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>