Input: add semaphore and user count to input_dev structure;
serialize open and close calls and ensure that device's
open and close methods are only called when first user
opens it or last user closes it.
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/drivers/input/input.c b/drivers/input/input.c
index 3385dd0..1885f36 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -219,10 +219,24 @@
int input_open_device(struct input_handle *handle)
{
+ struct input_dev *dev = handle->dev;
+ int err;
+
+ err = down_interruptible(&dev->sem);
+ if (err)
+ return err;
+
handle->open++;
- if (handle->dev->open)
- return handle->dev->open(handle->dev);
- return 0;
+
+ if (!dev->users++ && dev->open)
+ err = dev->open(dev);
+
+ if (err)
+ handle->open--;
+
+ up(&dev->sem);
+
+ return err;
}
int input_flush_device(struct input_handle* handle, struct file* file)
@@ -235,10 +249,17 @@
void input_close_device(struct input_handle *handle)
{
+ struct input_dev *dev = handle->dev;
+
input_release_device(handle);
- if (handle->dev->close)
- handle->dev->close(handle->dev);
+
+ down(&dev->sem);
+
+ if (!--dev->users && dev->close)
+ dev->close(dev);
handle->open--;
+
+ up(&dev->sem);
}
static void input_link_handle(struct input_handle *handle)
@@ -415,6 +436,8 @@
set_bit(EV_SYN, dev->evbit);
+ init_MUTEX(&dev->sem);
+
/*
* If delay and period are pre-set by the driver, then autorepeating
* is handled by the driver itself and we don't do it in input.c.