Input: use full RCU API

RT guys alerted me to the fact that in their tree spinlocks
are preemptible and it is better to use full RCU API
(rcu_read_lock()/rcu_read_unlock()) to be safe.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 9 insertions, 13 deletions

diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index 27026f7d3c03..1d62c8b88e12 100644
--- a/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -63,10 +63,7 @@ static void evdev_pass_event(struct evdev_client *client,
 }
 
 /*
- * Pass incoming event to all connected clients. Note that we are
- * caleld under a spinlock with interrupts off so we don't need
- * to use rcu_read_lock() here. Writers will be using syncronize_sched()
- * instead of synchrnoize_rcu().
+ * Pass incoming event to all connected clients.
  */
 static void evdev_event(struct input_handle *handle,
                         unsigned int type, unsigned int code, int value)
@@ -80,6 +77,8 @@ static void evdev_event(struct input_handle *handle,
         event.code = code;
         event.value = value;
 
+        rcu_read_lock();
+
         client = rcu_dereference(evdev->grab);
         if (client)
                 evdev_pass_event(client, &event);
@@ -87,6 +86,8 @@ static void evdev_event(struct input_handle *handle,
                 list_for_each_entry_rcu(client, &evdev->client_list, node)
                         evdev_pass_event(client, &event);
 
+        rcu_read_unlock();
+
         wake_up_interruptible(&evdev->wait);
 }
 
@@ -142,12 +143,7 @@ static int evdev_grab(struct evdev *evdev, struct evdev_client *client)
                 return error;
 
         rcu_assign_pointer(evdev->grab, client);
-        /*
-         * We don't use synchronize_rcu() here because read-side
-         * critical section is protected by a spinlock instead
-         * of rcu_read_lock().
-         */
-        synchronize_sched();
+        synchronize_rcu();
 
         return 0;
 }
@@ -158,7 +154,7 @@ static int evdev_ungrab(struct evdev *evdev, struct evdev_client *client)
                 return  -EINVAL;
 
         rcu_assign_pointer(evdev->grab, NULL);
-        synchronize_sched();
+        synchronize_rcu();
         input_release_device(&evdev->handle);
 
         return 0;
@@ -170,7 +166,7 @@ static void evdev_attach_client(struct evdev *evdev,
         spin_lock(&evdev->client_lock);
         list_add_tail_rcu(&client->node, &evdev->client_list);
         spin_unlock(&evdev->client_lock);
-        synchronize_sched();
+        synchronize_rcu();
 }
 
 static void evdev_detach_client(struct evdev *evdev,
@@ -179,7 +175,7 @@ static void evdev_detach_client(struct evdev *evdev,
         spin_lock(&evdev->client_lock);
         list_del_rcu(&client->node);
         spin_unlock(&evdev->client_lock);
-        synchronize_sched();
+        synchronize_rcu();
 }
 
 static int evdev_open_device(struct evdev *evdev)