bonding: verify if we still have slaves in bond_3ad_unbind_slave()

After commit 1f718f0f4f97145f4072d2d72dcf85069ca7226d ("bonding: populate
neighbour's private on enslave"), we've moved the unlinking of the slave
to the earliest position possible - so that nobody will see an
half-uninited slave.

However, bond_3ad_unbind_slave() relied that, even while removing the last
slave, it is still accessible - via __get_first_agg() (and, eventually,
bond_first_slave()).

Fix that by verifying if the aggregator return is an actual aggregator, but
not NULL.

CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
index 1337eafe4311..2715ea87d64c 100644
--- a/drivers/net/bonding/bond_3ad.c
+++ b/drivers/net/bonding/bond_3ad.c
@@ -2056,7 +2056,9 @@ void bond_3ad_unbind_slave(struct slave *slave)
                                 pr_info("%s: Removing an active aggregator\n",
                                         slave->bond->dev->name);
                                 // select new active aggregator
-                                ad_agg_selection_logic(__get_first_agg(port));
+                                temp_aggregator = __get_first_agg(port);
+                                if (temp_aggregator)
+                                        ad_agg_selection_logic(temp_aggregator);
                         }
                 }
         }