[PATCH net-next v2 04/10] net: sched: notify classifier on successful offload add/delete

[Vlad Buslov <vladbu@mellanox.com>]

To remove dependency on rtnl lock, extend classifier ops with new
ops->hw_add() and ops->hw_del() callbacks. Call them from cls API while
holding cb_lock every time filter if successfully added to or deleted from
hardware.

Implement the new API in flower classifier. Use it to manage hw_filters
list under cb_lock protection, instead of relying on rtnl lock to
synchronize with concurrent fl_reoffload() call.

Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
---
Changes from V1 to V2:
  - Keep success flow unindented in tc_setup_cb_{add|replace}().

 include/net/sch_generic.h |  4 ++++
 net/sched/cls_api.c       | 19 +++++++++++++++++--
 net/sched/cls_flower.c    | 33 ++++++++++++++++++++++++++-------
 3 files changed, 47 insertions(+), 9 deletions(-)

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index f90e3b2a3065..c4fbbaff30a2 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -312,6 +312,10 @@ struct tcf_proto_ops {
 	int			(*reoffload)(struct tcf_proto *tp, bool add,
 					     flow_setup_cb_t *cb, void *cb_priv,
 					     struct netlink_ext_ack *extack);
+	void			(*hw_add)(struct tcf_proto *tp,
+					  void *type_data);
+	void			(*hw_del)(struct tcf_proto *tp,
+					  void *type_data);
 	void			(*bind_class)(void *, u32, unsigned long);
 	void *			(*tmplt_create)(struct net *net,
 						struct tcf_chain *chain,
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 157bf3599ce1..dd16cf171f51 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -3099,6 +3099,11 @@ int tc_setup_cb_add(struct tcf_block *block, struct tcf_proto *tp,
 	}
 
 	ok_count = __tc_setup_cb_call(block, type, type_data, err_stop);
+	if (ok_count < 0)
+		goto err_unlock;
+
+	if (tp->ops->hw_add)
+		tp->ops->hw_add(tp, type_data);
 	if (ok_count > 0)
 		tc_cls_offload_cnt_update(block, tp, in_hw_count, flags,
 					  ok_count, true);
@@ -3130,11 +3135,18 @@ int tc_setup_cb_replace(struct tcf_block *block, struct tcf_proto *tp,
 	}
 
 	tc_cls_offload_cnt_reset(block, tp, old_in_hw_count, old_flags);
+	if (tp->ops->hw_del)
+		tp->ops->hw_del(tp, type_data);
 
 	ok_count = __tc_setup_cb_call(block, type, type_data, err_stop);
+	if (ok_count < 0)
+		goto err_unlock;
+
+	if (tp->ops->hw_add)
+		tp->ops->hw_add(tp, type_data);
 	if (ok_count > 0)
-		tc_cls_offload_cnt_update(block, tp, new_in_hw_count, new_flags,
-					  ok_count, true);
+		tc_cls_offload_cnt_update(block, tp, new_in_hw_count,
+					  new_flags, ok_count, true);
 err_unlock:
 	up_read(&block->cb_lock);
 	return ok_count < 0 ? ok_count : 0;
@@ -3155,6 +3167,9 @@ int tc_setup_cb_destroy(struct tcf_block *block, struct tcf_proto *tp,
 	ok_count = __tc_setup_cb_call(block, type, type_data, err_stop);
 
 	tc_cls_offload_cnt_reset(block, tp, in_hw_count, flags);
+	if (tp->ops->hw_del)
+		tp->ops->hw_del(tp, type_data);
+
 	up_read(&block->cb_lock);
 	return ok_count < 0 ? ok_count : 0;
 }
diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index 0978ae4a1428..9a7fd6bcd0a5 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -421,9 +421,6 @@ static void fl_hw_destroy_filter(struct tcf_proto *tp, struct cls_fl_filter *f,
 
 	tc_setup_cb_destroy(block, tp, TC_SETUP_CLSFLOWER, &cls_flower, false,
 			    &f->flags, &f->in_hw_count, true);
-	spin_lock(&tp->lock);
-	list_del_init(&f->hw_list);
-	spin_unlock(&tp->lock);
 
 	if (!rtnl_held)
 		rtnl_unlock();
@@ -433,7 +430,6 @@ static int fl_hw_replace_filter(struct tcf_proto *tp,
 				struct cls_fl_filter *f, bool rtnl_held,
 				struct netlink_ext_ack *extack)
 {
-	struct cls_fl_head *head = fl_head_dereference(tp);
 	struct tcf_block *block = tp->chain->block;
 	struct flow_cls_offload cls_flower = {};
 	bool skip_sw = tc_skip_sw(f->flags);
@@ -480,9 +476,6 @@ static int fl_hw_replace_filter(struct tcf_proto *tp,
 		goto errout;
 	}
 
-	spin_lock(&tp->lock);
-	list_add(&f->hw_list, &head->hw_filters);
-	spin_unlock(&tp->lock);
 errout:
 	if (!rtnl_held)
 		rtnl_unlock();
@@ -1856,6 +1849,30 @@ static int fl_reoffload(struct tcf_proto *tp, bool add, flow_setup_cb_t *cb,
 	return 0;
 }
 
+static void fl_hw_add(struct tcf_proto *tp, void *type_data)
+{
+	struct flow_cls_offload *cls_flower = type_data;
+	struct cls_fl_filter *f =
+		(struct cls_fl_filter *) cls_flower->cookie;
+	struct cls_fl_head *head = fl_head_dereference(tp);
+
+	spin_lock(&tp->lock);
+	list_add(&f->hw_list, &head->hw_filters);
+	spin_unlock(&tp->lock);
+}
+
+static void fl_hw_del(struct tcf_proto *tp, void *type_data)
+{
+	struct flow_cls_offload *cls_flower = type_data;
+	struct cls_fl_filter *f =
+		(struct cls_fl_filter *) cls_flower->cookie;
+
+	spin_lock(&tp->lock);
+	if (!list_empty(&f->hw_list))
+		list_del_init(&f->hw_list);
+	spin_unlock(&tp->lock);
+}
+
 static int fl_hw_create_tmplt(struct tcf_chain *chain,
 			      struct fl_flow_tmplt *tmplt)
 {
@@ -2516,6 +2533,8 @@ static struct tcf_proto_ops cls_fl_ops __read_mostly = {
 	.delete		= fl_delete,
 	.walk		= fl_walk,
 	.reoffload	= fl_reoffload,
+	.hw_add		= fl_hw_add,
+	.hw_del		= fl_hw_del,
 	.dump		= fl_dump,
 	.bind_class	= fl_bind_class,
 	.tmplt_create	= fl_tmplt_create,
-- 
2.21.0