[PATCH v2 0/8] some netpoll and netconsole fixes

[PATCH v2 0/8] some netpoll and netconsole fixes

[Cong Wang]

V2:
* update patch 1/8 as Eric suggested
* drop the bridge patch, add comments instead
* add patch 8/8

This patch fixes serval problems in netconsole and netpoll.

I ran this patch in my KVM guest with some netpoll test cases,
even covered with some corner cases, everything worked as expected.

BTW, my kernel config enables the following validatation options:

CONFIG_DEBUG_ATOMIC_SLEEP=y
CONFIG_PROVE_LOCKING=y
CONFIG_PROVE_RCU=y
CONFIG_LOCKDEP=y
CONFIG_RCU_CPU_STALL_TIMEOUT=60
CONFIG_LOCKUP_DETECTOR=y
CONFIG_HARDLOCKUP_DETECTOR=y

Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>

---

Cong Wang (8):
  netpoll: use GFP_ATOMIC in slave_enable_netpoll() and __netpoll_setup()
  netpoll: make __netpoll_cleanup non-block
  netconsole: do not release spin_lock when calling __netpoll_cleanup
  netpoll: take rcu_read_lock_bh() in netpoll_rx()
  netpoll: use netpoll_rx_on() in netpoll_rx()
  netpoll: take rcu_read_lock_bh() in netpoll_send_skb_on_dev()
  bridge: add some comments for NETDEV_RELEASE
  bridge: use list_for_each_entry() in netpoll functions

 drivers/net/bonding/bond_main.c |   10 ++---
 drivers/net/netconsole.c        |    5 --
 drivers/net/team/team.c         |   16 ++++---
 include/linux/netdevice.h       |    3 +-
 include/linux/netpoll.h         |   27 +++++++------
 net/8021q/vlan_dev.c            |   13 ++----
 net/bridge/br_device.c          |   27 +++++-------
 net/bridge/br_if.c              |    6 ++-
 net/bridge/br_private.h         |    4 +-
 net/core/netpoll.c              |   84 +++++++++++++++++++++++++--------------
 10 files changed, 107 insertions(+), 88 deletions(-)

-- 
1.7.7.6

[PATCH 1/8] netpoll: use GFP_ATOMIC in slave_enable_netpoll() and __netpoll_setup()

[Cong Wang]

slave_enable_netpoll() and __netpoll_setup() may be called
with read_lock() held, so should use GFP_ATOMIC to allocate
memory. Eric suggested to pass gfp flags to __netpoll_setup().

Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Cong Wang <amwang@redhat.com>
---
 drivers/net/bonding/bond_main.c |    6 +++---
 drivers/net/team/team.c         |   16 +++++++++-------
 include/linux/netdevice.h       |    3 ++-
 include/linux/netpoll.h         |    2 +-
 net/8021q/vlan_dev.c            |    7 ++++---
 net/bridge/br_device.c          |   12 ++++++------
 net/bridge/br_if.c              |    2 +-
 net/bridge/br_private.h         |    4 ++--
 net/core/netpoll.c              |    8 ++++----
 9 files changed, 32 insertions(+), 28 deletions(-)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 6fae5f3..8697136 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1235,12 +1235,12 @@ static inline int slave_enable_netpoll(struct slave *slave)
 	struct netpoll *np;
 	int err = 0;
 
-	np = kzalloc(sizeof(*np), GFP_KERNEL);
+	np = kzalloc(sizeof(*np), GFP_ATOMIC);
 	err = -ENOMEM;
 	if (!np)
 		goto out;
 
-	err = __netpoll_setup(np, slave->dev);
+	err = __netpoll_setup(np, slave->dev, GFP_ATOMIC);
 	if (err) {
 		kfree(np);
 		goto out;
@@ -1292,7 +1292,7 @@ static void bond_netpoll_cleanup(struct net_device *bond_dev)
 	read_unlock(&bond->lock);
 }
 
-static int bond_netpoll_setup(struct net_device *dev, struct netpoll_info *ni)
+static int bond_netpoll_setup(struct net_device *dev, struct netpoll_info *ni, gfp_t gfp)
 {
 	struct bonding *bond = netdev_priv(dev);
 	struct slave *slave;
diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c
index ba10c46..bbb8524 100644
--- a/drivers/net/team/team.c
+++ b/drivers/net/team/team.c
@@ -913,16 +913,17 @@ static void team_port_leave(struct team *team, struct team_port *port)
 }
 
 #ifdef CONFIG_NET_POLL_CONTROLLER
-static int team_port_enable_netpoll(struct team *team, struct team_port *port)
+static int team_port_enable_netpoll(struct team *team, struct team_port *port,
+				    gfp_t gfp)
 {
 	struct netpoll *np;
 	int err;
 
-	np = kzalloc(sizeof(*np), GFP_KERNEL);
+	np = kzalloc(sizeof(*np), gfp);
 	if (!np)
 		return -ENOMEM;
 
-	err = __netpoll_setup(np, port->dev);
+	err = __netpoll_setup(np, port->dev, gfp);
 	if (err) {
 		kfree(np);
 		return err;
@@ -951,7 +952,8 @@ static struct netpoll_info *team_netpoll_info(struct team *team)
 }
 
 #else
-static int team_port_enable_netpoll(struct team *team, struct team_port *port)
+static int team_port_enable_netpoll(struct team *team, struct team_port *port,
+				    gfp_t gfp)
 {
 	return 0;
 }
@@ -1032,7 +1034,7 @@ static int team_port_add(struct team *team, struct net_device *port_dev)
 	}
 
 	if (team_netpoll_info(team)) {
-		err = team_port_enable_netpoll(team, port);
+		err = team_port_enable_netpoll(team, port, GFP_KERNEL);
 		if (err) {
 			netdev_err(dev, "Failed to enable netpoll on device %s\n",
 				   portname);
@@ -1627,7 +1629,7 @@ static void team_netpoll_cleanup(struct net_device *dev)
 }
 
 static int team_netpoll_setup(struct net_device *dev,
-			      struct netpoll_info *npifo)
+			      struct netpoll_info *npifo, gfp_t gfp)
 {
 	struct team *team = netdev_priv(dev);
 	struct team_port *port;
@@ -1635,7 +1637,7 @@ static int team_netpoll_setup(struct net_device *dev,
 
 	mutex_lock(&team->lock);
 	list_for_each_entry(port, &team->port_list, list) {
-		err = team_port_enable_netpoll(team, port);
+		err = team_port_enable_netpoll(team, port, gfp);
 		if (err) {
 			__team_netpoll_cleanup(team);
 			break;
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index a9db4f3..3560d68 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -953,7 +953,8 @@ struct net_device_ops {
 #ifdef CONFIG_NET_POLL_CONTROLLER
 	void                    (*ndo_poll_controller)(struct net_device *dev);
 	int			(*ndo_netpoll_setup)(struct net_device *dev,
-						     struct netpoll_info *info);
+						     struct netpoll_info *info,
+						     gfp_t gfp);
 	void			(*ndo_netpoll_cleanup)(struct net_device *dev);
 #endif
 	int			(*ndo_set_vf_mac)(struct net_device *dev,
diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index 28f5389..bf2d51e 100644
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -43,7 +43,7 @@ struct netpoll_info {
 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, struct net_device *ndev);
+int __netpoll_setup(struct netpoll *np, struct net_device *ndev, gfp_t gfp);
 int netpoll_setup(struct netpoll *np);
 int netpoll_trap(void);
 void netpoll_set_trap(int trap);
diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index 73a2a83..ee4ae09 100644
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -669,19 +669,20 @@ static void vlan_dev_poll_controller(struct net_device *dev)
 	return;
 }
 
-static int vlan_dev_netpoll_setup(struct net_device *dev, struct netpoll_info *npinfo)
+static int vlan_dev_netpoll_setup(struct net_device *dev, struct netpoll_info *npinfo,
+				  gfp_t gfp)
 {
 	struct vlan_dev_priv *info = vlan_dev_priv(dev);
 	struct net_device *real_dev = info->real_dev;
 	struct netpoll *netpoll;
 	int err = 0;
 
-	netpoll = kzalloc(sizeof(*netpoll), GFP_KERNEL);
+	netpoll = kzalloc(sizeof(*netpoll), gfp);
 	err = -ENOMEM;
 	if (!netpoll)
 		goto out;
 
-	err = __netpoll_setup(netpoll, real_dev);
+	err = __netpoll_setup(netpoll, real_dev, gfp);
 	if (err) {
 		kfree(netpoll);
 		goto out;
diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index 3334845..ed0e0f9 100644
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -213,7 +213,8 @@ static void br_netpoll_cleanup(struct net_device *dev)
 	}
 }
 
-static int br_netpoll_setup(struct net_device *dev, struct netpoll_info *ni)
+static int br_netpoll_setup(struct net_device *dev, struct netpoll_info *ni,
+			    gfp_t gfp)
 {
 	struct net_bridge *br = netdev_priv(dev);
 	struct net_bridge_port *p, *n;
@@ -222,8 +223,7 @@ static int br_netpoll_setup(struct net_device *dev, struct netpoll_info *ni)
 	list_for_each_entry_safe(p, n, &br->port_list, list) {
 		if (!p->dev)
 			continue;
-
-		err = br_netpoll_enable(p);
+		err = br_netpoll_enable(p, gfp);
 		if (err)
 			goto fail;
 	}
@@ -236,17 +236,17 @@ fail:
 	goto out;
 }
 
-int br_netpoll_enable(struct net_bridge_port *p)
+int br_netpoll_enable(struct net_bridge_port *p, gfp_t gfp)
 {
 	struct netpoll *np;
 	int err = 0;
 
-	np = kzalloc(sizeof(*p->np), GFP_KERNEL);
+	np = kzalloc(sizeof(*p->np), gfp);
 	err = -ENOMEM;
 	if (!np)
 		goto out;
 
-	err = __netpoll_setup(np, p->dev);
+	err = __netpoll_setup(np, p->dev, gfp);
 	if (err) {
 		kfree(np);
 		goto out;
diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index e1144e1..171fd6b 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -361,7 +361,7 @@ int br_add_if(struct net_bridge *br, struct net_device *dev)
 	if (err)
 		goto err2;
 
-	if (br_netpoll_info(br) && ((err = br_netpoll_enable(p))))
+	if (br_netpoll_info(br) && ((err = br_netpoll_enable(p, GFP_KERNEL))))
 		goto err3;
 
 	err = netdev_set_master(dev, br->dev);
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index a768b24..f507d2a 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -316,7 +316,7 @@ static inline void br_netpoll_send_skb(const struct net_bridge_port *p,
 		netpoll_send_skb(np, skb);
 }
 
-extern int br_netpoll_enable(struct net_bridge_port *p);
+extern int br_netpoll_enable(struct net_bridge_port *p, gfp_t gfp);
 extern void br_netpoll_disable(struct net_bridge_port *p);
 #else
 static inline struct netpoll_info *br_netpoll_info(struct net_bridge *br)
@@ -329,7 +329,7 @@ static inline void br_netpoll_send_skb(const struct net_bridge_port *p,
 {
 }
 
-static inline int br_netpoll_enable(struct net_bridge_port *p)
+static inline int br_netpoll_enable(struct net_bridge_port *p, gfp_t gfp)
 {
 	return 0;
 }
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index b4c90e4..37cc854 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -715,7 +715,7 @@ int netpoll_parse_options(struct netpoll *np, char *opt)
 }
 EXPORT_SYMBOL(netpoll_parse_options);
 
-int __netpoll_setup(struct netpoll *np, struct net_device *ndev)
+int __netpoll_setup(struct netpoll *np, struct net_device *ndev, gfp_t gfp)
 {
 	struct netpoll_info *npinfo;
 	const struct net_device_ops *ops;
@@ -734,7 +734,7 @@ int __netpoll_setup(struct netpoll *np, struct net_device *ndev)
 	}
 
 	if (!ndev->npinfo) {
-		npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
+		npinfo = kmalloc(sizeof(*npinfo), gfp);
 		if (!npinfo) {
 			err = -ENOMEM;
 			goto out;
@@ -752,7 +752,7 @@ int __netpoll_setup(struct netpoll *np, struct net_device *ndev)
 
 		ops = np->dev->netdev_ops;
 		if (ops->ndo_netpoll_setup) {
-			err = ops->ndo_netpoll_setup(ndev, npinfo);
+			err = ops->ndo_netpoll_setup(ndev, npinfo, gfp);
 			if (err)
 				goto free_npinfo;
 		}
@@ -857,7 +857,7 @@ int netpoll_setup(struct netpoll *np)
 	refill_skbs();
 
 	rtnl_lock();
-	err = __netpoll_setup(np, ndev);
+	err = __netpoll_setup(np, ndev, GFP_KERNEL);
 	rtnl_unlock();
 
 	if (err)
-- 
1.7.7.6

Re: [PATCH 1/8] netpoll: use GFP_ATOMIC in slave_enable_netpoll() and __netpoll_setup()

[Eric Dumazet]

On Mon, 2012-08-06 at 22:23 +0800, Cong Wang wrote:
> slave_enable_netpoll() and __netpoll_setup() may be called
> with read_lock() held, so should use GFP_ATOMIC to allocate
> memory. Eric suggested to pass gfp flags to __netpoll_setup().
> 
> Cc: Eric Dumazet <eric.dumazet@gmail.com>
> Cc: "David S. Miller" <davem@davemloft.net>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Signed-off-by: Cong Wang <amwang@redhat.com>
> ---

You based this on net-next, but didnt add the net-next suffix in your
[PATCH ...] description.

Signed-off-by: Eric Dumazet <edumazet@google.com>

Re: [PATCH 1/8] netpoll: use GFP_ATOMIC in slave_enable_netpoll() and __netpoll_setup()

[Cong Wang]

On Mon, 2012-08-06 at 17:20 +0200, Eric Dumazet wrote:
> On Mon, 2012-08-06 at 22:23 +0800, Cong Wang wrote:
> > slave_enable_netpoll() and __netpoll_setup() may be called
> > with read_lock() held, so should use GFP_ATOMIC to allocate
> > memory. Eric suggested to pass gfp flags to __netpoll_setup().
> > 
> > Cc: Eric Dumazet <eric.dumazet@gmail.com>
> > Cc: "David S. Miller" <davem@davemloft.net>
> > Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> > Signed-off-by: Cong Wang <amwang@redhat.com>
> > ---
> 
> You based this on net-next, but didnt add the net-next suffix in your
> [PATCH ...] description.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> 

Oh, it is default, isn't it? :-D Anyway, I will add it the next time
when I send network patches.

Thanks!

[PATCH 2/8] netpoll: make __netpoll_cleanup non-block

[Cong Wang]

Like the previous patch, slave_disable_netpoll() and __netpoll_cleanup()
may be called with read_lock() held too, so we should make them
non-block, by moving the cleanup and kfree() to call_rcu_bh() callbacks.

Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
---
 drivers/net/bonding/bond_main.c |    4 +--
 include/linux/netpoll.h         |    3 ++
 net/8021q/vlan_dev.c            |    6 +----
 net/bridge/br_device.c          |    6 +----
 net/core/netpoll.c              |   42 +++++++++++++++++++++++++++++---------
 5 files changed, 38 insertions(+), 23 deletions(-)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 8697136..e428916 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1257,9 +1257,7 @@ static inline void slave_disable_netpoll(struct slave *slave)
 		return;
 
 	slave->np = NULL;
-	synchronize_rcu_bh();
-	__netpoll_cleanup(np);
-	kfree(np);
+	__netpoll_free_rcu(np);
 }
 static inline bool slave_dev_support_netpoll(struct net_device *slave_dev)
 {
diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index bf2d51e..907812e 100644
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -23,6 +23,7 @@ struct netpoll {
 	u8 remote_mac[ETH_ALEN];
 
 	struct list_head rx; /* rx_np list element */
+	struct rcu_head rcu;
 };
 
 struct netpoll_info {
@@ -38,6 +39,7 @@ struct netpoll_info {
 	struct delayed_work tx_work;
 
 	struct netpoll *netpoll;
+	struct rcu_head rcu;
 };
 
 void netpoll_send_udp(struct netpoll *np, const char *msg, int len);
@@ -48,6 +50,7 @@ int netpoll_setup(struct netpoll *np);
 int netpoll_trap(void);
 void netpoll_set_trap(int trap);
 void __netpoll_cleanup(struct netpoll *np);
+void __netpoll_free_rcu(struct netpoll *np);
 void netpoll_cleanup(struct netpoll *np);
 int __netpoll_rx(struct sk_buff *skb);
 void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index ee4ae09..b65623f 100644
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -704,11 +704,7 @@ static void vlan_dev_netpoll_cleanup(struct net_device *dev)
 
 	info->netpoll = NULL;
 
-        /* Wait for transmitting packets to finish before freeing. */
-        synchronize_rcu_bh();
-
-        __netpoll_cleanup(netpoll);
-        kfree(netpoll);
+	__netpoll_free_rcu(netpoll);
 }
 #endif /* CONFIG_NET_POLL_CONTROLLER */
 
diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index ed0e0f9..f41ba40 100644
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -267,11 +267,7 @@ void br_netpoll_disable(struct net_bridge_port *p)
 
 	p->np = NULL;
 
-	/* Wait for transmitting packets to finish before freeing. */
-	synchronize_rcu_bh();
-
-	__netpoll_cleanup(np);
-	kfree(np);
+	__netpoll_free_rcu(np);
 }
 
 #endif
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 37cc854..dc17f1d 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -878,6 +878,24 @@ static int __init netpoll_init(void)
 }
 core_initcall(netpoll_init);
 
+static void rcu_cleanup_netpoll_info(struct rcu_head *rcu_head)
+{
+	struct netpoll_info *npinfo =
+			container_of(rcu_head, struct netpoll_info, rcu);
+
+	skb_queue_purge(&npinfo->arp_tx);
+	skb_queue_purge(&npinfo->txq);
+
+	/* we can't call cancel_delayed_work_sync here, as we are in softirq */
+	cancel_delayed_work(&npinfo->tx_work);
+
+	/* clean after last, unfinished work */
+	__skb_queue_purge(&npinfo->txq);
+	/* now cancel it again */
+	cancel_delayed_work(&npinfo->tx_work);
+	kfree(npinfo);
+}
+
 void __netpoll_cleanup(struct netpoll *np)
 {
 	struct netpoll_info *npinfo;
@@ -903,20 +921,24 @@ void __netpoll_cleanup(struct netpoll *np)
 			ops->ndo_netpoll_cleanup(np->dev);
 
 		RCU_INIT_POINTER(np->dev->npinfo, NULL);
+		call_rcu_bh(&npinfo->rcu, rcu_cleanup_netpoll_info);
+	}
+}
+EXPORT_SYMBOL_GPL(__netpoll_cleanup);
 
-		/* avoid racing with NAPI reading npinfo */
-		synchronize_rcu_bh();
+static void rcu_cleanup_netpoll(struct rcu_head *rcu_head)
+{
+	struct netpoll *np = container_of(rcu_head, struct netpoll, rcu);
 
-		skb_queue_purge(&npinfo->arp_tx);
-		skb_queue_purge(&npinfo->txq);
-		cancel_delayed_work_sync(&npinfo->tx_work);
+	__netpoll_cleanup(np);
+	kfree(np);
+}
 
-		/* clean after last, unfinished work */
-		__skb_queue_purge(&npinfo->txq);
-		kfree(npinfo);
-	}
+void __netpoll_free_rcu(struct netpoll *np)
+{
+	call_rcu_bh(&np->rcu, rcu_cleanup_netpoll);
 }
-EXPORT_SYMBOL_GPL(__netpoll_cleanup);
+EXPORT_SYMBOL_GPL(__netpoll_free_rcu);
 
 void netpoll_cleanup(struct netpoll *np)
 {
-- 
1.7.7.6

[PATCH 3/8] netconsole: do not release spin_lock when calling __netpoll_cleanup

[Cong Wang]

With the previous patch applied, __netpoll_cleanup() is non-block now,
so we don't need to release the spin_lock before calling it.

Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
---
 drivers/net/netconsole.c |    5 -----
 1 files changed, 0 insertions(+), 5 deletions(-)

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index f9347ea..f0ad56c 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -640,12 +640,7 @@ static int netconsole_netdev_event(struct notifier_block *this,
 				 * rtnl_lock already held
 				 */
 				if (nt->np.dev) {
-					spin_unlock_irqrestore(
-							      &target_list_lock,
-							      flags);
 					__netpoll_cleanup(&nt->np);
-					spin_lock_irqsave(&target_list_lock,
-							  flags);
 					dev_put(nt->np.dev);
 					nt->np.dev = NULL;
 					netconsole_target_put(nt);
-- 
1.7.7.6

[PATCH 4/8] netpoll: take rcu_read_lock_bh() in netpoll_rx()

[Cong Wang]

In __netpoll_rx(), it dereferences ->npinfo without rcu_dereference_bh(),
this patch fixes it by using the 'npinfo' passed from netpoll_rx()
where it is already dereferenced with rcu_dereference_bh().

Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
---
 include/linux/netpoll.h |    4 ++--
 net/core/netpoll.c      |    3 +--
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index 907812e..5d881c3 100644
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -52,7 +52,7 @@ void netpoll_set_trap(int trap);
 void __netpoll_cleanup(struct netpoll *np);
 void __netpoll_free_rcu(struct netpoll *np);
 void netpoll_cleanup(struct netpoll *np);
-int __netpoll_rx(struct sk_buff *skb);
+int __netpoll_rx(struct sk_buff *skb, struct netpoll_info *npinfo);
 void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
 			     struct net_device *dev);
 static inline void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
@@ -77,7 +77,7 @@ static inline bool netpoll_rx(struct sk_buff *skb)
 
 	spin_lock(&npinfo->rx_lock);
 	/* check rx_flags again with the lock held */
-	if (npinfo->rx_flags && __netpoll_rx(skb))
+	if (npinfo->rx_flags && __netpoll_rx(skb, npinfo))
 		ret = true;
 	spin_unlock(&npinfo->rx_lock);
 
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index dc17f1d..d055bb0 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -543,13 +543,12 @@ static void arp_reply(struct sk_buff *skb)
 	spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 }
 
-int __netpoll_rx(struct sk_buff *skb)
+int __netpoll_rx(struct sk_buff *skb, struct netpoll_info *npinfo)
 {
 	int proto, len, ulen;
 	int hits = 0;
 	const struct iphdr *iph;
 	struct udphdr *uh;
-	struct netpoll_info *npinfo = skb->dev->npinfo;
 	struct netpoll *np, *tmp;
 
 	if (list_empty(&npinfo->rx_np))
-- 
1.7.7.6

[PATCH 5/8] netpoll: use netpoll_rx_on() in netpoll_rx()

[Cong Wang]

The logic of the code is same, just call netpoll_rx_on().

Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
---
 include/linux/netpoll.h |   18 +++++++++---------
 1 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index 5d881c3..2d178ba 100644
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -63,6 +63,13 @@ static inline void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
 
 
 #ifdef CONFIG_NETPOLL
+static inline int netpoll_rx_on(struct sk_buff *skb)
+{
+	struct netpoll_info *npinfo = rcu_dereference_bh(skb->dev->npinfo);
+
+	return npinfo && (!list_empty(&npinfo->rx_np) || npinfo->rx_flags);
+}
+
 static inline bool netpoll_rx(struct sk_buff *skb)
 {
 	struct netpoll_info *npinfo;
@@ -70,11 +77,11 @@ static inline bool netpoll_rx(struct sk_buff *skb)
 	bool ret = false;
 
 	local_irq_save(flags);
-	npinfo = rcu_dereference_bh(skb->dev->npinfo);
 
-	if (!npinfo || (list_empty(&npinfo->rx_np) && !npinfo->rx_flags))
+	if (!netpoll_rx_on(skb))
 		goto out;
 
+	npinfo = rcu_dereference_bh(skb->dev->npinfo);
 	spin_lock(&npinfo->rx_lock);
 	/* check rx_flags again with the lock held */
 	if (npinfo->rx_flags && __netpoll_rx(skb, npinfo))
@@ -86,13 +93,6 @@ out:
 	return ret;
 }
 
-static inline int netpoll_rx_on(struct sk_buff *skb)
-{
-	struct netpoll_info *npinfo = rcu_dereference_bh(skb->dev->npinfo);
-
-	return npinfo && (!list_empty(&npinfo->rx_np) || npinfo->rx_flags);
-}
-
 static inline int netpoll_receive_skb(struct sk_buff *skb)
 {
 	if (!list_empty(&skb->dev->napi_list))
-- 
1.7.7.6

[PATCH 6/8] netpoll: take rcu_read_lock_bh() in netpoll_send_skb_on_dev()

[Cong Wang]

This patch fixes several problems in the call path of
netpoll_send_skb_on_dev():

1. We already disable IRQ's before calling netpoll_send_skb_on_dev(),
   so we don't need to disable IRQ's again.
2. All the callees of netpoll_send_skb_on_dev() should use
   rcu_dereference_bh() to dereference ->npinfo.
3. Rename arp_reply() to netpoll_arp_reply(), the former is too generic.

Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
---
 net/core/netpoll.c |   31 +++++++++++++++++--------------
 1 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index d055bb0..174346a 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -54,7 +54,7 @@ static atomic_t trapped;
 	 MAX_UDP_CHUNK)
 
 static void zap_completion_queue(void);
-static void arp_reply(struct sk_buff *skb);
+static void netpoll_arp_reply(struct sk_buff *skb, struct netpoll_info *npinfo);
 
 static unsigned int carrier_timeout = 4;
 module_param(carrier_timeout, uint, 0644);
@@ -170,7 +170,8 @@ static void poll_napi(struct net_device *dev)
 	list_for_each_entry(napi, &dev->napi_list, dev_list) {
 		if (napi->poll_owner != smp_processor_id() &&
 		    spin_trylock(&napi->poll_lock)) {
-			budget = poll_one_napi(dev->npinfo, napi, budget);
+			budget = poll_one_napi(rcu_dereference_bh(dev->npinfo),
+					       napi, budget);
 			spin_unlock(&napi->poll_lock);
 
 			if (!budget)
@@ -185,13 +186,14 @@ static void service_arp_queue(struct netpoll_info *npi)
 		struct sk_buff *skb;
 
 		while ((skb = skb_dequeue(&npi->arp_tx)))
-			arp_reply(skb);
+			netpoll_arp_reply(skb, npi);
 	}
 }
 
 static void netpoll_poll_dev(struct net_device *dev)
 {
 	const struct net_device_ops *ops;
+	struct netpoll_info *ni = rcu_dereference_bh(dev->npinfo);
 
 	if (!dev || !netif_running(dev))
 		return;
@@ -206,17 +208,18 @@ static void netpoll_poll_dev(struct net_device *dev)
 	poll_napi(dev);
 
 	if (dev->flags & IFF_SLAVE) {
-		if (dev->npinfo) {
+		if (ni) {
 			struct net_device *bond_dev = dev->master;
 			struct sk_buff *skb;
-			while ((skb = skb_dequeue(&dev->npinfo->arp_tx))) {
+			struct netpoll_info *bond_ni = rcu_dereference_bh(bond_dev->npinfo);
+			while ((skb = skb_dequeue(&ni->arp_tx))) {
 				skb->dev = bond_dev;
-				skb_queue_tail(&bond_dev->npinfo->arp_tx, skb);
+				skb_queue_tail(&bond_ni->arp_tx, skb);
 			}
 		}
 	}
 
-	service_arp_queue(dev->npinfo);
+	service_arp_queue(ni);
 
 	zap_completion_queue();
 }
@@ -302,6 +305,7 @@ static int netpoll_owner_active(struct net_device *dev)
 	return 0;
 }
 
+/* call with IRQ disabled */
 void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
 			     struct net_device *dev)
 {
@@ -309,8 +313,11 @@ void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
 	unsigned long tries;
 	const struct net_device_ops *ops = dev->netdev_ops;
 	/* It is up to the caller to keep npinfo alive. */
-	struct netpoll_info *npinfo = np->dev->npinfo;
+	struct netpoll_info *npinfo;
+
+	WARN_ON_ONCE(!irqs_disabled());
 
+	npinfo = rcu_dereference_bh(np->dev->npinfo);
 	if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
 		__kfree_skb(skb);
 		return;
@@ -319,11 +326,9 @@ void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
 	/* don't get messages out of order, and no recursion */
 	if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) {
 		struct netdev_queue *txq;
-		unsigned long flags;
 
 		txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
 
-		local_irq_save(flags);
 		/* try until next clock tick */
 		for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
 		     tries > 0; --tries) {
@@ -347,10 +352,9 @@ void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
 		}
 
 		WARN_ONCE(!irqs_disabled(),
-			"netpoll_send_skb(): %s enabled interrupts in poll (%pF)\n",
+			"netpoll_send_skb_on_dev(): %s enabled interrupts in poll (%pF)\n",
 			dev->name, ops->ndo_start_xmit);
 
-		local_irq_restore(flags);
 	}
 
 	if (status != NETDEV_TX_OK) {
@@ -423,9 +427,8 @@ void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 }
 EXPORT_SYMBOL(netpoll_send_udp);
 
-static void arp_reply(struct sk_buff *skb)
+static void netpoll_arp_reply(struct sk_buff *skb, struct netpoll_info *npinfo)
 {
-	struct netpoll_info *npinfo = skb->dev->npinfo;
 	struct arphdr *arp;
 	unsigned char *arp_ptr;
 	int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
-- 
1.7.7.6

[PATCH 7/8] bridge: add some comments for NETDEV_RELEASE

[Cong Wang]

Add comments on why we don't notify NETDEV_RELEASE.

Cc: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Cong Wang <amwang@redhat.com>
---
 net/bridge/br_if.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index 171fd6b..910f4aa 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -427,6 +427,10 @@ int br_del_if(struct net_bridge *br, struct net_device *dev)
 	if (!p || p->br != br)
 		return -EINVAL;
 
+	/*
+	 * We don't notify NETDEV_RELEASE event, as this will
+	 * stop netconsole on the bridge.
+	 */
 	del_nbp(p);
 
 	spin_lock_bh(&br->lock);
-- 
1.7.7.6

Re: [PATCH 7/8] bridge: add some comments for NETDEV_RELEASE

[David Miller]

From: Cong Wang <amwang@redhat.com>
Date: Mon,  6 Aug 2012 22:23:31 +0800

> +	/*
> +	 * We don't notify NETDEV_RELEASE event, as this will
> +	 * stop netconsole on the bridge.
> +	 */

Please format comments in the networking:

	/* Like
	 * this.
	 */

Thanks.

Re: [PATCH 7/8] bridge: add some comments for NETDEV_RELEASE

[Joe Perches]

On Mon, 2012-08-06 at 13:50 -0700, David Miller wrote:
> From: Cong Wang <amwang@redhat.com>
> Date: Mon,  6 Aug 2012 22:23:31 +0800
> 
> > +	/*
> > +	 * We don't notify NETDEV_RELEASE event, as this will
> > +	 * stop netconsole on the bridge.
> > +	 */
> 
> Please format comments in the networking:
> 
> 	/* Like
> 	 * this.
> 	 */

Maybe add a networking specific block comment style
to checkpatch. This doesn't trigger on files outside
of drivers/net and net.

---

 scripts/checkpatch.pl |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 913d6bd..560f012 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -1873,6 +1873,13 @@ sub process {
 			    "No space is necessary after a cast\n" . $hereprev);
 		}
 
+		if ($realfile =~ m@^(drivers/net/|net/)@ &&
+		    $rawline =~ /^\+[ \t]*\/\*[ \t]*$/ &&
+		    $prevrawline =~ /^\+[ \t]*$/) {
+			WARN("NETWORKING_BLOCK_COMMENT_STYLE",
+			     "networking block comments don't use an empty /* line, use /* Comment...\n" . $hereprev);
+		}
+
 # check for spaces at the beginning of a line.
 # Exceptions:
 #  1) within comments

Re: [PATCH 7/8] bridge: add some comments for NETDEV_RELEASE

[Jan Engelhardt]

On Tuesday 2012-08-07 01:39, Joe Perches wrote:
>On Mon, 2012-08-06 at 13:50 -0700, David Miller wrote:
>> > +	/*
>> > +	 * We don't notify NETDEV_RELEASE event, as this will
>> > +	 * stop netconsole on the bridge.
>> > +	 */
>> 
>> Please format comments in the networking:
>> 
>> 	/* Like
>> 	 * this.
>> 	 */
>
>Maybe add a networking specific block comment style
>to checkpatch. This doesn't trigger on files outside
>of drivers/net and net.

Is there any particular reason why net/ wants to be special?
Before we know it, coding style is like laws across US states..

Re: [PATCH 7/8] bridge: add some comments for NETDEV_RELEASE

[Joe Perches]

On Fri, 2012-08-10 at 12:59 +0200, Jan Engelhardt wrote:
> On Tuesday 2012-08-07 01:39, Joe Perches wrote:
> >On Mon, 2012-08-06 at 13:50 -0700, David Miller wrote:
> >> > +	/*
> >> > +	 * We don't notify NETDEV_RELEASE event, as this will
> >> > +	 * stop netconsole on the bridge.
> >> > +	 */
> >> 
> >> Please format comments in the networking:
> >> 
> >> 	/* Like
> >> 	 * this.
> >> 	 */
> >
> >Maybe add a networking specific block comment style
> >to checkpatch. This doesn't trigger on files outside
> >of drivers/net and net.
> 
> Is there any particular reason why net/ wants to be special?

A determined maintainer with a strong desire
for consistency using an idiomatic style.

A thread about it:
https://lkml.org/lkml/2012/4/16/443

Re: [PATCH 7/8] bridge: add some comments for NETDEV_RELEASE

[Cong Wang]

On Mon, 2012-08-06 at 13:50 -0700, David Miller wrote:
> From: Cong Wang <amwang@redhat.com>
> Date: Mon,  6 Aug 2012 22:23:31 +0800
> 
> > +	/*
> > +	 * We don't notify NETDEV_RELEASE event, as this will
> > +	 * stop netconsole on the bridge.
> > +	 */
> 
> Please format comments in the networking:
> 
> 	/* Like
> 	 * this.
> 	 */
> 
> Thanks.

Ok, I will update and resend this single patch. :)

[Resend PATCH 7/8] bridge: add some comments for NETDEV_RELEASE

[Cong Wang]

Add comments on why we don't notify NETDEV_RELEASE.

Cc: David Miller <davem@davemloft.net>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Cong Wang <amwang@redhat.com>
---

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index 171fd6b..bf47d4f 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -427,6 +427,9 @@ int br_del_if(struct net_bridge *br, struct net_device *dev)
 	if (!p || p->br != br)
 		return -EINVAL;
 
+	/* We don't notify NETDEV_RELEASE event, as this will
+	 * stop netconsole on the bridge.
+	 */
 	del_nbp(p);
 
 	spin_lock_bh(&br->lock);

Re: [Resend PATCH 7/8] bridge: add some comments for NETDEV_RELEASE

[David Miller]

You must repost the entire series when you respinning patches in
response to feedback, thank you.

Re: [Resend PATCH 7/8] bridge: add some comments for NETDEV_RELEASE

[Cong Wang]

On Tue, 2012-08-07 at 00:10 -0700, David Miller wrote:
> You must repost the entire series when you respinning patches in
> response to feedback, thank you.

Okay. Will do!

[PATCH 8/8] bridge: use list_for_each_entry() in netpoll functions

[Cong Wang]

We don't delete 'p' from the list in the loop,
so we can just use list_for_each_entry().

Cc: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Cong Wang <amwang@redhat.com>
---
 net/bridge/br_device.c |    9 ++++-----
 1 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index f41ba40..32211fa 100644
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -206,21 +206,20 @@ static void br_poll_controller(struct net_device *br_dev)
 static void br_netpoll_cleanup(struct net_device *dev)
 {
 	struct net_bridge *br = netdev_priv(dev);
-	struct net_bridge_port *p, *n;
+	struct net_bridge_port *p;
 
-	list_for_each_entry_safe(p, n, &br->port_list, list) {
+	list_for_each_entry(p, &br->port_list, list)
 		br_netpoll_disable(p);
-	}
 }
 
 static int br_netpoll_setup(struct net_device *dev, struct netpoll_info *ni,
 			    gfp_t gfp)
 {
 	struct net_bridge *br = netdev_priv(dev);
-	struct net_bridge_port *p, *n;
+	struct net_bridge_port *p;
 	int err = 0;
 
-	list_for_each_entry_safe(p, n, &br->port_list, list) {
+	list_for_each_entry(p, &br->port_list, list) {
 		if (!p->dev)
 			continue;
 		err = br_netpoll_enable(p, gfp);
-- 
1.7.7.6

Re: [PATCH 8/8] bridge: use list_for_each_entry() in netpoll functions

[Stephen Hemminger]

On Mon,  6 Aug 2012 22:23:32 +0800
Cong Wang <amwang@redhat.com> wrote:

> We don't delete 'p' from the list in the loop,
> so we can just use list_for_each_entry().
> 
> Cc: Stephen Hemminger <shemminger@vyatta.com>
> Signed-off-by: Cong Wang <amwang@redhat.com>

Good idea.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>

Re: [PATCH v2 0/8] some netpoll and netconsole fixes

[Cong Wang]

On Mon, 2012-08-06 at 22:23 +0800, Cong Wang wrote:
> V2:
> * update patch 1/8 as Eric suggested
> * drop the bridge patch, add comments instead
> * add patch 8/8
> 

Hi, David,

Please do _not_ apply this patchset, I plan to add 2 more patches,
because I found another issue of netpoll.

I will send V3 soon.

Thanks!