netdev - [PATCH net-next 3/3] bonding: Fix the RTNL assertion failed for 802.3ad state machine

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Date:	Mon, 17 Feb 2014 16:35:51 +0800
From:	Ding Tianhong <dingtianhong@...wei.com>
To:	<fubar@...ibm.com>, <vfalico@...hat.com>, <andy@...yhouse.net>
CC:	<cwang@...pensource.com>, <jiri@...nulli.us>,
	<thomas@...nzmann.de>, <eric.dumazet@...il.com>,
	<sfeldma@...ulusnetworks.com>, <davem@...emloft.net>,
	<netdev@...r.kernel.org>
Subject: [PATCH net-next 3/3] bonding: Fix the RTNL assertion failed for 802.3ad state machine

The 802.3ad state machine don't run in RTNL, but when the slave's
state changed, the rtmsg_ifinfo will be called, it will cause
warning message because the RTML is not locked, acquiring RTNL
for the __enable_port and __disable_port cases is difficult, as
those calls generally already hold the state machine lock, and
can't unconditionally call rtnl_lock because either they already
hold RTNL (for calls via bond_3ad_unbind_slave) or due to the
potential for deadlock with bond_3ad_adapter_speed_changed,
bond_3ad_adapter_duplex_changed, bond_3ad_link_change, or
bond_3ad_update_lacp_rate. All four of those are called with RTNL
held, and acquire the state machine lock second, The calling contexts for
__enable_port and __disable_port already hold the state machine lock,
and may or may not need RTNL.

So according to the Jay's opinion, the __enable_port and __disable_port
should not call rtmsg_ifinfo in the state machine lock, any change in
the state of slave could set a flag in the slave, it will indicated that
an rtmsg_ifinfo should be called at the end of the state machine.

Cc: Jay Vosburgh <fubar@...ibm.com>
Cc: Veaceslav Falico <vfalico@...hat.com>
Cc: Andy Gospodarek <andy@...yhouse.net>
Signed-off-by: Ding Tianhong <dingtianhong@...wei.com>
---
 drivers/net/bonding/bond_3ad.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
index cce1f1b..e80b78f 100644
--- a/drivers/net/bonding/bond_3ad.c
+++ b/drivers/net/bonding/bond_3ad.c
@@ -181,7 +181,7 @@ static inline int __agg_has_partner(struct aggregator *agg)
  */
 static inline void __disable_port(struct port *port)
 {
-	bond_set_slave_inactive_flags(port->slave);
+	bond_set_slave_flags(port->slave, BOND_STATE_BACKUP, false);
 }

 /**
@@ -193,7 +193,7 @@ static inline void __enable_port(struct port *port)
 	struct slave *slave = port->slave;

 	if ((slave->link == BOND_LINK_UP) && IS_UP(slave->dev))
-		bond_set_slave_active_flags(slave);
+		bond_set_slave_flags(slave, BOND_STATE_ACTIVE, false);
 }

 /**
@@ -2123,6 +2123,7 @@ void bond_3ad_state_machine_handler(struct work_struct *work)
 re_arm:
 	rcu_read_unlock();
 	read_unlock(&bond->lock);
+	bond_slave_state_notify(bond, false);
 	queue_delayed_work(bond->wq, &bond->ad_work, ad_delta_in_ticks);
 }

-- 
1.8.0

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