PM / QoS: Add function dev_pm_qos_read_value() (v3)

To read the current PM QoS value for a given device we need to
make sure that the device's power.constraints object won't be
removed while we're doing that.  For this reason, put the
operation under dev->power.lock and acquire the lock
around the initialization and removal of power.constraints.

Moreover, since we're using the value of power.constraints to
determine whether or not the object is present, the
power.constraints_state field isn't necessary any more and may be
removed.  However, dev_pm_qos_add_request() needs to check if the
device is being removed from the system before allocating a new
PM QoS constraints object for it, so make it use the
power.power_state field of struct device for this purpose.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 956443f86254..c6291ab725a3 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -22,7 +22,6 @@
 #include <linux/mutex.h>
 #include <linux/pm.h>
 #include <linux/pm_runtime.h>
-#include <linux/pm_qos.h>
 #include <linux/resume-trace.h>
 #include <linux/interrupt.h>
 #include <linux/sched.h>
@@ -66,6 +65,7 @@ void device_pm_init(struct device *dev)
         spin_lock_init(&dev->power.lock);
         pm_runtime_init(dev);
         INIT_LIST_HEAD(&dev->power.entry);
+        dev->power.power_state = PMSG_INVALID;
 }
 
 /**
@@ -97,8 +97,8 @@ void device_pm_add(struct device *dev)
                 dev_warn(dev, "parent %s should not be sleeping\n",
                         dev_name(dev->parent));
         list_add_tail(&dev->power.entry, &dpm_list);
-        mutex_unlock(&dpm_list_mtx);
         dev_pm_qos_constraints_init(dev);
+        mutex_unlock(&dpm_list_mtx);
 }
 
 /**
@@ -109,9 +109,9 @@ void device_pm_remove(struct device *dev)
 {
         pr_debug("PM: Removing info for %s:%s\n",
                  dev->bus ? dev->bus->name : "No Bus", dev_name(dev));
-        dev_pm_qos_constraints_destroy(dev);
         complete_all(&dev->power.completion);
         mutex_lock(&dpm_list_mtx);
+        dev_pm_qos_constraints_destroy(dev);
         list_del_init(&dev->power.entry);
         mutex_unlock(&dpm_list_mtx);
         device_wakeup_disable(dev);