3 files changed, 76 insertions, 2 deletions

diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index f54c3bb6a22b..ab856d507b7e 100644
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -38,8 +38,9 @@ struct netpoll {
 struct netpoll_info {
         atomic_t refcnt;
 
-        int rx_flags;
+        unsigned long rx_flags;
         spinlock_t rx_lock;
+        struct mutex dev_lock;
         struct list_head rx_np; /* netpolls that registered an rx_hook */
 
         struct sk_buff_head neigh_tx; /* list of neigh requests to reply to */
@@ -51,6 +52,14 @@ struct netpoll_info {
         struct rcu_head rcu;
 };
 
+#ifdef CONFIG_NETPOLL
+extern int netpoll_rx_disable(struct net_device *dev);
+extern void netpoll_rx_enable(struct net_device *dev);
+#else
+static inline int netpoll_rx_disable(struct net_device *dev) { return 0; }
+static inline void netpoll_rx_enable(struct net_device *dev) { return; }
+#endif
+
 void netpoll_send_udp(struct netpoll *np, const char *msg, int len);
 void netpoll_print_options(struct netpoll *np);
 int netpoll_parse_options(struct netpoll *np, char *opt);
diff --git a/net/core/dev.c b/net/core/dev.c
index e04bfdc9e3e4..2b275a7b8677 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1266,6 +1266,14 @@ static int __dev_open(struct net_device *dev)
         if (!netif_device_present(dev))
                 return -ENODEV;
 
+        /* Block netpoll from trying to do any rx path servicing.
+         * If we don't do this there is a chance ndo_poll_controller
+         * or ndo_poll may be running while we open the device
+         */
+        ret = netpoll_rx_disable(dev);
+        if (ret)
+                return ret;
+
         ret = call_netdevice_notifiers(NETDEV_PRE_UP, dev);
         ret = notifier_to_errno(ret);
         if (ret)
@@ -1279,6 +1287,8 @@ static int __dev_open(struct net_device *dev)
         if (!ret && ops->ndo_open)
                 ret = ops->ndo_open(dev);
 
+        netpoll_rx_enable(dev);
+
         if (ret)
                 clear_bit(__LINK_STATE_START, &dev->state);
         else {
@@ -1370,9 +1380,16 @@ static int __dev_close(struct net_device *dev)
         int retval;
         LIST_HEAD(single);
 
+        /* Temporarily disable netpoll until the interface is down */
+        retval = netpoll_rx_disable(dev);
+        if (retval)
+                return retval;
+
         list_add(&dev->unreg_list, &single);
         retval = __dev_close_many(&single);
         list_del(&single);
+
+        netpoll_rx_enable(dev);
         return retval;
 }
 
@@ -1408,14 +1425,22 @@ static int dev_close_many(struct list_head *head)
  */
 int dev_close(struct net_device *dev)
 {
+        int ret = 0;
         if (dev->flags & IFF_UP) {
                 LIST_HEAD(single);
 
+                /* Block netpoll rx while the interface is going down */
+                ret = netpoll_rx_disable(dev);
+                if (ret)
+                        return ret;
+
                 list_add(&dev->unreg_list, &single);
                 dev_close_many(&single);
                 list_del(&single);
+
+                netpoll_rx_enable(dev);
         }
-        return 0;
+        return ret;
 }
 EXPORT_SYMBOL(dev_close);
 
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 331ccb90f915..edcd9ad95304 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -47,6 +47,8 @@ static struct sk_buff_head skb_pool;
 
 static atomic_t trapped;
 
+static struct srcu_struct netpoll_srcu;
+
 #define USEC_PER_POLL   50
 #define NETPOLL_RX_ENABLED  1
 #define NETPOLL_RX_DROP     2
@@ -199,6 +201,13 @@ static void netpoll_poll_dev(struct net_device *dev)
         const struct net_device_ops *ops;
         struct netpoll_info *ni = rcu_dereference_bh(dev->npinfo);
 
+        /* Don't do any rx activity if the dev_lock mutex is held
+         * the dev_open/close paths use this to block netpoll activity
+         * while changing device state
+         */
+        if (!mutex_trylock(&dev->npinfo->dev_lock))
+                return;
+
         if (!dev || !netif_running(dev))
                 return;
 
@@ -211,6 +220,8 @@ static void netpoll_poll_dev(struct net_device *dev)
 
         poll_napi(dev);
 
+        mutex_unlock(&dev->npinfo->dev_lock);
+
         if (dev->flags & IFF_SLAVE) {
                 if (ni) {
                         struct net_device *bond_dev;
@@ -231,6 +242,31 @@ static void netpoll_poll_dev(struct net_device *dev)
         zap_completion_queue();
 }
 
+int netpoll_rx_disable(struct net_device *dev)
+{
+        struct netpoll_info *ni;
+        int idx;
+        might_sleep();
+        idx = srcu_read_lock(&netpoll_srcu);
+        ni = srcu_dereference(dev->npinfo, &netpoll_srcu);
+        if (ni)
+                mutex_lock(&ni->dev_lock);
+        srcu_read_unlock(&netpoll_srcu, idx);
+        return 0;
+}
+EXPORT_SYMBOL(netpoll_rx_disable);
+
+void netpoll_rx_enable(struct net_device *dev)
+{
+        struct netpoll_info *ni;
+        rcu_read_lock();
+        ni = rcu_dereference(dev->npinfo);
+        if (ni)
+                mutex_unlock(&ni->dev_lock);
+        rcu_read_unlock();
+}
+EXPORT_SYMBOL(netpoll_rx_enable);
+
 static void refill_skbs(void)
 {
         struct sk_buff *skb;
@@ -1004,6 +1040,7 @@ int __netpoll_setup(struct netpoll *np, struct net_device *ndev, gfp_t gfp)
                 INIT_LIST_HEAD(&npinfo->rx_np);
 
                 spin_lock_init(&npinfo->rx_lock);
+                mutex_init(&npinfo->dev_lock);
                 skb_queue_head_init(&npinfo->neigh_tx);
                 skb_queue_head_init(&npinfo->txq);
                 INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
@@ -1169,6 +1206,7 @@ EXPORT_SYMBOL(netpoll_setup);
 static int __init netpoll_init(void)
 {
         skb_queue_head_init(&skb_pool);
+        init_srcu_struct(&netpoll_srcu);
         return 0;
 }
 core_initcall(netpoll_init);
@@ -1208,6 +1246,8 @@ void __netpoll_cleanup(struct netpoll *np)
                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
         }
 
+        synchronize_srcu(&netpoll_srcu);
+
         if (atomic_dec_and_test(&npinfo->refcnt)) {
                 const struct net_device_ops *ops;