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 (file)
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -708,7 +708,7 @@ out:
 
 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 bool bond_should_change_active(struct bonding *bond)
  */
 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 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
        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 @@ err_detach:
                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 @@ err_detach:
                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 @@ static int __bond_release_one(struct net_device *bond_dev,
                                    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 int bond_miimon_inspect(struct bonding *bond)
 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 @@ static void bond_miimon_commit(struct bonding *bond)
                        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 @@ static void bond_miimon_commit(struct bonding *bond)
                                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 @@ static void bond_ab_arp_commit(struct bonding *bond)
                                            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_master_netdev_event(unsigned long event,
 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 @@ static int bond_slave_netdev_event(unsigned long event,
                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 @@ static int bond_slave_netdev_event(unsigned long event,
                    !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);

diff --git a/drivers/net/bonding/bond_netlink.c b/drivers/net/bonding/bond_netlink.c
index e1489d9..c13d83e 100644 (file)
--- a/drivers/net/bonding/bond_netlink.c
+++ b/drivers/net/bonding/bond_netlink.c
@@ -443,6 +443,7 @@ static int bond_fill_info(struct sk_buff *skb,
        unsigned int packets_per_slave;
        int ifindex, i, targets_added;
        struct nlattr *targets;
+       struct slave *primary;
 
        if (nla_put_u8(skb, IFLA_BOND_MODE, BOND_MODE(bond)))
                goto nla_put_failure;
@@ -492,9 +493,9 @@ static int bond_fill_info(struct sk_buff *skb,
                        bond->params.arp_all_targets))
                goto nla_put_failure;
 
-       if (bond->primary_slave &&
-           nla_put_u32(skb, IFLA_BOND_PRIMARY,
-                       bond->primary_slave->dev->ifindex))
+       primary = rtnl_dereference(bond->primary_slave);
+       if (primary &&
+           nla_put_u32(skb, IFLA_BOND_PRIMARY, primary->dev->ifindex))
                goto nla_put_failure;
 
        if (nla_put_u8(skb, IFLA_BOND_PRIMARY_RESELECT,

diff --git a/drivers/net/bonding/bond_options.c b/drivers/net/bonding/bond_options.c
index d8dc17f..7c9e176 100644 (file)
--- a/drivers/net/bonding/bond_options.c
+++ b/drivers/net/bonding/bond_options.c
@@ -1090,7 +1090,7 @@ static int bond_option_primary_set(struct bonding *bond,
        /* check to see if we are clearing primary */
        if (!strlen(primary)) {
                netdev_info(bond->dev, "Setting primary slave to None\n");
-               bond->primary_slave = NULL;
+               RCU_INIT_POINTER(bond->primary_slave, NULL);
                memset(bond->params.primary, 0, sizeof(bond->params.primary));
                bond_select_active_slave(bond);
                goto out;
@@ -1100,16 +1100,16 @@ static int bond_option_primary_set(struct bonding *bond,
                if (strncmp(slave->dev->name, primary, IFNAMSIZ) == 0) {
                        netdev_info(bond->dev, "Setting %s as primary slave\n",
                                    slave->dev->name);
-                       bond->primary_slave = slave;
+                       rcu_assign_pointer(bond->primary_slave, slave);
                        strcpy(bond->params.primary, slave->dev->name);
                        bond_select_active_slave(bond);
                        goto out;
                }
        }
 
-       if (bond->primary_slave) {
+       if (rtnl_dereference(bond->primary_slave)) {
                netdev_info(bond->dev, "Setting primary slave to None\n");
-               bond->primary_slave = NULL;
+               RCU_INIT_POINTER(bond->primary_slave, NULL);
                bond_select_active_slave(bond);
        }
        strncpy(bond->params.primary, primary, IFNAMSIZ);

diff --git a/drivers/net/bonding/bond_procfs.c b/drivers/net/bonding/bond_procfs.c
index de62c03..1a9fe1b 100644 (file)
--- a/drivers/net/bonding/bond_procfs.c
+++ b/drivers/net/bonding/bond_procfs.c
@@ -66,7 +66,7 @@ static void bond_info_show_master(struct seq_file *seq)
 {
        struct bonding *bond = seq->private;
        const struct bond_opt_value *optval;
-       struct slave *curr;
+       struct slave *curr, *primary;
        int i;
 
        curr = rcu_dereference(bond->curr_active_slave);
@@ -92,10 +92,10 @@ static void bond_info_show_master(struct seq_file *seq)
        }
 
        if (bond_uses_primary(bond)) {
+               primary = rcu_dereference(bond->primary_slave);
                seq_printf(seq, "Primary Slave: %s",
-                          (bond->primary_slave) ?
-                          bond->primary_slave->dev->name : "None");
-               if (bond->primary_slave) {
+                          primary ? primary->dev->name : "None");
+               if (primary) {
                        optval = bond_opt_get_val(BOND_OPT_PRIMARY_RESELECT,
                                                  bond->params.primary_reselect);
                        seq_printf(seq, " (primary_reselect %s)",

diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
index 98db8ed..5555517 100644 (file)
--- a/drivers/net/bonding/bond_sysfs.c
+++ b/drivers/net/bonding/bond_sysfs.c
@@ -425,11 +425,15 @@ static ssize_t bonding_show_primary(struct device *d,
                                    struct device_attribute *attr,
                                    char *buf)
 {
-       int count = 0;
        struct bonding *bond = to_bond(d);
+       struct slave *primary;
+       int count = 0;
 
-       if (bond->primary_slave)
-               count = sprintf(buf, "%s\n", bond->primary_slave->dev->name);
+       rcu_read_lock();
+       primary = rcu_dereference(bond->primary_slave);
+       if (primary)
+               count = sprintf(buf, "%s\n", primary->dev->name);
+       rcu_read_unlock();
 
        return count;
 }

diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
index aace510..c798561 100644 (file)
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -195,7 +195,7 @@ struct bonding {
        struct   net_device *dev; /* first - useful for panic debug */
        struct   slave __rcu *curr_active_slave;
        struct   slave __rcu *current_arp_slave;
-       struct   slave *primary_slave;
+       struct   slave __rcu *primary_slave;
        bool     force_primary;
        s32      slave_cnt; /* never change this value outside the attach/detach wrappers */
        int     (*recv_probe)(const struct sk_buff *, struct bonding *,