netpoll: recursion fixes, queueing, and cleanups

Index: tiny-new/net/core/netpoll.c
===================================================================
@@ -584,7 +584,7 @@
 		rtnl_shunlock();
 
 		atleast = jiffies + HZ/10;
- 		atmost = jiffies + 10*HZ;
+ 		atmost = jiffies + 4*HZ;
 		while (!netif_carrier_ok(ndev)) {
 			if (time_after(jiffies, atmost)) {
 				printk(KERN_NOTICE

@@ -597,7 +597,7 @@
 
 		if (time_before(jiffies, atleast)) {
 			printk(KERN_NOTICE "%s: carrier detect appears flaky,"
-			       " waiting 10 seconds\n",
+			       " waiting 4 seconds\n",
 			       np->name);
 			while (time_before(jiffies, atmost))
 				cond_resched();

Index: rc4bk2/net/core/netpoll.c
===================================================================
@@ -368,7 +368,7 @@
 	netpoll_send_skb(np, send_skb);
 }
 
-int netpoll_rx(struct sk_buff *skb)
+int __netpoll_rx(struct sk_buff *skb)
 {
 	int proto, len, ulen;
 	struct iphdr *iph;

@@ -440,12 +440,18 @@
 				    (char *)(uh+1),
 				    ulen - sizeof(struct udphdr));
 
+		kfree_skb(skb);
 		return 1;
 	}
 	spin_unlock_irqrestore(&rx_list_lock, flags);
 
 out:
-	return atomic_read(&trapped);
+	if (atomic_read(&trapped)) {
+		kfree_skb(skb);
+		return 1;
+	}
+
+	return 0;
 }
 
 int netpoll_parse_options(struct netpoll *np, char *opt)

Index: rc4bk2/include/linux/netpoll.h
===================================================================
@@ -30,7 +30,15 @@
 int netpoll_trap(void);
 void netpoll_set_trap(int trap);
 void netpoll_cleanup(struct netpoll *np);
-int netpoll_rx(struct sk_buff *skb);
+int __netpoll_rx(struct sk_buff *skb);
 
+#ifdef CONFIG_NETPOLL
+static inline int netpoll_rx(struct sk_buff *skb)
+{
+	return skb->dev->netpoll_rx && __netpoll_rx(skb);
+}
+#else
+#define netpoll_rx(a) 0
+#endif
 
 #endif

Index: rc4bk2/net/core/dev.c
===================================================================
@@ -1427,13 +1427,10 @@
 	struct softnet_data *queue;
 	unsigned long flags;
 
-#ifdef CONFIG_NETPOLL
-	if (skb->dev->netpoll_rx && netpoll_rx(skb)) {
-		kfree_skb(skb);
+	/* if netpoll wants it, pretend we never saw it */
+	if (netpoll_rx(skb))
 		return NET_RX_DROP;
-	}
-#endif
-	
+
 	if (!skb->stamp.tv_sec)
 		net_timestamp(&skb->stamp);
 

@@ -1629,12 +1626,9 @@
 	int ret = NET_RX_DROP;
 	unsigned short type;
 
-#ifdef CONFIG_NETPOLL
-	if (skb->dev->netpoll_rx && skb->dev->poll && netpoll_rx(skb)) {
-		kfree_skb(skb);
+	/* if we've gotten here through NAPI, check netpoll */
+	if (skb->dev->poll && netpoll_rx(skb))
 		return NET_RX_DROP;
-	}
-#endif
 
 	if (!skb->stamp.tv_sec)
 		net_timestamp(&skb->stamp);

Index: rc4/include/linux/netdevice.h
===================================================================
@@ -41,7 +41,7 @@
 struct divert_blk;
 struct vlan_group;
 struct ethtool_ops;
-
+struct netpoll;
 					/* source back-compat hooks */
 #define SET_ETHTOOL_OPS(netdev,ops) \
 	( (netdev)->ethtool_ops = (ops) )

@@ -471,7 +471,7 @@
 	int			(*neigh_setup)(struct net_device *dev, struct neigh_parms *);
 	int			(*accept_fastpath)(struct net_device *, struct dst_entry*);
 #ifdef CONFIG_NETPOLL
-	int			netpoll_rx;
+	struct netpoll		*np;
 #endif
 #ifdef CONFIG_NET_POLL_CONTROLLER
 	void                    (*poll_controller)(struct net_device *dev);

149 lines not on this page · raw message

Index: rc4/include/linux/netpoll.h
===================================================================
@@ -16,11 +16,11 @@
 struct netpoll {
 	struct net_device *dev;
 	char dev_name[16], *name;
+	int rx_flags;
 	void (*rx_hook)(struct netpoll *, int, char *, int);
 	u32 local_ip, remote_ip;
 	u16 local_port, remote_port;
 	unsigned char local_mac[6], remote_mac[6];
-	struct list_head rx_list;
 };
 
 void netpoll_poll(struct netpoll *np);

@@ -35,7 +35,7 @@
 #ifdef CONFIG_NETPOLL
 static inline int netpoll_rx(struct sk_buff *skb)
 {
-	return skb->dev->netpoll_rx && __netpoll_rx(skb);
+	return skb->dev->np && skb->dev->np->rx_flags && __netpoll_rx(skb);
 }
 #else
 #define netpoll_rx(a) 0

Index: rc4/net/core/netpoll.c
===================================================================
@@ -36,7 +36,6 @@
 static struct sk_buff *skbs;
 
 static atomic_t trapped;
-static DEFINE_SPINLOCK(netpoll_poll_lock);
 
 #define NETPOLL_RX_ENABLED  1
 #define NETPOLL_RX_DROP     2

@@ -63,8 +62,15 @@
 }
 
 /*
- * Check whether delayed processing was scheduled for our current CPU,
- * and then manually invoke NAPI polling to pump data off the card.
+ * Check whether delayed processing was scheduled for our NIC. If so,
+ * we attempt to grab the poll lock and use ->poll() to pump the card.
+ * If this fails, either we've recursed in ->poll() or it's already
+ * running on another CPU.
+ *
+ * Note: we don't mask interrupts with this lock because we're using
+ * trylock here and interrupts are already disabled in the softirq
+ * case. Further, we test the poll_owner to avoid recursion on UP
+ * systems where the lock doesn't exist.
  *
  * In cases where there is bi-directional communications, reading only
  * one message at a time can lead to packets being dropped by the

@@ -74,13 +80,10 @@
 static void poll_napi(struct netpoll *np)
 {
 	int budget = 16;
-	unsigned long flags;
-	struct softnet_data *queue;
 
-	spin_lock_irqsave(&netpoll_poll_lock, flags);
-	queue = &__get_cpu_var(softnet_data);
 	if (test_bit(__LINK_STATE_RX_SCHED, &np->dev->state) &&
-	    !list_empty(&queue->poll_list)) {
+	    np->poll_owner != __smp_processor_id() &&
+	    spin_trylock(&np->poll_lock)) {
 		np->rx_flags |= NETPOLL_RX_DROP;
 		atomic_inc(&trapped);
 

@@ -88,8 +91,8 @@
 
 		atomic_dec(&trapped);
 		np->rx_flags &= ~NETPOLL_RX_DROP;
+		spin_unlock(&np->poll_lock);
 	}
-	spin_unlock_irqrestore(&netpoll_poll_lock, flags);
 }
 
 void netpoll_poll(struct netpoll *np)

@@ -194,6 +197,12 @@
 		return;
 	}
 
+	/* avoid ->poll recursion */
+	if(np->poll_owner == __smp_processor_id()) {
+		__kfree_skb(skb);
+		return;
+	}
+
 	spin_lock(&np->dev->xmit_lock);
 	np->dev->xmit_lock_owner = smp_processor_id();
 

@@ -542,6 +551,9 @@
 	struct net_device *ndev = NULL;
 	struct in_device *in_dev;
 
+	np->poll_lock = SPIN_LOCK_UNLOCKED;
+	np->poll_owner = -1;
+
 	if (np->dev_name)
 		ndev = dev_get_by_name(np->dev_name);
 	if (!ndev) {

Index: rc4/include/linux/netpoll.h
===================================================================
@@ -21,6 +21,8 @@
 	u32 local_ip, remote_ip;
 	u16 local_port, remote_port;
 	unsigned char local_mac[6], remote_mac[6];
+	spinlock_t poll_lock;
+	int poll_owner;
 };
 
 void netpoll_poll(struct netpoll *np);

@@ -37,8 +39,27 @@
 {
 	return skb->dev->np && skb->dev->np->rx_flags && __netpoll_rx(skb);
 }
+
+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();
+	}
+}
+
+static inline void netpoll_poll_unlock(struct net_device *dev)
+{
+	if (dev->np) {
+		spin_unlock(&dev->np->poll_lock);
+		dev->np->poll_owner = -1;
+	}
+}
+
 #else
 #define netpoll_rx(a) 0
+#define netpoll_poll_lock(a)
+#define netpoll_poll_unlock(a)
 #endif
 
 #endif

Index: rc4/net/core/dev.c
===================================================================
@@ -1775,8 +1775,10 @@
 
 		dev = list_entry(queue->poll_list.next,
 				 struct net_device, poll_list);
+		netpoll_poll_lock(dev);
 
 		if (dev->quota <= 0 || dev->poll(dev, &budget)) {
+			netpoll_poll_unlock(dev);
 			local_irq_disable();
 			list_del(&dev->poll_list);
 			list_add_tail(&dev->poll_list, &queue->poll_list);

@@ -1785,6 +1787,7 @@
 			else
 				dev->quota = dev->weight;
 		} else {
+			netpoll_poll_unlock(dev);
 			dev_put(dev);
 			local_irq_disable();
 		}

Index: rc4/drivers/net/netconsole.c
===================================================================
@@ -60,6 +60,7 @@
 	.local_port = 6665,
 	.remote_port = 6666,
 	.remote_mac = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
+	.drop = netpoll_queue,
 };
 static int configured = 0;
 

95 lines not on this page · raw message

Index: rc4/include/linux/netpoll.h
===================================================================
@@ -18,6 +18,7 @@
 	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];

@@ -33,6 +34,7 @@
 void netpoll_set_trap(int trap);
 void netpoll_cleanup(struct netpoll *np);
 int __netpoll_rx(struct sk_buff *skb);
+void netpoll_queue(struct sk_buff *skb);
 
 #ifdef CONFIG_NETPOLL
 static inline int netpoll_rx(struct sk_buff *skb)

Index: rc4/net/core/netpoll.c
===================================================================
@@ -247,8 +247,9 @@
 		return;
 	}
 
-	/* avoid ->poll recursion */
-	if(np->poll_owner == __smp_processor_id()) {
+	/* avoid recursion */
+	if(np->poll_owner == __smp_processor_id() ||
+	   np->dev->xmit_lock_owner == __smp_processor_id()) {
 		if (np->drop)
 			np->drop(skb);
 		else