While adding devices to their PM domains, dev_pm_qos_add_notifier() was
invoked while allocating the generic_pm_domain_data for the device.
Since the generic_pm_domain_data's device pointer will be assigned
after allocation, the ->genpd_dev_pm_qos_notifier() callback could be
called prior having a valid pointer to the device. Similar scenario
existed while removing a device from a genpd.
To cope with these scenarios a mutex was used to protect the pointer to
the device.
By re-order the sequence for when dev_pm_qos_add|remove_notifier() are
invoked, we make sure the ->genpd_dev_pm_qos_notifier() callback are
always called with a valid device pointer available.
In this way, we eliminate the need for protecting the pointer and thus
we can remove the mutex from the struct generic_pm_domain_data.
Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
---
drivers/base/power/domain.c | 37 ++++++++++++++-----------------------
include/linux/pm_domain.h | 1 -
2 files changed, 14 insertions(+), 24 deletions(-)
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 88198ba..1f026c1 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -344,14 +344,7 @@ static int genpd_dev_pm_qos_notifier(struct notifier_block *nb,
struct device *dev;
gpd_data = container_of(nb, struct generic_pm_domain_data, nb);
-
- mutex_lock(&gpd_data->lock);
dev = gpd_data->base.dev;
- if (!dev) {
- mutex_unlock(&gpd_data->lock);
- return NOTIFY_DONE;
- }
- mutex_unlock(&gpd_data->lock);
for (;;) {
struct generic_pm_domain *genpd;
@@ -1392,16 +1385,12 @@ static struct generic_pm_domain_data *genpd_alloc_dev_data(struct device *dev)
if (!gpd_data)
return NULL;
- mutex_init(&gpd_data->lock);
- gpd_data->nb.notifier_call = genpd_dev_pm_qos_notifier;
- dev_pm_qos_add_notifier(dev, &gpd_data->nb);
return gpd_data;
}
static void genpd_free_dev_data(struct device *dev,
struct generic_pm_domain_data *gpd_data)
{
- dev_pm_qos_remove_notifier(dev, &gpd_data->nb);
kfree(gpd_data);
}
@@ -1414,7 +1403,7 @@ static void genpd_free_dev_data(struct device *dev,
int __pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
struct gpd_timing_data *td)
{
- struct generic_pm_domain_data *gpd_data_new, *gpd_data = NULL;
+ struct generic_pm_domain_data *gpd_data;
int ret = 0;
dev_dbg(dev, "%s()\n", __func__);
@@ -1422,8 +1411,8 @@ int __pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(dev))
return -EINVAL;
- gpd_data_new = genpd_alloc_dev_data(dev);
- if (!gpd_data_new)
+ gpd_data = genpd_alloc_dev_data(dev);
+ if (!gpd_data)
return -ENOMEM;
genpd_acquire_lock(genpd);
@@ -1445,7 +1434,6 @@ int __pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
goto out;
}
- gpd_data = gpd_data_new;
dev->power.subsys_data->domain_data = &gpd_data->base;
if (td)
@@ -1461,19 +1449,20 @@ int __pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
genpd->device_count++;
genpd->max_off_time_changed = true;
- mutex_lock(&gpd_data->lock);
gpd_data->base.dev = dev;
list_add_tail(&gpd_data->base.list_node, &genpd->dev_list);
gpd_data->need_restore = -1;
gpd_data->td.constraint_changed = true;
gpd_data->td.effective_constraint_ns = -1;
- mutex_unlock(&gpd_data->lock);
+ gpd_data->nb.notifier_call = genpd_dev_pm_qos_notifier;
out:
genpd_release_lock(genpd);
- if (gpd_data != gpd_data_new)
- genpd_free_dev_data(dev, gpd_data_new);
+ if (ret)
+ genpd_free_dev_data(dev, gpd_data);
+ else
+ dev_pm_qos_add_notifier(dev, &gpd_data->nb);
return ret;
}
@@ -1509,6 +1498,11 @@ int pm_genpd_remove_device(struct generic_pm_domain *genpd,
|| pd_to_genpd(dev->pm_domain) != genpd)
return -EINVAL;
+ /* The above validation also means we have existing domain_data. */
+ pdd = dev->power.subsys_data->domain_data;
+ gpd_data = to_gpd_data(pdd);
+ dev_pm_qos_remove_notifier(dev, &gpd_data->nb);
+
genpd_acquire_lock(genpd);
if (genpd->prepared_count > 0) {
@@ -1525,16 +1519,12 @@ int pm_genpd_remove_device(struct generic_pm_domain *genpd,
spin_lock_irq(&dev->power.lock);
dev->pm_domain = NULL;
- pdd = dev->power.subsys_data->domain_data;
list_del_init(&pdd->list_node);
- gpd_data = to_gpd_data(pdd);
dev->power.subsys_data->domain_data = NULL;
spin_unlock_irq(&dev->power.lock);
- mutex_lock(&gpd_data->lock);
pdd->dev = NULL;
- mutex_unlock(&gpd_data->lock);
genpd_release_lock(genpd);
@@ -1545,6 +1535,7 @@ int pm_genpd_remove_device(struct generic_pm_domain *genpd,
out:
genpd_release_lock(genpd);
+ dev_pm_qos_add_notifier(dev, &gpd_data->nb);
return ret;
}
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index e160a0b..080e778 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -113,7 +113,6 @@ struct generic_pm_domain_data {
struct pm_domain_data base;
struct gpd_timing_data td;
struct notifier_block nb;
- struct mutex lock;
int need_restore;
};
--
1.9.1
--
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