RE: [Intel-wired-lan] [PATCH] i40e: improve locking of mac_filter_hash

-----Original Message-----
From: Intel-wired-lan <redacted> On Behalf Of
Stefan Assmann
Sent: czwartek, 4 marca 2021 10:35
To: intel-wired-lan@lists.osuosl.org
Cc: pabeni@redhat.com; netdev@vger.kernel.org; sassmann@kpanic.de
Subject: [Intel-wired-lan] [PATCH] i40e: improve locking of mac_filter_hash

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 [off-list ref]
Signed-off-by: Stefan Assmann <redacted>
---
 .../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