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 <pa...@netfilter.org>
---
v3: formerly known as "net: flow_offload: don't allow subsystem to reuse blocks"
    add flow_block_cb_is_busy() helper. Call it per driver to make it easier
    to remove this whenever the first driver client support for multiple
    subsystem offloads.

 drivers/net/ethernet/mellanox/mlx5/core/en_rep.c    |  4 ++++
 drivers/net/ethernet/mellanox/mlxsw/spectrum.c      |  4 ++++
 drivers/net/ethernet/mscc/ocelot_tc.c               |  3 +++
 drivers/net/ethernet/netronome/nfp/flower/offload.c |  4 ++++
 include/net/flow_offload.h                          |  3 +++
 net/core/flow_offload.c                             | 18 ++++++++++++++++++
 net/dsa/slave.c                                     |  3 +++
 7 files changed, 39 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c 
b/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c
index 19133b9e121a..e303149053e4 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c
@@ -721,6 +721,10 @@ 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;
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c 
b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
index 90a4241551ee..f5b4d5eaa35a 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -1696,6 +1696,10 @@ 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))
diff --git a/drivers/net/ethernet/mscc/ocelot_tc.c 
b/drivers/net/ethernet/mscc/ocelot_tc.c
index 9bca2cc77e6c..e7d2473129f0 100644
--- a/drivers/net/ethernet/mscc/ocelot_tc.c
+++ b/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);
diff --git a/drivers/net/ethernet/netronome/nfp/flower/offload.c 
b/drivers/net/ethernet/netronome/nfp/flower/offload.c
index 9ce61b6e8583..4bdbd322fddf 100644
--- a/drivers/net/ethernet/netronome/nfp/flower/offload.c
+++ b/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);
diff --git a/include/net/flow_offload.h b/include/net/flow_offload.h
index 7977508ec406..1751b31ea7e2 100644
--- a/include/net/flow_offload.h
+++ b/include/net/flow_offload.h
@@ -292,6 +292,9 @@ static inline void flow_block_cb_remove(struct 
flow_block_cb *block_cb,
        list_move(&block_cb->driver_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);
diff --git a/net/core/flow_offload.c b/net/core/flow_offload.c
index 4bea343d52a0..39219513181e 100644
--- a/net/core/flow_offload.c
+++ b/net/core/flow_offload.c
@@ -229,6 +229,21 @@ 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,
@@ -244,6 +259,9 @@ 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))
diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index d2e74d08c1c4..335580cfa486 100644
--- a/net/dsa/slave.c
+++ b/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);
-- 
2.11.0

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