PM / Domains: Eliminate the mutex for the generic_pm_domain_data

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@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 0 insertions, 1 deletions

diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index e160a0bba28d..080e778118ba 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;
 };