1 files changed, 37 insertions, 11 deletions

diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index c0d8b90c5202..5ade54a78dbb 100644
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -9,6 +9,7 @@
 
 #include <linux/netdevice.h>
 #include <linux/interrupt.h>
+#include <linux/rcupdate.h>
 #include <linux/list.h>
 
 struct netpoll;
@@ -16,14 +17,20 @@ struct netpoll;
 struct netpoll {
         struct net_device *dev;
         char dev_name[16], *name;
-        int rx_flags;
         void (*rx_hook)(struct netpoll *, int, char *, int);
         void (*drop)(struct sk_buff *skb);
         u32 local_ip, remote_ip;
         u16 local_port, remote_port;
         unsigned char local_mac[6], remote_mac[6];
+};
+
+struct netpoll_info {
         spinlock_t poll_lock;
         int poll_owner;
+        int tries;
+        int rx_flags;
+        spinlock_t rx_lock;
+        struct netpoll *rx_np; /* netpoll that registered an rx_hook */
 };
 
 void netpoll_poll(struct netpoll *np);
@@ -39,28 +46,47 @@ void netpoll_queue(struct sk_buff *skb);
 #ifdef CONFIG_NETPOLL
 static inline int netpoll_rx(struct sk_buff *skb)
 {
-        return skb->dev->np && skb->dev->np->rx_flags && __netpoll_rx(skb);
+        struct netpoll_info *npinfo = skb->dev->npinfo;
+        unsigned long flags;
+        int ret = 0;
+
+        if (!npinfo || (!npinfo->rx_np && !npinfo->rx_flags))
+                return 0;
+
+        spin_lock_irqsave(&npinfo->rx_lock, flags);
+        /* check rx_flags again with the lock held */
+        if (npinfo->rx_flags && __netpoll_rx(skb))
+                ret = 1;
+        spin_unlock_irqrestore(&npinfo->rx_lock, flags);
+
+        return ret;
 }
 
-static inline void netpoll_poll_lock(struct net_device *dev)
+static inline void *netpoll_poll_lock(struct net_device *dev)
 {
-        if (dev->np) {
-                spin_lock(&dev->np->poll_lock);
-                dev->np->poll_owner = smp_processor_id();
+        rcu_read_lock(); /* deal with race on ->npinfo */
+        if (dev->npinfo) {
+                spin_lock(&dev->npinfo->poll_lock);
+                dev->npinfo->poll_owner = smp_processor_id();
+                return dev->npinfo;
         }
+        return NULL;
 }
 
-static inline void netpoll_poll_unlock(struct net_device *dev)
+static inline void netpoll_poll_unlock(void *have)
 {
-        if (dev->np) {
-                spin_unlock(&dev->np->poll_lock);
-                dev->np->poll_owner = -1;
+        struct netpoll_info *npi = have;
+
+        if (npi) {
+                npi->poll_owner = -1;
+                spin_unlock(&npi->poll_lock);
         }
+        rcu_read_unlock();
 }
 
 #else
 #define netpoll_rx(a) 0
-#define netpoll_poll_lock(a)
+#define netpoll_poll_lock(a) 0
 #define netpoll_poll_unlock(a)
 #endif