mlxsw: spectrum_mr: Update egress RIF list before route's action

commit cbaf3f6 upstream.

Each multicast route that is forwarding packets (as opposed to trapping
them) points to a list of egress router interfaces (RIFs) through which
packets are replicated.

A route's action can transition from trap to forward when a RIF is
created for one of the route's egress virtual interfaces (eVIF). When
this happens, the route's action is first updated and only later the
list of egress RIFs is committed to the device.

This results in the route pointing to an invalid list. In case the list
pointer is out of range (due to uninitialized memory), the device will
complain:

mlxsw_spectrum2 0000:06:00.0: EMAD reg access failed (tid=5733bf490000905c,reg_id=300f(pefa),type=write,status=7(bad parameter))

Fix this by first committing the list of egress RIFs to the device and
only later update the route's action.

Note that a fix is not needed in the reverse function (i.e.,
mlxsw_sp_mr_route_evif_unresolve()), as there the route's action is
first updated and only later the RIF is removed from the list.

Cc: stable@vger.kernel.org
Fixes: c011ec1 ("mlxsw: spectrum: Add the multicast routing offloading logic")
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Link: https://lore.kernel.org/r/20210506072308.3834303-1-idosch@idosch.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/ethernet/mellanox/mlxsw/spectrum_mr.c

@@ -535,6 +535,16 @@ mlxsw_sp_mr_route_evif_resolve(struct mlxsw_sp_mr_table *mr_table,
 	u16 erif_index = 0;
 	int err;
 
+	/* Add the eRIF */
+	if (mlxsw_sp_mr_vif_valid(rve->mr_vif)) {
+		erif_index = mlxsw_sp_rif_index(rve->mr_vif->rif);
+		err = mr->mr_ops->route_erif_add(mlxsw_sp,
+						 rve->mr_route->route_priv,
+						 erif_index);
+		if (err)
+			return err;
+	}
+
 	/* Update the route action, as the new eVIF can be a tunnel or a pimreg
 	 * device which will require updating the action.
 	 */
@@ -544,17 +554,7 @@ mlxsw_sp_mr_route_evif_resolve(struct mlxsw_sp_mr_table *mr_table,
 						      rve->mr_route->route_priv,
 						      route_action);
 		if (err)
-			return err;
-	}
-
-	/* Add the eRIF */
-	if (mlxsw_sp_mr_vif_valid(rve->mr_vif)) {
-		erif_index = mlxsw_sp_rif_index(rve->mr_vif->rif);
-		err = mr->mr_ops->route_erif_add(mlxsw_sp,
-						 rve->mr_route->route_priv,
-						 erif_index);
-		if (err)
-			goto err_route_erif_add;
+			goto err_route_action_update;
 	}
 
 	/* Update the minimum MTU */
@@ -572,14 +572,14 @@ mlxsw_sp_mr_route_evif_resolve(struct mlxsw_sp_mr_table *mr_table,
 	return 0;
 
 err_route_min_mtu_update:
-	if (mlxsw_sp_mr_vif_valid(rve->mr_vif))
-		mr->mr_ops->route_erif_del(mlxsw_sp, rve->mr_route->route_priv,
-					   erif_index);
-err_route_erif_add:
 	if (route_action != rve->mr_route->route_action)
 		mr->mr_ops->route_action_update(mlxsw_sp,
 						rve->mr_route->route_priv,
 						rve->mr_route->route_action);
+err_route_action_update:
+	if (mlxsw_sp_mr_vif_valid(rve->mr_vif))
+		mr->mr_ops->route_erif_del(mlxsw_sp, rve->mr_route->route_priv,
+					   erif_index);
 	return err;
 }