On Wed, Jul 31, 2024 at 6:56 PM Jacob Keller <jacob.e.kel...@intel.com> wrote:
>
> When adding a switch filter (such as a MAC or VLAN filter), it is expected
> that the driver will detect the case where the filter already exists, and
> return -EEXIST. This is used by calling code such as ice_vc_add_mac_addr,
> and ice_vsi_add_vlan to avoid incrementing the accounting fields such as
> vsi->num_vlan or vf->num_mac.
>
> This logic works correctly for the case where only a single VSI has added a
> given switch filter.
>
> When a second VSI adds the same switch filter, the driver converts the
> existing filter from an ICE_FWD_TO_VSI filter into an ICE_FWD_TO_VSI_LIST
> filter. This saves switch resources, by ensuring that multiple VSIs can
> re-use the same filter.
>
> The ice_add_update_vsi_list() function is responsible for doing this
> conversion. When first converting a filter from the FWD_TO_VSI into
> FWD_TO_VSI_LIST, it checks if the VSI being added is the same as the
> existing rule's VSI. In such a case it returns -EEXIST.
>
> However, when the switch rule has already been converted to a
> FWD_TO_VSI_LIST, the logic is different. Adding a new VSI in this case just
> requires extending the VSI list entry. The logic for checking if the rule
> already exists in this case returns 0 instead of -EEXIST.
>
> This breaks the accounting logic mentioned above, so the counters for how
> many MAC and VLAN filters exist for a given VF or VSI no longer accurately
> reflect the actual count. This breaks other code which relies on these
> counts.
>
> In typical usage this primarily affects such filters generally shared by
> multiple VSIs such as VLAN 0, or broadcast and multicast MAC addresses.
>
> Fix this by correctly reporting -EEXIST in the case of adding the same VSI
> to a switch rule already converted to ICE_FWD_TO_VSI_LIST.
>
> Fixes: 9daf8208dd4d ("ice: Add support for switch filter programming")
> Signed-off-by: Jacob Keller <jacob.e.kel...@intel.com>
> ---
> ---
> drivers/net/ethernet/intel/ice/ice_switch.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/intel/ice/ice_switch.c
> b/drivers/net/ethernet/intel/ice/ice_switch.c
> index fe8847184cb1..0160f0bae8d6 100644
Reviewed-by: Michal Schmidt <mschm...@redhat.com>
