kernel: backport raw-ip mode for newer QMI LTE modems

Backport support for raw-ip mode including all known fixes afterwards.

Newer LTE modems only tend to support this mode, which was only
introduced in kernel 4.5.

Also backport support for the Quectel EC2x LTE modem series which is
a very popular device.

No custom changes were needed in order to apply these patches.

Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>

1 files changed, 81 insertions, 0 deletions

diff --git a/target/linux/generic/patches-4.4/099-0005-qmi_wwan-Add-missing-skb_reset_mac_header-call.patch b/target/linux/generic/patches-4.4/099-0005-qmi_wwan-Add-missing-skb_reset_mac_header-call.patch
new file mode 100644
index 0000000000..08408e2414
--- /dev/null
+++ b/target/linux/generic/patches-4.4/099-0005-qmi_wwan-Add-missing-skb_reset_mac_header-call.patch
@@ -0,0 +1,81 @@
+From 0de0add10e587effa880c741c9413c874f16be91 Mon Sep 17 00:00:00 2001
+From: Kristian Evensen <kristian.evensen@gmail.com>
+Date: Tue, 7 Nov 2017 13:47:56 +0100
+Subject: [PATCH] qmi_wwan: Add missing skb_reset_mac_header-call
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+When we receive a packet on a QMI device in raw IP mode, we should call
+skb_reset_mac_header() to ensure that skb->mac_header contains a valid
+offset in the packet. While it shouldn't really matter, the packets have
+no MAC header and the interface is configured as-such, it seems certain
+parts of the network stack expects a "good" value in skb->mac_header.
+
+Without the skb_reset_mac_header() call added in this patch, for example
+shaping traffic (using tc) triggers the following oops on the first
+received packet:
+
+[  303.642957] skbuff: skb_under_panic: text:8f137918 len:177 put:67 head:8e4b0f00 data:8e4b0eff tail:0x8e4b0fb0 end:0x8e4b1520 dev:wwan0
+[  303.655045] Kernel bug detected[#1]:
+[  303.658622] CPU: 1 PID: 1002 Comm: logd Not tainted 4.9.58 #0
+[  303.664339] task: 8fdf05e0 task.stack: 8f15c000
+[  303.668844] $ 0   : 00000000 00000001 0000007a 00000000
+[  303.674062] $ 4   : 8149a2fc 8149a2fc 8149ce20 00000000
+[  303.679284] $ 8   : 00000030 3878303a 31623465 20303235
+[  303.684510] $12   : ded731e3 2626a277 00000000 03bd0000
+[  303.689747] $16   : 8ef62b40 00000043 8f137918 804db5fc
+[  303.694978] $20   : 00000001 00000004 8fc13800 00000003
+[  303.700215] $24   : 00000001 8024ab10
+[  303.705442] $28   : 8f15c000 8fc19cf0 00000043 802cc920
+[  303.710664] Hi    : 00000000
+[  303.713533] Lo    : 74e58000
+[  303.716436] epc   : 802cc920 skb_panic+0x58/0x5c
+[  303.721046] ra    : 802cc920 skb_panic+0x58/0x5c
+[  303.725639] Status: 11007c03 KERNEL EXL IE
+[  303.729823] Cause : 50800024 (ExcCode 09)
+[  303.733817] PrId  : 0001992f (MIPS 1004Kc)
+[  303.737892] Modules linked in: rt2800pci rt2800mmio rt2800lib qcserial ppp_async option usb_wwan rt2x00pci rt2x00mmio rt2x00lib rndis_host qmi_wwan ppp_generic nf_nat_pptp nf_conntrack_pptp nf_conntrack_ipv6 mt76x2i
+Process logd (pid: 1002, threadinfo=8f15c000, task=8fdf05e0, tls=77b3eee4)
+[  303.962509] Stack : 00000000 80408990 8f137918 000000b1 00000043 8e4b0f00 8e4b0eff 8e4b0fb0
+[  303.970871]         8e4b1520 8fec1800 00000043 802cd2a4 6e000045 00000043 00000000 8ef62000
+[  303.979219]         8eef5d00 8ef62b40 8fea7300 8f137918 00000000 00000000 0002bb01 793e5664
+[  303.987568]         8ef08884 00000001 8fea7300 00000002 8fc19e80 8eef5d00 00000006 00000003
+[  303.995934]         00000000 8030ba90 00000003 77ab3fd0 8149dc80 8004d1bc 8f15c000 8f383700
+[  304.004324]         ...
+[  304.006767] Call Trace:
+[  304.009241] [<802cc920>] skb_panic+0x58/0x5c
+[  304.013504] [<802cd2a4>] skb_push+0x78/0x90
+[  304.017783] [<8f137918>] 0x8f137918
+[  304.021269] Code: 00602825  0c02a3b4  24842888 <000c000d> 8c870060  8c8200a0  0007382b  00070336  8c88005c
+[  304.031034]
+[  304.032805] ---[ end trace b778c482b3f0bda9 ]---
+[  304.041384] Kernel panic - not syncing: Fatal exception in interrupt
+[  304.051975] Rebooting in 3 seconds..
+
+While the oops is for a 4.9-kernel, I was able to trigger the same oops with
+net-next as of yesterday.
+
+Fixes: 32f7adf633b9 ("net: qmi_wwan: support "raw IP" mode")
+Signed-off-by: Kristian Evensen <kristian.evensen@gmail.com>
+Acked-by: Bjørn Mork <bjorn@mork.no>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+---
+ drivers/net/usb/qmi_wwan.c | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c
+index a4f229edcceb..8d4a6f7cba61 100644
+--- a/drivers/net/usb/qmi_wwan.c
++++ b/drivers/net/usb/qmi_wwan.c
+@@ -499,6 +499,7 @@ static int qmi_wwan_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
+ 		return 1;
+ 	}
+ 	if (rawip) {
++		skb_reset_mac_header(skb);
+ 		skb->dev = dev->net; /* normally set by eth_type_trans */
+ 		skb->protocol = proto;
+ 		return 1;
+-- 
+2.7.4
+