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Subject[RFC][PATCH 1/2] PM / cpuidle: Add driver reference counter
Date
From: Rafael J. Wysocki <rjw@sisk.pl>

Add a reference counter for the cpuidle driver, so that it can't
be unregistered when it is in use.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
drivers/cpuidle/driver.c | 29 ++++++++++++++++++++++++++++-
include/linux/cpuidle.h | 6 +++++-
2 files changed, 33 insertions(+), 2 deletions(-)
Index: linux/drivers/cpuidle/driver.c
===================================================================
--- linux.orig/drivers/cpuidle/driver.c
+++ linux/drivers/cpuidle/driver.c
@@ -16,6 +16,7 @@

static struct cpuidle_driver *cpuidle_curr_driver;
DEFINE_SPINLOCK(cpuidle_driver_lock);
+int cpuidle_driver_refcount;

static void __cpuidle_register_driver(struct cpuidle_driver *drv)
{
@@ -89,8 +90,34 @@ void cpuidle_unregister_driver(struct cp
}

spin_lock(&cpuidle_driver_lock);
- cpuidle_curr_driver = NULL;
+
+ if (!WARN_ON(cpuidle_driver_refcount > 0))
+ cpuidle_curr_driver = NULL;
+
spin_unlock(&cpuidle_driver_lock);
}

EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
+
+struct cpuidle_driver *cpuidle_driver_ref(void)
+{
+ struct cpuidle_driver *drv;
+
+ spin_lock(&cpuidle_driver_lock);
+
+ drv = cpuidle_curr_driver;
+ cpuidle_driver_refcount++;
+
+ spin_unlock(&cpuidle_driver_lock);
+ return drv;
+}
+
+void cpuidle_driver_unref(void)
+{
+ spin_lock(&cpuidle_driver_lock);
+
+ if (!WARN_ON(cpuidle_driver_refcount <= 0))
+ cpuidle_driver_refcount--;
+
+ spin_unlock(&cpuidle_driver_lock);
+}
Index: linux/include/linux/cpuidle.h
===================================================================
--- linux.orig/include/linux/cpuidle.h
+++ linux/include/linux/cpuidle.h
@@ -136,7 +136,9 @@ struct cpuidle_driver {
extern void disable_cpuidle(void);
extern int cpuidle_idle_call(void);
extern int cpuidle_register_driver(struct cpuidle_driver *drv);
-struct cpuidle_driver *cpuidle_get_driver(void);
+extern struct cpuidle_driver *cpuidle_get_driver(void);
+extern struct cpuidle_driver *cpuidle_driver_ref(void);
+extern void cpuidle_driver_unref(void);
extern void cpuidle_unregister_driver(struct cpuidle_driver *drv);
extern int cpuidle_register_device(struct cpuidle_device *dev);
extern void cpuidle_unregister_device(struct cpuidle_device *dev);
@@ -157,6 +159,8 @@ static inline int cpuidle_idle_call(void
static inline int cpuidle_register_driver(struct cpuidle_driver *drv)
{return -ENODEV; }
static inline struct cpuidle_driver *cpuidle_get_driver(void) {return NULL; }
+static inline struct cpuidle_driver *cpuidle_driver_ref(void) {return NULL; }
+static inline void cpuidle_driver_unref(void) {}
static inline void cpuidle_unregister_driver(struct cpuidle_driver *drv) { }
static inline int cpuidle_register_device(struct cpuidle_device *dev)
{return -ENODEV; }


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