netdev - [ PATCH] usbnet.c mtu change needs to stop RX

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Date:	Thu, 23 Jun 2016 18:43:35 +0000
From:	Soohoon Lee <Soohoon.Lee@...com>
To:	"oneukum@...e.com" <oneukum@...e.com>
CC:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: [ PATCH] usbnet.c mtu change needs to stop RX


When MTU is changed unlink_urbs() flushes RX Q but mean while usbnet_bh() can fill up the Q at the same time.
Depends on which HCD is down there unlink takes long time then the flush never ends.


diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index 61ba464..e03e3e6 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -708,6 +708,7 @@ static int unlink_urbs (struct usbnet *dev, struct sk_buff_head *q)
        int                     count = 0;
 
        spin_lock_irqsave (&q->lock, flags);
+       usbnet_pause_rx(dev);
        while (!skb_queue_empty(q)) {
                struct skb_data         *entry;
                struct urb              *urb;
@@ -742,6 +743,7 @@ found:
                usb_put_urb(urb);
                spin_lock_irqsave(&q->lock, flags);
        }
+       usbnet_resume_rx(dev);
        spin_unlock_irqrestore (&q->lock, flags);
        return count;
 }
@@ -1509,6 +1511,7 @@ static void usbnet_bh (unsigned long param)
                   netif_device_present (dev->net) &&
                   netif_carrier_ok(dev->net) &&
                   !timer_pending (&dev->delay) &&
+                  !test_bit (EVENT_RX_PAUSED, &dev->flags) &&
                   !test_bit (EVENT_RX_HALT, &dev->flags)) {
                int     temp = dev->rxq.qlen;