Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 82ba56c2 authored by Dmitry Torokhov's avatar Dmitry Torokhov
Browse files

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: default avatarDmitry Torokhov <dtor@mail.ru>
parent 70093178

drivers/input/evdev.c

+9 −13
Original line number Diff line number Diff line
@@ -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)

drivers/input/input.c

+15 −21
Original line number Diff line number Diff line
@@ -65,16 +65,16 @@ static int input_defuzz_abs_event(int value, int old_val, int fuzz) 


/*

 * Pass event through all open handles. This function is called with

 * dev->event_lock held and interrupts disabled. Because of that we

 * do not need to use rcu_read_lock() here although we are using RCU

 * to access handle list. Note that because of that write-side uses

 * synchronize_sched() instead of synchronize_ru().

 * dev->event_lock held and interrupts disabled.

 */

static void input_pass_event(struct input_dev *dev,

			     unsigned int type, unsigned int code, int value)

{

	struct input_handle *handle = rcu_dereference(dev->grab);

	struct input_handle *handle;



	rcu_read_lock();



	handle = rcu_dereference(dev->grab);

	if (handle)

		handle->handler->event(handle, type, code, value);

	else
@@ -82,6 +82,7 @@ static void input_pass_event(struct input_dev *dev, 
			if (handle->open)

				handle->handler->event(handle,

							type, code, value);

	rcu_read_unlock();

}



/*
@@ -293,9 +294,11 @@ void input_inject_event(struct input_handle *handle, 
	if (is_event_supported(type, dev->evbit, EV_MAX)) {

		spin_lock_irqsave(&dev->event_lock, flags);



		rcu_read_lock();

		grab = rcu_dereference(dev->grab);

		if (!grab || grab == handle)

			input_handle_event(dev, type, code, value);

		rcu_read_unlock();



		spin_unlock_irqrestore(&dev->event_lock, flags);

	}
@@ -325,11 +328,7 @@ int input_grab_device(struct input_handle *handle) 
	}



	rcu_assign_pointer(dev->grab, handle);

	/*

	 * Not using synchronize_rcu() because read-side is protected

	 * by a spinlock with interrupts off instead of rcu_read_lock().

	 */

	synchronize_sched();

	synchronize_rcu();



 out:

	mutex_unlock(&dev->mutex);
@@ -344,7 +343,7 @@ static void __input_release_device(struct input_handle *handle) 
	if (dev->grab == handle) {

		rcu_assign_pointer(dev->grab, NULL);

		/* Make sure input_pass_event() notices that grab is gone */

		synchronize_sched();

		synchronize_rcu();



		list_for_each_entry(handle, &dev->h_list, d_node)

			if (handle->open && handle->handler->start)
@@ -404,7 +403,7 @@ int input_open_device(struct input_handle *handle) 
			 * Make sure we are not delivering any more events

			 * through this handle

			 */

			synchronize_sched();

			synchronize_rcu();

		}

	}
@@ -451,11 +450,11 @@ void input_close_device(struct input_handle *handle) 


	if (!--handle->open) {

		/*

		 * synchronize_sched() makes sure that input_pass_event()

		 * synchronize_rcu() makes sure that input_pass_event()

		 * completed and that no more input events are delivered

		 * through this handle

		 */

		synchronize_sched();

		synchronize_rcu();

	}



	mutex_unlock(&dev->mutex);
@@ -1477,12 +1476,7 @@ int input_register_handle(struct input_handle *handle) 
		return error;

	list_add_tail_rcu(&handle->d_node, &dev->h_list);

	mutex_unlock(&dev->mutex);

	/*

	 * We don't use synchronize_rcu() here because we rely

	 * on dev->event_lock to protect read-side critical

	 * section in input_pass_event().

	 */

	synchronize_sched();

	synchronize_rcu();



	/*

	 * Since we are supposed to be called from ->connect()
@@ -1521,7 +1515,7 @@ void input_unregister_handle(struct input_handle *handle) 
	mutex_lock(&dev->mutex);

	list_del_rcu(&handle->d_node);

	mutex_unlock(&dev->mutex);

	synchronize_sched();

	synchronize_rcu();

}

EXPORT_SYMBOL(input_unregister_handle);

drivers/input/joydev.c

+4 −7
Original line number Diff line number Diff line
@@ -149,8 +149,10 @@ static void joydev_event(struct input_handle *handle, 


	event.time = jiffies_to_msecs(jiffies);



	rcu_read_lock();

	list_for_each_entry_rcu(client, &joydev->client_list, node)

		joydev_pass_event(client, &event);

	rcu_read_unlock();



	wake_up_interruptible(&joydev->wait);

}
@@ -178,12 +180,7 @@ static void joydev_attach_client(struct joydev *joydev, 
	spin_lock(&joydev->client_lock);

	list_add_tail_rcu(&client->node, &joydev->client_list);

	spin_unlock(&joydev->client_lock);

	/*

	 * We don't use synchronize_rcu() here because read-side

	 * critical section is protected by a spinlock (dev->event_lock)

	 * instead of rcu_read_lock().

	 */

	synchronize_sched();

	synchronize_rcu();

}



static void joydev_detach_client(struct joydev *joydev,
@@ -192,7 +189,7 @@ static void joydev_detach_client(struct joydev *joydev, 
	spin_lock(&joydev->client_lock);

	list_del_rcu(&client->node);

	spin_unlock(&joydev->client_lock);

	synchronize_sched();

	synchronize_rcu();

}



static int joydev_open_device(struct joydev *joydev)

drivers/input/mousedev.c

+4 −7
Original line number Diff line number Diff line
@@ -265,6 +265,7 @@ static void mousedev_notify_readers(struct mousedev *mousedev, 
	unsigned int new_head;

	int wake_readers = 0;



	rcu_read_lock();

	list_for_each_entry_rcu(client, &mousedev->client_list, node) {



		/* Just acquire the lock, interrupts already disabled */
@@ -309,6 +310,7 @@ static void mousedev_notify_readers(struct mousedev *mousedev, 
			wake_readers = 1;

		}

	}

	rcu_read_unlock();



	if (wake_readers)

		wake_up_interruptible(&mousedev->wait);
@@ -499,12 +501,7 @@ static void mousedev_attach_client(struct mousedev *mousedev, 
	spin_lock(&mousedev->client_lock);

	list_add_tail_rcu(&client->node, &mousedev->client_list);

	spin_unlock(&mousedev->client_lock);

	/*

	 * We don't use synchronize_rcu() here because read-side

	 * critical section is protected by a spinlock (dev->event_lock)

	 * instead of rcu_read_lock().

	 */

	synchronize_sched();

	synchronize_rcu();

}



static void mousedev_detach_client(struct mousedev *mousedev,
@@ -513,7 +510,7 @@ static void mousedev_detach_client(struct mousedev *mousedev, 
	spin_lock(&mousedev->client_lock);

	list_del_rcu(&client->node);

	spin_unlock(&mousedev->client_lock);

	synchronize_sched();

	synchronize_rcu();

}



static int mousedev_release(struct inode *inode, struct file *file)