r8152: fix lockup when runtime PM is enabled

When an interface is brought up which was previously suspended (via
runtime PM), it would hang. This happens because napi_disable is called
before napi_enable.

Solve this by avoiding napi_enable in the resume during open function
(netif_running is true when open is called, IFF_UP is set after a
successful open; netif_running is false when close is called, but IFF_UP
is then still set).

While at it, remove WORK_ENABLE check from rtl8152_open (introduced with
the original change) because it cannot happen:

 - After this patch, runtime resume will not set it during rtl8152_open.
 - When link is up, rtl8152_open is not called.
 - When link is down during system/auto suspend/resume, it is not set.

Fixes: 41cec84 ("r8152: don't enable napi before rx ready")
Link: https://lkml.kernel.org/r/20151205105912.GA1766@al
Signed-off-by: Peter Wu <peter@lekensteyn.nl>
Acked-by: Hayes Wang <hayeswang@realtek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/usb/r8152.c

@@ -3067,17 +3067,6 @@ static int rtl8152_open(struct net_device *netdev)
 
 	mutex_lock(&tp->control);
 
-	/* The WORK_ENABLE may be set when autoresume occurs */
-	if (test_bit(WORK_ENABLE, &tp->flags)) {
-		clear_bit(WORK_ENABLE, &tp->flags);
-		usb_kill_urb(tp->intr_urb);
-		cancel_delayed_work_sync(&tp->schedule);
-
-		/* disable the tx/rx, if the workqueue has enabled them. */
-		if (netif_carrier_ok(netdev))
-			tp->rtl_ops.disable(tp);
-	}
-
 	tp->rtl_ops.up(tp);
 
 	rtl8152_set_speed(tp, AUTONEG_ENABLE,
@@ -3124,12 +3113,6 @@ static int rtl8152_close(struct net_device *netdev)
 	} else {
 		mutex_lock(&tp->control);
 
-		/* The autosuspend may have been enabled and wouldn't
-		 * be disable when autoresume occurs, because the
-		 * netif_running() would be false.
-		 */
-		rtl_runtime_suspend_enable(tp, false);
-
 		tp->rtl_ops.down(tp);
 
 		mutex_unlock(&tp->control);
@@ -3512,7 +3495,7 @@ static int rtl8152_resume(struct usb_interface *intf)
 		netif_device_attach(tp->netdev);
 	}
 
-	if (netif_running(tp->netdev)) {
+	if (netif_running(tp->netdev) && tp->netdev->flags & IFF_UP) {
 		if (test_bit(SELECTIVE_SUSPEND, &tp->flags)) {
 			rtl_runtime_suspend_enable(tp, false);
 			clear_bit(SELECTIVE_SUSPEND, &tp->flags);
@@ -3532,6 +3515,8 @@ static int rtl8152_resume(struct usb_interface *intf)
 		}
 		usb_submit_urb(tp->intr_urb, GFP_KERNEL);
 	} else if (test_bit(SELECTIVE_SUSPEND, &tp->flags)) {
+		if (tp->netdev->flags & IFF_UP)
+			rtl_runtime_suspend_enable(tp, false);
 		clear_bit(SELECTIVE_SUSPEND, &tp->flags);
 	}