (sys_write+0x2f/0x50)
[  146.795384] [<c00b4523>] (sys_write+0x2f/0x50) from [<c000cdc1>] (ret_fast_syscall+0x1/0x52)

Of course this only impacted drivers which have have_governor_per_policy set to
true. i.e. big LITTLE cpufreq driver.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/cpufreq.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 1b8a48e..b7acfd1 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1075,14 +1075,14 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
 				__func__, cpu_dev->id, cpu);
 	}
 
+	if ((cpus == 1) && (cpufreq_driver->target))
+		__cpufreq_governor(data, CPUFREQ_GOV_POLICY_EXIT);
+
 	pr_debug("%s: removing link, cpu: %d\n", __func__, cpu);
 	cpufreq_cpu_put(data);
 
 	/* If cpu is last user of policy, free policy */
 	if (cpus == 1) {
-		if (cpufreq_driver->target)
-			__cpufreq_governor(data, CPUFREQ_GOV_POLICY_EXIT);
-
 		lock_policy_rwsem_read(cpu);
 		kobj = &data->kobj;
 		cmp = &data->kobj_unregister;
-- 
1.7.12.rc2.18.g61b472e

Re: [PATCH 0/2] CPUFreq core fixes for v3.10-rc2

[Rafael J. Wysocki]

On Tuesday, April 30, 2013 08:02:16 PM Viresh Kumar wrote:
> I just saw your pull request and so these should go in rc2 now.
> 
> These are fixes for cpufreq core and common governor part. They mostly impact
> systems which have set have_governor_per_policy to true. i.e. big LITTLE cpufreq
> driver.
> 
> Viresh Kumar (2):
>   cpufreq: governors: Fix CPUFREQ_GOV_POLICY_{INIT|EXIT} notifiers
>   cpufreq: Issue CPUFREQ_GOV_POLICY_EXIT notifier before dropping
>     policy refcount
> 
>  drivers/cpufreq/cpufreq.c          |  6 +++---
>  drivers/cpufreq/cpufreq_governor.c | 11 +++++++----
>  drivers/cpufreq/cpufreq_governor.h |  1 +
>  3 files changed, 11 insertions(+), 7 deletions(-)

Both queued up for the v3.10-rc2 push.

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.