[PATCH net-next 11/17] sfc: Take mac_lock before calling efx_ef10_filter_table_probe

[Edward Cree]

From: Martin Habets <mhab...@solarflare.com>

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 <ec...@solarflare.com>
---
 drivers/net/ethernet/sfc/ef10.c       | 4 ++++
 drivers/net/ethernet/sfc/ef10_sriov.c | 7 +++++--
 drivers/net/ethernet/sfc/efx.c        | 2 ++
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c
index a3c00ff..add9f46 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);
diff --git a/drivers/net/ethernet/sfc/ef10_sriov.c 
b/drivers/net/ethernet/sfc/ef10_sriov.c
index 3c17f27..a76610a 100644
--- a/drivers/net/ethernet/sfc/ef10_sriov.c
+++ b/drivers/net/ethernet/sfc/ef10_sriov.c
@@ -554,6 +554,7 @@ int efx_ef10_sriov_set_vf_vlan(struct efx_nic *efx, int 
vf_i, u16 vlan,
                efx_device_detach_sync(vf->efx);
                efx_net_stop(vf->efx->net_dev);
 
+               mutex_lock(&vf->efx->mac_lock);
                down_write(&vf->efx->filter_sem);
                vf->efx->type->filter_table_remove(vf->efx);
 
@@ -630,6 +631,7 @@ restore_filters:
                        goto reset_nic_up_write;
 
                up_write(&vf->efx->filter_sem);
+               mutex_unlock(&vf->efx->mac_lock);
 
                up_write(&vf->efx->filter_sem);
 
@@ -642,9 +644,10 @@ restore_filters:
        return rc;
 
 reset_nic_up_write:
-       if (vf->efx)
+       if (vf->efx) {
                up_write(&vf->efx->filter_sem);
-
+               mutex_unlock(&vf->efx->mac_lock);
+       }
 reset_nic:
        if (vf->efx) {
                netif_err(efx, drv, efx->net_dev,
diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index 902bcf2..130ee17 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -1729,6 +1729,7 @@ static int efx_probe_filters(struct efx_nic *efx)
 
        spin_lock_init(&efx->filter_lock);
        init_rwsem(&efx->filter_sem);
+       mutex_lock(&efx->mac_lock);
        down_write(&efx->filter_sem);
        rc = efx->type->filter_table_probe(efx);
        if (rc)
@@ -1767,6 +1768,7 @@ static int efx_probe_filters(struct efx_nic *efx)
 #endif
 out_unlock:
        up_write(&efx->filter_sem);
+       mutex_unlock(&efx->mac_lock);
        return rc;
 }