Re: [PATCH] usb: gadget: rndis: add multi packages support for rndis

Re: [PATCH] usb: gadget: rndis: add multi packages support for rndis

[庞苏荣 (Surong Pang)]

Dear Greg,

These values are just used to recorded water mask of received packages per transfer.
Just to print the water mask information, they can be deleted.

Anyway, if rndis will be deleted entirely, this patch can be abandoned.

> 
> 
> On Wed, Mar 06, 2024 at 01:49:49PM +0800, Surong Pang wrote:
> > --- a/drivers/usb/gadget/function/rndis.c
> > +++ b/drivers/usb/gadget/function/rndis.c
> > @@ -39,6 +39,8 @@
> >
> >  #include "rndis.h"
> >
> > +static int max_out_pkts_per_xfer;
> > +static int max_out_size_per_xfer;
> 
> Note, this will not work, you can't have device-specific variables as a single entry, otherwise multiple devices at the same time will not
> work at all.
> 
> thanks,
> 
> greg k-h

Re: [PATCH] usb: gadget: rndis: add multi packages support for rndis

[Greg KH]

On Tue, Mar 26, 2024 at 10:47:16AM +0000, 庞苏荣 (Surong Pang) wrote:
> Dear Greg，
> Share Android Phone internet to Windows PC via USB still need the rndis feature.

What supported Windows PC still only has rndis and not cdc-ncm support?
Or the other USB networking driver support built in?  Windows has
deprecated RNDIS for a good reason, let's not continue to insist on
using insecure protocols please.

> OK, if rndis will be deleted entirely, this patch can be abandoned.

Eventually, yes, but as is, your patch can't be taken given the quick
review I already provided.

If you can show that there are Windows systems that only have RNDIS
support, and need this increased speed (i.e. that they can also support
the speedup), and fix up the other issues, then we can review your new
submission.  But please provide that proof when you do so.

thanks,

greg k-h

Re: [PATCH] usb: gadget: rndis: add multi packages support for rndis

[庞苏荣 (Surong Pang)]

Dear Greg，
Share Android Phone internet to Windows PC via USB still need the rndis feature.
OK, if rndis will be deleted entirely, this patch can be abandoned.

> 
> 
> On Wed, Mar 06, 2024 at 01:49:49PM +0800, Surong Pang wrote:
> > As ncm, aggergate multi skb packages and transfer them at one URB.
> > In USB2.0, the network throughput can be improved from about 18MB/S to
> > 35MB/S.
> 
> Why is rndis still being used?  It's an insecure and obsolete protocol that should not be used at all anywhere.  I keep trying to delete it
> entirely, but need to go and write an active exploit to prove to people just how bad it really is before I can do so...
> 
> Adding more functionality to it is not a good idea, what is wrong with the other, built-in, networking protocols instead?  Why are you
> using this old one still when there are so many better options out there?
> 
> thanks,
> 
> greg k-h

Re: [PATCH] usb: gadget: rndis: add multi packages support for rndis

[Greg KH]

On Wed, Mar 06, 2024 at 01:49:49PM +0800, Surong Pang wrote:
> --- a/drivers/usb/gadget/function/rndis.c
> +++ b/drivers/usb/gadget/function/rndis.c
> @@ -39,6 +39,8 @@
>  
>  #include "rndis.h"
>  
> +static int max_out_pkts_per_xfer;
> +static int max_out_size_per_xfer;

Note, this will not work, you can't have device-specific variables as a
single entry, otherwise multiple devices at the same time will not work
at all.

thanks,

greg k-h

Re: [PATCH] usb: gadget: rndis: add multi packages support for rndis

[Greg KH]

On Wed, Mar 06, 2024 at 01:49:49PM +0800, Surong Pang wrote:
> As ncm, aggergate multi skb packages and transfer them at one URB.
> In USB2.0, the network throughput can be improved from about 18MB/S
> to 35MB/S.

Why is rndis still being used?  It's an insecure and obsolete protocol
that should not be used at all anywhere.  I keep trying to delete it
entirely, but need to go and write an active exploit to prove to people
just how bad it really is before I can do so...

Adding more functionality to it is not a good idea, what is wrong with
the other, built-in, networking protocols instead?  Why are you using
this old one still when there are so many better options out there?

thanks,

greg k-h

[PATCH] usb: gadget: rndis: add multi packages support for rndis

[Surong Pang]

As ncm, aggergate multi skb packages and transfer them at one URB.
In USB2.0, the network throughput can be improved from about 18MB/S
to 35MB/S.

Signed-off-by: Surong Pang <surong.pang@unisoc.com>
---
 drivers/usb/gadget/function/f_rndis.c | 123 ++++++++++++++++++++---
 drivers/usb/gadget/function/rndis.c   | 135 +++++++++++++++++++++-----
 drivers/usb/gadget/function/rndis.h   |  13 ++-
 3 files changed, 234 insertions(+), 37 deletions(-)

diff --git a/drivers/usb/gadget/function/f_rndis.c b/drivers/usb/gadget/function/f_rndis.c
index b47f99d17ee9..a87497b80946 100644
--- a/drivers/usb/gadget/function/f_rndis.c
+++ b/drivers/usb/gadget/function/f_rndis.c
@@ -77,6 +77,12 @@ struct f_rndis {
 	struct usb_ep			*notify;
 	struct usb_request		*notify_req;
 	atomic_t			notify_count;
+
+	struct net_device		*netdev;
+	/* For multi-frame RNDIS TX */
+	u16				prepared_tx_skb_count;
+	struct sk_buff			*prepared_tx_skb;
+	struct hrtimer			task_timer;
 };
 
 static inline struct f_rndis *func_to_rndis(struct usb_function *f)
@@ -92,6 +98,7 @@ static inline struct f_rndis *func_to_rndis(struct usb_function *f)
 #define RNDIS_STATUS_INTERVAL_MS	32
 #define STATUS_BYTECOUNT		8	/* 8 bytes data */
 
+#define TX_TIMEOUT_NSECS 200000
 
 /* interface descriptor: */
 
@@ -102,9 +109,9 @@ static struct usb_interface_descriptor rndis_control_intf = {
 	/* .bInterfaceNumber = DYNAMIC */
 	/* status endpoint is optional; this could be patched later */
 	.bNumEndpoints =	1,
-	.bInterfaceClass =	USB_CLASS_COMM,
-	.bInterfaceSubClass =   USB_CDC_SUBCLASS_ACM,
-	.bInterfaceProtocol =   USB_CDC_ACM_PROTO_VENDOR,
+	.bInterfaceClass =	USB_CLASS_WIRELESS_CONTROLLER,
+	.bInterfaceSubClass =	0x01,
+	.bInterfaceProtocol =	USB_CDC_ACM_PROTO_AT_PCCA101_WAKE,
 	/* .iInterface = DYNAMIC */
 };
 
@@ -162,10 +169,10 @@ rndis_iad_descriptor = {
 	.bDescriptorType =	USB_DT_INTERFACE_ASSOCIATION,
 
 	.bFirstInterface =	0, /* XXX, hardcoded */
-	.bInterfaceCount = 	2,	// control + data
-	.bFunctionClass =	USB_CLASS_COMM,
-	.bFunctionSubClass =	USB_CDC_SUBCLASS_ETHERNET,
-	.bFunctionProtocol =	USB_CDC_PROTO_NONE,
+	.bInterfaceCount =	2, // control + data
+	.bFunctionClass =	USB_CLASS_WIRELESS_CONTROLLER,
+	.bFunctionSubClass =	0x01,
+	.bFunctionProtocol =	USB_CDC_ACM_PROTO_AT_PCCA101_WAKE,
 	/* .iFunction = DYNAMIC */
 };
 
@@ -352,20 +359,104 @@ static struct usb_gadget_strings *rndis_strings[] = {
 	NULL,
 };
 
+/*
+ * The transmit should only be run if no skb data has been sent
+ * for a certain duration.
+ */
+static enum hrtimer_restart rndis_tx_timeout(struct hrtimer *data)
+{
+	struct f_rndis *rndis = container_of(data, struct f_rndis, task_timer);
+	struct net_device *netdev = READ_ONCE(rndis->netdev);
+
+	if (netdev) {
+		/* XXX This allowance of a NULL skb argument to ndo_start_xmit
+		 * XXX is not sane.  The gadget layer should be redesigned so
+		 * XXX that the dev->wrap() invocations to build SKBs is transparent
+		 * XXX and performed in some way outside of the ndo_start_xmit
+		 * XXX interface.
+		 *
+		 * This will call directly into u_ether's eth_start_xmit()
+		 */
+		netdev->netdev_ops->ndo_start_xmit(NULL, netdev);
+	}
+	return HRTIMER_NORESTART;
+}
+
+static struct sk_buff *package_for_tx(struct f_rndis *rndis)
+{
+	struct sk_buff *skb = NULL;
+
+	/* Stop the timer */
+	hrtimer_try_to_cancel(&rndis->task_timer);
+
+	/* Merge the skbs */
+	swap(skb, rndis->prepared_tx_skb);
+
+	return skb;
+}
+
 /*-------------------------------------------------------------------------*/
 
 static struct sk_buff *rndis_add_header(struct gether *port,
 					struct sk_buff *skb)
 {
-	struct sk_buff *skb2;
+	struct f_rndis *rndis = func_to_rndis(&port->func);
+	struct usb_composite_dev *cdev = rndis->port.func.config->cdev;
+	struct rndis_params *params = rndis->params;
+	struct sk_buff *skb2 = NULL;
+	int head_len = sizeof(struct rndis_packet_msg_type);
+
+	if (skb) {
+		if (rndis->prepared_tx_skb &&
+			(rndis->prepared_tx_skb_count >= params->max_in_pkts_per_xfer ||
+			(rndis->prepared_tx_skb->len + skb->len + head_len) >=
+			params->max_in_size_per_xfer)) {
+			DBG(cdev, "prepared tx skb count %d, len %d\n",
+				rndis->prepared_tx_skb_count, rndis->prepared_tx_skb->len);
+			skb2 = package_for_tx(rndis);
+		}
+
+		if (!rndis->prepared_tx_skb) {
+			/* Create a new skb for multi xfer. */
+			DBG(cdev, "create a new multi skb, len %d\n", params->max_in_size_per_xfer);
+
+			rndis->prepared_tx_skb =
+				alloc_skb(params->max_in_size_per_xfer, GFP_ATOMIC);
+			if (!rndis->prepared_tx_skb)
+				goto err;
 
-	if (!skb)
-		return NULL;
+			rndis->prepared_tx_skb->dev = rndis->netdev;
+			rndis->prepared_tx_skb_count = 0;
 
+			/* Start the timer. */
+			hrtimer_start(&rndis->task_timer, TX_TIMEOUT_NSECS,
+				      HRTIMER_MODE_REL_SOFT);
+		}
+
+		/*
+		 * Add the new data to the skb
+		 * PacketAlignmentFactor is 0, no need to add padding
+		 */
+		rndis_copy_hdr(rndis->prepared_tx_skb, skb);
+		skb_put_data(rndis->prepared_tx_skb, skb->data, skb->len);
+		rndis->prepared_tx_skb_count++;
+		dev_consume_skb_any(skb);
+		skb = NULL;
+	} else if (rndis->prepared_tx_skb) {
+		/* If we get here eth_start_xmit() was called with NULL skb by
+		 * rndis_tx_timeout() - hence, this is our signal to flush/send.
+		 */
+		DBG(cdev, "timer expired, prepared tx skb count %d, len %d\n",
+			rndis->prepared_tx_skb_count, rndis->prepared_tx_skb->len);
+		skb2 = package_for_tx(rndis);
+	}
+	return skb2;
+
+err:
 	skb2 = skb_realloc_headroom(skb, sizeof(struct rndis_packet_msg_type));
 	rndis_add_hdr(skb2);
 
-	dev_kfree_skb(skb);
+	dev_consume_skb_any(skb);
 	return skb2;
 }
 
@@ -546,6 +637,7 @@ static int rndis_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 
 		if (rndis->port.in_ep->enabled) {
 			DBG(cdev, "reset rndis\n");
+			rndis->netdev = NULL;
 			gether_disconnect(&rndis->port);
 		}
 
@@ -582,8 +674,9 @@ static int rndis_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 		net = gether_connect(&rndis->port);
 		if (IS_ERR(net))
 			return PTR_ERR(net);
+		rndis->netdev = net;
 
-		rndis_set_param_dev(rndis->params, net,
+		rndis_set_param_dev(&rndis->port, rndis->params, net,
 				&rndis->port.cdc_filter);
 	} else
 		goto fail;
@@ -604,6 +697,7 @@ static void rndis_disable(struct usb_function *f)
 	DBG(cdev, "rndis deactivated\n");
 
 	rndis_uninit(rndis->params);
+	rndis->netdev = NULL;
 	gether_disconnect(&rndis->port);
 
 	usb_ep_disable(rndis->notify);
@@ -793,6 +887,9 @@ rndis_bind(struct usb_configuration *c, struct usb_function *f)
 		goto fail_free_descs;
 	}
 
+	hrtimer_init(&rndis->task_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);
+	rndis->task_timer.function = rndis_tx_timeout;
+
 	/* NOTE:  all that is done without knowing or caring about
 	 * the network link ... which is unavailable to this code
 	 * until we're activated via set_alt().
@@ -956,6 +1053,8 @@ static void rndis_unbind(struct usb_configuration *c, struct usb_function *f)
 {
 	struct f_rndis		*rndis = func_to_rndis(f);
 
+	hrtimer_cancel(&rndis->task_timer);
+
 	kfree(f->os_desc_table);
 	f->os_desc_n = 0;
 	usb_free_all_descriptors(f);
diff --git a/drivers/usb/gadget/function/rndis.c b/drivers/usb/gadget/function/rndis.c
index 29bf8664bf58..fd321b53e46f 100644
--- a/drivers/usb/gadget/function/rndis.c
+++ b/drivers/usb/gadget/function/rndis.c
@@ -39,6 +39,8 @@
 
 #include "rndis.h"
 
+static int max_out_pkts_per_xfer;
+static int max_out_size_per_xfer;
 
 /* The driver for your USB chip needs to support ep0 OUT to work with
  * RNDIS, plus all three CDC Ethernet endpoints (interrupt not optional).
@@ -574,12 +576,12 @@ static int rndis_init_response(struct rndis_params *params,
 	resp->MinorVersion = cpu_to_le32(RNDIS_MINOR_VERSION);
 	resp->DeviceFlags = cpu_to_le32(RNDIS_DF_CONNECTIONLESS);
 	resp->Medium = cpu_to_le32(RNDIS_MEDIUM_802_3);
-	resp->MaxPacketsPerTransfer = cpu_to_le32(1);
-	resp->MaxTransferSize = cpu_to_le32(
-		  params->dev->mtu
+	resp->MaxPacketsPerTransfer = cpu_to_le32(params->max_out_pkts_per_xfer);
+	resp->MaxTransferSize = cpu_to_le32(params->max_out_pkts_per_xfer *
+		  (params->dev->mtu
 		+ sizeof(struct ethhdr)
 		+ sizeof(struct rndis_packet_msg_type)
-		+ 22);
+		+ 22));
 	resp->PacketAlignmentFactor = cpu_to_le32(0);
 	resp->AFListOffset = cpu_to_le32(0);
 	resp->AFListSize = cpu_to_le32(0);
@@ -790,7 +792,7 @@ EXPORT_SYMBOL_GPL(rndis_set_host_mac);
  */
 int rndis_msg_parser(struct rndis_params *params, u8 *buf)
 {
-	u32 MsgType, MsgLength;
+	u32 MsgType, MsgLength, RequestID, MajorVersion, MinorVersion, MaxTransferSize;
 	__le32 *tmp;
 
 	if (!buf)
@@ -813,7 +815,12 @@ int rndis_msg_parser(struct rndis_params *params, u8 *buf)
 	case RNDIS_MSG_INIT:
 		pr_debug("%s: RNDIS_MSG_INIT\n",
 			__func__);
+		RequestID   = get_unaligned_le32(tmp++);
+		MajorVersion = get_unaligned_le32(tmp++);
+		MinorVersion = get_unaligned_le32(tmp++);
+		MaxTransferSize = get_unaligned_le32(tmp++);
 		params->state = RNDIS_INITIALIZED;
+		params->max_in_size_per_xfer = MaxTransferSize;
 		return rndis_init_response(params, (rndis_init_msg_type *)buf);
 
 	case RNDIS_MSG_HALT:
@@ -922,6 +929,8 @@ struct rndis_params *rndis_register(void (*resp_avail)(void *v), void *v)
 	params->media_state = RNDIS_MEDIA_STATE_DISCONNECTED;
 	params->resp_avail = resp_avail;
 	params->v = v;
+	params->max_in_pkts_per_xfer  = RNDIS_MAX_IN_PKTS_PER_XFER;
+	params->max_out_pkts_per_xfer = RNDIS_MAX_OUT_PKTS_PER_XFER;
 	INIT_LIST_HEAD(&params->resp_queue);
 	spin_lock_init(&params->resp_lock);
 	pr_debug("%s: configNr = %d\n", __func__, i);
@@ -954,8 +963,8 @@ void rndis_deregister(struct rndis_params *params)
 	rndis_put_nr(i);
 }
 EXPORT_SYMBOL_GPL(rndis_deregister);
-int rndis_set_param_dev(struct rndis_params *params, struct net_device *dev,
-			u16 *cdc_filter)
+int rndis_set_param_dev(struct gether *port, struct rndis_params *params,
+			struct net_device *dev, u16 *cdc_filter)
 {
 	pr_debug("%s:\n", __func__);
 	if (!dev)
@@ -965,7 +974,18 @@ int rndis_set_param_dev(struct rndis_params *params, struct net_device *dev,
 
 	params->dev = dev;
 	params->filter = cdc_filter;
-
+	params->max_out_size_per_xfer = (params->max_out_pkts_per_xfer *
+					(dev->mtu
+					+ sizeof(struct ethhdr)
+					+ sizeof(struct rndis_packet_msg_type)
+					+ 22));
+	port->is_fixed = true;
+	port->fixed_out_len = params->max_out_size_per_xfer;
+
+	pr_debug("mtu %d, fixed_out_len %d\n", dev->mtu, port->fixed_out_len);
+
+	max_out_pkts_per_xfer = params->max_out_pkts_per_xfer;
+	max_out_size_per_xfer = params->max_out_size_per_xfer;
 	return 0;
 }
 EXPORT_SYMBOL_GPL(rndis_set_param_dev);
@@ -1013,6 +1033,23 @@ void rndis_add_hdr(struct sk_buff *skb)
 }
 EXPORT_SYMBOL_GPL(rndis_add_hdr);
 
+void rndis_copy_hdr(struct sk_buff *dest_skb, struct sk_buff *new_skb)
+{
+	struct rndis_packet_msg_type header;
+	int head_len = sizeof(header);
+
+	if (!dest_skb || !new_skb)
+		return;
+
+	memset(&header, 0, head_len);
+	header.MessageType = cpu_to_le32(RNDIS_MSG_PACKET);
+	header.MessageLength = cpu_to_le32(head_len + new_skb->len);
+	header.DataOffset = cpu_to_le32(36);
+	header.DataLength = cpu_to_le32(new_skb->len);
+	skb_put_data(dest_skb, &header, head_len);
+}
+EXPORT_SYMBOL_GPL(rndis_copy_hdr);
+
 void rndis_free_response(struct rndis_params *params, u8 *buf)
 {
 	rndis_resp_t *r, *n;
@@ -1071,26 +1108,78 @@ int rndis_rm_hdr(struct gether *port,
 			struct sk_buff *skb,
 			struct sk_buff_head *list)
 {
-	/* tmp points to a struct rndis_packet_msg_type */
-	__le32 *tmp = (void *)skb->data;
+	int ret = 0;
+	int num_pkts = 1;
 
-	/* MessageType, MessageLength */
-	if (cpu_to_le32(RNDIS_MSG_PACKET)
-			!= get_unaligned(tmp++)) {
-		dev_kfree_skb_any(skb);
-		return -EINVAL;
-	}
-	tmp++;
+	while (skb->len) {
+		struct rndis_packet_msg_type *hdr;
+		struct sk_buff *skb2;
+		u32 msg_len, data_offset, data_len;
+
+		/* some rndis hosts send extra byte to avoid zlp, ignore it */
+		if (skb->len == 1) {
+			pr_info("skb len 1, should ignore!\n");
+			break;
+		}
+
+		if (skb->len < sizeof(*hdr)) {
+			pr_err("invalid rndis pkt: skblen:%u hdr_len:%zu",
+			       skb->len, sizeof(*hdr));
+			skb->len = 0;
+			ret = -EINVAL;
+			break;
+		}
 
-	/* DataOffset, DataLength */
-	if (!skb_pull(skb, get_unaligned_le32(tmp++) + 8)) {
-		dev_kfree_skb_any(skb);
-		return -EOVERFLOW;
+		hdr = (void *)skb->data;
+		msg_len = le32_to_cpu(hdr->MessageLength);
+		data_offset = le32_to_cpu(hdr->DataOffset);
+		data_len = le32_to_cpu(hdr->DataLength);
+
+		if (skb->len < msg_len ||
+		    ((data_offset + data_len + 8) > msg_len)) {
+			pr_err("invalid rndis message: %d/%d/%d/%d, len:%d\n",
+			       le32_to_cpu(hdr->MessageType),
+			       msg_len, data_offset, data_len, skb->len);
+			skb->len = 0;
+			ret = -EOVERFLOW;
+			break;
+		}
+		if (le32_to_cpu(hdr->MessageType) != RNDIS_MSG_PACKET) {
+			pr_err("invalid rndis message: %d/%d/%d/%d, len:%d\n",
+			       le32_to_cpu(hdr->MessageType), msg_len,
+			       data_offset, data_len, skb->len);
+			skb->len = 0;
+			ret = -EINVAL;
+			break;
+		}
+
+		skb_pull(skb, data_offset + 8);
+
+		if (data_len == skb->len) {
+			skb_trim(skb, data_len);
+			break;
+		}
+
+		skb2 = skb_clone(skb, GFP_ATOMIC);
+		if (!skb2) {
+			pr_err("%s:skb clone failed\n", __func__);
+			skb->len = 0;
+			ret = -ENOMEM;
+			break;
+		}
+
+		skb_pull(skb, msg_len - (data_offset + 8));
+		skb_trim(skb2, data_len);
+		skb_queue_tail(list, skb2);
+
+		num_pkts++;
 	}
-	skb_trim(skb, get_unaligned_le32(tmp++));
+
+	if (num_pkts > max_out_pkts_per_xfer)
+		pr_err("max out pkts per xfer rcvd %d\n", num_pkts);
 
 	skb_queue_tail(list, skb);
-	return 0;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(rndis_rm_hdr);
 
diff --git a/drivers/usb/gadget/function/rndis.h b/drivers/usb/gadget/function/rndis.h
index 6206b8b7490f..d6acbc1577f8 100644
--- a/drivers/usb/gadget/function/rndis.h
+++ b/drivers/usb/gadget/function/rndis.h
@@ -19,6 +19,9 @@
 #define RNDIS_MAXIMUM_FRAME_SIZE	1518
 #define RNDIS_MAX_TOTAL_SIZE		1558
 
+#define RNDIS_MAX_IN_PKTS_PER_XFER	10
+#define RNDIS_MAX_OUT_PKTS_PER_XFER	3
+
 typedef struct rndis_init_msg_type {
 	__le32	MessageType;
 	__le32	MessageLength;
@@ -175,18 +178,24 @@ typedef struct rndis_params {
 	void			*v;
 	struct list_head	resp_queue;
 	spinlock_t		resp_lock;
+
+	u32			max_in_size_per_xfer;
+	u32			max_in_pkts_per_xfer;
+	u32			max_out_size_per_xfer;
+	u32			max_out_pkts_per_xfer;
 } rndis_params;
 
 /* RNDIS Message parser and other useless functions */
 int  rndis_msg_parser(struct rndis_params *params, u8 *buf);
 struct rndis_params *rndis_register(void (*resp_avail)(void *v), void *v);
 void rndis_deregister(struct rndis_params *params);
-int  rndis_set_param_dev(struct rndis_params *params, struct net_device *dev,
-			 u16 *cdc_filter);
+int  rndis_set_param_dev(struct gether *port, struct rndis_params *params,
+			 struct net_device *dev, u16 *cdc_filter);
 int  rndis_set_param_vendor(struct rndis_params *params, u32 vendorID,
 			    const char *vendorDescr);
 int  rndis_set_param_medium(struct rndis_params *params, u32 medium,
 			     u32 speed);
+void rndis_copy_hdr(struct sk_buff *dest_skb, struct sk_buff *new_skb);
 void rndis_add_hdr(struct sk_buff *skb);
 int rndis_rm_hdr(struct gether *port, struct sk_buff *skb,
 			struct sk_buff_head *list);
-- 
2.34.1