X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=datapath%2Fdatapath.c;h=9f415ac5c3ce90062126220ebb26f46f527ca59a;hb=35f7605b3f40ebe49e4a1ad2555ef89ba48433b5;hp=e0b0e2c26d861ee541face2b094e5f1df73b65e9;hpb=a4fbb689b03ad18651ee119ba5ce0ff8cf8d95b5;p=openvswitch

diff --git a/datapath/datapath.c b/datapath/datapath.c
index e0b0e2c2..9f415ac5 100644
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2007, 2008, 2009 Nicira Networks.
+ * Copyright (c) 2007, 2008, 2009, 2010 Nicira Networks.
  * Distributed under the terms of the GNU GPL version 2.
  *
  * Significant portions of this file may be copied from parts of the Linux
@@ -56,9 +56,7 @@ int (*dp_ioctl_hook)(struct net_device *dev, struct ifreq *rq, int cmd);
 EXPORT_SYMBOL(dp_ioctl_hook);
 
 /* Datapaths.  Protected on the read side by rcu_read_lock, on the write side
- * by dp_mutex.  dp_mutex is almost completely redundant with genl_mutex
- * maintained by the Generic Netlink code, but the timeout path needs mutual
- * exclusion too.
+ * by dp_mutex.
  *
  * dp_mutex nests inside the RTNL lock: if you need both you must take the RTNL
  * lock first.
@@ -83,7 +81,7 @@ struct datapath *get_dp(int dp_idx)
 }
 EXPORT_SYMBOL_GPL(get_dp);
 
-struct datapath *get_dp_locked(int dp_idx)
+static struct datapath *get_dp_locked(int dp_idx)
 {
 	struct datapath *dp;
 
@@ -165,7 +163,8 @@ static void dp_ifinfo_notify(int event, struct net_bridge_port *port)
 		kfree_skb(skb);
 		goto errout;
 	}
-	err = rtnl_notify(skb, net, 0, RTNLGRP_LINK, NULL, GFP_KERNEL);
+	rtnl_notify(skb, net, 0, RTNLGRP_LINK, NULL, GFP_KERNEL);
+	return;
 errout:
 	if (err < 0)
 		rtnl_set_sk_err(net, RTNLGRP_LINK, err);
@@ -177,7 +176,7 @@ static void release_dp(struct kobject *kobj)
 	kfree(dp);
 }
 
-struct kobj_type dp_ktype = {
+static struct kobj_type dp_ktype = {
 	.release = release_dp
 };
 
@@ -224,9 +223,7 @@ static int create_dp(int dp_idx, const char __user *devnamep)
 
 	/* Initialize kobject for bridge.  This will be added as
 	 * /sys/class/net/<devname>/brif later, if sysfs is enabled. */
-	kobject_set_name(&dp->ifobj, SYSFS_BRIDGE_PORT_SUBDIR); /* "brif" */
 	dp->ifobj.kset = NULL;
-	dp->ifobj.parent = NULL;
 	kobject_init(&dp->ifobj, &dp_ktype);
 
 	/* Allocate table. */
@@ -235,7 +232,7 @@ static int create_dp(int dp_idx, const char __user *devnamep)
 	if (!dp->table)
 		goto err_free_dp;
 
-	/* Setup our datapath device */
+	/* Set up our datapath device. */
 	dp_dev = dp_dev_create(dp, devname, ODPP_LOCAL);
 	err = PTR_ERR(dp_dev);
 	if (IS_ERR(dp_dev))
@@ -256,9 +253,7 @@ static int create_dp(int dp_idx, const char __user *devnamep)
 	mutex_unlock(&dp_mutex);
 	rtnl_unlock();
 
-#ifdef SUPPORT_SYSFS
 	dp_sysfs_add_dp(dp);
-#endif
 
 	return 0;
 
@@ -286,9 +281,7 @@ static void do_destroy_dp(struct datapath *dp)
 		if (p->port_no != ODPP_LOCAL)
 			dp_del_port(p);
 
-#ifdef SUPPORT_SYSFS
 	dp_sysfs_del_dp(dp);
-#endif
 
 	rcu_assign_pointer(dps[dp->dp_idx], NULL);
 
@@ -332,8 +325,8 @@ static void release_nbp(struct kobject *kobj)
 	kfree(p);
 }
 
-struct kobj_type brport_ktype = {
-#ifdef SUPPORT_SYSFS
+static struct kobj_type brport_ktype = {
+#ifdef CONFIG_SYSFS
 	.sysfs_ops = &brport_sysfs_ops,
 #endif
 	.release = release_nbp
@@ -356,6 +349,7 @@ static int new_nbp(struct datapath *dp, struct net_device *dev, int port_no)
 	p->port_no = port_no;
 	p->dp = dp;
 	p->dev = dev;
+	atomic_set(&p->sflow_pool, 0);
 	if (!is_dp_dev(dev))
 		rcu_assign_pointer(dev->br_port, p);
 	else {
@@ -370,9 +364,7 @@ static int new_nbp(struct datapath *dp, struct net_device *dev, int port_no)
 
 	/* Initialize kobject for bridge.  This will be added as
 	 * /sys/class/net/<devname>/brport later, if sysfs is enabled. */
-	kobject_set_name(&p->kobj, SYSFS_BRIDGE_PORT_ATTR); /* "brport" */
 	p->kobj.kset = NULL;
-	p->kobj.parent = &p->dev->NETDEV_DEV_MEMBER.kobj;
 	kobject_init(&p->kobj, &brport_ktype);
 
 	dp_ifinfo_notify(RTM_NEWLINK, p);
@@ -392,11 +384,6 @@ static int add_port(int dp_idx, struct odp_port __user *portp)
 	if (copy_from_user(&port, portp, sizeof port))
 		goto out;
 	port.devname[IFNAMSIZ - 1] = '\0';
-	port_no = port.port;
-
-	err = -EINVAL;
-	if (port_no < 0 || port_no >= DP_MAX_PORTS)
-		goto out;
 
 	rtnl_lock();
 	dp = get_dp_locked(dp_idx);
@@ -404,10 +391,13 @@ static int add_port(int dp_idx, struct odp_port __user *portp)
 	if (!dp)
 		goto out_unlock_rtnl;
 
-	err = -EEXIST;
-	if (dp->ports[port_no])
-		goto out_unlock_dp;
+	for (port_no = 1; port_no < DP_MAX_PORTS; port_no++)
+		if (!dp->ports[port_no])
+			goto got_port_no;
+	err = -EFBIG;
+	goto out_unlock_dp;
 
+got_port_no:
 	if (!(port.flags & ODP_PORT_INTERNAL)) {
 		err = -ENODEV;
 		dev = dev_get_by_name(&init_net, port.devname);
@@ -430,9 +420,9 @@ static int add_port(int dp_idx, struct odp_port __user *portp)
 	if (err)
 		goto out_put;
 
-#ifdef SUPPORT_SYSFS
 	dp_sysfs_add_if(dp->ports[port_no]);
-#endif
+
+	err = __put_user(port_no, &portp->port);
 
 out_put:
 	dev_put(dev);
@@ -448,10 +438,8 @@ int dp_del_port(struct net_bridge_port *p)
 {
 	ASSERT_RTNL();
 
-#ifdef SUPPORT_SYSFS
 	if (p->port_no != ODPP_LOCAL)
 		dp_sysfs_del_if(p);
-#endif
 	dp_ifinfo_notify(RTM_DELLINK, p);
 
 	p->dp->n_ports--;
@@ -587,7 +575,7 @@ static int dp_frame_hook(struct net_bridge_port *p, struct sk_buff **pskb)
 #error
 #endif
 
-#ifdef CONFIG_XEN
+#if defined(CONFIG_XEN) && defined(HAVE_PROTO_DATA_VALID)
 /* This code is copied verbatim from net/dev/core.c in Xen's
  * linux-2.6.18-92.1.10.el5.xs5.0.0.394.644.  We can't call those functions
  * directly because they aren't exported. */
@@ -603,7 +591,7 @@ static int skb_pull_up_to(struct sk_buff *skb, void *ptr)
 	}
 }
 
-int skb_checksum_setup(struct sk_buff *skb)
+int vswitch_skb_checksum_setup(struct sk_buff *skb)
 {
 	if (skb->proto_csum_blank) {
 		if (skb->protocol != htons(ETH_P_IP))
@@ -634,59 +622,104 @@ int skb_checksum_setup(struct sk_buff *skb)
 out:
 	return -EPROTO;
 }
+#endif /* CONFIG_XEN && HAVE_PROTO_DATA_VALID */
+
+/* Append each packet in 'skb' list to 'queue'.  There will be only one packet
+ * unless we broke up a GSO packet. */
+static int
+queue_control_packets(struct sk_buff *skb, struct sk_buff_head *queue,
+		      int queue_no, u32 arg)
+{
+	struct sk_buff *nskb;
+	int port_no;
+	int err;
+
+	port_no = ODPP_LOCAL;
+	if (skb->dev) {
+		if (skb->dev->br_port)
+			port_no = skb->dev->br_port->port_no;
+		else if (is_dp_dev(skb->dev))
+			port_no = dp_dev_priv(skb->dev)->port_no;
+	}
+
+	do {
+		struct odp_msg *header;
+
+		nskb = skb->next;
+		skb->next = NULL;
+
+		/* If a checksum-deferred packet is forwarded to the
+		 * controller, correct the pointers and checksum.  This happens
+		 * on a regular basis only on Xen, on which VMs can pass up
+		 * packets that do not have their checksum computed.
+		 */
+		err = vswitch_skb_checksum_setup(skb);
+		if (err)
+			goto err_kfree_skbs;
+#ifndef CHECKSUM_HW
+		if (skb->ip_summed == CHECKSUM_PARTIAL) {
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,22)
+			/* Until 2.6.22, the start of the transport header was
+			 * also the start of data to be checksummed.  Linux
+			 * 2.6.22 introduced the csum_start field for this
+			 * purpose, but we should point the transport header to
+			 * it anyway for backward compatibility, as
+			 * dev_queue_xmit() does even in 2.6.28. */
+			skb_set_transport_header(skb, skb->csum_start -
+						 skb_headroom(skb));
+#endif
+			err = skb_checksum_help(skb);
+			if (err)
+				goto err_kfree_skbs;
+		}
+#else
+		if (skb->ip_summed == CHECKSUM_HW) {
+			err = skb_checksum_help(skb, 0);
+			if (err)
+				goto err_kfree_skbs;
+		}
 #endif
 
+		err = skb_cow(skb, sizeof *header);
+		if (err)
+			goto err_kfree_skbs;
+
+		header = (struct odp_msg*)__skb_push(skb, sizeof *header);
+		header->type = queue_no;
+		header->length = skb->len;
+		header->port = port_no;
+		header->reserved = 0;
+		header->arg = arg;
+		skb_queue_tail(queue, skb);
+
+		skb = nskb;
+	} while (skb);
+	return 0;
+
+err_kfree_skbs:
+	kfree_skb(skb);
+	while ((skb = nskb) != NULL) {
+		nskb = skb->next;
+		kfree_skb(skb);
+	}
+	return err;
+}
+
 int
 dp_output_control(struct datapath *dp, struct sk_buff *skb, int queue_no,
 		  u32 arg)
 {
 	struct dp_stats_percpu *stats;
 	struct sk_buff_head *queue;
-	int port_no;
 	int err;
 
 	WARN_ON_ONCE(skb_shared(skb));
-	BUG_ON(queue_no != _ODPL_MISS_NR && queue_no != _ODPL_ACTION_NR);
-
+	BUG_ON(queue_no != _ODPL_MISS_NR && queue_no != _ODPL_ACTION_NR && queue_no != _ODPL_SFLOW_NR);
 	queue = &dp->queues[queue_no];
 	err = -ENOBUFS;
 	if (skb_queue_len(queue) >= DP_MAX_QUEUE_LEN)
 		goto err_kfree_skb;
 
- 	/* If a checksum-deferred packet is forwarded to the controller,
-	 * correct the pointers and checksum.  This happens on a regular basis
-	 * only on Xen (the CHECKSUM_HW case), on which VMs can pass up packets
-	 * that do not have their checksum computed.  We also implement it for
-	 * the non-Xen case, but it is difficult to trigger or test this case
-	 * there, hence the WARN_ON_ONCE().
- 	 */
-	err = skb_checksum_setup(skb);
- 	if (err)
-		goto err_kfree_skb;
-#ifndef CHECKSUM_HW
-	if (skb->ip_summed == CHECKSUM_PARTIAL) {
-		WARN_ON_ONCE(1);
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,22)
-		/* Until 2.6.22, the start of the transport header was also the
-		 * start of data to be checksummed.  Linux 2.6.22 introduced
-		 * the csum_start field for this purpose, but we should point
-		 * the transport header to it anyway for backward
-		 * compatibility, as dev_queue_xmit() does even in 2.6.28. */
-		skb_set_transport_header(skb, skb->csum_start -
-					      skb_headroom(skb));
-#endif
-		err = skb_checksum_help(skb);
-		if (err)
-			goto err_kfree_skb;
-	}
-#else
-	if (skb->ip_summed == CHECKSUM_HW) {
-		err = skb_checksum_help(skb, 0);
-		if (err)
-			goto err_kfree_skb;
-	}
-#endif
-
 	/* Break apart GSO packets into their component pieces.  Otherwise
 	 * userspace may try to stuff a 64kB packet into a 1500-byte MTU. */
 	if (skb_is_gso(skb)) {
@@ -704,45 +737,9 @@ dp_output_control(struct datapath *dp, struct sk_buff *skb, int queue_no,
 		}
 	}
 
-	/* Figure out port number. */
-	port_no = ODPP_LOCAL;
-	if (skb->dev) {
-		if (skb->dev->br_port)
-			port_no = skb->dev->br_port->port_no;
-		else if (is_dp_dev(skb->dev))
-			port_no = dp_dev_priv(skb->dev)->port_no;
-	}
-
-	/* Append each packet to queue.  There will be only one packet unless
-	 * we broke up a GSO packet above. */
-	do {
-		struct odp_msg *header;
-		struct sk_buff *nskb = skb->next;
-		skb->next = NULL;
-
-		err = skb_cow(skb, sizeof *header);
-		if (err) {
-			while (nskb) {
-				kfree_skb(skb);
-				skb = nskb;
-				nskb = skb->next;
-			}
-			goto err_kfree_skb;
-		}
-
-		header = (struct odp_msg*)__skb_push(skb, sizeof *header);
-		header->type = queue_no;
-		header->length = skb->len;
-		header->port = port_no;
-		header->reserved = 0;
-		header->arg = arg;
-		skb_queue_tail(queue, skb);
-
-		skb = nskb;
-	} while (skb);
-
+	err = queue_control_packets(skb, queue, queue_no, arg);
 	wake_up_interruptible(&dp->waitqueue);
-	return 0;
+	return err;
 
 err_kfree_skb:
 	kfree_skb(skb);
@@ -837,6 +834,7 @@ static void get_stats(struct sw_flow *flow, struct odp_flow_stats *stats)
 	stats->n_bytes = flow->byte_count;
 	stats->ip_tos = flow->ip_tos;
 	stats->tcp_flags = flow->tcp_flags;
+	stats->error = 0;
 }
 
 static void clear_stats(struct sw_flow *flow)
@@ -964,8 +962,6 @@ static int put_actions(const struct sw_flow *flow, struct odp_flow __user *ufp)
 
 	if (!n_actions)
 		return 0;
-	if (ufp->n_actions > INT_MAX / sizeof(union odp_action))
-		return -EINVAL;
 
 	sf_acts = rcu_dereference(flow->sf_acts);
 	if (__put_user(sf_acts->n_actions, &ufp->n_actions) ||
@@ -977,13 +973,18 @@ static int put_actions(const struct sw_flow *flow, struct odp_flow __user *ufp)
 	return 0;
 }
 
-static int answer_query(struct sw_flow *flow, struct odp_flow __user *ufp)
+static int answer_query(struct sw_flow *flow, u32 query_flags,
+			struct odp_flow __user *ufp)
 {
 	struct odp_flow_stats stats;
 	unsigned long int flags;
 
 	spin_lock_irqsave(&flow->lock, flags);
 	get_stats(flow, &stats);
+
+	if (query_flags & ODPFF_ZERO_TCP_FLAGS) {
+		flow->tcp_flags = 0;
+	}
 	spin_unlock_irqrestore(&flow->lock, flags);
 
 	if (__copy_to_user(&ufp->stats, &stats, sizeof(struct odp_flow_stats)))
@@ -991,9 +992,7 @@ static int answer_query(struct sw_flow *flow, struct odp_flow __user *ufp)
 	return put_actions(flow, ufp);
 }
 
-static int del_or_query_flow(struct datapath *dp,
-			     struct odp_flow __user *ufp,
-			     unsigned int cmd)
+static int del_flow(struct datapath *dp, struct odp_flow __user *ufp)
 {
 	struct dp_table *table = rcu_dereference(dp->table);
 	struct odp_flow uf;
@@ -1010,29 +1009,24 @@ static int del_or_query_flow(struct datapath *dp,
 	if (!flow)
 		goto error;
 
-	if (cmd == ODP_FLOW_DEL) {
-		/* XXX redundant lookup */
-		error = dp_table_delete(table, flow);
-		if (error)
-			goto error;
+	/* XXX redundant lookup */
+	error = dp_table_delete(table, flow);
+	if (error)
+		goto error;
 
-		/* XXX These statistics might lose a few packets, since other
-		 * CPUs can be using this flow.  We used to synchronize_rcu()
-		 * to make sure that we get completely accurate stats, but that
-		 * blows our performance, badly. */
-		dp->n_flows--;
-		error = answer_query(flow, ufp);
-		flow_deferred_free(flow);
-	} else {
-		error = answer_query(flow, ufp);
-	}
+	/* XXX These statistics might lose a few packets, since other CPUs can
+	 * be using this flow.  We used to synchronize_rcu() to make sure that
+	 * we get completely accurate stats, but that blows our performance,
+	 * badly. */
+	dp->n_flows--;
+	error = answer_query(flow, 0, ufp);
+	flow_deferred_free(flow);
 
 error:
 	return error;
 }
 
-static int query_multiple_flows(struct datapath *dp,
-				const struct odp_flowvec *flowvec)
+static int query_flows(struct datapath *dp, const struct odp_flowvec *flowvec)
 {
 	struct dp_table *table = rcu_dereference(dp->table);
 	int i;
@@ -1048,9 +1042,9 @@ static int query_multiple_flows(struct datapath *dp,
 
 		flow = dp_table_lookup(table, &uf.key);
 		if (!flow)
-			error = __clear_user(&ufp->stats, sizeof ufp->stats);
+			error = __put_user(ENOENT, &ufp->stats.error);
 		else
-			error = answer_query(flow, ufp);
+			error = answer_query(flow, uf.flags, ufp);
 		if (error)
 			return -EFAULT;
 	}
@@ -1071,7 +1065,7 @@ static int list_flow(struct sw_flow *flow, void *cbdata_)
 
 	if (__copy_to_user(&ufp->key, &flow->key, sizeof flow->key))
 		return -EFAULT;
-	error = answer_query(flow, ufp);
+	error = answer_query(flow, 0, ufp);
 	if (error)
 		return error;
 
@@ -1171,9 +1165,9 @@ static int do_execute(struct datapath *dp, const struct odp_execute *executep)
 	skb_reset_mac_header(skb);
 	eth = eth_hdr(skb);
 
-    /* Normally, setting the skb 'protocol' field would be handled by a
-     * call to eth_type_trans(), but it assumes there's a sending
-     * device, which we may not have. */
+	/* Normally, setting the skb 'protocol' field would be handled by a
+	 * call to eth_type_trans(), but it assumes there's a sending
+	 * device, which we may not have. */
 	if (ntohs(eth->h_proto) >= 1536)
 		skb->protocol = eth->h_proto;
 	else
@@ -1193,8 +1187,7 @@ error:
 	return err;
 }
 
-static int
-get_dp_stats(struct datapath *dp, struct odp_stats __user *statsp)
+static int get_dp_stats(struct datapath *dp, struct odp_stats __user *statsp)
 {
 	struct odp_stats stats;
 	int i;
@@ -1309,7 +1302,7 @@ list_ports(struct datapath *dp, struct odp_portvec __user *pvp)
 				break;
 		}
 	}
-	return put_user(idx, &pvp->n_ports);
+	return put_user(dp->n_ports, &pvp->n_ports);
 }
 
 /* RCU callback for freeing a dp_port_group */
@@ -1382,35 +1375,50 @@ get_port_group(struct datapath *dp, struct odp_port_group *upg)
 	return 0;
 }
 
+static int get_listen_mask(const struct file *f)
+{
+	return (long)f->private_data;
+}
+
+static void set_listen_mask(struct file *f, int listen_mask)
+{
+	f->private_data = (void*)(long)listen_mask;
+}
+
 static long openvswitch_ioctl(struct file *f, unsigned int cmd,
 			   unsigned long argp)
 {
 	int dp_idx = iminor(f->f_dentry->d_inode);
 	struct datapath *dp;
 	int drop_frags, listeners, port_no;
+	unsigned int sflow_probability;
 	int err;
 
 	/* Handle commands with special locking requirements up front. */
 	switch (cmd) {
 	case ODP_DP_CREATE:
-		return create_dp(dp_idx, (char __user *)argp);
+		err = create_dp(dp_idx, (char __user *)argp);
+		goto exit;
 
 	case ODP_DP_DESTROY:
-		return destroy_dp(dp_idx);
+		err = destroy_dp(dp_idx);
+		goto exit;
 
 	case ODP_PORT_ADD:
-		return add_port(dp_idx, (struct odp_port __user *)argp);
+		err = add_port(dp_idx, (struct odp_port __user *)argp);
+		goto exit;
 
 	case ODP_PORT_DEL:
 		err = get_user(port_no, (int __user *)argp);
-		if (err)
-			break;
-		return del_port(dp_idx, port_no);
+		if (!err)
+			err = del_port(dp_idx, port_no);
+		goto exit;
 	}
 
 	dp = get_dp_locked(dp_idx);
+	err = -ENODEV;
 	if (!dp)
-		return -ENODEV;
+		goto exit;
 
 	switch (cmd) {
 	case ODP_DP_STATS:
@@ -1433,7 +1441,7 @@ static long openvswitch_ioctl(struct file *f, unsigned int cmd,
 		break;
 
 	case ODP_GET_LISTEN_MASK:
-		err = put_user((int)f->private_data, (int __user *)argp);
+		err = put_user(get_listen_mask(f), (int __user *)argp);
 		break;
 
 	case ODP_SET_LISTEN_MASK:
@@ -1444,7 +1452,17 @@ static long openvswitch_ioctl(struct file *f, unsigned int cmd,
 		if (listeners & ~ODPL_ALL)
 			break;
 		err = 0;
-		f->private_data = (void*)listeners;
+		set_listen_mask(f, listeners);
+		break;
+
+	case ODP_GET_SFLOW_PROBABILITY:
+		err = put_user(dp->sflow_probability, (unsigned int __user *)argp);
+		break;
+
+	case ODP_SET_SFLOW_PROBABILITY:
+		err = get_user(sflow_probability, (unsigned int __user *)argp);
+		if (!err)
+			dp->sflow_probability = sflow_probability;
 		break;
 
 	case ODP_PORT_QUERY:
@@ -1472,13 +1490,11 @@ static long openvswitch_ioctl(struct file *f, unsigned int cmd,
 		break;
 
 	case ODP_FLOW_DEL:
-	case ODP_FLOW_GET:
-		err = del_or_query_flow(dp, (struct odp_flow __user *)argp,
-					cmd);
+		err = del_flow(dp, (struct odp_flow __user *)argp);
 		break;
 
-	case ODP_FLOW_GET_MULTIPLE:
-		err = do_flowvec_ioctl(dp, argp, query_multiple_flows);
+	case ODP_FLOW_GET:
+		err = do_flowvec_ioctl(dp, argp, query_flows);
 		break;
 
 	case ODP_FLOW_LIST:
@@ -1494,6 +1510,7 @@ static long openvswitch_ioctl(struct file *f, unsigned int cmd,
 		break;
 	}
 	mutex_unlock(&dp->mutex);
+exit:
 	return err;
 }
 
@@ -1511,7 +1528,7 @@ ssize_t openvswitch_read(struct file *f, char __user *buf, size_t nbytes,
 		      loff_t *ppos)
 {
 	/* XXX is there sufficient synchronization here? */
-	int listeners = (int) f->private_data;
+	int listeners = get_listen_mask(f);
 	int dp_idx = iminor(f->f_dentry->d_inode);
 	struct datapath *dp = get_dp(dp_idx);
 	struct sk_buff *skb;
@@ -1551,7 +1568,7 @@ ssize_t openvswitch_read(struct file *f, char __user *buf, size_t nbytes,
 		}
 	}
 success:
-	copy_bytes = min(skb->len, nbytes);
+	copy_bytes = min_t(size_t, skb->len, nbytes);
 	iov.iov_base = buf;
 	iov.iov_len = copy_bytes;
 	retval = skb_copy_datagram_iovec(skb, 0, &iov, iov.iov_len);
@@ -1573,7 +1590,7 @@ static unsigned int openvswitch_poll(struct file *file, poll_table *wait)
 	if (dp) {
 		mask = 0;
 		poll_wait(file, &dp->waitqueue, wait);
-		if (dp_has_packet_of_interest(dp, (int)file->private_data))
+		if (dp_has_packet_of_interest(dp, get_listen_mask(file)))
 			mask |= POLLIN | POLLRDNORM;
 	} else {
 		mask = POLLIN | POLLRDNORM | POLLHUP;
@@ -1590,6 +1607,8 @@ struct file_operations openvswitch_fops = {
 };
 
 static int major;
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,27)
 static struct llc_sap *dp_stp_sap;
 
 static int dp_stp_rcv(struct sk_buff *skb, struct net_device *dev,
@@ -1602,12 +1621,8 @@ static int dp_stp_rcv(struct sk_buff *skb, struct net_device *dev,
 	return 0;
 }
 
-static int __init dp_init(void)
+static int dp_avoid_bridge_init(void)
 {
-	int err;
-
-	printk("Open vSwitch %s, built "__DATE__" "__TIME__"\n", VERSION BUILDNR);
-
 	/* Register to receive STP packets because the bridge module also
 	 * attempts to do so.  Since there can only be a single listener for a
 	 * given protocol, this provides mutual exclusion against the bridge
@@ -1618,6 +1633,43 @@ static int __init dp_init(void)
 		printk(KERN_ERR "openvswitch: can't register sap for STP (probably the bridge module is loaded)\n");
 		return -EADDRINUSE;
 	}
+	return 0;
+}
+
+static void dp_avoid_bridge_exit(void)
+{
+	llc_sap_put(dp_stp_sap);
+}
+#else  /* Linux 2.6.27 or later. */
+static int dp_avoid_bridge_init(void)
+{
+	/* Linux 2.6.27 introduces a way for multiple clients to register for
+	 * STP packets, which interferes with what we try to do above.
+	 * Instead, just check whether there's a bridge hook defined.  This is
+	 * not as safe--the bridge module is willing to load over the top of
+	 * us--but it provides a little bit of protection. */
+	if (br_handle_frame_hook) {
+		printk(KERN_ERR "openvswitch: bridge module is loaded, cannot load over it\n");
+		return -EADDRINUSE;
+	}
+	return 0;
+}
+
+static void dp_avoid_bridge_exit(void)
+{
+	/* Nothing to do. */
+}
+#endif	/* Linux 2.6.27 or later */
+
+static int __init dp_init(void)
+{
+	int err;
+
+	printk("Open vSwitch %s, built "__DATE__" "__TIME__"\n", VERSION BUILDNR);
+
+	err = dp_avoid_bridge_init();
+	if (err)
+		return err;
 
 	err = flow_init();
 	if (err)
@@ -1652,7 +1704,7 @@ static void dp_cleanup(void)
 	unregister_netdevice_notifier(&dp_device_notifier);
 	flow_exit();
 	br_handle_frame_hook = NULL;
-	llc_sap_put(dp_stp_sap);
+	dp_avoid_bridge_exit();
 }
 
 module_init(dp_init);