Subject: [PATCHv2 net] sunvnet: set queue mapping when doing packet copies

From: David L Stevens <[email-masked]>
Date: Thu, 29 Jan 2015 14:42:44 -0500

This patch fixes a bug where vnet_skb_shape() didn't set the already-selected
queue mapping when a packet copy was required. This results in using the
wrong queue index for stops/starts, hung tx queues and watchdog timeouts
under heavy load. It also transfers the destructor, truesize, and the owning
socket for flow control (code adapted from skb_segment).

Signed-off-by: David L Stevens <[email-masked]>
Acked-by: Sowmini Varadhan <[email-masked]>

--
Changes since v1:
 move truesize, destructor and socket per Eric Dumazet <[email-masked]>

---
 drivers/net/ethernet/sun/sunvnet.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/drivers/net/ethernet/sun/sunvnet.c b/drivers/net/ethernet/sun/sunvnet.c
index 2b719cc..0a1d3eb 100644
--- a/drivers/net/ethernet/sun/sunvnet.c
+++ b/drivers/net/ethernet/sun/sunvnet.c
@@ -1123,6 +1123,16 @@ static inline struct sk_buff *vnet_skb_shape(struct sk_buff *skb, int ncookies)
 			skb_shinfo(nskb)->gso_size = skb_shinfo(skb)->gso_size;
 			skb_shinfo(nskb)->gso_type = skb_shinfo(skb)->gso_type;
 		}
+		nskb->queue_mapping = skb->queue_mapping;
+		/* Following permits correct back-pressure, for protocols
+		 * using skb_set_owner_w().
+		 * Idea is to transfer ownership from skb to nskb.
+		 */
+		if (skb->destructor == sock_wfree) {
+			swap(nskb->truesize, skb->truesize);
+			swap(nskb->destructor, skb->destructor);
+			swap(nskb->sk, skb->sk);
+		}
 		dev_kfree_skb(skb);
 		skb = nskb;
 	}
-- 
1.7.1