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Message-Id: <926F1DDD-E3E6-4FB2-8D45-CF01CE8E1956@cumulusnetworks.com>
Date: Thu, 20 Feb 2014 19:38:26 -0800
From: Scott Feldman <sfeldma@...ulusnetworks.com>
To: Jay Vosburgh <fubar@...ibm.com>
Cc: Ding Tianhong <dingtianhong@...wei.com>,
Andy Gospodarek <andy@...yhouse.net>,
Veaceslav Falico <vfalico@...hat.com>,
Cong Wang <cwang@...pensource.com>,
Thomas Glanzmann <thomas@...nzmann.de>,
Jiri Pirko <jiri@...nulli.us>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] bonding: Fix RTNL: assertion failed at net/core/rtnetlink.c for 802.3ad mode
On Feb 18, 2014, at 3:18 PM, Jay Vosburgh <fubar@...ibm.com> wrote:
> Ding Tianhong <dingtianhong@...wei.com> wrote:
>
>> The problem was introduced by the commit 1d3ee88ae0d
>> (bonding: add netlink attributes to slave link dev).
>> The bond_set_active_slave() and bond_set_backup_slave()
>> will use rtmsg_ifinfo to send slave's states, so these
>> two functions should be called in RTNL.
>>
>> In 802.3ad mode, acquiring RTNL for the __enable_port and
>> __disable_port cases is difficult, as those calls generally
>> already hold the state machine lock, and cannot unconditionally
>> call rtnl_lock because either they already hold RTNL (for calls
>> via bond_3ad_unbind_slave) or due to the potential for deadlock
>> with bond_3ad_adapter_speed_changed, bond_3ad_adapter_duplex_changed,
>> bond_3ad_link_change, or bond_3ad_update_lacp_rate. All four of
>> those are called with RTNL held, and acquire the state machine lock
>> second. The calling contexts for __enable_port and __disable_port
>> already hold the state machine lock, and may or may not need RTNL.
>>
>> According to the Jay's opinion, I don't think it is a problem that
>> the slave don't send notify message synchronously when the status
>> changed, normally the state machine is running every 100 ms, send
>> the notify message at the end of the state machine if the slave's
>> state changed should be better.
>>
>> I fix the problem through these steps:
>>
>> 1). add a new function bond_set_slave_state() which could change
>> the slave's state and call rtmsg_ifinfo() according to the input
>> parameters called notify.
>>
>> 2). Add a new slave parameter which called should_notify, if the slave's state
>> changed and don't notify yet, the parameter will be set to 1, and then if
>> the slave's state changed again, the param will be set to 0, it indicate that
>> the slave's state has been restored, no need to notify any one.
>>
>> 3). the __enable_port and __disable_port should not call rtmsg_ifinfo
>> in the state machine lock, any change in the state of slave could
>> set a flag in the slave, it will indicated that an rtmsg_ifinfo
>> should be called at the end of the state machine.
>>
>> Cc: Jay Vosburgh <fubar@...ibm.com>
>> Cc: Veaceslav Falico <vfalico@...hat.com>
>> Cc: Andy Gospodarek <andy@...yhouse.net>
>> Signed-off-by: Ding Tianhong <dingtianhong@...wei.com>
>> ---
>> drivers/net/bonding/bond_3ad.c | 22 ++++++++++++++++++++--
>> drivers/net/bonding/bond_main.c | 30 +++++++++++++++---------------
>> drivers/net/bonding/bonding.h | 31 ++++++++++++++++++++++++++-----
>> 3 files changed, 61 insertions(+), 22 deletions(-)
>>
>> diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
>> index e9edd84..c450d04 100644
>> --- a/drivers/net/bonding/bond_3ad.c
>> +++ b/drivers/net/bonding/bond_3ad.c
>> @@ -181,7 +181,7 @@ static inline int __agg_has_partner(struct aggregator *agg)
>> */
>> static inline void __disable_port(struct port *port)
>> {
>> - bond_set_slave_inactive_flags(port->slave);
>> + bond_set_slave_inactive_flags(port->slave, false);
>> }
>>
>> /**
>> @@ -193,7 +193,7 @@ static inline void __enable_port(struct port *port)
>> struct slave *slave = port->slave;
>>
>> if ((slave->link == BOND_LINK_UP) && IS_UP(slave->dev))
>> - bond_set_slave_active_flags(slave);
>> + bond_set_slave_active_flags(slave, false);
>> }
>>
>> /**
>> @@ -2065,6 +2065,7 @@ void bond_3ad_state_machine_handler(struct work_struct *work)
>> struct list_head *iter;
>> struct slave *slave;
>> struct port *port;
>> + int slave_should_notify = 0;
>>
>> read_lock(&bond->lock);
>> rcu_read_lock();
>> @@ -2122,8 +2123,25 @@ void bond_3ad_state_machine_handler(struct work_struct *work)
>> }
>>
>> re_arm:
>> + bond_for_each_slave_rcu(bond, slave, iter) {
>> + if (slave->should_notify) {
>> + slave_should_notify = 1;
>> + break;
>> + }
>> + }
>> rcu_read_unlock();
>> read_unlock(&bond->lock);
>> +
>> + if (slave_should_notify && rtnl_trylock()) {
>> + bond_for_each_slave(bond, slave, iter) {
>> + if (slave->should_notify) {
>> + rtmsg_ifinfo(RTM_NEWLINK, slave->dev, 0,
>> + GFP_KERNEL);
>> + slave->should_notify = 0;
>> + }
>> + }
>> + rtnl_unlock();
>> + }
>> queue_delayed_work(bond->wq, &bond->ad_work, ad_delta_in_ticks);
>> }
>>
>> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>> index 3bce855..1c14e64 100644
>> --- a/drivers/net/bonding/bond_main.c
>> +++ b/drivers/net/bonding/bond_main.c
>> @@ -829,21 +829,21 @@ void bond_change_active_slave(struct bonding *bond, struct slave *new_active)
>> if (bond_is_lb(bond)) {
>> bond_alb_handle_active_change(bond, new_active);
>> if (old_active)
>> - bond_set_slave_inactive_flags(old_active);
>> + bond_set_slave_inactive_flags(old_active, true);
>> if (new_active)
>> - bond_set_slave_active_flags(new_active);
>> + bond_set_slave_active_flags(new_active, true);
>> } else {
>> rcu_assign_pointer(bond->curr_active_slave, new_active);
>> }
>>
>> if (bond->params.mode == BOND_MODE_ACTIVEBACKUP) {
>> if (old_active)
>> - bond_set_slave_inactive_flags(old_active);
>> + bond_set_slave_inactive_flags(old_active, true);
>>
>> if (new_active) {
>> bool should_notify_peers = false;
>>
>> - bond_set_slave_active_flags(new_active);
>> + bond_set_slave_active_flags(new_active, true);
>>
>> if (bond->params.fail_over_mac)
>> bond_do_fail_over_mac(bond, new_active,
>> @@ -1462,14 +1462,14 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
>>
>> switch (bond->params.mode) {
>> case BOND_MODE_ACTIVEBACKUP:
>> - bond_set_slave_inactive_flags(new_slave);
>> + bond_set_slave_inactive_flags(new_slave, true);
>> break;
>> case BOND_MODE_8023AD:
>> /* in 802.3ad mode, the internal mechanism
>> * will activate the slaves in the selected
>> * aggregator
>> */
>> - bond_set_slave_inactive_flags(new_slave);
>> + bond_set_slave_inactive_flags(new_slave, true);
>> /* if this is the first slave */
>> if (!prev_slave) {
>> SLAVE_AD_INFO(new_slave).id = 1;
>> @@ -1487,7 +1487,7 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
>> case BOND_MODE_TLB:
>> case BOND_MODE_ALB:
>> bond_set_active_slave(new_slave);
>> - bond_set_slave_inactive_flags(new_slave);
>> + bond_set_slave_inactive_flags(new_slave, true);
>> break;
>> default:
>> pr_debug("This slave is always active in trunk mode\n");
>> @@ -2009,7 +2009,7 @@ static void bond_miimon_commit(struct bonding *bond)
>>
>> if (bond->params.mode == BOND_MODE_ACTIVEBACKUP ||
>> bond->params.mode == BOND_MODE_8023AD)
>> - bond_set_slave_inactive_flags(slave);
>> + bond_set_slave_inactive_flags(slave, true);
>>
>> pr_info("%s: link status definitely down for interface %s, disabling it\n",
>> bond->dev->name, slave->dev->name);
>> @@ -2555,7 +2555,7 @@ static void bond_ab_arp_commit(struct bonding *bond)
>> slave->link = BOND_LINK_UP;
>> if (bond->current_arp_slave) {
>> bond_set_slave_inactive_flags(
>> - bond->current_arp_slave);
>> + bond->current_arp_slave, true);
>> bond->current_arp_slave = NULL;
>> }
>>
>> @@ -2575,7 +2575,7 @@ static void bond_ab_arp_commit(struct bonding *bond)
>> slave->link_failure_count++;
>>
>> slave->link = BOND_LINK_DOWN;
>> - bond_set_slave_inactive_flags(slave);
>> + bond_set_slave_inactive_flags(slave, true);
>>
>> pr_info("%s: link status definitely down for interface %s, disabling it\n",
>> bond->dev->name, slave->dev->name);
>> @@ -2650,7 +2650,7 @@ static bool bond_ab_arp_probe(struct bonding *bond)
>> }
>> }
>>
>> - bond_set_slave_inactive_flags(curr_arp_slave);
>> + bond_set_slave_inactive_flags(curr_arp_slave, true);
>
> This...
>
>> bond_for_each_slave(bond, slave, iter) {
>> if (!found && !before && IS_UP(slave->dev))
>> @@ -2670,7 +2670,7 @@ static bool bond_ab_arp_probe(struct bonding *bond)
>> if (slave->link_failure_count < UINT_MAX)
>> slave->link_failure_count++;
>>
>> - bond_set_slave_inactive_flags(slave);
>> + bond_set_slave_inactive_flags(slave, true);
>
> [ but not this one ]
>
>> pr_info("%s: backup interface %s is now down\n",
>> bond->dev->name, slave->dev->name);
>> @@ -2688,7 +2688,7 @@ static bool bond_ab_arp_probe(struct bonding *bond)
>> }
>>
>> new_slave->link = BOND_LINK_BACK;
>> - bond_set_slave_active_flags(new_slave);
>> + bond_set_slave_active_flags(new_slave, true);
>
> and this should arguably never send an rtmsg_ifinfo
> notification.
>
> My presumption is that the notification is to indicate that the
> interface has actually changed state in a meaningful way
[Sorry for late response...my inbox filter let thread slip thru to netdev pile]
That was the original intent: notify (via netlink) that slave state changed. Admittedly, I was looking at 802.3ad mode and didn’t appreciate the locking subtleties with the other modes. I want notification to program real HW that’s backing the 802.3ad bond. For an active slave, the HW port corresponding to slave would be included in HW hash for egress, as well as rx/tx LACP. For an inactive slave, the HW port only rx/tx LACP. Inactive port is not included in egress hash. Delayed notification when it’s safe (after state machines run) is fine.
Thank you Ding for working thru a safer design.
-scott
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