bonding: convert primary_slave to use RCU
This is necessary mainly for two bonding call sites: procfs and
sysfs as it was dereferenced without any real protection.
Signed-off-by: Nikolay Aleksandrov <nikolay@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 dcd331b..629037f 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -708,7 +708,7 @@
static bool bond_should_change_active(struct bonding *bond)
{
- struct slave *prim = bond->primary_slave;
+ struct slave *prim = rtnl_dereference(bond->primary_slave);
struct slave *curr = bond_deref_active_protected(bond);
if (!prim || !curr || curr->link != BOND_LINK_UP)
@@ -732,13 +732,14 @@
*/
static struct slave *bond_find_best_slave(struct bonding *bond)
{
- struct slave *slave, *bestslave = NULL;
+ struct slave *slave, *bestslave = NULL, *primary;
struct list_head *iter;
int mintime = bond->params.updelay;
- if (bond->primary_slave && bond->primary_slave->link == BOND_LINK_UP &&
+ primary = rtnl_dereference(bond->primary_slave);
+ if (primary && primary->link == BOND_LINK_UP &&
bond_should_change_active(bond))
- return bond->primary_slave;
+ return primary;
bond_for_each_slave(bond, slave, iter) {
if (slave->link == BOND_LINK_UP)
@@ -1482,7 +1483,7 @@
if (bond_uses_primary(bond) && bond->params.primary[0]) {
/* if there is a primary slave, remember it */
if (strcmp(bond->params.primary, new_slave->dev->name) == 0) {
- bond->primary_slave = new_slave;
+ rcu_assign_pointer(bond->primary_slave, new_slave);
bond->force_primary = true;
}
}
@@ -1596,8 +1597,8 @@
bond_hw_addr_flush(bond_dev, slave_dev);
vlan_vids_del_by_dev(slave_dev, bond_dev);
- if (bond->primary_slave == new_slave)
- bond->primary_slave = NULL;
+ if (rcu_access_pointer(bond->primary_slave) == new_slave)
+ RCU_INIT_POINTER(bond->primary_slave, NULL);
if (rcu_access_pointer(bond->curr_active_slave) == new_slave) {
block_netpoll_tx();
write_lock_bh(&bond->curr_slave_lock);
@@ -1606,6 +1607,8 @@
write_unlock_bh(&bond->curr_slave_lock);
unblock_netpoll_tx();
}
+ /* either primary_slave or curr_active_slave might've changed */
+ synchronize_rcu();
slave_disable_netpoll(new_slave);
err_close:
@@ -1714,8 +1717,8 @@
bond_dev->name, slave_dev->name);
}
- if (bond->primary_slave == slave)
- bond->primary_slave = NULL;
+ if (rtnl_dereference(bond->primary_slave) == slave)
+ RCU_INIT_POINTER(bond->primary_slave, NULL);
if (oldcurrent == slave) {
write_lock_bh(&bond->curr_slave_lock);
@@ -1976,7 +1979,7 @@
static void bond_miimon_commit(struct bonding *bond)
{
struct list_head *iter;
- struct slave *slave;
+ struct slave *slave, *primary;
bond_for_each_slave(bond, slave, iter) {
switch (slave->new_link) {
@@ -1987,13 +1990,14 @@
slave->link = BOND_LINK_UP;
slave->last_link_up = jiffies;
+ primary = rtnl_dereference(bond->primary_slave);
if (BOND_MODE(bond) == BOND_MODE_8023AD) {
/* prevent it from being the active one */
bond_set_backup_slave(slave);
} else if (BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP) {
/* make it immediately active */
bond_set_active_slave(slave);
- } else if (slave != bond->primary_slave) {
+ } else if (slave != primary) {
/* prevent it from being the active one */
bond_set_backup_slave(slave);
}
@@ -2011,8 +2015,7 @@
bond_alb_handle_link_change(bond, slave,
BOND_LINK_UP);
- if (!bond->curr_active_slave ||
- (slave == bond->primary_slave))
+ if (!bond->curr_active_slave || slave == primary)
goto do_failover;
continue;
@@ -2633,7 +2636,7 @@
slave->dev->name);
if (!rtnl_dereference(bond->curr_active_slave) ||
- (slave == bond->primary_slave))
+ slave == rtnl_dereference(bond->primary_slave))
goto do_failover;
}
@@ -2860,7 +2863,7 @@
static int bond_slave_netdev_event(unsigned long event,
struct net_device *slave_dev)
{
- struct slave *slave = bond_slave_get_rtnl(slave_dev);
+ struct slave *slave = bond_slave_get_rtnl(slave_dev), *primary;
struct bonding *bond;
struct net_device *bond_dev;
u32 old_speed;
@@ -2874,6 +2877,7 @@
return NOTIFY_DONE;
bond_dev = slave->bond->dev;
bond = slave->bond;
+ primary = rtnl_dereference(bond->primary_slave);
switch (event) {
case NETDEV_UNREGISTER:
@@ -2921,18 +2925,18 @@
!bond->params.primary[0])
break;
- if (slave == bond->primary_slave) {
+ if (slave == primary) {
/* slave's name changed - he's no longer primary */
- bond->primary_slave = NULL;
+ RCU_INIT_POINTER(bond->primary_slave, NULL);
} else if (!strcmp(slave_dev->name, bond->params.primary)) {
/* we have a new primary slave */
- bond->primary_slave = slave;
+ rcu_assign_pointer(bond->primary_slave, slave);
} else { /* we didn't change primary - exit */
break;
}
netdev_info(bond->dev, "Primary slave changed to %s, reselecting active slave\n",
- bond->primary_slave ? slave_dev->name : "none");
+ primary ? slave_dev->name : "none");
block_netpoll_tx();
write_lock_bh(&bond->curr_slave_lock);