net: usbnet: fix softirq storm on suspend

Suspending an open usbnet device results in constant
rescheduling of usbnet_bh.

commit 65841fd5 "usbnet: handle remote wakeup asap"
refactored the usbnet_bh code to allow sharing the
urb allocate and submit code with usbnet_resume. In
this process, a test for, and immediate return on,
ENOLINK from rx_submit was unintentionally dropped.

The rx queue will not grow if rx_submit fails,
making usbnet_bh reschedule itself.  This results
in a softirq storm if the error is persistent.
rx_submit translates the usb_submit_urb error
EHOSTUNREACH into ENOLINK, so this is an expected
and persistent error for a suspended device. The
old code tested for this condition and avoided
rescheduling.  Putting this test back.

Cc: <stable@vger.kernel.org> # v3.5
Cc: Ming Lei <ming.lei@canonical.com>
Cc: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 12 insertions, 4 deletions

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index fd4b26d46fd5..fc9f578a1e25 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1201,19 +1201,26 @@ deferred:
 }
 EXPORT_SYMBOL_GPL(usbnet_start_xmit);
 
-static void rx_alloc_submit(struct usbnet *dev, gfp_t flags)
+static int rx_alloc_submit(struct usbnet *dev, gfp_t flags)
 {
         struct urb      *urb;
         int             i;
+        int             ret = 0;
 
         /* don't refill the queue all at once */
         for (i = 0; i < 10 && dev->rxq.qlen < RX_QLEN(dev); i++) {
                 urb = usb_alloc_urb(0, flags);
                 if (urb != NULL) {
-                        if (rx_submit(dev, urb, flags) == -ENOLINK)
-                                return;
+                        ret = rx_submit(dev, urb, flags);
+                        if (ret)
+                                goto err;
+                } else {
+                        ret = -ENOMEM;
+                        goto err;
                 }
         }
+err:
+        return ret;
 }
 
 /*-------------------------------------------------------------------------*/
@@ -1257,7 +1264,8 @@ static void usbnet_bh (unsigned long param)
                 int     temp = dev->rxq.qlen;
 
                 if (temp < RX_QLEN(dev)) {
-                        rx_alloc_submit(dev, GFP_ATOMIC);
+                        if (rx_alloc_submit(dev, GFP_ATOMIC) == -ENOLINK)
+                                return;
                         if (temp != dev->rxq.qlen)
                                 netif_dbg(dev, link, dev->net,
                                           "rxqlen %d --> %d\n",