4 files changed, 67 insertions, 10 deletions

diff --git a/drivers/net/usb/cdc_mbim.c b/drivers/net/usb/cdc_mbim.c
index e4b7a47a825c..efc18e05af0a 100644
--- a/drivers/net/usb/cdc_mbim.c
+++ b/drivers/net/usb/cdc_mbim.c
@@ -158,7 +158,7 @@ static int cdc_mbim_bind(struct usbnet *dev, struct usb_interface *intf)
         if (!cdc_ncm_comm_intf_is_mbim(intf->cur_altsetting))
                 goto err;
 
-        ret = cdc_ncm_bind_common(dev, intf, data_altsetting);
+        ret = cdc_ncm_bind_common(dev, intf, data_altsetting, 0);
         if (ret)
                 goto err;
 
diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index 8067b8fbb0ee..1991e4a24657 100644
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -684,10 +684,12 @@ static void cdc_ncm_free(struct cdc_ncm_ctx *ctx)
                 ctx->tx_curr_skb = NULL;
         }
 
+        kfree(ctx->delayed_ndp16);
+
         kfree(ctx);
 }
 
-int cdc_ncm_bind_common(struct usbnet *dev, struct usb_interface *intf, u8 data_altsetting)
+int cdc_ncm_bind_common(struct usbnet *dev, struct usb_interface *intf, u8 data_altsetting, int drvflags)
 {
         const struct usb_cdc_union_desc *union_desc = NULL;
         struct cdc_ncm_ctx *ctx;
@@ -855,6 +857,17 @@ advance:
         /* finish setting up the device specific data */
         cdc_ncm_setup(dev);
 
+        /* Device-specific flags */
+        ctx->drvflags = drvflags;
+
+        /* Allocate the delayed NDP if needed. */
+        if (ctx->drvflags & CDC_NCM_FLAG_NDP_TO_END) {
+                ctx->delayed_ndp16 = kzalloc(ctx->max_ndp_size, GFP_KERNEL);
+                if (!ctx->delayed_ndp16)
+                        goto error2;
+                dev_info(&intf->dev, "NDP will be placed at end of frame for this device.");
+        }
+
         /* override ethtool_ops */
         dev->net->ethtool_ops = &cdc_ncm_ethtool_ops;
 
@@ -954,8 +967,11 @@ static int cdc_ncm_bind(struct usbnet *dev, struct usb_interface *intf)
         if (cdc_ncm_select_altsetting(intf) != CDC_NCM_COMM_ALTSETTING_NCM)
                 return -ENODEV;
 
-        /* The NCM data altsetting is fixed */
-        ret = cdc_ncm_bind_common(dev, intf, CDC_NCM_DATA_ALTSETTING_NCM);
+        /* The NCM data altsetting is fixed, so we hard-coded it.
+         * Additionally, generic NCM devices are assumed to accept arbitrarily
+         * placed NDP.
+         */
+        ret = cdc_ncm_bind_common(dev, intf, CDC_NCM_DATA_ALTSETTING_NCM, 0);
 
         /*
          * We should get an event when network connection is "connected" or
@@ -986,6 +1002,14 @@ static struct usb_cdc_ncm_ndp16 *cdc_ncm_ndp(struct cdc_ncm_ctx *ctx, struct sk_
         struct usb_cdc_ncm_nth16 *nth16 = (void *)skb->data;
         size_t ndpoffset = le16_to_cpu(nth16->wNdpIndex);
 
+        /* If NDP should be moved to the end of the NCM package, we can't follow the
+        * NTH16 header as we would normally do. NDP isn't written to the SKB yet, and
+        * the wNdpIndex field in the header is actually not consistent with reality. It will be later.
+        */
+        if (ctx->drvflags & CDC_NCM_FLAG_NDP_TO_END)
+                if (ctx->delayed_ndp16->dwSignature == sign)
+                        return ctx->delayed_ndp16;
+
         /* follow the chain of NDPs, looking for a match */
         while (ndpoffset) {
                 ndp16 = (struct usb_cdc_ncm_ndp16 *)(skb->data + ndpoffset);
@@ -995,7 +1019,8 @@ static struct usb_cdc_ncm_ndp16 *cdc_ncm_ndp(struct cdc_ncm_ctx *ctx, struct sk_
         }
 
         /* align new NDP */
-        cdc_ncm_align_tail(skb, ctx->tx_ndp_modulus, 0, ctx->tx_max);
+        if (!(ctx->drvflags & CDC_NCM_FLAG_NDP_TO_END))
+                cdc_ncm_align_tail(skb, ctx->tx_ndp_modulus, 0, ctx->tx_max);
 
         /* verify that there is room for the NDP and the datagram (reserve) */
         if ((ctx->tx_max - skb->len - reserve) < ctx->max_ndp_size)
@@ -1008,7 +1033,11 @@ static struct usb_cdc_ncm_ndp16 *cdc_ncm_ndp(struct cdc_ncm_ctx *ctx, struct sk_
                 nth16->wNdpIndex = cpu_to_le16(skb->len);
 
         /* push a new empty NDP */
-        ndp16 = (struct usb_cdc_ncm_ndp16 *)memset(skb_put(skb, ctx->max_ndp_size), 0, ctx->max_ndp_size);
+        if (!(ctx->drvflags & CDC_NCM_FLAG_NDP_TO_END))
+                ndp16 = (struct usb_cdc_ncm_ndp16 *)memset(skb_put(skb, ctx->max_ndp_size), 0, ctx->max_ndp_size);
+        else
+                ndp16 = ctx->delayed_ndp16;
+
         ndp16->dwSignature = sign;
         ndp16->wLength = cpu_to_le16(sizeof(struct usb_cdc_ncm_ndp16) + sizeof(struct usb_cdc_ncm_dpe16));
         return ndp16;
@@ -1023,6 +1052,15 @@ cdc_ncm_fill_tx_frame(struct usbnet *dev, struct sk_buff *skb, __le32 sign)
         struct sk_buff *skb_out;
         u16 n = 0, index, ndplen;
         u8 ready2send = 0;
+        u32 delayed_ndp_size;
+
+        /* When our NDP gets written in cdc_ncm_ndp(), then skb_out->len gets updated
+         * accordingly. Otherwise, we should check here.
+         */
+        if (ctx->drvflags & CDC_NCM_FLAG_NDP_TO_END)
+                delayed_ndp_size = ctx->max_ndp_size;
+        else
+                delayed_ndp_size = 0;
 
         /* if there is a remaining skb, it gets priority */
         if (skb != NULL) {
@@ -1077,7 +1115,7 @@ cdc_ncm_fill_tx_frame(struct usbnet *dev, struct sk_buff *skb, __le32 sign)
                 cdc_ncm_align_tail(skb_out,  ctx->tx_modulus, ctx->tx_remainder, ctx->tx_max);
 
                 /* check if we had enough room left for both NDP and frame */
-                if (!ndp16 || skb_out->len + skb->len > ctx->tx_max) {
+                if (!ndp16 || skb_out->len + skb->len + delayed_ndp_size > ctx->tx_max) {
                         if (n == 0) {
                                 /* won't fit, MTU problem? */
                                 dev_kfree_skb_any(skb);
@@ -1150,6 +1188,17 @@ cdc_ncm_fill_tx_frame(struct usbnet *dev, struct sk_buff *skb, __le32 sign)
                 /* variables will be reset at next call */
         }
 
+        /* If requested, put NDP at end of frame. */
+        if (ctx->drvflags & CDC_NCM_FLAG_NDP_TO_END) {
+                nth16 = (struct usb_cdc_ncm_nth16 *)skb_out->data;
+                cdc_ncm_align_tail(skb_out, ctx->tx_ndp_modulus, 0, ctx->tx_max);
+                nth16->wNdpIndex = cpu_to_le16(skb_out->len);
+                memcpy(skb_put(skb_out, ctx->max_ndp_size), ctx->delayed_ndp16, ctx->max_ndp_size);
+
+                /* Zero out delayed NDP - signature checking will naturally fail. */
+                ndp16 = memset(ctx->delayed_ndp16, 0, ctx->max_ndp_size);
+        }
+
         /* If collected data size is less or equal ctx->min_tx_pkt
          * bytes, we send buffers as it is. If we get more data, it
          * would be more efficient for USB HS mobile device with DMA
diff --git a/drivers/net/usb/huawei_cdc_ncm.c b/drivers/net/usb/huawei_cdc_ncm.c
index 735f7dadb9a0..2680a65cd5e4 100644
--- a/drivers/net/usb/huawei_cdc_ncm.c
+++ b/drivers/net/usb/huawei_cdc_ncm.c
@@ -73,11 +73,14 @@ static int huawei_cdc_ncm_bind(struct usbnet *usbnet_dev,
         struct usb_driver *subdriver = ERR_PTR(-ENODEV);
         int ret = -ENODEV;
         struct huawei_cdc_ncm_state *drvstate = (void *)&usbnet_dev->data;
+        int drvflags = 0;
 
         /* altsetting should always be 1 for NCM devices - so we hard-coded
-         * it here
+         * it here. Some huawei devices will need the NDP part of the NCM package to
+         * be at the end of the frame.
          */
-        ret = cdc_ncm_bind_common(usbnet_dev, intf, 1);
+        drvflags |= CDC_NCM_FLAG_NDP_TO_END;
+        ret = cdc_ncm_bind_common(usbnet_dev, intf, 1, drvflags);
         if (ret)
                 goto err;
 
diff --git a/include/linux/usb/cdc_ncm.h b/include/linux/usb/cdc_ncm.h
index 7c9b484735c5..1f6526c76ee8 100644
--- a/include/linux/usb/cdc_ncm.h
+++ b/include/linux/usb/cdc_ncm.h
@@ -80,6 +80,9 @@
 #define CDC_NCM_TIMER_INTERVAL_MIN              5UL
 #define CDC_NCM_TIMER_INTERVAL_MAX              (U32_MAX / NSEC_PER_USEC)
 
+/* Driver flags */
+#define CDC_NCM_FLAG_NDP_TO_END 0x02            /* NDP is placed at end of frame */
+
 #define cdc_ncm_comm_intf_is_mbim(x)  ((x)->desc.bInterfaceSubClass == USB_CDC_SUBCLASS_MBIM && \
                                        (x)->desc.bInterfaceProtocol == USB_CDC_PROTO_NONE)
 #define cdc_ncm_data_intf_is_mbim(x)  ((x)->desc.bInterfaceProtocol == USB_CDC_MBIM_PROTO_NTB)
@@ -103,9 +106,11 @@ struct cdc_ncm_ctx {
 
         spinlock_t mtx;
         atomic_t stop;
+        int drvflags;
 
         u32 timer_interval;
         u32 max_ndp_size;
+        struct usb_cdc_ncm_ndp16 *delayed_ndp16;
 
         u32 tx_timer_pending;
         u32 tx_curr_frame_num;
@@ -133,7 +138,7 @@ struct cdc_ncm_ctx {
 };
 
 u8 cdc_ncm_select_altsetting(struct usb_interface *intf);
-int cdc_ncm_bind_common(struct usbnet *dev, struct usb_interface *intf, u8 data_altsetting);
+int cdc_ncm_bind_common(struct usbnet *dev, struct usb_interface *intf, u8 data_altsetting, int drvflags);
 void cdc_ncm_unbind(struct usbnet *dev, struct usb_interface *intf);
 struct sk_buff *cdc_ncm_fill_tx_frame(struct usbnet *dev, struct sk_buff *skb, __le32 sign);
 int cdc_ncm_rx_verify_nth16(struct cdc_ncm_ctx *ctx, struct sk_buff *skb_in);