netpoll: Allow netpoll_setup/cleanup recursion

This patch adds the functions __netpoll_setup/__netpoll_cleanup
which is designed to be called recursively through ndo_netpoll_seutp.

They must be called with RTNL held, and the caller must initialise
np->dev and ensure that it has a valid reference count.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 99 insertions, 79 deletions

diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index 95c9f7e16776..f3ad74af7e1f 100644
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -46,9 +46,11 @@ void netpoll_poll(struct netpoll *np);
 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);
+int __netpoll_setup(struct netpoll *np);
 int netpoll_setup(struct netpoll *np);
 int netpoll_trap(void);
 void netpoll_set_trap(int trap);
+void __netpoll_cleanup(struct netpoll *np);
 void netpoll_cleanup(struct netpoll *np);
 int __netpoll_rx(struct sk_buff *skb);
 void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb);
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 7de6dcad5d79..560297ee55b4 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -693,15 +693,78 @@ int netpoll_parse_options(struct netpoll *np, char *opt)
         return -1;
 }
 
-int netpoll_setup(struct netpoll *np)
+int __netpoll_setup(struct netpoll *np)
 {
-        struct net_device *ndev = NULL;
-        struct in_device *in_dev;
+        struct net_device *ndev = np->dev;
         struct netpoll_info *npinfo;
         const struct net_device_ops *ops;
         unsigned long flags;
         int err;
 
+        if ((ndev->priv_flags & IFF_DISABLE_NETPOLL) ||
+            !ndev->netdev_ops->ndo_poll_controller) {
+                printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n",
+                       np->name, np->dev_name);
+                err = -ENOTSUPP;
+                goto out;
+        }
+
+        if (!ndev->npinfo) {
+                npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
+                if (!npinfo) {
+                        err = -ENOMEM;
+                        goto out;
+                }
+
+                npinfo->rx_flags = 0;
+                INIT_LIST_HEAD(&npinfo->rx_np);
+
+                spin_lock_init(&npinfo->rx_lock);
+                skb_queue_head_init(&npinfo->arp_tx);
+                skb_queue_head_init(&npinfo->txq);
+                INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
+
+                atomic_set(&npinfo->refcnt, 1);
+
+                ops = np->dev->netdev_ops;
+                if (ops->ndo_netpoll_setup) {
+                        err = ops->ndo_netpoll_setup(ndev, npinfo);
+                        if (err)
+                                goto free_npinfo;
+                }
+        } else {
+                npinfo = ndev->npinfo;
+                atomic_inc(&npinfo->refcnt);
+        }
+
+        npinfo->netpoll = np;
+
+        if (np->rx_hook) {
+                spin_lock_irqsave(&npinfo->rx_lock, flags);
+                npinfo->rx_flags |= NETPOLL_RX_ENABLED;
+                list_add_tail(&np->rx, &npinfo->rx_np);
+                spin_unlock_irqrestore(&npinfo->rx_lock, flags);
+        }
+
+        /* last thing to do is link it to the net device structure */
+        rcu_assign_pointer(ndev->npinfo, npinfo);
+        rtnl_unlock();
+
+        return 0;
+
+free_npinfo:
+        kfree(npinfo);
+out:
+        return err;
+}
+EXPORT_SYMBOL_GPL(__netpoll_setup);
+
+int netpoll_setup(struct netpoll *np)
+{
+        struct net_device *ndev = NULL;
+        struct in_device *in_dev;
+        int err;
+
         if (np->dev_name)
                 ndev = dev_get_by_name(&init_net, np->dev_name);
         if (!ndev) {
@@ -774,61 +837,14 @@ int netpoll_setup(struct netpoll *np)
         refill_skbs();
 
         rtnl_lock();
-        if ((ndev->priv_flags & IFF_DISABLE_NETPOLL) ||
-            !ndev->netdev_ops->ndo_poll_controller) {
-                printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n",
-                       np->name, np->dev_name);
-                err = -ENOTSUPP;
-                goto unlock;
-        }
-
-        if (!ndev->npinfo) {
-                npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
-                if (!npinfo) {
-                        err = -ENOMEM;
-                        goto unlock;
-                }
-
-                npinfo->rx_flags = 0;
-                INIT_LIST_HEAD(&npinfo->rx_np);
-
-                spin_lock_init(&npinfo->rx_lock);
-                skb_queue_head_init(&npinfo->arp_tx);
-                skb_queue_head_init(&npinfo->txq);
-                INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
-
-                atomic_set(&npinfo->refcnt, 1);
-
-                ops = np->dev->netdev_ops;
-                if (ops->ndo_netpoll_setup) {
-                        err = ops->ndo_netpoll_setup(ndev, npinfo);
-                        if (err)
-                                goto free_npinfo;
-                }
-        } else {
-                npinfo = ndev->npinfo;
-                atomic_inc(&npinfo->refcnt);
-        }
-
-        npinfo->netpoll = np;
-
-        if (np->rx_hook) {
-                spin_lock_irqsave(&npinfo->rx_lock, flags);
-                npinfo->rx_flags |= NETPOLL_RX_ENABLED;
-                list_add_tail(&np->rx, &npinfo->rx_np);
-                spin_unlock_irqrestore(&npinfo->rx_lock, flags);
-        }
-
-        /* last thing to do is link it to the net device structure */
-        rcu_assign_pointer(ndev->npinfo, npinfo);
+        err = __netpoll_setup(np);
         rtnl_unlock();
 
+        if (err)
+                goto put;
+
         return 0;
 
-free_npinfo:
-        kfree(npinfo);
-unlock:
-        rtnl_unlock();
 put:
         dev_put(ndev);
         return err;
@@ -841,40 +857,32 @@ static int __init netpoll_init(void)
 }
 core_initcall(netpoll_init);
 
-void netpoll_cleanup(struct netpoll *np)
+void __netpoll_cleanup(struct netpoll *np)
 {
         struct netpoll_info *npinfo;
         unsigned long flags;
-        int free = 0;
 
-        if (!np->dev)
+        npinfo = np->dev->npinfo;
+        if (!npinfo)
                 return;
 
-        rtnl_lock();
-        npinfo = np->dev->npinfo;
-        if (npinfo) {
-                if (!list_empty(&npinfo->rx_np)) {
-                        spin_lock_irqsave(&npinfo->rx_lock, flags);
-                        list_del(&np->rx);
-                        if (list_empty(&npinfo->rx_np))
-                                npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
-                        spin_unlock_irqrestore(&npinfo->rx_lock, flags);
-                }
+        if (!list_empty(&npinfo->rx_np)) {
+                spin_lock_irqsave(&npinfo->rx_lock, flags);
+                list_del(&np->rx);
+                if (list_empty(&npinfo->rx_np))
+                        npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
+                spin_unlock_irqrestore(&npinfo->rx_lock, flags);
+        }
 
-                free = atomic_dec_and_test(&npinfo->refcnt);
-                if (free) {
-                        const struct net_device_ops *ops;
+        if (atomic_dec_and_test(&npinfo->refcnt)) {
+                const struct net_device_ops *ops;
 
-                        ops = np->dev->netdev_ops;
-                        if (ops->ndo_netpoll_cleanup)
-                                ops->ndo_netpoll_cleanup(np->dev);
+                ops = np->dev->netdev_ops;
+                if (ops->ndo_netpoll_cleanup)
+                        ops->ndo_netpoll_cleanup(np->dev);
 
-                        rcu_assign_pointer(np->dev->npinfo, NULL);
-                }
-        }
-        rtnl_unlock();
+                rcu_assign_pointer(np->dev->npinfo, NULL);
 
-        if (free) {
                 /* avoid racing with NAPI reading npinfo */
                 synchronize_rcu_bh();
 
@@ -886,9 +894,19 @@ void netpoll_cleanup(struct netpoll *np)
                 __skb_queue_purge(&npinfo->txq);
                 kfree(npinfo);
         }
+}
+EXPORT_SYMBOL_GPL(__netpoll_cleanup);
 
-        dev_put(np->dev);
+void netpoll_cleanup(struct netpoll *np)
+{
+        if (!np->dev)
+                return;
 
+        rtnl_lock();
+        __netpoll_cleanup(np);
+        rtnl_unlock();
+
+        dev_put(np->dev);
         np->dev = NULL;
 }