sfc: Take mac_lock before calling efx_ef10_filter_table_probe

When trying to enslave an SFC interface to a bond the following BUG_ON was
hit:

 kernel BUG [in ef10.c]!
 CPU: 0 PID: 4383 Comm: ifenslave Tainted: G
...
 Call Trace:
  efx_ef10_filter_add_vlan+0x121/0x180 [sfc]
  efx_ef10_filter_table_probe+0x2a2/0x4f0 [sfc]
  efx_ef10_set_mac_address+0x370/0x6d0 [sfc]
  efx_set_mac_address+0x7d/0x120 [sfc]
  dev_set_mac_address+0x43/0xa0
  bond_enslave+0x337/0xea0 [bonding]
This comes from function efx_ef10_filter_vlan_sync_rx_mode.

To solve the bug we ensure the mac_lock is taken before calling
efx_ef10_filter_add_vlan. But to avoid a priority inversion mac_lock must
be taken before filter_sem.
To satisfy these requirements we end up taking mac_lock in
efx_ef10_vport_set_mac_address, efx_ef10_set_mac_address,
efx_ef10_sriov_set_vf_vlan and efx_probe_filters.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c
index a3c00ffae8a0..add9f46542fc 100644
--- a/drivers/net/ethernet/sfc/ef10.c
+++ b/drivers/net/ethernet/sfc/ef10.c
@@ -4666,6 +4666,8 @@ static int efx_ef10_set_mac_address(struct efx_nic *efx)
 
 	efx_device_detach_sync(efx);
 	efx_net_stop(efx->net_dev);
+
+	mutex_lock(&efx->mac_lock);
 	down_write(&efx->filter_sem);
 	efx_ef10_filter_table_remove(efx);
 
@@ -4678,6 +4680,8 @@ static int efx_ef10_set_mac_address(struct efx_nic *efx)
 
 	efx_ef10_filter_table_probe(efx);
 	up_write(&efx->filter_sem);
+	mutex_unlock(&efx->mac_lock);
+
 	if (was_enabled)
 		efx_net_open(efx->net_dev);
 	netif_device_attach(efx->net_dev);