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Date: Thu, 7 Feb 2013 13:11:52 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: "Rafael J. Wysocki" <rjw@...k.pl>
Cc: Valdis Kletnieks <Valdis.Kletnieks@...edu>,
linux-kernel@...r.kernel.org, cpufreq@...r.kernel.org,
linux-pm@...r.kernel.org
Subject: Re: next-20130206 cpufreq - WARN in sysfs_add_one
On Thu, Feb 7, 2013 at 2:54 AM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> On Wednesday, February 06, 2013 12:44:35 PM Valdis Kletnieks wrote:
>> Seen in dmesg. next-20130128 was OK. Haven't done a bisect, but can
>> do so if the offender isn't obvious...
>
> I suppose this is 73bf0fc "cpufreq: Don't remove sysfs link for policy->cpu".
Not really. :)
Hi Valdis,
First of all i want to confirm something about your system. I am sure it is a
multi-policy system (or multi cluster system). i.e. there are more than one
clock line for different cpus ? And so multiple struct policy exist
simultaneously.
Because this crash can only come on those.
Anyway, i have tested and pushed a fix here:
http://git.linaro.org/gitweb?p=people/vireshk/linux.git;a=shortlog;h=refs/heads/for-valdis
Please test it.
For others, the patch is:
commit 007dda326f1b1415846671d7fcfbd520f4f16151
Author: Viresh Kumar <viresh.kumar@...aro.org>
Date: Thu Feb 7 12:51:27 2013 +0530
cpufreq: governors: Fix WARN_ON() for multi-policy platforms
On multi-policy systems there is a single instance of governor for both the
policies (if same governor is chosen for both policies). With the
code update
from following patches:
8eeed09 cpufreq: governors: Get rid of dbs_data->enable field
b394058 cpufreq: governors: Reset tunables only for
cpufreq_unregister_governor()
We are creating/removing sysfs directory of governor for for every call to
GOV_START and STOP. This would fail for multi-policy system as there is a
per-policy call to START/STOP.
This patch reuses the governor->initialized variable to detect
total users of
governor.
Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
drivers/cpufreq/cpufreq.c | 6 ++++--
drivers/cpufreq/cpufreq_governor.c | 32 +++++++++++++++++++-------------
2 files changed, 23 insertions(+), 15 deletions(-)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index ccc598a..3b941a1 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1567,8 +1567,10 @@ static int __cpufreq_governor(struct
cpufreq_policy *policy,
policy->cpu, event);
ret = policy->governor->governor(policy, event);
- if (!policy->governor->initialized && (event == CPUFREQ_GOV_START))
- policy->governor->initialized = 1;
+ if (event == CPUFREQ_GOV_START)
+ policy->governor->initialized++;
+ else if (event == CPUFREQ_GOV_STOP)
+ policy->governor->initialized--;
/* we keep one module reference alive for
each CPU governed by this CPU */
diff --git a/drivers/cpufreq/cpufreq_governor.c
b/drivers/cpufreq/cpufreq_governor.c
index e4a306c..5a76086 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -247,11 +247,13 @@ int cpufreq_governor_dbs(struct dbs_data *dbs_data,
dbs_data->gov_dbs_timer);
}
- rc = sysfs_create_group(cpufreq_global_kobject,
- dbs_data->attr_group);
- if (rc) {
- mutex_unlock(&dbs_data->mutex);
- return rc;
+ if (!policy->governor->initialized) {
+ rc = sysfs_create_group(cpufreq_global_kobject,
+ dbs_data->attr_group);
+ if (rc) {
+ mutex_unlock(&dbs_data->mutex);
+ return rc;
+ }
}
/*
@@ -262,13 +264,15 @@ int cpufreq_governor_dbs(struct dbs_data *dbs_data,
cs_dbs_info->down_skip = 0;
cs_dbs_info->enable = 1;
cs_dbs_info->requested_freq = policy->cur;
- cpufreq_register_notifier(cs_ops->notifier_block,
- CPUFREQ_TRANSITION_NOTIFIER);
- if (!policy->governor->initialized)
+ if (!policy->governor->initialized) {
+
cpufreq_register_notifier(cs_ops->notifier_block,
+ CPUFREQ_TRANSITION_NOTIFIER);
+
dbs_data->min_sampling_rate =
MIN_SAMPLING_RATE_RATIO *
jiffies_to_usecs(10);
+ }
} else {
od_dbs_info->rate_mult = 1;
od_dbs_info->sample_type = OD_NORMAL_SAMPLE;
@@ -311,11 +315,13 @@ unlock:
mutex_lock(&dbs_data->mutex);
mutex_destroy(&cpu_cdbs->timer_mutex);
- sysfs_remove_group(cpufreq_global_kobject,
- dbs_data->attr_group);
- if (dbs_data->governor == GOV_CONSERVATIVE)
- cpufreq_unregister_notifier(cs_ops->notifier_block,
- CPUFREQ_TRANSITION_NOTIFIER);
+ if (policy->governor->initialized == 1) {
+ sysfs_remove_group(cpufreq_global_kobject,
+ dbs_data->attr_group);
+ if (dbs_data->governor == GOV_CONSERVATIVE)
+
cpufreq_unregister_notifier(cs_ops->notifier_block,
+ CPUFREQ_TRANSITION_NOTIFIER);
+ }
mutex_unlock(&dbs_data->mutex);
break;
--
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