From: Bjørn Mork <bjorn@mork.no>
Date: Sun, 2 Sep 2012 22:26:18 +0000 (+0000)
Subject: net: usbnet: fix softirq storm on suspend
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=85e87870fa18ec9f5df98e2d3b48f3699560a570;p=GitHub%2FLineageOS%2Fandroid_kernel_samsung_universal7580.git

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 fd4b26d46fd..fc9f578a1e2 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",