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>

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index fd4b26d..fc9f578 100644 (file)
--- 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",