Sorry, I fat-fingered the address in the get send-email...
--- Begin Message ---
In the case when a frontend only negotiates a single queue with xen-
netback it is possible for a skbuff with a s/w hash to result in a
hash extra_info segment being sent to the frontend even when no hash
algorithm has been configured. (The ndo_select_queue() entry point makes
sure the hash is not set if no algorithm is configured, but this entry
point is not called when there is only a single queue). This can result
in a frontend that is unable to handle extra_info segments being given
such a segment, causing it to crash.
This patch fixes the problem by clearing the hash in ndo_start_xmit()
instead, which is clearly guaranteed to be called irrespective of the
number of queues.
Signed-off-by: Paul Durrant <paul.durr...@citrix.com>
Cc: Wei Liu <wei.l...@citrix.com>
---
v2:
- Simplified and re-based onto re-factored net branch
---
drivers/net/xen-netback/interface.c | 20 +++++++++-----------
1 file changed, 9 insertions(+), 11 deletions(-)
diff --git a/drivers/net/xen-netback/interface.c
b/drivers/net/xen-netback/interface.c
index 4af532a..74dc2bf 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -149,17 +149,8 @@ static u16 xenvif_select_queue(struct net_device *dev,
struct sk_buff *skb,
struct xenvif *vif = netdev_priv(dev);
unsigned int size = vif->hash.size;
- if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE) {
- u16 index = fallback(dev, skb) % dev->real_num_tx_queues;
-
- /* Make sure there is no hash information in the socket
- * buffer otherwise it would be incorrectly forwarded
- * to the frontend.
- */
- skb_clear_hash(skb);
-
- return index;
- }
+ if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE)
+ return fallback(dev, skb) % dev->real_num_tx_queues;
xenvif_set_skb_hash(vif, skb);
@@ -208,6 +199,13 @@ static int xenvif_start_xmit(struct sk_buff *skb, struct
net_device *dev)
cb = XENVIF_RX_CB(skb);
cb->expires = jiffies + vif->drain_timeout;
+ /* If there is no hash algorithm configured then make sure there
+ * is no hash information in the socket buffer otherwise it
+ * would be incorrectly forwarded to the frontend.
+ */
+ if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE)
+ skb_clear_hash(skb);
+
xenvif_rx_queue_tail(queue, skb);
xenvif_kick_thread(queue);
--
2.1.4
--- End Message ---
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