netdev - [PATCH net] bonding: Fix deadlock in bonding driver when using netpoll

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 12 Feb 2014 12:06:40 +0800
From:	Ding Tianhong <dingtianhong@...wei.com>
To:	Jay Vosburgh <fubar@...ibm.com>,
	Veaceslav Falico <vfalico@...hat.com>,
	Andy Gospodarek <andy@...yhouse.net>,
	"David S. Miller" <davem@...emloft.net>,
	Netdev <netdev@...r.kernel.org>
Subject: [PATCH net] bonding: Fix deadlock in bonding driver when using netpoll

The bonding driver take write locks and spin locks that are shared
by the tx path in enslave processing and notification processing,
If the netconsole is in use, the bonding can call printk which puts
us in the netpoll tx path, if the netconsole is attached to the bonding
driver, result in deadlock.

So add protection for these place, by checking the netpoll_block_tx
state, we can defer the sending of the netconsole frames until a later
time using the retransmit feature of netpoll_send_skb that is triggered
on the return code NETDEV_TX_BUSY.

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_main.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 71ba18e..8676649 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1543,9 +1543,11 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 	bond_set_carrier(bond);
 
 	if (USES_PRIMARY(bond->params.mode)) {
+		block_netpoll_tx();
 		write_lock_bh(&bond->curr_slave_lock);
 		bond_select_active_slave(bond);
 		write_unlock_bh(&bond->curr_slave_lock);
+		unblock_netpoll_tx();
 	}
 
 	pr_info("%s: enslaving %s as a%s interface with a%s link.\n",
@@ -1571,10 +1573,12 @@ err_detach:
 	if (bond->primary_slave == new_slave)
 		bond->primary_slave = NULL;
 	if (bond->curr_active_slave == new_slave) {
+		block_netpoll_tx();
 		write_lock_bh(&bond->curr_slave_lock);
 		bond_change_active_slave(bond, NULL);
 		bond_select_active_slave(bond);
 		write_unlock_bh(&bond->curr_slave_lock);
+		unblock_netpoll_tx();
 	}
 	slave_disable_netpoll(new_slave);
 
@@ -2864,9 +2868,12 @@ static int bond_slave_netdev_event(unsigned long event,
 		pr_info("%s: Primary slave changed to %s, reselecting active slave.\n",
 			bond->dev->name, bond->primary_slave ? slave_dev->name :
 							       "none");
+
+		block_netpoll_tx();
 		write_lock_bh(&bond->curr_slave_lock);
 		bond_select_active_slave(bond);
 		write_unlock_bh(&bond->curr_slave_lock);
+		unblock_netpoll_tx();
 		break;
 	case NETDEV_FEAT_CHANGE:
 		bond_compute_features(bond);
-- 
1.8.0



--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html