linux-kernel - [PATCH 3.13.y-ckt 41/43] cdc_ncm: do not call usbnet_link_change from cdc_ncm

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Date:	Tue, 22 Mar 2016 14:03:56 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Bjørn Mork <bjorn@...k.no>,
	"David S . Miller" <davem@...emloft.net>,
	Luis Henriques <luis.henriques@...onical.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.13.y-ckt 41/43] cdc_ncm: do not call usbnet_link_change from cdc_ncm_bind

3.13.11-ckt37 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: =?UTF-8?q?Bj=C3=B8rn=20Mork?= <bjorn@...k.no>

commit 4d06dd537f95683aba3651098ae288b7cbff8274 upstream.

usbnet_link_change will call schedule_work and should be
avoided if bind is failing. Otherwise we will end up with
scheduled work referring to a netdev which has gone away.

Instead of making the call conditional, we can just defer
it to usbnet_probe, using the driver_info flag made for
this purpose.

Fixes: 8a34b0ae8778 ("usbnet: cdc_ncm: apply usbnet_link_change")
Reported-by: Andrey Konovalov <andreyknvl@...il.com>
Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Bjørn Mork <bjorn@...k.no>
Signed-off-by: David S. Miller <davem@...emloft.net>
[ luis: backported to 3.16:
  - cdc_ncm_bind_common() takes only 3 args in 3.16
  - adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
[ kamal: bakcported to 3.13: context ]
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/net/usb/cdc_ncm.c | 21 +++++----------------
 1 file changed, 5 insertions(+), 16 deletions(-)

diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index f2c3646..7fc1278 100644
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -561,24 +561,12 @@ EXPORT_SYMBOL_GPL(cdc_ncm_select_altsetting);
 
 static int cdc_ncm_bind(struct usbnet *dev, struct usb_interface *intf)
 {
-	int ret;
-
 	/* MBIM backwards compatible function? */
 	cdc_ncm_select_altsetting(dev, intf);
 	if (cdc_ncm_comm_intf_is_mbim(intf->cur_altsetting))
 		return -ENODEV;
 
-	/* NCM data altsetting is always 1 */
-	ret = cdc_ncm_bind_common(dev, intf, 1);
-
-	/*
-	 * We should get an event when network connection is "connected" or
-	 * "disconnected". Set network connection in "disconnected" state
-	 * (carrier is OFF) during attach, so the IP network stack does not
-	 * start IPv6 negotiation and more.
-	 */
-	usbnet_link_change(dev, 0, 0);
-	return ret;
+	return cdc_ncm_bind_common(dev, intf, 1);
 }
 
 static void cdc_ncm_align_tail(struct sk_buff *skb, size_t modulus, size_t remainder, size_t max)
@@ -1107,7 +1095,8 @@ static int cdc_ncm_check_connect(struct usbnet *dev)
 
 static const struct driver_info cdc_ncm_info = {
 	.description = "CDC NCM",
-	.flags = FLAG_POINTTOPOINT | FLAG_NO_SETINT | FLAG_MULTI_PACKET,
+	.flags = FLAG_POINTTOPOINT | FLAG_NO_SETINT | FLAG_MULTI_PACKET
+			| FLAG_LINK_INTR,
 	.bind = cdc_ncm_bind,
 	.unbind = cdc_ncm_unbind,
 	.check_connect = cdc_ncm_check_connect,
@@ -1121,7 +1110,7 @@ static const struct driver_info cdc_ncm_info = {
 static const struct driver_info wwan_info = {
 	.description = "Mobile Broadband Network Device",
 	.flags = FLAG_POINTTOPOINT | FLAG_NO_SETINT | FLAG_MULTI_PACKET
-			| FLAG_WWAN,
+			| FLAG_LINK_INTR | FLAG_WWAN,
 	.bind = cdc_ncm_bind,
 	.unbind = cdc_ncm_unbind,
 	.check_connect = cdc_ncm_check_connect,
@@ -1135,7 +1124,7 @@ static const struct driver_info wwan_info = {
 static const struct driver_info wwan_noarp_info = {
 	.description = "Mobile Broadband Network Device (NO ARP)",
 	.flags = FLAG_POINTTOPOINT | FLAG_NO_SETINT | FLAG_MULTI_PACKET
-			| FLAG_WWAN | FLAG_NOARP,
+			| FLAG_LINK_INTR | FLAG_WWAN | FLAG_NOARP,
 	.bind = cdc_ncm_bind,
 	.unbind = cdc_ncm_unbind,
 	.check_connect = cdc_ncm_check_connect,
-- 
2.7.0