bonding: 3ad: Fix the conflict between bond_update_slave_arr and the state machine

The bond works in mode 4, and performs down/up operations on the bond
that is normally negotiated. The probability of bond-> slave_arr is NULL

Test commands:
   ifconfig bond1 down
   ifconfig bond1 up

The conflict occurs in the following process：

__dev_open (CPU A)
--bond_open
  --queue_delayed_work(bond->wq,&bond->ad_work,0);
  --bond_update_slave_arr
    --bond_3ad_get_active_agg_info

ad_work(CPU B)
--bond_3ad_state_machine_handler
  --ad_agg_selection_logic

ad_work runs on cpu B. In the function ad_agg_selection_logic, all
agg->is_active will be cleared. Before the new active aggregator is
selected on CPU B, bond_3ad_get_active_agg_info failed on CPU A,
bond->slave_arr will be set to NULL. The best aggregator in
ad_agg_selection_logic has not changed, no need to update slave arr.

The conflict occurred in that ad_agg_selection_logic clears
agg->is_active under mode_lock, but bond_open -> bond_update_slave_arr
is inspecting agg->is_active outside the lock.

Also, bond_update_slave_arr is normal for potential sleep when
allocating memory, so replace the WARN_ON with a call to might_sleep.

Signed-off-by: jinyiting <jinyiting@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 74cbbb2..83ef62d 100644 (file)
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -4391,9 +4391,7 @@ int bond_update_slave_arr(struct bonding *bond, struct slave *skipslave)
        int agg_id = 0;
        int ret = 0;
 
-#ifdef CONFIG_LOCKDEP
-       WARN_ON(lockdep_is_held(&bond->mode_lock));
-#endif
+       might_sleep();
 
        usable_slaves = kzalloc(struct_size(usable_slaves, arr,
                                            bond->slave_cnt), GFP_KERNEL);
@@ -4406,7 +4404,9 @@ int bond_update_slave_arr(struct bonding *bond, struct slave *skipslave)
        if (BOND_MODE(bond) == BOND_MODE_8023AD) {
                struct ad_info ad_info;
 
+               spin_lock_bh(&bond->mode_lock);
                if (bond_3ad_get_active_agg_info(bond, &ad_info)) {
+                       spin_unlock_bh(&bond->mode_lock);
                        pr_debug("bond_3ad_get_active_agg_info failed\n");
                        /* No active aggragator means it's not safe to use
                         * the previous array.
@@ -4414,6 +4414,7 @@ int bond_update_slave_arr(struct bonding *bond, struct slave *skipslave)
                        bond_reset_slave_arr(bond);
                        goto out;
                }
+               spin_unlock_bh(&bond->mode_lock);
                agg_id = ad_info.aggregator_id;
        }
        bond_for_each_slave(bond, slave, iter) {