Linux Ethernet Bridging - Mar 2010 - [Bridge] [RFC Patch 1/3] netpoll: add generic support for bridge and bonding devices

This whole patchset is for adding netpoll support to bridge and bonding
devices. I already tested it for bridge, bonding, bridge over bonding,
and bonding over bridge. It looks fine now.

Please comment.


To make bridge and bonding support netpoll, we need to adjust
some netpoll generic code. This patch does the following things:

1) introduce two new priv_flags for struct net_device:
   IFF_IN_NETPOLL which identifies we are processing a netpoll;
   IFF_DISABLE_NETPOLL is used to disable netpoll support for a device
   at run-time;

2) introduce three new methods for netdev_ops:
   ->ndo_netpoll_setup() is used to setup netpoll for a device;
   ->ndo_netpoll_xmit() is used to transmit netpoll requests;
   ->ndo_netpoll_cleanup() is used to clean up netpoll when a device is
     removed.

3) introduce netpoll_poll_dev() which takes a struct net_device * parameter;

4) export netpoll_send_skb() and netpoll_poll_dev() which will be used later;

5) hide a pointer to struct netpoll in struct netpoll_info, ditto.

Cc: David Miller <davem at davemloft.net>
Cc: Neil Horman <nhorman at tuxdriver.com>
Signed-off-by: WANG Cong <amwang at redhat.com>

---
Index: linux-2.6/include/linux/if.h
==================================================================---
linux-2.6.orig/include/linux/if.h
+++ linux-2.6/include/linux/if.h
@@ -71,6 +71,8 @@
 					 * release skb->dst
 					 */
 #define IFF_DONT_BRIDGE 0x800		/* disallow bridging this ether dev */
+#define IFF_IN_NETPOLL	0x1000		/* whether we are processing netpoll */
+#define IFF_DISABLE_NETPOLL	0x2000	/* disable netpoll at run-time */
 
 #define IF_GET_IFACE	0x0001		/* for querying only */
 #define IF_GET_PROTO	0x0002
Index: linux-2.6/include/linux/netdevice.h
==================================================================---
linux-2.6.orig/include/linux/netdevice.h
+++ linux-2.6/include/linux/netdevice.h
@@ -530,6 +530,8 @@ struct netdev_queue {
 	unsigned long		tx_dropped;
 } ____cacheline_aligned_in_smp;
 
+struct netpoll;
+struct netpoll_info;
 
 /*
  * This structure defines the management hooks for network devices.
@@ -667,6 +669,12 @@ struct net_device_ops {
 						        unsigned short vid);
 #ifdef CONFIG_NET_POLL_CONTROLLER
 	void                    (*ndo_poll_controller)(struct net_device *dev);
+	void			(*ndo_netpoll_setup)(struct net_device *dev,
+						     struct netpoll_info *npinfo);
+	int			(*ndo_netpoll_xmit)(struct netpoll *np,
+						    struct sk_buff *skb,
+						    struct net_device *dev);
+	void			(*ndo_netpoll_cleanup)(struct net_device *dev);
 #endif
 	int			(*ndo_set_vf_mac)(struct net_device *dev,
 						  int queue, u8 *mac);
Index: linux-2.6/include/linux/netpoll.h
==================================================================---
linux-2.6.orig/include/linux/netpoll.h
+++ linux-2.6/include/linux/netpoll.h
@@ -36,8 +36,11 @@ struct netpoll_info {
 	struct sk_buff_head txq;
 
 	struct delayed_work tx_work;
+
+	struct netpoll *netpoll;
 };
 
+void netpoll_poll_dev(struct net_device *dev);
 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);
@@ -47,6 +50,7 @@ int netpoll_trap(void);
 void netpoll_set_trap(int trap);
 void netpoll_cleanup(struct netpoll *np);
 int __netpoll_rx(struct sk_buff *skb);
+void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb);
 
 
 #ifdef CONFIG_NETPOLL
Index: linux-2.6/net/core/netpoll.c
==================================================================---
linux-2.6.orig/net/core/netpoll.c
+++ linux-2.6/net/core/netpoll.c
@@ -178,9 +178,8 @@ static void service_arp_queue(struct net
 	}
 }
 
-void netpoll_poll(struct netpoll *np)
+void netpoll_poll_dev(struct net_device *dev)
 {
-	struct net_device *dev = np->dev;
 	const struct net_device_ops *ops;
 
 	if (!dev || !netif_running(dev))
@@ -200,6 +199,13 @@ void netpoll_poll(struct netpoll *np)
 	zap_completion_queue();
 }
 
+void netpoll_poll(struct netpoll *np)
+{
+	if (!np->dev)
+		return;
+	netpoll_poll_dev(np->dev);
+}
+
 static void refill_skbs(void)
 {
 	struct sk_buff *skb;
@@ -281,7 +287,7 @@ static int netpoll_owner_active(struct n
 	return 0;
 }
 
-static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
+void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
 {
 	int status = NETDEV_TX_BUSY;
 	unsigned long tries;
@@ -307,7 +313,10 @@ static void netpoll_send_skb(struct netp
 		     tries > 0; --tries) {
 			if (__netif_tx_trylock(txq)) {
 				if (!netif_tx_queue_stopped(txq)) {
-					status = ops->ndo_start_xmit(skb, dev);
+					if (ops->ndo_netpoll_xmit)
+						status = ops->ndo_netpoll_xmit(np, skb, dev);
+					else
+						status = ops->ndo_start_xmit(skb, dev);
 					if (status == NETDEV_TX_OK)
 						txq_trans_update(txq);
 				}
@@ -752,7 +761,10 @@ int netpoll_setup(struct netpoll *np)
 		atomic_inc(&npinfo->refcnt);
 	}
 
-	if (!ndev->netdev_ops->ndo_poll_controller) {
+	npinfo->netpoll = np;
+
+	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;
@@ -830,6 +842,9 @@ int netpoll_setup(struct netpoll *np)
 	/* last thing to do is link it to the net device structure */
 	ndev->npinfo = npinfo;
 
+	if (ndev->netdev_ops->ndo_netpoll_setup)
+		ndev->netdev_ops->ndo_netpoll_setup(ndev, npinfo);
+
 	/* avoid racing with NAPI reading npinfo */
 	synchronize_rcu();
 
@@ -904,6 +919,7 @@ void netpoll_set_trap(int trap)
 		atomic_dec(&trapped);
 }
 
+EXPORT_SYMBOL(netpoll_send_skb);
 EXPORT_SYMBOL(netpoll_set_trap);
 EXPORT_SYMBOL(netpoll_trap);
 EXPORT_SYMBOL(netpoll_print_options);
@@ -911,4 +927,5 @@ EXPORT_SYMBOL(netpoll_parse_options);
 EXPORT_SYMBOL(netpoll_setup);
 EXPORT_SYMBOL(netpoll_cleanup);
 EXPORT_SYMBOL(netpoll_send_udp);
+EXPORT_SYMBOL(netpoll_poll_dev);
 EXPORT_SYMBOL(netpoll_poll);

Based on the previous patch, make bridge support netpoll by:

1) implement the 4 methods to support netpoll for bridge;

2) modify netpoll during forwarding packets in bridge;

3) disable netpoll support of bridge when a netpoll-unabled device
   is added to bridge;

4) enable netpoll support when all underlying devices support netpoll.

Cc: David Miller <davem at davemloft.net>
Cc: Neil Horman <nhorman at tuxdriver.com>
Cc: Stephen Hemminger <shemminger at linux-foundation.org>
Signed-off-by: WANG Cong <amwang at redhat.com>

---
Index: linux-2.6/net/bridge/br_device.c
==================================================================---
linux-2.6.orig/net/bridge/br_device.c
+++ linux-2.6/net/bridge/br_device.c
@@ -13,6 +13,7 @@
 
 #include <linux/kernel.h>
 #include <linux/netdevice.h>
+#include <linux/netpoll.h>
 #include <linux/etherdevice.h>
 #include <linux/ethtool.h>
 
@@ -162,6 +163,87 @@ static int br_set_tx_csum(struct net_dev
 	return 0;
 }
 
+#ifdef CONFIG_NET_POLL_CONTROLLER
+bool br_devices_support_netpoll(struct net_bridge *br)
+{
+	struct net_bridge_port *p;
+	bool ret = true;
+	int count = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&br->lock, flags);
+	list_for_each_entry(p, &br->port_list, list) {
+		count++;
+		if (p->dev->priv_flags & IFF_DISABLE_NETPOLL
+				|| !p->dev->netdev_ops->ndo_poll_controller)
+			ret = false;
+	}
+	spin_unlock_irqrestore(&br->lock, flags);
+	return count != 0 && ret;
+}
+
+static void br_poll_controller(struct net_device *br_dev)
+{
+	struct net_bridge *br = netdev_priv(br_dev);
+	struct net_bridge_port *p;
+	unsigned long flags;
+
+	spin_lock_irqsave(&br->lock, flags);
+	list_for_each_entry(p, &br->port_list, list) {
+		if (p->dev->netdev_ops->ndo_poll_controller)
+			netpoll_poll_dev(p->dev);
+	}
+	spin_unlock_irqrestore(&br->lock, flags);
+}
+
+static void br_netpoll_setup(struct net_device *br_dev, struct netpoll_info
*npinfo)
+{
+	struct net_bridge *br = netdev_priv(br_dev);
+	struct net_bridge_port *p;
+	unsigned long flags;
+
+	spin_lock_irqsave(&br->lock, flags);
+	list_for_each_entry(p, &br->port_list, list) {
+		if (p->dev)
+			p->dev->npinfo = npinfo;
+	}
+	spin_unlock_irqrestore(&br->lock, flags);
+}
+
+static void br_netpoll_cleanup(struct net_device *br_dev)
+{
+	struct net_bridge *br = netdev_priv(br_dev);
+	struct net_bridge_port *p;
+	const struct net_device_ops *ops;
+	unsigned long flags;
+
+	spin_lock_irqsave(&br->lock, flags);
+	br->dev->npinfo = NULL;
+	list_for_each_entry(p, &br->port_list, list) {
+		if (p->dev) {
+			ops = p->dev->netdev_ops;
+			if (ops->ndo_netpoll_cleanup)
+				ops->ndo_netpoll_cleanup(p->dev);
+			else
+				p->dev->npinfo = NULL;
+		}
+	}
+	spin_unlock_irqrestore(&br->lock, flags);
+}
+
+static int br_netpoll_xmit(struct netpoll *np, struct sk_buff *skb, struct
net_device *dev)
+{
+	int ret;
+
+	dev->priv_flags |= IFF_IN_NETPOLL;
+	ret = dev->netdev_ops->ndo_start_xmit(skb, dev);
+	np->dev = dev;
+	dev->priv_flags &= ~IFF_IN_NETPOLL;
+	return ret;
+}
+
+#endif
+
 static const struct ethtool_ops br_ethtool_ops = {
 	.get_drvinfo    = br_getinfo,
 	.get_link	= ethtool_op_get_link,
@@ -184,6 +266,12 @@ static const struct net_device_ops br_ne
 	.ndo_set_multicast_list	 = br_dev_set_multicast_list,
 	.ndo_change_mtu		 = br_change_mtu,
 	.ndo_do_ioctl		 = br_dev_ioctl,
+#ifdef CONFIG_NET_POLL_CONTROLLER
+	.ndo_netpoll_setup	 = br_netpoll_setup,
+	.ndo_netpoll_xmit	 = br_netpoll_xmit,
+	.ndo_netpoll_cleanup	 = br_netpoll_cleanup,
+	.ndo_poll_controller	 = br_poll_controller,
+#endif
 };
 
 void br_dev_setup(struct net_device *dev)
Index: linux-2.6/net/bridge/br_forward.c
==================================================================---
linux-2.6.orig/net/bridge/br_forward.c
+++ linux-2.6/net/bridge/br_forward.c
@@ -14,6 +14,7 @@
 #include <linux/err.h>
 #include <linux/kernel.h>
 #include <linux/netdevice.h>
+#include <linux/netpoll.h>
 #include <linux/skbuff.h>
 #include <linux/if_vlan.h>
 #include <linux/netfilter_bridge.h>
@@ -44,7 +45,13 @@ int br_dev_queue_push_xmit(struct sk_buf
 		else {
 			skb_push(skb, ETH_HLEN);
 
-			dev_queue_xmit(skb);
+#ifdef CONFIG_NET_POLL_CONTROLLER
+			if (skb->dev->priv_flags & IFF_IN_NETPOLL) {
+				netpoll_send_skb(skb->dev->npinfo->netpoll, skb);
+				skb->dev->priv_flags &= ~IFF_IN_NETPOLL;
+			} else
+#endif
+				dev_queue_xmit(skb);
 		}
 	}
 
@@ -60,6 +67,16 @@ int br_forward_finish(struct sk_buff *sk
 
 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
 {
+#ifdef CONFIG_NET_POLL_CONTROLLER
+	struct net_bridge *br = to->br;
+	if (br->dev->priv_flags & IFF_IN_NETPOLL) {
+		skb->dev->npinfo->netpoll->dev = to->dev;
+		if (!to->dev->npinfo)
+			to->dev->npinfo = skb->dev->npinfo;
+
+		to->dev->priv_flags |= IFF_IN_NETPOLL;
+	}
+#endif
 	skb->dev = to->dev;
 	NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
 			br_forward_finish);
Index: linux-2.6/net/bridge/br_if.c
==================================================================---
linux-2.6.orig/net/bridge/br_if.c
+++ linux-2.6/net/bridge/br_if.c
@@ -19,6 +19,7 @@
 #include <linux/init.h>
 #include <linux/rtnetlink.h>
 #include <linux/if_ether.h>
+#include <linux/netpoll.h>
 #include <net/sock.h>
 
 #include "br_private.h"
@@ -152,6 +153,14 @@ static void del_nbp(struct net_bridge_po
 	kobject_uevent(&p->kobj, KOBJ_REMOVE);
 	kobject_del(&p->kobj);
 
+#ifdef CONFIG_NET_POLL_CONTROLLER
+	if (br_devices_support_netpoll(br))
+		br->dev->priv_flags &= ~IFF_DISABLE_NETPOLL;
+	if (br->dev->netdev_ops->ndo_netpoll_cleanup)
+		br->dev->netdev_ops->ndo_netpoll_cleanup(br->dev);
+	else
+		dev->npinfo = NULL;
+#endif
 	call_rcu(&p->rcu, destroy_nbp_rcu);
 }
 
@@ -437,6 +446,20 @@ int br_add_if(struct net_bridge *br, str
 
 	kobject_uevent(&p->kobj, KOBJ_ADD);
 
+#ifdef CONFIG_NET_POLL_CONTROLLER
+	if (br_devices_support_netpoll(br)) {
+		br->dev->priv_flags &= ~IFF_DISABLE_NETPOLL;
+		if (br->dev->npinfo)
+			dev->npinfo = br->dev->npinfo;
+	} else if (!(br->dev->priv_flags & IFF_DISABLE_NETPOLL)) {
+		br->dev->priv_flags |= IFF_DISABLE_NETPOLL;
+		printk(KERN_INFO "New device %s does not support netpoll\n",
+			dev->name);
+		printk(KERN_INFO "Disabling netpoll for %s\n",
+			br->dev->name);
+	}
+#endif
+
 	return 0;
 err2:
 	br_fdb_delete_by_port(br, p, 1);
Index: linux-2.6/net/bridge/br_private.h
==================================================================---
linux-2.6.orig/net/bridge/br_private.h
+++ linux-2.6/net/bridge/br_private.h
@@ -225,6 +225,7 @@ static inline int br_is_root_bridge(cons
 extern void br_dev_setup(struct net_device *dev);
 extern netdev_tx_t br_dev_xmit(struct sk_buff *skb,
 			       struct net_device *dev);
+extern bool br_devices_support_netpoll(struct net_bridge *br);
 
 /* br_fdb.c */
 extern int br_fdb_init(void);

Based on Andy's work, but I modify a lot.

Similar to the patch for bridge, this patch does:

1) implement the 4 methods to support netpoll for bonding;

2) modify netpoll during forwarding packets in bonding;

3) disable netpoll support of bridge when a netpoll-unabled device
   is added to bonding;

4) enable netpoll support when all underlying devices support netpoll.

Cc: Andy Gospodarek <gospo at redhat.com>
Cc: Neil Horman <nhorman at tuxdriver.com>
Cc: Jay Vosburgh <fubar at us.ibm.com>
Cc: David Miller <davem at davemloft.net>
Signed-off-by: WANG Cong <amwang at redhat.com>


---
Index: linux-2.6/drivers/net/bonding/bond_main.c
==================================================================---
linux-2.6.orig/drivers/net/bonding/bond_main.c
+++ linux-2.6/drivers/net/bonding/bond_main.c
@@ -59,6 +59,7 @@
 #include <linux/uaccess.h>
 #include <linux/errno.h>
 #include <linux/netdevice.h>
+#include <linux/netpoll.h>
 #include <linux/inetdevice.h>
 #include <linux/igmp.h>
 #include <linux/etherdevice.h>
@@ -430,7 +431,17 @@ int bond_dev_queue_xmit(struct bonding *
 	}
 
 	skb->priority = 1;
-	dev_queue_xmit(skb);
+#ifdef CONFIG_NET_POLL_CONTROLLER
+	if (bond->dev->priv_flags & IFF_IN_NETPOLL) {
+		bond->dev->npinfo->netpoll->dev = skb->dev;
+		if (!slave_dev->npinfo)
+			slave_dev->npinfo = bond->dev->npinfo;
+		slave_dev->priv_flags |= IFF_IN_NETPOLL;
+		netpoll_send_skb(bond->dev->npinfo->netpoll, skb);
+		slave_dev->priv_flags &= ~IFF_IN_NETPOLL;
+	} else
+#endif
+		dev_queue_xmit(skb);
 
 	return 0;
 }
@@ -1324,6 +1335,87 @@ static void bond_detach_slave(struct bon
 	bond->slave_cnt--;
 }
 
+#ifdef CONFIG_NET_POLL_CONTROLLER
+static bool slaves_support_netpoll(struct net_device *bond_dev)
+{
+	struct bonding *bond = netdev_priv(bond_dev);
+	struct slave *slave;
+	int i = 0;
+	bool ret = true;
+
+	read_lock_bh(&bond->lock);
+	bond_for_each_slave(bond, slave, i) {
+		if ((slave->dev->priv_flags & IFF_DISABLE_NETPOLL)
+				|| !slave->dev->netdev_ops->ndo_poll_controller)
+			ret = false;
+	}
+	read_unlock_bh(&bond->lock);
+	return i != 0 && ret;
+}
+
+static void bond_poll_controller(struct net_device *bond_dev)
+{
+	struct bonding *bond = netdev_priv(bond_dev);
+	struct slave *slave;
+	int i;
+
+	read_lock(&bond->lock);
+	bond_for_each_slave(bond, slave, i) {
+		if (slave->dev->netdev_ops->ndo_poll_controller)
+			netpoll_poll_dev(slave->dev);
+	}
+	read_unlock(&bond->lock);
+}
+
+static void bond_netpoll_setup(struct net_device *bond_dev,
+			      struct netpoll_info *npinfo)
+{
+	struct bonding *bond = netdev_priv(bond_dev);
+	struct slave *slave;
+	int i;
+
+	write_lock_bh(&bond->lock);
+	bond_for_each_slave(bond, slave, i) {
+		if (slave->dev)
+			slave->dev->npinfo = npinfo;
+	}
+	write_unlock_bh(&bond->lock);
+}
+
+static void bond_netpoll_cleanup(struct net_device *bond_dev)
+{
+	struct bonding *bond = netdev_priv(bond_dev);
+	struct slave *slave;
+	const struct net_device_ops *ops;
+	int i;
+
+	write_lock_bh(&bond->lock);
+	bond_dev->npinfo = NULL;
+	bond_for_each_slave(bond, slave, i) {
+		if (slave->dev) {
+			ops = slave->dev->netdev_ops;
+			if (ops->ndo_netpoll_cleanup)
+				ops->ndo_netpoll_cleanup(slave->dev);
+			else
+				slave->dev->npinfo = NULL;
+		}
+	}
+	write_unlock_bh(&bond->lock);
+}
+
+static int bond_netpoll_xmit(struct netpoll *np, struct sk_buff *skb,
+			     struct net_device *dev)
+{
+	int ret;
+
+	dev->priv_flags |= IFF_IN_NETPOLL;
+	ret = dev->netdev_ops->ndo_start_xmit(skb, dev);
+	np->dev = dev;
+	dev->priv_flags &= ~IFF_IN_NETPOLL;
+	return ret;
+}
+#endif
+
 /*---------------------------------- IOCTL ----------------------------------*/
 
 static int bond_sethwaddr(struct net_device *bond_dev,
@@ -1741,6 +1833,18 @@ int bond_enslave(struct net_device *bond
 		new_slave->state == BOND_STATE_ACTIVE ? "n active" : "
backup",
 		new_slave->link != BOND_LINK_DOWN ? "n up" : " down");
 
+#ifdef CONFIG_NET_POLL_CONTROLLER
+	if (slaves_support_netpoll(bond_dev)) {
+		bond_dev->priv_flags &= ~IFF_DISABLE_NETPOLL;
+		if (bond_dev->npinfo)
+			slave_dev->npinfo = bond_dev->npinfo;
+	} else if (!(bond_dev->priv_flags & IFF_DISABLE_NETPOLL)) {
+		bond_dev->priv_flags |= IFF_DISABLE_NETPOLL;
+		pr_info("New slave device %s does not support netpoll\n",
+			slave_dev->name);
+		pr_info("Disabling netpoll support for %s\n", bond_dev->name);
+	}
+#endif
 	/* enslave is successful */
 	return 0;
 
@@ -1924,6 +2028,15 @@ int bond_release(struct net_device *bond
 
 	netdev_set_master(slave_dev, NULL);
 
+#ifdef CONFIG_NET_POLL_CONTROLLER
+	if (slaves_support_netpoll(bond_dev))
+		bond_dev->priv_flags &= ~IFF_DISABLE_NETPOLL;
+	if (slave_dev->netdev_ops->ndo_netpoll_cleanup)
+		slave_dev->netdev_ops->ndo_netpoll_cleanup(slave_dev);
+	else
+		slave_dev->npinfo = NULL;
+#endif
+
 	/* close slave before restoring its mac address */
 	dev_close(slave_dev);
 
@@ -2032,6 +2145,9 @@ static int bond_release_all(struct net_d
 
 		netdev_set_master(slave_dev, NULL);
 
+#ifdef CONFIG_NET_POLL_CONTROLLER
+		slave_dev->npinfo = NULL;
+#endif
 		/* close slave before restoring its mac address */
 		dev_close(slave_dev);
 
@@ -4424,6 +4540,12 @@ static const struct net_device_ops bond_
 	.ndo_vlan_rx_register	= bond_vlan_rx_register,
 	.ndo_vlan_rx_add_vid 	= bond_vlan_rx_add_vid,
 	.ndo_vlan_rx_kill_vid	= bond_vlan_rx_kill_vid,
+#ifdef CONFIG_NET_POLL_CONTROLLER
+	.ndo_netpoll_setup	= bond_netpoll_setup,
+	.ndo_netpoll_xmit	= bond_netpoll_xmit,
+	.ndo_netpoll_cleanup	= bond_netpoll_cleanup,
+	.ndo_poll_controller	= bond_poll_controller,
+#endif
 };
 
 static void bond_setup(struct net_device *bond_dev)

On Mon, 2010-03-22 at 04:17 -0400, Amerigo Wang wrote:
> This whole patchset is for adding netpoll support to bridge and bonding
> devices. I already tested it for bridge, bonding, bridge over bonding,
> and bonding over bridge. It looks fine now.
Ages ago, Jeff Moyer took a run at this, added him to the cc: on the off
chance he still cares.
> Please comment.
> 
> 
> To make bridge and bonding support netpoll, we need to adjust
> some netpoll generic code. This patch does the following things:
> 
> 1) introduce two new priv_flags for struct net_device:
>    IFF_IN_NETPOLL which identifies we are processing a netpoll;
>    IFF_DISABLE_NETPOLL is used to disable netpoll support for a device
>    at run-time;
This one is a little worrisome. I've tried to keep the netpoll code
restricted to as tight an area as possible. Adding new flags like these
that random drivers might try to fiddle with seems like a good way for a
driver writer to get in trouble. Also flag space is filling up.
> 2) introduce three new methods for netdev_ops:
>    ->ndo_netpoll_setup() is used to setup netpoll for a device;
>    ->ndo_netpoll_xmit() is used to transmit netpoll requests;
>    ->ndo_netpoll_cleanup() is used to clean up netpoll when a device is
>      removed.
Seems like a lot of interface for something to be used by only a couple
core drivers. Hopefully Dave has an opinion here.
> 3) introduce netpoll_poll_dev() which takes a struct net_device *
parameter;
> 
> 4) export netpoll_send_skb() and netpoll_poll_dev() which will be used
later;
> 
> 5) hide a pointer to struct netpoll in struct netpoll_info, ditto.
> 
> Cc: David Miller <davem at davemloft.net>
> Cc: Neil Horman <nhorman at tuxdriver.com>
> Signed-off-by: WANG Cong <amwang at redhat.com>
> 
> ---
> Index: linux-2.6/include/linux/if.h
> ==================================================================> ---
linux-2.6.orig/include/linux/if.h
> +++ linux-2.6/include/linux/if.h
> @@ -71,6 +71,8 @@
>  					 * release skb->dst
>  					 */
>  #define IFF_DONT_BRIDGE 0x800		/* disallow bridging this ether dev */
> +#define IFF_IN_NETPOLL	0x1000		/* whether we are processing netpoll */
> +#define IFF_DISABLE_NETPOLL	0x2000	/* disable netpoll at run-time */
>  
>  #define IF_GET_IFACE	0x0001		/* for querying only */
>  #define IF_GET_PROTO	0x0002
> Index: linux-2.6/include/linux/netdevice.h
> ==================================================================> ---
linux-2.6.orig/include/linux/netdevice.h
> +++ linux-2.6/include/linux/netdevice.h
> @@ -530,6 +530,8 @@ struct netdev_queue {
>  	unsigned long		tx_dropped;
>  } ____cacheline_aligned_in_smp;
>  
> +struct netpoll;
> +struct netpoll_info;
>  
>  /*
>   * This structure defines the management hooks for network devices.
> @@ -667,6 +669,12 @@ struct net_device_ops {
>  						        unsigned short vid);
>  #ifdef CONFIG_NET_POLL_CONTROLLER
>  	void                    (*ndo_poll_controller)(struct net_device *dev);
> +	void			(*ndo_netpoll_setup)(struct net_device *dev,
> +						     struct netpoll_info *npinfo);
> +	int			(*ndo_netpoll_xmit)(struct netpoll *np,
> +						    struct sk_buff *skb,
> +						    struct net_device *dev);
> +	void			(*ndo_netpoll_cleanup)(struct net_device *dev);
>  #endif
>  	int			(*ndo_set_vf_mac)(struct net_device *dev,
>  						  int queue, u8 *mac);
> Index: linux-2.6/include/linux/netpoll.h
> ==================================================================> ---
linux-2.6.orig/include/linux/netpoll.h
> +++ linux-2.6/include/linux/netpoll.h
> @@ -36,8 +36,11 @@ struct netpoll_info {
>  	struct sk_buff_head txq;
>  
>  	struct delayed_work tx_work;
> +
> +	struct netpoll *netpoll;
>  };
>  
> +void netpoll_poll_dev(struct net_device *dev);
>  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);
> @@ -47,6 +50,7 @@ int netpoll_trap(void);
>  void netpoll_set_trap(int trap);
>  void netpoll_cleanup(struct netpoll *np);
>  int __netpoll_rx(struct sk_buff *skb);
> +void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb);
>  
> 
>  #ifdef CONFIG_NETPOLL
> Index: linux-2.6/net/core/netpoll.c
> ==================================================================> ---
linux-2.6.orig/net/core/netpoll.c
> +++ linux-2.6/net/core/netpoll.c
> @@ -178,9 +178,8 @@ static void service_arp_queue(struct net
>  	}
>  }
>  
> -void netpoll_poll(struct netpoll *np)
> +void netpoll_poll_dev(struct net_device *dev)
>  {
> -	struct net_device *dev = np->dev;
>  	const struct net_device_ops *ops;
>  
>  	if (!dev || !netif_running(dev))
> @@ -200,6 +199,13 @@ void netpoll_poll(struct netpoll *np)
>  	zap_completion_queue();
>  }
>  
> +void netpoll_poll(struct netpoll *np)
> +{
> +	if (!np->dev)
> +		return;
> +	netpoll_poll_dev(np->dev);
> +}
> +
>  static void refill_skbs(void)
>  {
>  	struct sk_buff *skb;
> @@ -281,7 +287,7 @@ static int netpoll_owner_active(struct n
>  	return 0;
>  }
>  
> -static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
> +void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
>  {
>  	int status = NETDEV_TX_BUSY;
>  	unsigned long tries;
> @@ -307,7 +313,10 @@ static void netpoll_send_skb(struct netp
>  		     tries > 0; --tries) {
>  			if (__netif_tx_trylock(txq)) {
>  				if (!netif_tx_queue_stopped(txq)) {
> -					status = ops->ndo_start_xmit(skb, dev);
> +					if (ops->ndo_netpoll_xmit)
> +						status = ops->ndo_netpoll_xmit(np, skb, dev);
> +					else
> +						status = ops->ndo_start_xmit(skb, dev);
>  					if (status == NETDEV_TX_OK)
>  						txq_trans_update(txq);
>  				}
> @@ -752,7 +761,10 @@ int netpoll_setup(struct netpoll *np)
>  		atomic_inc(&npinfo->refcnt);
>  	}
>  
> -	if (!ndev->netdev_ops->ndo_poll_controller) {
> +	npinfo->netpoll = np;
> +
> +	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;
> @@ -830,6 +842,9 @@ int netpoll_setup(struct netpoll *np)
>  	/* last thing to do is link it to the net device structure */
>  	ndev->npinfo = npinfo;
>  
> +	if (ndev->netdev_ops->ndo_netpoll_setup)
> +		ndev->netdev_ops->ndo_netpoll_setup(ndev, npinfo);
> +
>  	/* avoid racing with NAPI reading npinfo */
>  	synchronize_rcu();
>  
> @@ -904,6 +919,7 @@ void netpoll_set_trap(int trap)
>  		atomic_dec(&trapped);
>  }
>  
> +EXPORT_SYMBOL(netpoll_send_skb);
>  EXPORT_SYMBOL(netpoll_set_trap);
>  EXPORT_SYMBOL(netpoll_trap);
>  EXPORT_SYMBOL(netpoll_print_options);
> @@ -911,4 +927,5 @@ EXPORT_SYMBOL(netpoll_parse_options);
>  EXPORT_SYMBOL(netpoll_setup);
>  EXPORT_SYMBOL(netpoll_cleanup);
>  EXPORT_SYMBOL(netpoll_send_udp);
> +EXPORT_SYMBOL(netpoll_poll_dev);
>  EXPORT_SYMBOL(netpoll_poll);
> --
> To unsubscribe from this list: send the line "unsubscribe
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> Please read the FAQ at  http://www.tux.org/lkml/


-- 
http://selenic.com : development and support for Mercurial and Linux

On Mon, Mar 22, 2010 at 04:17:40AM -0400, Amerigo Wang
wrote:
> 
> Based on Andy's work, but I modify a lot.
> 
> Similar to the patch for bridge, this patch does:
> 
> 1) implement the 4 methods to support netpoll for bonding;
> 
> 2) modify netpoll during forwarding packets in bonding;
> 
> 3) disable netpoll support of bridge when a netpoll-unabled device
>    is added to bonding;
> 
> 4) enable netpoll support when all underlying devices support netpoll.
> 
> Cc: Andy Gospodarek <gospo at redhat.com>
> Cc: Neil Horman <nhorman at tuxdriver.com>
> Cc: Jay Vosburgh <fubar at us.ibm.com>
> Cc: David Miller <davem at davemloft.net>
> Signed-off-by: WANG Cong <amwang at redhat.com>
> 
How much testing was done on this?

One of the potential problems with this code is how gracefully the
system can handle tear-down of interfaces or removal of the bonding
module when netconsole is active.  Was that tested heavily?
> 
> ---
> Index: linux-2.6/drivers/net/bonding/bond_main.c
> ==================================================================> ---
linux-2.6.orig/drivers/net/bonding/bond_main.c
> +++ linux-2.6/drivers/net/bonding/bond_main.c
> @@ -59,6 +59,7 @@
>  #include <linux/uaccess.h>
>  #include <linux/errno.h>
>  #include <linux/netdevice.h>
> +#include <linux/netpoll.h>
>  #include <linux/inetdevice.h>
>  #include <linux/igmp.h>
>  #include <linux/etherdevice.h>
> @@ -430,7 +431,17 @@ int bond_dev_queue_xmit(struct bonding *
>  	}
>  
>  	skb->priority = 1;
> -	dev_queue_xmit(skb);
> +#ifdef CONFIG_NET_POLL_CONTROLLER
> +	if (bond->dev->priv_flags & IFF_IN_NETPOLL) {
> +		bond->dev->npinfo->netpoll->dev = skb->dev;
> +		if (!slave_dev->npinfo)
> +			slave_dev->npinfo = bond->dev->npinfo;
> +		slave_dev->priv_flags |= IFF_IN_NETPOLL;
> +		netpoll_send_skb(bond->dev->npinfo->netpoll, skb);
> +		slave_dev->priv_flags &= ~IFF_IN_NETPOLL;
> +	} else
> +#endif
> +		dev_queue_xmit(skb);
>  
>  	return 0;
>  }
> @@ -1324,6 +1335,87 @@ static void bond_detach_slave(struct bon
>  	bond->slave_cnt--;
>  }
>  
> +#ifdef CONFIG_NET_POLL_CONTROLLER
> +static bool slaves_support_netpoll(struct net_device *bond_dev)
> +{
> +	struct bonding *bond = netdev_priv(bond_dev);
> +	struct slave *slave;
> +	int i = 0;
> +	bool ret = true;
> +
> +	read_lock_bh(&bond->lock);
> +	bond_for_each_slave(bond, slave, i) {
> +		if ((slave->dev->priv_flags & IFF_DISABLE_NETPOLL)
> +				|| !slave->dev->netdev_ops->ndo_poll_controller)
> +			ret = false;
> +	}
> +	read_unlock_bh(&bond->lock);
> +	return i != 0 && ret;
> +}
> +
> +static void bond_poll_controller(struct net_device *bond_dev)
> +{
> +	struct bonding *bond = netdev_priv(bond_dev);
> +	struct slave *slave;
> +	int i;
> +
> +	read_lock(&bond->lock);
> +	bond_for_each_slave(bond, slave, i) {
> +		if (slave->dev->netdev_ops->ndo_poll_controller)
> +			netpoll_poll_dev(slave->dev);
> +	}
> +	read_unlock(&bond->lock);
> +}
> +
> +static void bond_netpoll_setup(struct net_device *bond_dev,
> +			      struct netpoll_info *npinfo)
> +{
> +	struct bonding *bond = netdev_priv(bond_dev);
> +	struct slave *slave;
> +	int i;
> +
> +	write_lock_bh(&bond->lock);
> +	bond_for_each_slave(bond, slave, i) {
> +		if (slave->dev)
> +			slave->dev->npinfo = npinfo;
> +	}
> +	write_unlock_bh(&bond->lock);
> +}
> +
> +static void bond_netpoll_cleanup(struct net_device *bond_dev)
> +{
> +	struct bonding *bond = netdev_priv(bond_dev);
> +	struct slave *slave;
> +	const struct net_device_ops *ops;
> +	int i;
> +
> +	write_lock_bh(&bond->lock);
> +	bond_dev->npinfo = NULL;
> +	bond_for_each_slave(bond, slave, i) {
> +		if (slave->dev) {
> +			ops = slave->dev->netdev_ops;
> +			if (ops->ndo_netpoll_cleanup)
> +				ops->ndo_netpoll_cleanup(slave->dev);
> +			else
> +				slave->dev->npinfo = NULL;
> +		}
> +	}
> +	write_unlock_bh(&bond->lock);
> +}
> +
> +static int bond_netpoll_xmit(struct netpoll *np, struct sk_buff *skb,
> +			     struct net_device *dev)
> +{
> +	int ret;
> +
> +	dev->priv_flags |= IFF_IN_NETPOLL;
> +	ret = dev->netdev_ops->ndo_start_xmit(skb, dev);
> +	np->dev = dev;
> +	dev->priv_flags &= ~IFF_IN_NETPOLL;
> +	return ret;
> +}
> +#endif
> +
>  /*---------------------------------- IOCTL
----------------------------------*/
>  
>  static int bond_sethwaddr(struct net_device *bond_dev,
> @@ -1741,6 +1833,18 @@ int bond_enslave(struct net_device *bond
>  		new_slave->state == BOND_STATE_ACTIVE ? "n active" : "
backup",
>  		new_slave->link != BOND_LINK_DOWN ? "n up" : "
down");
>  
> +#ifdef CONFIG_NET_POLL_CONTROLLER
> +	if (slaves_support_netpoll(bond_dev)) {
> +		bond_dev->priv_flags &= ~IFF_DISABLE_NETPOLL;
> +		if (bond_dev->npinfo)
> +			slave_dev->npinfo = bond_dev->npinfo;
> +	} else if (!(bond_dev->priv_flags & IFF_DISABLE_NETPOLL)) {
> +		bond_dev->priv_flags |= IFF_DISABLE_NETPOLL;
> +		pr_info("New slave device %s does not support netpoll\n",
> +			slave_dev->name);
> +		pr_info("Disabling netpoll support for %s\n",
bond_dev->name);
> +	}
> +#endif
>  	/* enslave is successful */
>  	return 0;
>  
> @@ -1924,6 +2028,15 @@ int bond_release(struct net_device *bond
>  
>  	netdev_set_master(slave_dev, NULL);
>  
> +#ifdef CONFIG_NET_POLL_CONTROLLER
> +	if (slaves_support_netpoll(bond_dev))
> +		bond_dev->priv_flags &= ~IFF_DISABLE_NETPOLL;
> +	if (slave_dev->netdev_ops->ndo_netpoll_cleanup)
> +		slave_dev->netdev_ops->ndo_netpoll_cleanup(slave_dev);
> +	else
> +		slave_dev->npinfo = NULL;
> +#endif
> +
>  	/* close slave before restoring its mac address */
>  	dev_close(slave_dev);
>  
> @@ -2032,6 +2145,9 @@ static int bond_release_all(struct net_d
>  
>  		netdev_set_master(slave_dev, NULL);
>  
> +#ifdef CONFIG_NET_POLL_CONTROLLER
> +		slave_dev->npinfo = NULL;
> +#endif
>  		/* close slave before restoring its mac address */
>  		dev_close(slave_dev);
>  
> @@ -4424,6 +4540,12 @@ static const struct net_device_ops bond_
>  	.ndo_vlan_rx_register	= bond_vlan_rx_register,
>  	.ndo_vlan_rx_add_vid 	= bond_vlan_rx_add_vid,
>  	.ndo_vlan_rx_kill_vid	= bond_vlan_rx_kill_vid,
> +#ifdef CONFIG_NET_POLL_CONTROLLER
> +	.ndo_netpoll_setup	= bond_netpoll_setup,
> +	.ndo_netpoll_xmit	= bond_netpoll_xmit,
> +	.ndo_netpoll_cleanup	= bond_netpoll_cleanup,
> +	.ndo_poll_controller	= bond_poll_controller,
> +#endif
>  };
>  
>  static void bond_setup(struct net_device *bond_dev)