From a2288d4e355992d369c50c45d017a85f6061ff71 Mon Sep 17 00:00:00 2001 From: Igor Druzhinin Date: Thu, 28 Feb 2019 14:11:26 +0000 Subject: [PATCH] xen-netback: don't populate the hash cache on XenBus disconnect Occasionally, during the disconnection procedure on XenBus which includes hash cache deinitialization there might be some packets still in-flight on other processors. Handling of these packets includes hashing and hash cache population that finally results in hash cache data structure corruption. In order to avoid this we prevent hashing of those packets if there are no queues initialized. In that case RCU protection of queues guards the hash cache as well. Signed-off-by: Igor Druzhinin Reviewed-by: Paul Durrant Signed-off-by: David S. Miller --- drivers/net/xen-netback/hash.c | 2 ++ drivers/net/xen-netback/interface.c | 7 +++++++ 2 files changed, 9 insertions(+) diff --git a/drivers/net/xen-netback/hash.c b/drivers/net/xen-netback/hash.c index 0ccb021f1e78..10d580c3dea3 100644 --- a/drivers/net/xen-netback/hash.c +++ b/drivers/net/xen-netback/hash.c @@ -454,6 +454,8 @@ void xenvif_init_hash(struct xenvif *vif) if (xenvif_hash_cache_size == 0) return; + BUG_ON(vif->hash.cache.count); + spin_lock_init(&vif->hash.cache.lock); INIT_LIST_HEAD(&vif->hash.cache.list); } diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index 182d6770f102..6da12518e693 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -153,6 +153,13 @@ 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; + unsigned int num_queues; + + /* If queues are not set up internally - always return 0 + * as the packet going to be dropped anyway */ + num_queues = READ_ONCE(vif->num_queues); + if (num_queues < 1) + return 0; if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE) return fallback(dev, skb, NULL) % dev->real_num_tx_queues;