net: sched: flower: protect flower classifier state with spinlock

struct tcf_proto was extended with spinlock to be used by classifiers
instead of global rtnl lock. Use it to protect shared flower classifier
data structures (handle_idr, mask hashtable and list) and fields of
individual filters that can be accessed concurrently. This patch set uses
tcf_proto->lock as per instance lock that protects all filters on
tcf_proto.
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/cls_flower.c

@@ -384,7 +384,9 @@ static void fl_hw_destroy_filter(struct tcf_proto *tp, struct cls_fl_filter *f,
 	cls_flower.cookie = (unsigned long) f;
 
 	tc_setup_cb_call(block, TC_SETUP_CLSFLOWER, &cls_flower, false);
+	spin_lock(&tp->lock);
 	tcf_block_offload_dec(block, &f->flags);
+	spin_unlock(&tp->lock);
 }
 
 static int fl_hw_replace_filter(struct tcf_proto *tp,
@@ -426,7 +428,9 @@ static int fl_hw_replace_filter(struct tcf_proto *tp,
 		return err;
 	} else if (err > 0) {
 		f->in_hw_count = err;
+		spin_lock(&tp->lock);
 		tcf_block_offload_inc(block, &f->flags);
+		spin_unlock(&tp->lock);
 	}
 
 	if (skip_sw && !(f->flags & TCA_CLS_FLAGS_IN_HW))
@@ -514,14 +518,19 @@ static int __fl_delete(struct tcf_proto *tp, struct cls_fl_filter *f,
 
 	*last = false;
 
-	if (f->deleted)
+	spin_lock(&tp->lock);
+	if (f->deleted) {
+		spin_unlock(&tp->lock);
 		return -ENOENT;
+	}
 
 	f->deleted = true;
 	rhashtable_remove_fast(&f->mask->ht, &f->ht_node,
 			       f->mask->filter_ht_params);
 	idr_remove(&head->handle_idr, f->handle);
 	list_del_rcu(&f->list);
+	spin_unlock(&tp->lock);
+
 	*last = fl_mask_put(head, f->mask, async);
 	if (!tc_skip_hw(f->flags))
 		fl_hw_destroy_filter(tp, f, extack);
@@ -1500,6 +1509,8 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
 	if (!tc_in_hw(fnew->flags))
 		fnew->flags |= TCA_CLS_FLAGS_NOT_IN_HW;
 
+	spin_lock(&tp->lock);
+
 	/* tp was deleted concurrently. -EAGAIN will cause caller to lookup
 	 * proto again or create new one, if necessary.
 	 */
@@ -1530,6 +1541,8 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
 		list_replace_rcu(&fold->list, &fnew->list);
 		fold->deleted = true;
 
+		spin_unlock(&tp->lock);
+
 		fl_mask_put(head, fold->mask, true);
 		if (!tc_skip_hw(fold->flags))
 			fl_hw_destroy_filter(tp, fold, NULL);
@@ -1575,6 +1588,7 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
 			goto errout_idr;
 
 		list_add_tail_rcu(&fnew->list, &fnew->mask->filters);
+		spin_unlock(&tp->lock);
 	}
 
 	*arg = fnew;
@@ -1586,6 +1600,7 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
 errout_idr:
 	idr_remove(&head->handle_idr, fnew->handle);
 errout_hw:
+	spin_unlock(&tp->lock);
 	if (!tc_skip_hw(fnew->flags))
 		fl_hw_destroy_filter(tp, fnew, NULL);
 errout_mask:
@@ -1688,8 +1703,10 @@ static int fl_reoffload(struct tcf_proto *tp, bool add, tc_setup_cb_t *cb,
 				continue;
 			}
 
+			spin_lock(&tp->lock);
 			tc_cls_offload_cnt_update(block, &f->in_hw_count,
 						  &f->flags, add);
+			spin_unlock(&tp->lock);
 		}
 	}
 
@@ -2223,6 +2240,7 @@ static int fl_dump(struct net *net, struct tcf_proto *tp, void *fh,
 	struct cls_fl_filter *f = fh;
 	struct nlattr *nest;
 	struct fl_flow_key *key, *mask;
+	bool skip_hw;
 
 	if (!f)
 		return skb->len;
@@ -2233,21 +2251,26 @@ static int fl_dump(struct net *net, struct tcf_proto *tp, void *fh,
 	if (!nest)
 		goto nla_put_failure;
 
+	spin_lock(&tp->lock);
+
 	if (f->res.classid &&
 	    nla_put_u32(skb, TCA_FLOWER_CLASSID, f->res.classid))
-		goto nla_put_failure;
+		goto nla_put_failure_locked;
 
 	key = &f->key;
 	mask = &f->mask->key;
+	skip_hw = tc_skip_hw(f->flags);
 
 	if (fl_dump_key(skb, net, key, mask))
-		goto nla_put_failure;
-
-	if (!tc_skip_hw(f->flags))
-		fl_hw_update_stats(tp, f);
+		goto nla_put_failure_locked;
 
 	if (f->flags && nla_put_u32(skb, TCA_FLOWER_FLAGS, f->flags))
-		goto nla_put_failure;
+		goto nla_put_failure_locked;
+
+	spin_unlock(&tp->lock);
+
+	if (!skip_hw)
+		fl_hw_update_stats(tp, f);
 
 	if (nla_put_u32(skb, TCA_FLOWER_IN_HW_COUNT, f->in_hw_count))
 		goto nla_put_failure;
@@ -2262,6 +2285,8 @@ static int fl_dump(struct net *net, struct tcf_proto *tp, void *fh,
 
 	return skb->len;
 
+nla_put_failure_locked:
+	spin_unlock(&tp->lock);
 nla_put_failure:
 	nla_nest_cancel(skb, nest);
 	return -1;