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Merge branch 'bonding'

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Veaceslav Falico says:

====================
bonding: fix locking in bond_ab_arp_prob

After the latest patches, on every call of bond_ab_arp_probe() without an
active slave I see the following warning:

[    7.912314] RTNL: assertion failed at net/core/dev.c (4494)
...
[    7.922495]  [<ffffffff817acc6f>] dump_stack+0x51/0x72
[    7.923714]  [<ffffffff8168795e>] netdev_master_upper_dev_get+0x6e/0x70
[    7.924940]  [<ffffffff816a2a66>] rtnl_link_fill+0x116/0x260
[    7.926143]  [<ffffffff817acc6f>] ? dump_stack+0x51/0x72
[    7.927333]  [<ffffffff816a350c>] rtnl_fill_ifinfo+0x95c/0xb90
[    7.928529]  [<ffffffff8167af2b>] ? __kmalloc_reserve+0x3b/0xa0
[    7.929681]  [<ffffffff8167bfcf>] ? __alloc_skb+0x9f/0x1e0
[    7.930827]  [<ffffffff816a3b64>] rtmsg_ifinfo+0x84/0x100
[    7.931960]  [<ffffffffa00bca07>] bond_ab_arp_probe+0x1a7/0x370 [bonding]
[    7.933133]  [<ffffffffa00bcd78>] bond_activebackup_arp_mon+0x1a8/0x2f0 [bonding]
...

It happens because in bond_ab_arp_probe() we change the flags of a slave
without holding the RTNL lock.

To fix this - remove the useless curr_active_lock, RCUify it and lock RTNL
while changing the slave's flags. Also, remove bond_ab_arp_probe() from
under any locks in bond_ab_arp_mon().
====================

Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2014-01-27 13:12:50 -08:00
commit 66dd1c077a
1 changed files with 39 additions and 28 deletions
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67
drivers/net/bonding/bond_main.c
View file

@ -2599,45 +2599,51 @@ static void bond_ab_arp_commit(struct bonding *bond)
/*
* Send ARP probes for active-backup mode ARP monitor.
*
* Called with rcu_read_lock hold.
*/
static void bond_ab_arp_probe(struct bonding *bond)
static bool bond_ab_arp_probe(struct bonding *bond)
{
struct slave *slave, *before = NULL, *new_slave = NULL,
*curr_arp_slave = rcu_dereference(bond->current_arp_slave);
*curr_arp_slave, *curr_active_slave;
struct list_head *iter;
bool found = false;
read_lock(&bond->curr_slave_lock);
rcu_read_lock();
curr_arp_slave = rcu_dereference(bond->current_arp_slave);
curr_active_slave = rcu_dereference(bond->curr_active_slave);
if (curr_arp_slave && bond->curr_active_slave)
if (curr_arp_slave && curr_active_slave)
pr_info("PROBE: c_arp %s && cas %s BAD\n",
curr_arp_slave->dev->name,
bond->curr_active_slave->dev->name);
curr_active_slave->dev->name);
if (bond->curr_active_slave) {
bond_arp_send_all(bond, bond->curr_active_slave);
read_unlock(&bond->curr_slave_lock);
return;
if (curr_active_slave) {
bond_arp_send_all(bond, curr_active_slave);
rcu_read_unlock();
return true;
}
read_unlock(&bond->curr_slave_lock);
rcu_read_unlock();
/* if we don't have a curr_active_slave, search for the next available
* backup slave from the current_arp_slave and make it the candidate
* for becoming the curr_active_slave
*/
if (!rtnl_trylock())
return false;
/* curr_arp_slave might have gone away */
curr_arp_slave = ACCESS_ONCE(bond->current_arp_slave);
if (!curr_arp_slave) {
curr_arp_slave = bond_first_slave_rcu(bond);
if (!curr_arp_slave)
return;
curr_arp_slave = bond_first_slave(bond);
if (!curr_arp_slave) {
rtnl_unlock();
return true;
}
}
bond_set_slave_inactive_flags(curr_arp_slave);
bond_for_each_slave_rcu(bond, slave, iter) {
bond_for_each_slave(bond, slave, iter) {
if (!found && !before && IS_UP(slave->dev))
before = slave;
@ -2667,21 +2673,26 @@ static void bond_ab_arp_probe(struct bonding *bond)
if (!new_slave && before)
new_slave = before;
if (!new_slave)
return;
if (!new_slave) {
rtnl_unlock();
return true;
}
new_slave->link = BOND_LINK_BACK;
bond_set_slave_active_flags(new_slave);
bond_arp_send_all(bond, new_slave);
new_slave->jiffies = jiffies;
rcu_assign_pointer(bond->current_arp_slave, new_slave);
rtnl_unlock();
return true;
}
static void bond_activebackup_arp_mon(struct work_struct *work)
{
struct bonding *bond = container_of(work, struct bonding,
arp_work.work);
bool should_notify_peers = false;
bool should_notify_peers = false, should_commit = false;
int delta_in_ticks;
delta_in_ticks = msecs_to_jiffies(bond->params.arp_interval);
@ -2690,12 +2701,11 @@ static void bond_activebackup_arp_mon(struct work_struct *work)
goto re_arm;
rcu_read_lock();
should_notify_peers = bond_should_notify_peers(bond);
should_commit = bond_ab_arp_inspect(bond);
rcu_read_unlock();
if (bond_ab_arp_inspect(bond)) {
rcu_read_unlock();
if (should_commit) {
/* Race avoidance with bond_close flush of workqueue */
if (!rtnl_trylock()) {
delta_in_ticks = 1;
@ -2704,13 +2714,14 @@ static void bond_activebackup_arp_mon(struct work_struct *work)
}
bond_ab_arp_commit(bond);
rtnl_unlock();
rcu_read_lock();
}
bond_ab_arp_probe(bond);
rcu_read_unlock();
if (!bond_ab_arp_probe(bond)) {
/* rtnl locking failed, re-arm */
delta_in_ticks = 1;
should_notify_peers = false;
}
re_arm:
if (bond->params.arp_interval)