In VF lag mode when remove the bonding module without bring down the
bond device first, we could potentially have circular dependency when we
unload IB devices and also handle fib events:
1. The bond work starts first;
2. The "modprobe -rv bonding" process tries to release the bond device,
with the "pernet_ops_rwsem" lock hold;
3. The bond work blocks in unregister_netdevice_notifier() and waits for
the lock because fib event came right before;
4. The kernel fib module tries to free all the fib entries by broadcasting
the "FIB_EVENT_NH_DEL" event;
5. Upon the fib event this lag_mp module holds the fib lock and queue a
fib work.
So:
bond work -> modprobe task -> kernel fib module -> lag_mp -> bond work
Today we either reload IB devices in roce lag in nic mode or either handle
fib events in switchdev mode, but a new feature could change that we'll
need to reload IB devices also in switchdev mode so this is a future proof
fix as one may not notice this later.
Signed-off-by: Mark Zhang <markz@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
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