[patch net-next v10 06/13] net: sched: keep track of offloaded filters and check tc offload feature

[Jiri Pirko <jiri@resnulli.us>]

From: Jiri Pirko <jiri@mellanox.com>

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>
---
v4->v5:
- add tracking of binding of devs that are unable to offload and check
  that before block cbs call.
v3->v4:
- propagate netdev_ops->ndo_setup_tc error up to tcf_block_offload_bind
  caller
v2->v3:
- new patch
---
 include/net/sch_generic.h | 18 +++++++++++
 net/sched/cls_api.c       | 80 ++++++++++++++++++++++++++++++++++++++---------
 net/sched/cls_bpf.c       |  5 ++-
 net/sched/cls_flower.c    |  3 +-
 net/sched/cls_matchall.c  |  3 +-
 net/sched/cls_u32.c       | 13 ++++----
 6 files changed, 99 insertions(+), 23 deletions(-)

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index dba2214..ab86b64 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -289,8 +289,26 @@ struct tcf_block {
 	struct list_head cb_list;
 	struct list_head owner_list;
 	bool keep_dst;
+	unsigned int offloadcnt; /* Number of oddloaded filters */
+	unsigned int nooffloaddevcnt; /* Number of devs unable to do offload */
 };
 
+static inline void tcf_block_offload_inc(struct tcf_block *block, u32 *flags)
+{
+	if (*flags & TCA_CLS_FLAGS_IN_HW)
+		return;
+	*flags |= TCA_CLS_FLAGS_IN_HW;
+	block->offloadcnt++;
+}
+
+static inline void tcf_block_offload_dec(struct tcf_block *block, u32 *flags)
+{
+	if (!(*flags & TCA_CLS_FLAGS_IN_HW))
+		return;
+	*flags &= ~TCA_CLS_FLAGS_IN_HW;
+	block->offloadcnt--;
+}
+
 static inline void qdisc_cb_private_validate(const struct sk_buff *skb, int sz)
 {
 	struct qdisc_skb_cb *qcb;
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 8a130e2..0ff8ae9 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) {
diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c
index d79cc50..cf72aef 100644
--- a/net/sched/cls_bpf.c
+++ b/net/sched/cls_bpf.c
@@ -167,13 +167,16 @@ static int cls_bpf_offload_cmd(struct tcf_proto *tp, struct cls_bpf_prog *prog,
 	cls_bpf.exts_integrated = obj->exts_integrated;
 	cls_bpf.gen_flags = obj->gen_flags;
 
+	if (oldprog)
+		tcf_block_offload_dec(block, &oldprog->gen_flags);
+
 	err = tc_setup_cb_call(block, NULL, TC_SETUP_CLSBPF, &cls_bpf, skip_sw);
 	if (prog) {
 		if (err < 0) {
 			cls_bpf_offload_cmd(tp, oldprog, prog);
 			return err;
 		} else if (err > 0) {
-			prog->gen_flags |= TCA_CLS_FLAGS_IN_HW;
+			tcf_block_offload_inc(block, &prog->gen_flags);
 		}
 	}
 
diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index 6132a73..f61df19 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -229,6 +229,7 @@ static void fl_hw_destroy_filter(struct tcf_proto *tp, struct cls_fl_filter *f)
 
 	tc_setup_cb_call(block, &f->exts, TC_SETUP_CLSFLOWER,
 			 &cls_flower, false);
+	tcf_block_offload_dec(block, &f->flags);
 }
 
 static int fl_hw_replace_filter(struct tcf_proto *tp,
@@ -256,7 +257,7 @@ static int fl_hw_replace_filter(struct tcf_proto *tp,
 		fl_hw_destroy_filter(tp, f);
 		return err;
 	} else if (err > 0) {
-		f->flags |= TCA_CLS_FLAGS_IN_HW;
+		tcf_block_offload_inc(block, &f->flags);
 	}
 
 	if (skip_sw && !(f->flags & TCA_CLS_FLAGS_IN_HW))
diff --git a/net/sched/cls_matchall.c b/net/sched/cls_matchall.c
index 66d4e00..d0e57c8 100644
--- a/net/sched/cls_matchall.c
+++ b/net/sched/cls_matchall.c
@@ -81,6 +81,7 @@ static void mall_destroy_hw_filter(struct tcf_proto *tp,
 	cls_mall.cookie = cookie;
 
 	tc_setup_cb_call(block, NULL, TC_SETUP_CLSMATCHALL, &cls_mall, false);
+	tcf_block_offload_dec(block, &head->flags);
 }
 
 static int mall_replace_hw_filter(struct tcf_proto *tp,
@@ -103,7 +104,7 @@ static int mall_replace_hw_filter(struct tcf_proto *tp,
 		mall_destroy_hw_filter(tp, head, cookie);
 		return err;
 	} else if (err > 0) {
-		head->flags |= TCA_CLS_FLAGS_IN_HW;
+		tcf_block_offload_inc(block, &head->flags);
 	}
 
 	if (skip_sw && !(head->flags & TCA_CLS_FLAGS_IN_HW))
diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
index 507859c..020d328 100644
--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c
@@ -529,16 +529,17 @@ static int u32_replace_hw_hnode(struct tcf_proto *tp, struct tc_u_hnode *h,
 	return 0;
 }
 
-static void u32_remove_hw_knode(struct tcf_proto *tp, u32 handle)
+static void u32_remove_hw_knode(struct tcf_proto *tp, struct tc_u_knode *n)
 {
 	struct tcf_block *block = tp->chain->block;
 	struct tc_cls_u32_offload cls_u32 = {};
 
 	tc_cls_common_offload_init(&cls_u32.common, tp);
 	cls_u32.command = TC_CLSU32_DELETE_KNODE;
-	cls_u32.knode.handle = handle;
+	cls_u32.knode.handle = n->handle;
 
 	tc_setup_cb_call(block, NULL, TC_SETUP_CLSU32, &cls_u32, false);
+	tcf_block_offload_dec(block, &n->flags);
 }
 
 static int u32_replace_hw_knode(struct tcf_proto *tp, struct tc_u_knode *n,
@@ -567,10 +568,10 @@ static int u32_replace_hw_knode(struct tcf_proto *tp, struct tc_u_knode *n,
 
 	err = tc_setup_cb_call(block, NULL, TC_SETUP_CLSU32, &cls_u32, skip_sw);
 	if (err < 0) {
-		u32_remove_hw_knode(tp, n->handle);
+		u32_remove_hw_knode(tp, n);
 		return err;
 	} else if (err > 0) {
-		n->flags |= TCA_CLS_FLAGS_IN_HW;
+		tcf_block_offload_inc(block, &n->flags);
 	}
 
 	if (skip_sw && !(n->flags & TCA_CLS_FLAGS_IN_HW))
@@ -589,7 +590,7 @@ static void u32_clear_hnode(struct tcf_proto *tp, struct tc_u_hnode *ht)
 			RCU_INIT_POINTER(ht->ht[h],
 					 rtnl_dereference(n->next));
 			tcf_unbind_filter(tp, &n->res);
-			u32_remove_hw_knode(tp, n->handle);
+			u32_remove_hw_knode(tp, n);
 			idr_remove_ext(&ht->handle_idr, n->handle);
 			if (tcf_exts_get_net(&n->exts))
 				call_rcu(&n->rcu, u32_delete_key_freepf_rcu);
@@ -682,7 +683,7 @@ static int u32_delete(struct tcf_proto *tp, void *arg, bool *last)
 		goto out;
 
 	if (TC_U32_KEY(ht->handle)) {
-		u32_remove_hw_knode(tp, ht->handle);
+		u32_remove_hw_knode(tp, (struct tc_u_knode *)ht);
 		ret = u32_delete_key(tp, (struct tc_u_knode *)ht);
 		goto out;
 	}
-- 
2.9.5