• Nikolay Aleksandrov's avatar
    bonding: fix system hang due to fast igmp timer rescheduling · 4beac029
    Nikolay Aleksandrov authored
    After commit 4aa5dee4
     ("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
    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: default avatarNikolay Aleksandrov <nikolay@redhat.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>