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>
diff --git a/drivers/input/input.c b/drivers/input/input.c
index 3070c7a..2f2b020 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -65,16 +65,16 @@
/*
* 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 @@
if (handle->open)
handle->handler->event(handle,
type, code, value);
+ rcu_read_unlock();
}
/*
@@ -293,9 +294,11 @@
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 @@
}
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 @@
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 @@
* Make sure we are not delivering any more events
* through this handle
*/
- synchronize_sched();
+ synchronize_rcu();
}
}
@@ -451,11 +450,11 @@
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 @@
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 @@
mutex_lock(&dev->mutex);
list_del_rcu(&handle->d_node);
mutex_unlock(&dev->mutex);
- synchronize_sched();
+ synchronize_rcu();
}
EXPORT_SYMBOL(input_unregister_handle);
