net: cdc_ncm: reduce skb truesize in rx path

Cloning the big skbs we use for USB buffering chokes up TCP and
SCTP because the socket memory limits are hitting earlier than
they should. It is better to unconditionally copy the unwrapped
packets to freshly allocated skbs.

Reported-by: Jim Baxter <jim_baxter@mentor.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index 93c9ca9924ebe3c29078a7ffe269ba490a4f6dbc..2bbbd65591c7d6ba4aaccb2fbe7c79b2f56ce95f 100644 (file)
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -1289,12 +1289,11 @@ next_ndp:
                        break;
 
                } else {
-                       skb = skb_clone(skb_in, GFP_ATOMIC);
+                       /* create a fresh copy to reduce truesize */
+                       skb = netdev_alloc_skb_ip_align(dev->net,  len);
                        if (!skb)
                                goto error;
-                       skb->len = len;
-                       skb->data = ((u8 *)skb_in->data) + offset;
-                       skb_set_tail_pointer(skb, len);
+                       memcpy(skb_put(skb, len), skb_in->data + offset, len);
                        usbnet_skb_return(dev, skb);
                        payload += len; /* count payload bytes in this NTB */
                }