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Subject[PATCH 4.20 06/57] cpufreq: scpi/scmi: Fix freeing of dynamic OPPs
Date
4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Viresh Kumar <viresh.kumar@linaro.org>

commit 1690d8bb91e370ab772062b79bd434ce815c4729 upstream.

Since the commit 2a4eb7358aba "OPP: Don't remove dynamic OPPs from
_dev_pm_opp_remove_table()", dynamically created OPP aren't
automatically removed anymore by dev_pm_opp_cpumask_remove_table(). This
affects the scpi and scmi cpufreq drivers which no longer free OPPs on
failures or on invocations of the policy->exit() callback.

Create a generic OPP helper dev_pm_opp_remove_all_dynamic() which can be
called from these drivers instead of dev_pm_opp_cpumask_remove_table().

In dev_pm_opp_remove_all_dynamic(), we need to make sure that the
opp_list isn't getting accessed simultaneously from other parts of the
OPP core while the helper is freeing dynamic OPPs, i.e. we can't drop
the opp_table->lock while traversing through the OPP list. And to
accomplish that, this patch also creates _opp_kref_release_unlocked()
which can be called from this new helper with the opp_table lock already
held.

Cc: 4.20 <stable@vger.kernel.org> # v4.20
Reported-by: Valentin Schneider <valentin.schneider@arm.com>
Fixes: 2a4eb7358aba "OPP: Don't remove dynamic OPPs from _dev_pm_opp_remove_table()"
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/cpufreq/scmi-cpufreq.c | 4 +-
drivers/cpufreq/scpi-cpufreq.c | 4 +-
drivers/opp/core.c | 63 +++++++++++++++++++++++++++++++++++++----
include/linux/pm_opp.h | 5 +++
4 files changed, 67 insertions(+), 9 deletions(-)

--- a/drivers/cpufreq/scmi-cpufreq.c
+++ b/drivers/cpufreq/scmi-cpufreq.c
@@ -176,7 +176,7 @@ static int scmi_cpufreq_init(struct cpuf
out_free_priv:
kfree(priv);
out_free_opp:
- dev_pm_opp_cpumask_remove_table(policy->cpus);
+ dev_pm_opp_remove_all_dynamic(cpu_dev);

return ret;
}
@@ -188,7 +188,7 @@ static int scmi_cpufreq_exit(struct cpuf
cpufreq_cooling_unregister(priv->cdev);
dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
kfree(priv);
- dev_pm_opp_cpumask_remove_table(policy->related_cpus);
+ dev_pm_opp_remove_all_dynamic(priv->cpu_dev);

return 0;
}
--- a/drivers/cpufreq/scpi-cpufreq.c
+++ b/drivers/cpufreq/scpi-cpufreq.c
@@ -177,7 +177,7 @@ out_free_cpufreq_table:
out_free_priv:
kfree(priv);
out_free_opp:
- dev_pm_opp_cpumask_remove_table(policy->cpus);
+ dev_pm_opp_remove_all_dynamic(cpu_dev);

return ret;
}
@@ -190,7 +190,7 @@ static int scpi_cpufreq_exit(struct cpuf
clk_put(priv->clk);
dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
kfree(priv);
- dev_pm_opp_cpumask_remove_table(policy->related_cpus);
+ dev_pm_opp_remove_all_dynamic(priv->cpu_dev);

return 0;
}
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -951,11 +951,9 @@ void _opp_free(struct dev_pm_opp *opp)
kfree(opp);
}

-static void _opp_kref_release(struct kref *kref)
+static void _opp_kref_release(struct dev_pm_opp *opp,
+ struct opp_table *opp_table)
{
- struct dev_pm_opp *opp = container_of(kref, struct dev_pm_opp, kref);
- struct opp_table *opp_table = opp->opp_table;
-
/*
* Notify the changes in the availability of the operable
* frequency/voltage list.
@@ -964,7 +962,22 @@ static void _opp_kref_release(struct kre
opp_debug_remove_one(opp);
list_del(&opp->node);
kfree(opp);
+}
+
+static void _opp_kref_release_unlocked(struct kref *kref)
+{
+ struct dev_pm_opp *opp = container_of(kref, struct dev_pm_opp, kref);
+ struct opp_table *opp_table = opp->opp_table;
+
+ _opp_kref_release(opp, opp_table);
+}

+static void _opp_kref_release_locked(struct kref *kref)
+{
+ struct dev_pm_opp *opp = container_of(kref, struct dev_pm_opp, kref);
+ struct opp_table *opp_table = opp->opp_table;
+
+ _opp_kref_release(opp, opp_table);
mutex_unlock(&opp_table->lock);
}

@@ -975,10 +988,16 @@ void dev_pm_opp_get(struct dev_pm_opp *o

void dev_pm_opp_put(struct dev_pm_opp *opp)
{
- kref_put_mutex(&opp->kref, _opp_kref_release, &opp->opp_table->lock);
+ kref_put_mutex(&opp->kref, _opp_kref_release_locked,
+ &opp->opp_table->lock);
}
EXPORT_SYMBOL_GPL(dev_pm_opp_put);

+static void dev_pm_opp_put_unlocked(struct dev_pm_opp *opp)
+{
+ kref_put(&opp->kref, _opp_kref_release_unlocked);
+}
+
/**
* dev_pm_opp_remove() - Remove an OPP from OPP table
* @dev: device for which we do this operation
@@ -1022,6 +1041,40 @@ void dev_pm_opp_remove(struct device *de
}
EXPORT_SYMBOL_GPL(dev_pm_opp_remove);

+/**
+ * dev_pm_opp_remove_all_dynamic() - Remove all dynamically created OPPs
+ * @dev: device for which we do this operation
+ *
+ * This function removes all dynamically created OPPs from the opp table.
+ */
+void dev_pm_opp_remove_all_dynamic(struct device *dev)
+{
+ struct opp_table *opp_table;
+ struct dev_pm_opp *opp, *temp;
+ int count = 0;
+
+ opp_table = _find_opp_table(dev);
+ if (IS_ERR(opp_table))
+ return;
+
+ mutex_lock(&opp_table->lock);
+ list_for_each_entry_safe(opp, temp, &opp_table->opp_list, node) {
+ if (opp->dynamic) {
+ dev_pm_opp_put_unlocked(opp);
+ count++;
+ }
+ }
+ mutex_unlock(&opp_table->lock);
+
+ /* Drop the references taken by dev_pm_opp_add() */
+ while (count--)
+ dev_pm_opp_put_opp_table(opp_table);
+
+ /* Drop the reference taken by _find_opp_table() */
+ dev_pm_opp_put_opp_table(opp_table);
+}
+EXPORT_SYMBOL_GPL(dev_pm_opp_remove_all_dynamic);
+
struct dev_pm_opp *_opp_allocate(struct opp_table *table)
{
struct dev_pm_opp *opp;
--- a/include/linux/pm_opp.h
+++ b/include/linux/pm_opp.h
@@ -108,6 +108,7 @@ void dev_pm_opp_put(struct dev_pm_opp *o
int dev_pm_opp_add(struct device *dev, unsigned long freq,
unsigned long u_volt);
void dev_pm_opp_remove(struct device *dev, unsigned long freq);
+void dev_pm_opp_remove_all_dynamic(struct device *dev);

int dev_pm_opp_enable(struct device *dev, unsigned long freq);

@@ -214,6 +215,10 @@ static inline void dev_pm_opp_remove(str
{
}

+static inline void dev_pm_opp_remove_all_dynamic(struct device *dev)
+{
+}
+
static inline int dev_pm_opp_enable(struct device *dev, unsigned long freq)
{
return 0;

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