[PATCH] i40e: improve locking of mac_filter_hash

[Stefan Assmann]

i40e_config_vf_promiscuous_mode() calls
i40e_getnum_vf_vsi_vlan_filters() without acquiring the
mac_filter_hash_lock spinlock.

This is unsafe because mac_filter_hash may get altered in another thread
while i40e_getnum_vf_vsi_vlan_filters() traverses the hashes.

Simply adding the spinlock in i40e_getnum_vf_vsi_vlan_filters() is not
possible as it already gets called in i40e_get_vlan_list_sync() with the
spinlock held. Therefore adding a wrapper that acquires the spinlock and
call the correct function where appropriate.

Fixes: 37d318d7805f ("i40e: Remove scheduling while atomic possibility")
Fix-suggested-by: Paolo Abeni <pab...@redhat.com>
Signed-off-by: Stefan Assmann <sassm...@kpanic.de>
---
 .../ethernet/intel/i40e/i40e_virtchnl_pf.c    | 23 ++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c 
b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
index 1b6ec9be155a..61d3e9a00f65 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
@@ -1101,12 +1101,12 @@ static int i40e_quiesce_vf_pci(struct i40e_vf *vf)
 }
 
 /**
- * i40e_getnum_vf_vsi_vlan_filters
+ * __i40e_getnum_vf_vsi_vlan_filters
  * @vsi: pointer to the vsi
  *
  * called to get the number of VLANs offloaded on this VF
  **/
-static int i40e_getnum_vf_vsi_vlan_filters(struct i40e_vsi *vsi)
+static int __i40e_getnum_vf_vsi_vlan_filters(struct i40e_vsi *vsi)
 {
        struct i40e_mac_filter *f;
        u16 num_vlans = 0, bkt;
@@ -1119,6 +1119,23 @@ static int i40e_getnum_vf_vsi_vlan_filters(struct 
i40e_vsi *vsi)
        return num_vlans;
 }
 
+/**
+ * i40e_getnum_vf_vsi_vlan_filters
+ * @vsi: pointer to the vsi
+ *
+ * wrapper for __i40e_getnum_vf_vsi_vlan_filters() with spinlock held
+ **/
+static int i40e_getnum_vf_vsi_vlan_filters(struct i40e_vsi *vsi)
+{
+       int num_vlans;
+
+       spin_lock_bh(&vsi->mac_filter_hash_lock);
+       num_vlans = __i40e_getnum_vf_vsi_vlan_filters(vsi);
+       spin_unlock_bh(&vsi->mac_filter_hash_lock);
+
+       return num_vlans;
+}
+
 /**
  * i40e_get_vlan_list_sync
  * @vsi: pointer to the VSI
@@ -1136,7 +1153,7 @@ static void i40e_get_vlan_list_sync(struct i40e_vsi *vsi, 
u16 *num_vlans,
        int bkt;
 
        spin_lock_bh(&vsi->mac_filter_hash_lock);
-       *num_vlans = i40e_getnum_vf_vsi_vlan_filters(vsi);
+       *num_vlans = __i40e_getnum_vf_vsi_vlan_filters(vsi);
        *vlan_list = kcalloc(*num_vlans, sizeof(**vlan_list), GFP_ATOMIC);
        if (!(*vlan_list))
                goto err;
-- 
2.29.2