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bonding: fix system hang due to fast igmp timer rescheduling 

After commit 4aa5dee4d9 ("net: convert resend IGMP to notifier event")
we try to acquire rtnl in bond_resend_igmp_join_requests but it can be
scheduled with rtnl already held (e.g. when bond_change_active_slave is
called with rtnl) causing a loop of immediate reschedules + calls because
rtnl_trylock fails each time since it's being already held.
For me this issue leads to system hangs very easy:
modprobe bonding; ifconfig bond0 up; ifenslave bond0 eth0; rmmod
bonding;

The fix is to introduce a small (1 jiffy) delay which is enough for the
sections holding rtnl to finish without putting any strain on the system.
Also adjust the timer in bond_change_active_slave to be 1 jiffy, since
most of the time it's called with rtnl already held.

Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Nikolay Aleksandrov 2013-08-01 11:51:42 +02:00 committed by David S. Miller
parent 9ab5ec59c8
commit 4beac0293f
1 changed files with 2 additions and 2 deletions
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4
drivers/net/bonding/bond_main.c
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@ -723,7 +723,7 @@ static int bond_set_allmulti(struct bonding *bond, int inc)
static void bond_resend_igmp_join_requests(struct bonding *bond)
{
if (!rtnl_trylock()) {
queue_delayed_work(bond->wq, &bond->mcast_work, 0);
queue_delayed_work(bond->wq, &bond->mcast_work, 1);
return;
}
call_netdevice_notifiers(NETDEV_RESEND_IGMP, bond->dev);
@ -1084,7 +1084,7 @@ void bond_change_active_slave(struct bonding *bond, struct slave *new_active)
((USES_PRIMARY(bond->params.mode) && new_active) ||
bond->params.mode == BOND_MODE_ROUNDROBIN)) {
bond->igmp_retrans = bond->params.resend_igmp;
queue_delayed_work(bond->wq, &bond->mcast_work, 0);
queue_delayed_work(bond->wq, &bond->mcast_work, 1);
}
}