netdev - [PATCH] sky2: don't do GRO on second port

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Date:	Mon, 30 Aug 2010 10:51:17 -0700
From:	Stephen Hemminger <shemminger@...tta.com>
To:	David Miller <davem@...emloft.net>
Cc:	jarkao2@...il.com, eric.dumazet@...il.com,
	herbert@...dor.apana.org.au, netdev@...r.kernel.org
Subject: [PATCH] sky2: don't do GRO on second port


 There's something very important I forgot to tell you.
 What?

 Don't cross the GRO streams.
 Why?

 It would be bad.
 I'm fuzzy on the whole good/bad thing. What do you mean, "bad"?

 Try to imagine all the Internet as you know it stopping instantaneously
  and every bit in every packet swapping at the speed of light.
 Total packet reordering.
 Right. That's bad. Okay. All right. Important safety tip. Thanks, Hubert

The simplest way to stop this is just avoid doing GRO on the second port.
Very few Marvell boards support two ports per ring, and GRO is just
an optimization.

Signed-off-by: Stephen Hemminger <shemminger@...tta.com>


--- a/drivers/net/sky2.c	2010-08-30 10:13:28.211536096 -0700
+++ b/drivers/net/sky2.c	2010-08-30 10:22:01.347183151 -0700
@@ -2520,24 +2520,27 @@ static inline void sky2_tx_done(struct n
 	}
 }
 
-static inline void sky2_skb_rx(const struct sky2_port *sky2,
+static inline void sky2_skb_rx(struct napi_struct *napi,
+			       const struct sky2_port *sky2,
 			       u32 status, struct sk_buff *skb)
 {
 #ifdef SKY2_VLAN_TAG_USED
-	u16 vlan_tag = be16_to_cpu(sky2->rx_tag);
 	if (sky2->vlgrp && (status & GMR_FS_VLAN)) {
-		if (skb->ip_summed == CHECKSUM_NONE)
+		u16 vlan_tag = be16_to_cpu(sky2->rx_tag);
+
+		if (skb->ip_summed == CHECKSUM_NONE ||
+		    sky2->netdev != napi->dev)
 			vlan_hwaccel_receive_skb(skb, sky2->vlgrp, vlan_tag);
 		else
-			vlan_gro_receive(&sky2->hw->napi, sky2->vlgrp,
-					 vlan_tag, skb);
+			vlan_gro_receive(napi, sky2->vlgrp, vlan_tag, skb);
 		return;
 	}
 #endif
-	if (skb->ip_summed == CHECKSUM_NONE)
+	if (skb->ip_summed == CHECKSUM_NONE ||
+	    sky2->netdev != napi->dev)
 		netif_receive_skb(skb);
 	else
-		napi_gro_receive(&sky2->hw->napi, skb);
+		napi_gro_receive(napi, skb);
 }
 
 static inline void sky2_rx_done(struct sky2_hw *hw, unsigned port,
@@ -2638,7 +2641,7 @@ static int sky2_status_intr(struct sky2_
 
 			skb->protocol = eth_type_trans(skb, dev);
 
-			sky2_skb_rx(sky2, status, skb);
+			sky2_skb_rx(&hw->napi, sky2, status, skb);
 
 			/* Stop after net poll weight */
 			if (++work_done >= to_do)
--
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