net: flow_offload: add flow_block_cb_is_busy() and use it

This patch adds a function to check if flow block callback is already in
use.  Call this new function from flow_block_cb_setup_simple() and from
drivers.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx5/core/en_rep.c

@@ -722,6 +722,10 @@ mlx5e_rep_indr_setup_tc_block(struct net_device *netdev,
 		if (indr_priv)
 			return -EEXIST;
 
+		if (flow_block_cb_is_busy(mlx5e_rep_indr_setup_block_cb,
+					  indr_priv, &mlx5e_block_cb_list))
+			return -EBUSY;
+
 		indr_priv = kmalloc(sizeof(*indr_priv), GFP_KERNEL);
 		if (!indr_priv)
 			return -ENOMEM;

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

@@ -1698,6 +1698,10 @@ static int mlxsw_sp_setup_tc_block(struct mlxsw_sp_port *mlxsw_sp_port,
 
 	switch (f->command) {
 	case FLOW_BLOCK_BIND:
+		if (flow_block_cb_is_busy(cb, mlxsw_sp_port,
+					  &mlxsw_sp_block_cb_list))
+			return -EBUSY;
+
 		block_cb = flow_block_cb_alloc(f->net, cb, mlxsw_sp_port,
 					       mlxsw_sp_port, NULL);
 		if (IS_ERR(block_cb))

drivers/net/ethernet/mscc/ocelot_tc.c

@@ -153,6 +153,9 @@ static int ocelot_setup_tc_block(struct ocelot_port *port,
 
 	switch (f->command) {
 	case FLOW_BLOCK_BIND:
+		if (flow_block_cb_is_busy(cb, port, &ocelot_block_cb_list))
+			return -EBUSY;
+
 		block_cb = flow_block_cb_alloc(f->net, cb, port, port, NULL);
 		if (IS_ERR(block_cb))
 			return PTR_ERR(block_cb);

drivers/net/ethernet/netronome/nfp/flower/offload.c

@@ -1320,6 +1320,10 @@ static int nfp_flower_setup_tc_block(struct net_device *netdev,
 
 	switch (f->command) {
 	case FLOW_BLOCK_BIND:
+		if (flow_block_cb_is_busy(nfp_flower_setup_tc_block_cb, repr,
+					  &nfp_block_cb_list))
+			return -EBUSY;
+
 		block_cb = flow_block_cb_alloc(f->net,
 					       nfp_flower_setup_tc_block_cb,
 					       repr, repr, NULL);

include/net/flow_offload.h

@@ -296,6 +296,9 @@ static inline void flow_block_cb_remove(struct flow_block_cb *block_cb,
 	list_move(&block_cb->list, &offload->cb_list);
 }
 
+bool flow_block_cb_is_busy(tc_setup_cb_t *cb, void *cb_ident,
+			   struct list_head *driver_block_list);
+
 int flow_block_cb_setup_simple(struct flow_block_offload *f,
 			       struct list_head *driver_list, tc_setup_cb_t *cb,
 			       void *cb_ident, void *cb_priv, bool ingress_only);

net/core/flow_offload.c

@@ -228,6 +228,21 @@ unsigned int flow_block_cb_decref(struct flow_block_cb *block_cb)
 }
 EXPORT_SYMBOL(flow_block_cb_decref);
 
+bool flow_block_cb_is_busy(tc_setup_cb_t *cb, void *cb_ident,
+			   struct list_head *driver_block_list)
+{
+	struct flow_block_cb *block_cb;
+
+	list_for_each_entry(block_cb, driver_block_list, driver_list) {
+		if (block_cb->cb == cb &&
+		    block_cb->cb_ident == cb_ident)
+			return true;
+	}
+
+	return false;
+}
+EXPORT_SYMBOL(flow_block_cb_is_busy);
+
 int flow_block_cb_setup_simple(struct flow_block_offload *f,
 			       struct list_head *driver_block_list,
 			       tc_setup_cb_t *cb, void *cb_ident, void *cb_priv,
@@ -243,6 +258,9 @@ int flow_block_cb_setup_simple(struct flow_block_offload *f,
 
 	switch (f->command) {
 	case FLOW_BLOCK_BIND:
+		if (flow_block_cb_is_busy(cb, cb_ident, driver_block_list))
+			return -EBUSY;
+
 		block_cb = flow_block_cb_alloc(f->net, cb, cb_ident,
 					       cb_priv, NULL);
 		if (IS_ERR(block_cb))

net/dsa/slave.c

@@ -961,6 +961,9 @@ static int dsa_slave_setup_tc_block(struct net_device *dev,
 
 	switch (f->command) {
 	case FLOW_BLOCK_BIND:
+		if (flow_block_cb_is_busy(cb, dev, &dsa_slave_block_cb_list))
+			return -EBUSY;
+
 		block_cb = flow_block_cb_alloc(f->net, cb, dev, dev, NULL);
 		if (IS_ERR(block_cb))
 			return PTR_ERR(block_cb);