bonding: eliminate bond_close race conditions
This patch resolves two sets of race conditions.
Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com> reported the
first, as follows:
The bond_close() calls cancel_delayed_work() to cancel delayed works.
It, however, cannot cancel works that were already queued in workqueue.
The bond_open() initializes work->data, and proccess_one_work() refers
get_work_cwq(work)->wq->flags. The get_work_cwq() returns NULL when
work->data has been initialized. Thus, a panic occurs.
He included a patch that converted the cancel_delayed_work calls
in bond_close to flush_delayed_work_sync, which eliminated the above
problem.
His patch is incorporated, at least in principle, into this
patch. In this patch, we use cancel_delayed_work_sync in place of
flush_delayed_work_sync, and also convert bond_uninit in addition to
bond_close.
This conversion to _sync, however, opens new races between
bond_close and three periodically executing workqueue functions:
bond_mii_monitor, bond_alb_monitor and bond_activebackup_arp_mon.
The race occurs because bond_close and bond_uninit are always
called with RTNL held, and these workqueue functions may acquire RTNL to
perform failover-related activities. If bond_close or bond_uninit is
waiting in cancel_delayed_work_sync, deadlock occurs.
These deadlocks are resolved by having the workqueue functions
acquire RTNL conditionally. If the rtnl_trylock() fails, the functions
reschedule and return immediately. For the cases that are attempting to
perform link failover, a delay of 1 is used; for the other cases, the
normal interval is used (as those activities are not as time critical).
Additionally, the bond_mii_monitor function now stores the delay
in a variable (mimicing the structure of activebackup_arp_mon).
Lastly, all of the above renders the kill_timers sentinel moot,
and therefore it has been removed.
Tested-by: Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>
Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
index b33c099..0ae0d7c 100644
--- a/drivers/net/bonding/bond_3ad.c
+++ b/drivers/net/bonding/bond_3ad.c
@@ -2110,9 +2110,6 @@
read_lock(&bond->lock);
- if (bond->kill_timers)
- goto out;
-
//check if there are any slaves
if (bond->slave_cnt == 0)
goto re_arm;
@@ -2161,9 +2158,8 @@
}
re_arm:
- if (!bond->kill_timers)
- queue_delayed_work(bond->wq, &bond->ad_work, ad_delta_in_ticks);
-out:
+ queue_delayed_work(bond->wq, &bond->ad_work, ad_delta_in_ticks);
+
read_unlock(&bond->lock);
}
diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
index d4fbd2e..106b88a 100644
--- a/drivers/net/bonding/bond_alb.c
+++ b/drivers/net/bonding/bond_alb.c
@@ -1343,10 +1343,6 @@
read_lock(&bond->lock);
- if (bond->kill_timers) {
- goto out;
- }
-
if (bond->slave_cnt == 0) {
bond_info->tx_rebalance_counter = 0;
bond_info->lp_counter = 0;
@@ -1401,10 +1397,13 @@
/*
* dev_set_promiscuity requires rtnl and
- * nothing else.
+ * nothing else. Avoid race with bond_close.
*/
read_unlock(&bond->lock);
- rtnl_lock();
+ if (!rtnl_trylock()) {
+ read_lock(&bond->lock);
+ goto re_arm;
+ }
bond_info->rlb_promisc_timeout_counter = 0;
@@ -1440,9 +1439,8 @@
}
re_arm:
- if (!bond->kill_timers)
- queue_delayed_work(bond->wq, &bond->alb_work, alb_delta_in_ticks);
-out:
+ queue_delayed_work(bond->wq, &bond->alb_work, alb_delta_in_ticks);
+
read_unlock(&bond->lock);
}
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index c5944f1..c34cc1e 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -773,9 +773,6 @@
read_lock(&bond->lock);
- if (bond->kill_timers)
- goto out;
-
/* rejoin all groups on bond device */
__bond_resend_igmp_join_requests(bond->dev);
@@ -789,9 +786,9 @@
__bond_resend_igmp_join_requests(vlan_dev);
}
- if ((--bond->igmp_retrans > 0) && !bond->kill_timers)
+ if (--bond->igmp_retrans > 0)
queue_delayed_work(bond->wq, &bond->mcast_work, HZ/5);
-out:
+
read_unlock(&bond->lock);
}
@@ -2517,10 +2514,11 @@
struct bonding *bond = container_of(work, struct bonding,
mii_work.work);
bool should_notify_peers = false;
+ unsigned long delay;
read_lock(&bond->lock);
- if (bond->kill_timers)
- goto out;
+
+ delay = msecs_to_jiffies(bond->params.miimon);
if (bond->slave_cnt == 0)
goto re_arm;
@@ -2529,7 +2527,15 @@
if (bond_miimon_inspect(bond)) {
read_unlock(&bond->lock);
- rtnl_lock();
+
+ /* Race avoidance with bond_close cancel of workqueue */
+ if (!rtnl_trylock()) {
+ read_lock(&bond->lock);
+ delay = 1;
+ should_notify_peers = false;
+ goto re_arm;
+ }
+
read_lock(&bond->lock);
bond_miimon_commit(bond);
@@ -2540,14 +2546,18 @@
}
re_arm:
- if (bond->params.miimon && !bond->kill_timers)
- queue_delayed_work(bond->wq, &bond->mii_work,
- msecs_to_jiffies(bond->params.miimon));
-out:
+ if (bond->params.miimon)
+ queue_delayed_work(bond->wq, &bond->mii_work, delay);
+
read_unlock(&bond->lock);
if (should_notify_peers) {
- rtnl_lock();
+ if (!rtnl_trylock()) {
+ read_lock(&bond->lock);
+ bond->send_peer_notif++;
+ read_unlock(&bond->lock);
+ return;
+ }
netdev_bonding_change(bond->dev, NETDEV_NOTIFY_PEERS);
rtnl_unlock();
}
@@ -2789,9 +2799,6 @@
delta_in_ticks = msecs_to_jiffies(bond->params.arp_interval);
- if (bond->kill_timers)
- goto out;
-
if (bond->slave_cnt == 0)
goto re_arm;
@@ -2888,9 +2895,9 @@
}
re_arm:
- if (bond->params.arp_interval && !bond->kill_timers)
+ if (bond->params.arp_interval)
queue_delayed_work(bond->wq, &bond->arp_work, delta_in_ticks);
-out:
+
read_unlock(&bond->lock);
}
@@ -3131,9 +3138,6 @@
read_lock(&bond->lock);
- if (bond->kill_timers)
- goto out;
-
delta_in_ticks = msecs_to_jiffies(bond->params.arp_interval);
if (bond->slave_cnt == 0)
@@ -3143,7 +3147,15 @@
if (bond_ab_arp_inspect(bond, delta_in_ticks)) {
read_unlock(&bond->lock);
- rtnl_lock();
+
+ /* 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, delta_in_ticks);
@@ -3156,13 +3168,18 @@
bond_ab_arp_probe(bond);
re_arm:
- if (bond->params.arp_interval && !bond->kill_timers)
+ if (bond->params.arp_interval)
queue_delayed_work(bond->wq, &bond->arp_work, delta_in_ticks);
-out:
+
read_unlock(&bond->lock);
if (should_notify_peers) {
- rtnl_lock();
+ if (!rtnl_trylock()) {
+ read_lock(&bond->lock);
+ bond->send_peer_notif++;
+ read_unlock(&bond->lock);
+ return;
+ }
netdev_bonding_change(bond->dev, NETDEV_NOTIFY_PEERS);
rtnl_unlock();
}
@@ -3424,8 +3441,6 @@
struct slave *slave;
int i;
- bond->kill_timers = 0;
-
/* reset slave->backup and slave->inactive */
read_lock(&bond->lock);
if (bond->slave_cnt > 0) {
@@ -3494,33 +3509,30 @@
bond->send_peer_notif = 0;
- /* signal timers not to re-arm */
- bond->kill_timers = 1;
-
write_unlock_bh(&bond->lock);
if (bond->params.miimon) { /* link check interval, in milliseconds. */
- cancel_delayed_work(&bond->mii_work);
+ cancel_delayed_work_sync(&bond->mii_work);
}
if (bond->params.arp_interval) { /* arp interval, in milliseconds. */
- cancel_delayed_work(&bond->arp_work);
+ cancel_delayed_work_sync(&bond->arp_work);
}
switch (bond->params.mode) {
case BOND_MODE_8023AD:
- cancel_delayed_work(&bond->ad_work);
+ cancel_delayed_work_sync(&bond->ad_work);
break;
case BOND_MODE_TLB:
case BOND_MODE_ALB:
- cancel_delayed_work(&bond->alb_work);
+ cancel_delayed_work_sync(&bond->alb_work);
break;
default:
break;
}
if (delayed_work_pending(&bond->mcast_work))
- cancel_delayed_work(&bond->mcast_work);
+ cancel_delayed_work_sync(&bond->mcast_work);
if (bond_is_lb(bond)) {
/* Must be called only after all
@@ -4367,26 +4379,22 @@
static void bond_work_cancel_all(struct bonding *bond)
{
- write_lock_bh(&bond->lock);
- bond->kill_timers = 1;
- write_unlock_bh(&bond->lock);
-
if (bond->params.miimon && delayed_work_pending(&bond->mii_work))
- cancel_delayed_work(&bond->mii_work);
+ cancel_delayed_work_sync(&bond->mii_work);
if (bond->params.arp_interval && delayed_work_pending(&bond->arp_work))
- cancel_delayed_work(&bond->arp_work);
+ cancel_delayed_work_sync(&bond->arp_work);
if (bond->params.mode == BOND_MODE_ALB &&
delayed_work_pending(&bond->alb_work))
- cancel_delayed_work(&bond->alb_work);
+ cancel_delayed_work_sync(&bond->alb_work);
if (bond->params.mode == BOND_MODE_8023AD &&
delayed_work_pending(&bond->ad_work))
- cancel_delayed_work(&bond->ad_work);
+ cancel_delayed_work_sync(&bond->ad_work);
if (delayed_work_pending(&bond->mcast_work))
- cancel_delayed_work(&bond->mcast_work);
+ cancel_delayed_work_sync(&bond->mcast_work);
}
/*
diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
index 82fec5f..1aecc37 100644
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -222,7 +222,6 @@
struct slave *);
rwlock_t lock;
rwlock_t curr_slave_lock;
- s8 kill_timers;
u8 send_peer_notif;
s8 setup_by_slave;
s8 igmp_retrans;