net: sched: keep track of offloaded filters and check tc offload feature

During block bind, we need to check tc offload feature. If it is
disabled yet still the block contains offloaded filters, forbid the
bind. Also forbid to register callback for a block that already
contains offloaded filters, as the play back is not supported now.
For keeping track of offloaded filters there is a new counter
introduced, alongside with couple of helpers called from cls_* code.
These helpers set and clear TCA_CLS_FLAGS_IN_HW flag.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Acked-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 66 insertions, 14 deletions

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index e36d90c20f04..03e2fa092d9e 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -265,31 +265,66 @@ void tcf_chain_put(struct tcf_chain *chain)
 }
 EXPORT_SYMBOL(tcf_chain_put);
 
-static void tcf_block_offload_cmd(struct tcf_block *block, struct Qdisc *q,
-				  struct tcf_block_ext_info *ei,
-				  enum tc_block_command command)
+static bool tcf_block_offload_in_use(struct tcf_block *block)
+{
+	return block->offloadcnt;
+}
+
+static int tcf_block_offload_cmd(struct tcf_block *block,
+				 struct net_device *dev,
+				 struct tcf_block_ext_info *ei,
+				 enum tc_block_command command)
 {
-	struct net_device *dev = q->dev_queue->dev;
 	struct tc_block_offload bo = {};
 
-	if (!dev->netdev_ops->ndo_setup_tc)
-		return;
 	bo.command = command;
 	bo.binder_type = ei->binder_type;
 	bo.block = block;
-	dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_BLOCK, &bo);
+	return dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_BLOCK, &bo);
 }
 
-static void tcf_block_offload_bind(struct tcf_block *block, struct Qdisc *q,
-				   struct tcf_block_ext_info *ei)
+static int tcf_block_offload_bind(struct tcf_block *block, struct Qdisc *q,
+				  struct tcf_block_ext_info *ei)
 {
-	tcf_block_offload_cmd(block, q, ei, TC_BLOCK_BIND);
+	struct net_device *dev = q->dev_queue->dev;
+	int err;
+
+	if (!dev->netdev_ops->ndo_setup_tc)
+		goto no_offload_dev_inc;
+
+	/* If tc offload feature is disabled and the block we try to bind
+	 * to already has some offloaded filters, forbid to bind.
+	 */
+	if (!tc_can_offload(dev) && tcf_block_offload_in_use(block))
+		return -EOPNOTSUPP;
+
+	err = tcf_block_offload_cmd(block, dev, ei, TC_BLOCK_BIND);
+	if (err == -EOPNOTSUPP)
+		goto no_offload_dev_inc;
+	return err;
+
+no_offload_dev_inc:
+	if (tcf_block_offload_in_use(block))
+		return -EOPNOTSUPP;
+	block->nooffloaddevcnt++;
+	return 0;
 }
 
 static void tcf_block_offload_unbind(struct tcf_block *block, struct Qdisc *q,
 				     struct tcf_block_ext_info *ei)
 {
-	tcf_block_offload_cmd(block, q, ei, TC_BLOCK_UNBIND);
+	struct net_device *dev = q->dev_queue->dev;
+	int err;
+
+	if (!dev->netdev_ops->ndo_setup_tc)
+		goto no_offload_dev_dec;
+	err = tcf_block_offload_cmd(block, dev, ei, TC_BLOCK_UNBIND);
+	if (err == -EOPNOTSUPP)
+		goto no_offload_dev_dec;
+	return;
+
+no_offload_dev_dec:
+	WARN_ON(block->nooffloaddevcnt-- == 0);
 }
 
 static int
@@ -502,10 +537,16 @@ int tcf_block_get_ext(struct tcf_block **p_block, struct Qdisc *q,
 					   ei, extack);
 	if (err)
 		goto err_chain_head_change_cb_add;
-	tcf_block_offload_bind(block, q, ei);
+
+	err = tcf_block_offload_bind(block, q, ei);
+	if (err)
+		goto err_block_offload_bind;
+
 	*p_block = block;
 	return 0;
 
+err_block_offload_bind:
+	tcf_chain_head_change_cb_del(tcf_block_chain_zero(block), ei);
 err_chain_head_change_cb_add:
 	tcf_block_owner_del(block, q, ei->binder_type);
 err_block_owner_add:
@@ -637,9 +678,16 @@ struct tcf_block_cb *__tcf_block_cb_register(struct tcf_block *block,
 {
 	struct tcf_block_cb *block_cb;
 
+	/* At this point, playback of previous block cb calls is not supported,
+	 * so forbid to register to block which already has some offloaded
+	 * filters present.
+	 */
+	if (tcf_block_offload_in_use(block))
+		return ERR_PTR(-EOPNOTSUPP);
+
 	block_cb = kzalloc(sizeof(*block_cb), GFP_KERNEL);
 	if (!block_cb)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 	block_cb->cb = cb;
 	block_cb->cb_ident = cb_ident;
 	block_cb->cb_priv = cb_priv;
@@ -655,7 +703,7 @@ int tcf_block_cb_register(struct tcf_block *block,
 	struct tcf_block_cb *block_cb;
 
 	block_cb = __tcf_block_cb_register(block, cb, cb_ident, cb_priv);
-	return block_cb ? 0 : -ENOMEM;
+	return IS_ERR(block_cb) ? PTR_ERR(block_cb) : 0;
 }
 EXPORT_SYMBOL(tcf_block_cb_register);
 
@@ -685,6 +733,10 @@ static int tcf_block_cb_call(struct tcf_block *block, enum tc_setup_type type,
 	int ok_count = 0;
 	int err;
 
+	/* Make sure all netdevs sharing this block are offload-capable. */
+	if (block->nooffloaddevcnt && err_stop)
+		return -EOPNOTSUPP;
+
 	list_for_each_entry(block_cb, &block->cb_list, list) {
 		err = block_cb->cb(type, type_data, block_cb->cb_priv);
 		if (err) {