From 275c4147544d4ed4f05cee3a5dabf1e6efeeb371 Mon Sep 17 00:00:00 2001
From: Steve Glendinning <steve.glendinning@smsc.com>
Date: Thu, 18 Mar 2010 22:18:41 -0700
Subject: [PATCH] --- yaml --- r: 188861 b: refs/heads/master c:
 11bc3088373e913f165a8652601c6f8b8dc4aea2 h: refs/heads/master i:   188859:
 b6c0b4d67a2e3aa4f375666e86358fa2642a5021 v: v3

---
 [refs]                           |  2 +-
 trunk/drivers/net/usb/smsc95xx.c | 18 +++++++++++++++---
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/[refs] b/[refs]
index 5dec18311f50..15f603c8dc55 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 0ecad5a262923967147e2d1725e277a2a5fbcdd4
+refs/heads/master: 11bc3088373e913f165a8652601c6f8b8dc4aea2
diff --git a/trunk/drivers/net/usb/smsc95xx.c b/trunk/drivers/net/usb/smsc95xx.c
index d222d7e25273..73f9a31cf94d 100644
--- a/trunk/drivers/net/usb/smsc95xx.c
+++ b/trunk/drivers/net/usb/smsc95xx.c
@@ -1189,9 +1189,21 @@ static struct sk_buff *smsc95xx_tx_fixup(struct usbnet *dev,
 	}
 
 	if (csum) {
-		u32 csum_preamble = smsc95xx_calc_csum_preamble(skb);
-		skb_push(skb, 4);
-		memcpy(skb->data, &csum_preamble, 4);
+		if (skb->len <= 45) {
+			/* workaround - hardware tx checksum does not work
+			 * properly with extremely small packets */
+			long csstart = skb->csum_start - skb_headroom(skb);
+			__wsum calc = csum_partial(skb->data + csstart,
+				skb->len - csstart, 0);
+			*((__sum16 *)(skb->data + csstart
+				+ skb->csum_offset)) = csum_fold(calc);
+
+			csum = false;
+		} else {
+			u32 csum_preamble = smsc95xx_calc_csum_preamble(skb);
+			skb_push(skb, 4);
+			memcpy(skb->data, &csum_preamble, 4);
+		}
 	}
 
 	skb_push(skb, 4);