The ice_vsi_add_vlan() function is used to add a VLAN filter for the target
VSI. This function prepares a filter in the switch table for the given VSI.
If it succeeds, the vsi->num_vlan counter is incremented.

It is not considered an error to add a VLAN which already exists in the
switch table, so the function explicitly checks and ignores -EEXIST. The
vsi->num_vlan counter is still incremented.

This seems incorrect, as it means we can double-count in the case where the
same VLAN is added twice by the caller. The actual table will have one less
filter than the count.

The ice_vsi_del_vlan() function similarly checks and handles the -ENOENT
condition for when deleting a filter that doesn't exist. This flow only
decrements the vsi->num_vlan if it actually deleted a filter.

The vsi->num_vlan counter is used only in a few places, primarily related
to tracking the number of non-zero VLANs. If the vsi->num_vlans gets out of
sync, then ice_vsi_num_non_zero_vlans() will incorrectly report more VLANs
than are present, and ice_vsi_has_non_zero_vlans() could return true
potentially in cases where there are only VLAN 0 filters left.

Fix this by only incrementing the vsi->num_vlan in the case where we
actually added an entry, and not in the case where the entry already
existed.

Fixes: a1ffafb0b4a4 ("ice: Support configuring the device to Double VLAN Mode")
Signed-off-by: Jacob Keller <[email protected]>
---
 drivers/net/ethernet/intel/ice/ice_vsi_vlan_lib.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_vsi_vlan_lib.c 
b/drivers/net/ethernet/intel/ice/ice_vsi_vlan_lib.c
index 2e9ad27cb9d1..6e8f2aab6080 100644
--- a/drivers/net/ethernet/intel/ice/ice_vsi_vlan_lib.c
+++ b/drivers/net/ethernet/intel/ice/ice_vsi_vlan_lib.c
@@ -45,14 +45,15 @@ int ice_vsi_add_vlan(struct ice_vsi *vsi, struct ice_vlan 
*vlan)
                return -EINVAL;
 
        err = ice_fltr_add_vlan(vsi, vlan);
-       if (err && err != -EEXIST) {
+       if (!err)
+               vsi->num_vlan++;
+       else if (err == -EEXIST)
+               err = 0;
+       else
                dev_err(ice_pf_to_dev(vsi->back), "Failure Adding VLAN %d on 
VSI %i, status %d\n",
                        vlan->vid, vsi->vsi_num, err);
-               return err;
-       }
 
-       vsi->num_vlan++;
-       return 0;
+       return err;
 }
 
 /**

---
base-commit: 02754103e1f75761066bd45d467b41ab5ad725e5
change-id: 20240508-e810-live-migration-jk-fix-vsi-vlan-counting-402c6d262e26

Best regards,
-- 
Jacob Keller <[email protected]>

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