mei: bus: fix RX event scheduling

In this particular case this more correct and safer to check if the RX
event is set in the event mask rather than query waitqueue_active
Since the check is already performed in the mei_cl_bus_rx_event
function,  it is just required to check for its return value.
Second, since we don't have exclusive waiter wake_up_interruptible_all
is not used correctly here.
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/mei/bus.c

@@ -252,23 +252,28 @@ void mei_cl_bus_notify_event(struct mei_cl *cl)
 }
 
 /**
- * mei_cl_bus_rx_event  - schedule rx evenet
+ * mei_cl_bus_rx_event  - schedule rx event
  *
  * @cl: host client
+ *
+ * Return: true if event was scheduled
+ *         false if the client is not waiting for event
  */
-void mei_cl_bus_rx_event(struct mei_cl *cl)
+bool mei_cl_bus_rx_event(struct mei_cl *cl)
 {
 	struct mei_cl_device *cldev = cl->cldev;
 
 	if (!cldev || !cldev->event_cb)
-		return;
+		return false;
 
 	if (!(cldev->events_mask & BIT(MEI_CL_EVENT_RX)))
-		return;
+		return false;
 
 	set_bit(MEI_CL_EVENT_RX, &cldev->events);
 
 	schedule_work(&cldev->event_work);
+
+	return true;
 }
 
 /**

drivers/misc/mei/client.c

@@ -1735,10 +1735,8 @@ void mei_cl_complete(struct mei_cl *cl, struct mei_cl_cb *cb)
 
 	case MEI_FOP_READ:
 		list_add_tail(&cb->list, &cl->rd_completed);
-		if (waitqueue_active(&cl->rx_wait))
-			wake_up_interruptible_all(&cl->rx_wait);
-		else
-			mei_cl_bus_rx_event(cl);
+		if (!mei_cl_bus_rx_event(cl))
+			wake_up_interruptible(&cl->rx_wait);
 		break;
 
 	case MEI_FOP_CONNECT:

drivers/misc/mei/mei_dev.h

@@ -316,7 +316,7 @@ void mei_cl_bus_dev_fixup(struct mei_cl_device *dev);
 ssize_t __mei_cl_send(struct mei_cl *cl, u8 *buf, size_t length,
 			bool blocking);
 ssize_t __mei_cl_recv(struct mei_cl *cl, u8 *buf, size_t length);
-void mei_cl_bus_rx_event(struct mei_cl *cl);
+bool mei_cl_bus_rx_event(struct mei_cl *cl);
 void mei_cl_bus_notify_event(struct mei_cl *cl);
 void mei_cl_bus_remove_devices(struct mei_device *bus);
 int mei_cl_bus_init(void);