bonding: RCUify bond_set_rx_mode()

Currently we rely on rtnl locking in bond_set_rx_mode(), however it's not
always the case:

RTNL: assertion failed at drivers/net/bonding/bond_main.c (3391)
...
 [<ffffffff81651ca5>] dump_stack+0x54/0x74
 [<ffffffffa029e717>] bond_set_rx_mode+0xc7/0xd0 [bonding]
 [<ffffffff81553af7>] __dev_set_rx_mode+0x57/0xa0
 [<ffffffff81557ff8>] __dev_mc_add+0x58/0x70
 [<ffffffff81558020>] dev_mc_add+0x10/0x20
 [<ffffffff8161e26e>] igmp6_group_added+0x18e/0x1d0
 [<ffffffff81186f76>] ? kmem_cache_alloc_trace+0x236/0x260
 [<ffffffff8161f80f>] ipv6_dev_mc_inc+0x29f/0x320
 [<ffffffff8161f9e7>] ipv6_sock_mc_join+0x157/0x260
...

Fix this by using RCU primitives.

Reported-by: Joe Lawrence <joe.lawrence@stratus.com>
Tested-by: Joe Lawrence <joe.lawrence@stratus.com>
CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 0367f80953906cb980cb11a17be4883eac0c926f..894a7f34f88efc2e95768ad29681a438efe543f1 100644 (file)
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -3393,20 +3393,21 @@ static void bond_set_rx_mode(struct net_device *bond_dev)
        struct list_head *iter;
        struct slave *slave;
 
-       ASSERT_RTNL();
 
+       rcu_read_lock();
        if (USES_PRIMARY(bond->params.mode)) {
-               slave = rtnl_dereference(bond->curr_active_slave);
+               slave = rcu_dereference(bond->curr_active_slave);
                if (slave) {
                        dev_uc_sync(slave->dev, bond_dev);
                        dev_mc_sync(slave->dev, bond_dev);
                }
        } else {
-               bond_for_each_slave(bond, slave, iter) {
+               bond_for_each_slave_rcu(bond, slave, iter) {
                        dev_uc_sync_multiple(slave->dev, bond_dev);
                        dev_mc_sync_multiple(slave->dev, bond_dev);
                }
        }
+       rcu_read_unlock();
 }
 
 static int bond_neigh_init(struct neighbour *n)