Commit b84c5632 authored by Faicker Mo's avatar Faicker Mo Committed by Jakub Kicinski
Browse files

net: net_failover: Fix the deadlock in slave register 



There is netdev_lock_ops() before the NETDEV_REGISTER notifier
in register_netdevice(), so use the non-locking functions
in net_failover_slave_register().
failover_slave_register() in failover_existing_slave_register() adds lock
and unlock ops too.

Call Trace:
 <TASK>
 __schedule+0x30d/0x7a0
 schedule+0x27/0x90
 schedule_preempt_disabled+0x15/0x30
 __mutex_lock.constprop.0+0x538/0x9e0
 __mutex_lock_slowpath+0x13/0x20
 mutex_lock+0x3b/0x50
 dev_set_mtu+0x40/0xe0
 net_failover_slave_register+0x24/0x280
 failover_slave_register+0x103/0x1b0
 failover_event+0x15e/0x210
 ? dropmon_net_event+0xac/0xe0
 notifier_call_chain+0x5e/0xe0
 raw_notifier_call_chain+0x16/0x30
 call_netdevice_notifiers_info+0x52/0xa0
 register_netdevice+0x5f4/0x7c0
 register_netdev+0x1e/0x40
 _mlx5e_probe+0xe2/0x370 [mlx5_core]
 mlx5e_probe+0x59/0x70 [mlx5_core]
 ? __pfx_mlx5e_probe+0x10/0x10 [mlx5_core]

Fixes: 4c975fd7 ("net: hold instance lock during NETDEV_REGISTER/UP")
Signed-off-by: default avatarFaicker Mo <faicker.mo@gmail.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 9a390d34

drivers/net/net_failover.c

+6 −6
Original line number Diff line number Diff line
@@ -502,7 +502,7 @@ static int net_failover_slave_register(struct net_device *slave_dev, 


	/* Align MTU of slave with failover dev */

	orig_mtu = slave_dev->mtu;

	err = dev_set_mtu(slave_dev, failover_dev->mtu);

	err = netif_set_mtu(slave_dev, failover_dev->mtu);

	if (err) {

		netdev_err(failover_dev, "unable to change mtu of %s to %u register failed\n",

			   slave_dev->name, failover_dev->mtu);
@@ -512,11 +512,11 @@ static int net_failover_slave_register(struct net_device *slave_dev, 
	dev_hold(slave_dev);



	if (netif_running(failover_dev)) {

		err = dev_open(slave_dev, NULL);

		err = netif_open(slave_dev, NULL);

		if (err && (err != -EBUSY)) {

			netdev_err(failover_dev, "Opening slave %s failed err:%d\n",

				   slave_dev->name, err);

			goto err_dev_open;

			goto err_netif_open;

		}

	}
@@ -562,10 +562,10 @@ static int net_failover_slave_register(struct net_device *slave_dev, 
err_vlan_add:

	dev_uc_unsync(slave_dev, failover_dev);

	dev_mc_unsync(slave_dev, failover_dev);

	dev_close(slave_dev);

err_dev_open:

	netif_close(slave_dev);

err_netif_open:

	dev_put(slave_dev);

	dev_set_mtu(slave_dev, orig_mtu);

	netif_set_mtu(slave_dev, orig_mtu);

done:

	return err;

}

net/core/failover.c

+5 −1
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include <uapi/linux/if_arp.h>

#include <linux/rtnetlink.h>

#include <linux/if_vlan.h>

#include <net/netdev_lock.h>

#include <net/failover.h>



static LIST_HEAD(failover_list);
@@ -221,8 +222,11 @@ failover_existing_slave_register(struct net_device *failover_dev) 
	for_each_netdev(net, dev) {

		if (netif_is_failover(dev))

			continue;

		if (ether_addr_equal(failover_dev->perm_addr, dev->perm_addr))

		if (ether_addr_equal(failover_dev->perm_addr, dev->perm_addr)) {

			netdev_lock_ops(dev);

			failover_slave_register(dev);

			netdev_unlock_ops(dev);

		}

	}

	rtnl_unlock();

}