Input: uinput - take event lock when fetching events from buffer
When fetching events form device's buffer in uinput_read() we need to
take input device's event_lock to avoid racing with new event delivery.
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
index 7360568..1b4ee4a 100644
--- a/drivers/input/misc/uinput.c
+++ b/drivers/input/misc/uinput.c
@@ -452,9 +452,28 @@
return retval;
}
+static bool uinput_fetch_next_event(struct uinput_device *udev,
+ struct input_event *event)
+{
+ bool have_event;
+
+ spin_lock_irq(&udev->dev->event_lock);
+
+ have_event = udev->head != udev->tail;
+ if (have_event) {
+ *event = udev->buff[udev->tail];
+ udev->tail = (udev->tail + 1) % UINPUT_BUFFER_SIZE;
+ }
+
+ spin_unlock_irq(&udev->dev->event_lock);
+
+ return have_event;
+}
+
static ssize_t uinput_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
{
struct uinput_device *udev = file->private_data;
+ struct input_event event;
int retval = 0;
if (udev->state != UIST_CREATED)
@@ -477,12 +496,14 @@
goto out;
}
- while (udev->head != udev->tail && retval + input_event_size() <= count) {
- if (input_event_to_user(buffer + retval, &udev->buff[udev->tail])) {
+ while (retval + input_event_size() <= count &&
+ uinput_fetch_next_event(udev, &event)) {
+
+ if (input_event_to_user(buffer + retval, &event)) {
retval = -EFAULT;
goto out;
}
- udev->tail = (udev->tail + 1) % UINPUT_BUFFER_SIZE;
+
retval += input_event_size();
}