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bonding: rebuild the lock use for bond_activebackup_arp_mon() 

The bond_activebackup_arp_mon() use the bond lock for read to
protect the slave list, it is no effect, and the RTNL is only
called for bond_ab_arp_commit() and peer notify, for the performance
better, use RCU to replace with the bond lock, to the bond slave
list need to called in RCU, add a new bond_first_slave_rcu()
to get the first slave in RCU protection.

In bond_ab_arp_probe(), the bond->current_arp_slave may changd
if bond release slave, just like:

        bond_ab_arp_probe()                     bond_release()
        cpu 0                                   cpu 1
        ...
        if (bond->current_arp_slave...)         ...
        ...                             bond->current_arp_slave = NULl
        bond->current_arp_slave->dev->name      ...

So the current_arp_slave need to dereference in the section.

Suggested-by: Nikolay Aleksandrov <nikolay@redhat.com>
Suggested-by: Jay Vosburgh <fubar@us.ibm.com>
Suggested-by: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
dingtianhong 2013-12-13 10:20:02 +08:00 committed by David S. Miller
parent e001bfad91
commit eb9fa4b019
1 changed files with 20 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

45
drivers/net/bonding/bond_main.c
View File

@ -2517,7 +2517,7 @@ re_arm:
* place for the slave. Returns 0 if no changes are found, >0 if changes
* to link states must be committed.
*
* Called with bond->lock held for read.
* Called with rcu_read_lock hold.
*/
static int bond_ab_arp_inspect(struct bonding *bond)
{
@ -2526,7 +2526,7 @@ static int bond_ab_arp_inspect(struct bonding *bond)
struct slave *slave;
int commit = 0;
bond_for_each_slave(bond, slave, iter) {
bond_for_each_slave_rcu(bond, slave, iter) {
slave->new_link = BOND_LINK_NOCHANGE;
last_rx = slave_last_rx(bond, slave);
@ -2588,7 +2588,7 @@ static int bond_ab_arp_inspect(struct bonding *bond)
* Called to commit link state changes noted by inspection step of
* active-backup mode ARP monitor.
*
* Called with RTNL and bond->lock for read.
* Called with RTNL hold.
*/
static void bond_ab_arp_commit(struct bonding *bond)
{
@ -2663,19 +2663,20 @@ do_failover:
/*
* Send ARP probes for active-backup mode ARP monitor.
*
* Called with bond->lock held for read.
* Called with rcu_read_lock hold.
*/
static void bond_ab_arp_probe(struct bonding *bond)
{
struct slave *slave, *before = NULL, *new_slave = NULL;
struct slave *slave, *before = NULL, *new_slave = NULL,
*curr_arp_slave = rcu_dereference(bond->current_arp_slave);
struct list_head *iter;
bool found = false;
read_lock(&bond->curr_slave_lock);
if (bond->current_arp_slave && bond->curr_active_slave)
if (curr_arp_slave && bond->curr_active_slave)
pr_info("PROBE: c_arp %s && cas %s BAD\n",
bond->current_arp_slave->dev->name,
curr_arp_slave->dev->name,
bond->curr_active_slave->dev->name);
if (bond->curr_active_slave) {
@ -2691,15 +2692,15 @@ static void bond_ab_arp_probe(struct bonding *bond)
* for becoming the curr_active_slave
*/
if (!bond->current_arp_slave) {
bond->current_arp_slave = bond_first_slave(bond);
if (!bond->current_arp_slave)
if (!curr_arp_slave) {
curr_arp_slave = bond_first_slave_rcu(bond);
if (!curr_arp_slave)
return;
}
bond_set_slave_inactive_flags(bond->current_arp_slave);
bond_set_slave_inactive_flags(curr_arp_slave);
bond_for_each_slave(bond, slave, iter) {
bond_for_each_slave_rcu(bond, slave, iter) {
if (!found && !before && IS_UP(slave->dev))
before = slave;
@ -2722,7 +2723,7 @@ static void bond_ab_arp_probe(struct bonding *bond)
pr_info("%s: backup interface %s is now down.\n",
bond->dev->name, slave->dev->name);
}
if (slave == bond->current_arp_slave)
if (slave == curr_arp_slave)
found = true;
}
@ -2736,8 +2737,7 @@ static void bond_ab_arp_probe(struct bonding *bond)
bond_set_slave_active_flags(new_slave);
bond_arp_send_all(bond, new_slave);
new_slave->jiffies = jiffies;
bond->current_arp_slave = new_slave;
rcu_assign_pointer(bond->current_arp_slave, new_slave);
}
void bond_activebackup_arp_mon(struct work_struct *work)
@ -2747,43 +2747,38 @@ void bond_activebackup_arp_mon(struct work_struct *work)
bool should_notify_peers = false;
int delta_in_ticks;
read_lock(&bond->lock);
delta_in_ticks = msecs_to_jiffies(bond->params.arp_interval);
if (!bond_has_slaves(bond))
goto re_arm;
rcu_read_lock();
should_notify_peers = bond_should_notify_peers(bond);
if (bond_ab_arp_inspect(bond)) {
read_unlock(&bond->lock);
rcu_read_unlock();
/* Race avoidance with bond_close flush of workqueue */
if (!rtnl_trylock()) {
read_lock(&bond->lock);
delta_in_ticks = 1;
should_notify_peers = false;
goto re_arm;
}
read_lock(&bond->lock);
bond_ab_arp_commit(bond);
read_unlock(&bond->lock);
rtnl_unlock();
read_lock(&bond->lock);
rcu_read_lock();
}
bond_ab_arp_probe(bond);
rcu_read_unlock();
re_arm:
if (bond->params.arp_interval)
queue_delayed_work(bond->wq, &bond->arp_work, delta_in_ticks);
read_unlock(&bond->lock);
if (should_notify_peers) {
if (!rtnl_trylock())
return;