net: sched: introduce tcf block infractructure

Currently, the filter chains are direcly put into the private structures
of qdiscs. In order to be able to have multiple chains per qdisc and to
allow filter chains sharing among qdiscs, there is a need for common
object that would hold the chains. This introduces such object and calls
it "tcf_block".

Helpers to get and put the blocks are provided to be called from
individual qdisc code. Also, the original filter_list pointers are left
in qdisc privs to allow the entry into tcf_block processing without any
added overhead of possible multiple pointer dereference on fast path.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c
index 42ba81a..f201e73 100644
--- a/net/sched/sch_fq_codel.c
+++ b/net/sched/sch_fq_codel.c
@@ -55,6 +55,7 @@
 
 struct fq_codel_sched_data {
 	struct tcf_proto __rcu *filter_list; /* optional external classifier */
+	struct tcf_block *block;
 	struct fq_codel_flow *flows;	/* Flows table [flows_cnt] */
 	u32		*backlogs;	/* backlog table [flows_cnt] */
 	u32		flows_cnt;	/* number of flows */
@@ -450,7 +451,7 @@
 {
 	struct fq_codel_sched_data *q = qdisc_priv(sch);
 
-	tcf_destroy_chain(&q->filter_list);
+	tcf_block_put(q->block);
 	kvfree(q->backlogs);
 	kvfree(q->flows);
 }
@@ -459,6 +460,7 @@
 {
 	struct fq_codel_sched_data *q = qdisc_priv(sch);
 	int i;
+	int err;
 
 	sch->limit = 10*1024;
 	q->flows_cnt = 1024;
@@ -478,6 +480,10 @@
 			return err;
 	}
 
+	err = tcf_block_get(&q->block, &q->filter_list);
+	if (err)
+		return err;
+
 	if (!q->flows) {
 		q->flows = kvzalloc(q->flows_cnt *
 					   sizeof(struct fq_codel_flow), GFP_KERNEL);
@@ -589,14 +595,13 @@
 {
 }
 
-static struct tcf_proto __rcu **fq_codel_find_tcf(struct Qdisc *sch,
-						  unsigned long cl)
+static struct tcf_block *fq_codel_tcf_block(struct Qdisc *sch, unsigned long cl)
 {
 	struct fq_codel_sched_data *q = qdisc_priv(sch);
 
 	if (cl)
 		return NULL;
-	return &q->filter_list;
+	return q->block;
 }
 
 static int fq_codel_dump_class(struct Qdisc *sch, unsigned long cl,
@@ -679,7 +684,7 @@
 	.leaf		=	fq_codel_leaf,
 	.get		=	fq_codel_get,
 	.put		=	fq_codel_put,
-	.tcf_chain	=	fq_codel_find_tcf,
+	.tcf_block	=	fq_codel_tcf_block,
 	.bind_tcf	=	fq_codel_bind,
 	.unbind_tcf	=	fq_codel_put,
 	.dump		=	fq_codel_dump_class,