From baf4e91f709ceca40347f8b0784a1e76ad50bf91 Mon Sep 17 00:00:00 2001
From: Yufeng Mo <moyufeng@huawei.com>
Date: Fri, 30 Jul 2021 10:19:11 +0800
Subject: [PATCH] bonding: 3ad: fix the concurrency between __bond_release_one() and bond_3ad_state_machine_handler()
Git-commit: 220ade77452c15ecb1ab94c3f8aaeb6d033c3582
Patch-mainline: v5.15-rc1
References: stable-5.14.6
[ Upstream commit 220ade77452c15ecb1ab94c3f8aaeb6d033c3582 ]
Some time ago, I reported a calltrace issue
"did not find a suitable aggregator", please see[1].
After a period of analysis and reproduction, I find
that this problem is caused by concurrency.
Before the problem occurs, the bond structure is like follows:
bond0 - slaver0(eth0) - agg0.lag_ports -> port0 - port1
\
port0
\
slaver1(eth1) - agg1.lag_ports -> NULL
\
port1
If we run 'ifenslave bond0 -d eth1', the process is like below:
excuting __bond_release_one()
|
bond_upper_dev_unlink()[step1]
| | |
| | bond_3ad_lacpdu_recv()
| | ->bond_3ad_rx_indication()
| | spin_lock_bh()
| | ->ad_rx_machine()
| | ->__record_pdu()[step2]
| | spin_unlock_bh()
| | |
| bond_3ad_state_machine_handler()
| spin_lock_bh()
| ->ad_port_selection_logic()
| ->try to find free aggregator[step3]
| ->try to find suitable aggregator[step4]
| ->did not find a suitable aggregator[step5]
| spin_unlock_bh()
| |
| |
bond_3ad_unbind_slave() |
spin_lock_bh()
spin_unlock_bh()
Step1: already removed slaver1(eth1) from list, but port1 remains
Step2: receive a lacpdu and update port0
Step3: port0 will be removed from agg0.lag_ports. The struct is "agg0.lag_ports -> port1" now, and agg0 is not free. At the same time, slaver1/agg1 has been removed from the list by step1. So we can't find a free aggregator now.
Step4: can't find suitable aggregator because of step2
Step5: cause a calltrace since port->aggregator is NULL
To solve this concurrency problem, put bond_upper_dev_unlink()
after bond_3ad_unbind_slave(). In this way, we can invalid the port
first and skip this port in bond_3ad_state_machine_handler(). This
eliminates the situation that the slaver has been removed from the
list but the port is still valid.
[1]https://lore.kernel.org/netdev/10374.1611947473@famine/
Signed-off-by: Yufeng Mo <moyufeng@huawei.com>
Acked-by: Jay Vosburgh <jay.vosburgh@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/net/bonding/bond_main.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 31730efa7538..8aef6005bfee 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -2252,7 +2252,6 @@ static int __bond_release_one(struct net_device *bond_dev,
/* recompute stats just before removing the slave */
bond_get_stats(bond->dev, &bond->bond_stats);
- bond_upper_dev_unlink(bond, slave);
/* unregister rx_handler early so bond_handle_frame wouldn't be called
* for this slave anymore.
*/
@@ -2261,6 +2260,8 @@ static int __bond_release_one(struct net_device *bond_dev,
if (BOND_MODE(bond) == BOND_MODE_8023AD)
bond_3ad_unbind_slave(slave);
+ bond_upper_dev_unlink(bond, slave);
+
if (bond_mode_can_use_xmit_hash(bond))
bond_update_slave_arr(bond, slave);
--
2.26.2