Merge branch 'net-sched-cls_u32-use-proper-refcounts'

Pedro Tammela says: ==================== net/sched: cls_u32: use proper refcounts In u32 we are open coding refcounts of hashtables with integers which is far from ideal. Update those with proper refcount and add a couple of tests to tdc that exercise the refcounts explicitly. ==================== Link: https://lore.kernel.org/r/20231114141856.974326-1-pctammela@mojatatu.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-05-07 13:57:54 -04:00 · 2023-11-18 19:38:25 -08:00
parent 289354f21b 54293e4d6a
commit 516cba96e8
2 changed files with 75 additions and 18 deletions
--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c
@@ -71,7 +71,7 @@ struct tc_u_hnode {
 	struct tc_u_hnode __rcu	*next;
 	u32			handle;
 	u32			prio;
-	int			refcnt;
+	refcount_t		refcnt;
 	unsigned int		divisor;
 	struct idr		handle_idr;
 	bool			is_root;
@@ -86,7 +86,7 @@ struct tc_u_hnode {
 struct tc_u_common {
 	struct tc_u_hnode __rcu	*hlist;
 	void			*ptr;
-	int			refcnt;
+	refcount_t		refcnt;
 	struct idr		handle_idr;
 	struct hlist_node	hnode;
 	long			knodes;
@@ -359,7 +359,7 @@ static int u32_init(struct tcf_proto *tp)
 	if (root_ht == NULL)
 		return -ENOBUFS;

-	root_ht->refcnt++;
+	refcount_set(&root_ht->refcnt, 1);
 	root_ht->handle = tp_c ? gen_new_htid(tp_c, root_ht) : 0x80000000;
 	root_ht->prio = tp->prio;
 	root_ht->is_root = true;
@@ -371,18 +371,20 @@ static int u32_init(struct tcf_proto *tp)
 			kfree(root_ht);
 			return -ENOBUFS;
 		}
+		refcount_set(&tp_c->refcnt, 1);
 		tp_c->ptr = key;
 		INIT_HLIST_NODE(&tp_c->hnode);
 		idr_init(&tp_c->handle_idr);

 		hlist_add_head(&tp_c->hnode, tc_u_hash(key));
+	} else {
+		refcount_inc(&tp_c->refcnt);
 	}

-	tp_c->refcnt++;
 	RCU_INIT_POINTER(root_ht->next, tp_c->hlist);
 	rcu_assign_pointer(tp_c->hlist, root_ht);

-	root_ht->refcnt++;
+	/* root_ht must be destroyed when tcf_proto is destroyed */
 	rcu_assign_pointer(tp->root, root_ht);
 	tp->data = tp_c;
 	return 0;
@@ -393,7 +395,7 @@ static void __u32_destroy_key(struct tc_u_knode *n)
 	struct tc_u_hnode *ht = rtnl_dereference(n->ht_down);

 	tcf_exts_destroy(&n->exts);
-	if (ht && --ht->refcnt == 0)
+	if (ht && refcount_dec_and_test(&ht->refcnt))
 		kfree(ht);
 	kfree(n);
 }
@@ -601,8 +603,6 @@ static int u32_destroy_hnode(struct tcf_proto *tp, struct tc_u_hnode *ht,
 	struct tc_u_hnode __rcu **hn;
 	struct tc_u_hnode *phn;

-	WARN_ON(--ht->refcnt);
-
 	u32_clear_hnode(tp, ht, extack);

 	hn = &tp_c->hlist;
@@ -630,10 +630,10 @@ static void u32_destroy(struct tcf_proto *tp, bool rtnl_held,

 	WARN_ON(root_ht == NULL);

-	if (root_ht && --root_ht->refcnt == 1)
+	if (root_ht && refcount_dec_and_test(&root_ht->refcnt))
 		u32_destroy_hnode(tp, root_ht, extack);

-	if (--tp_c->refcnt == 0) {
+	if (refcount_dec_and_test(&tp_c->refcnt)) {
 		struct tc_u_hnode *ht;

 		hlist_del(&tp_c->hnode);
@@ -645,7 +645,7 @@ static void u32_destroy(struct tcf_proto *tp, bool rtnl_held,
 			/* u32_destroy_key() will later free ht for us, if it's
 			 * still referenced by some knode
 			 */
-			if (--ht->refcnt == 0)
+			if (refcount_dec_and_test(&ht->refcnt))
 				kfree_rcu(ht, rcu);
 		}

@@ -674,7 +674,7 @@ static int u32_delete(struct tcf_proto *tp, void *arg, bool *last,
 		return -EINVAL;
 	}

-	if (ht->refcnt == 1) {
+	if (refcount_dec_if_one(&ht->refcnt)) {
 		u32_destroy_hnode(tp, ht, extack);
 	} else {
 		NL_SET_ERR_MSG_MOD(extack, "Can not delete in-use filter");
@@ -682,7 +682,7 @@ static int u32_delete(struct tcf_proto *tp, void *arg, bool *last,
 	}

 out:
-	*last = tp_c->refcnt == 1 && tp_c->knodes == 0;
+	*last = refcount_read(&tp_c->refcnt) == 1 && tp_c->knodes == 0;
 	return ret;
 }

@@ -766,14 +766,14 @@ static int u32_set_parms(struct net *net, struct tcf_proto *tp,
 				NL_SET_ERR_MSG_MOD(extack, "Not linking to root node");
 				return -EINVAL;
 			}
-			ht_down->refcnt++;
+			refcount_inc(&ht_down->refcnt);
 		}

 		ht_old = rtnl_dereference(n->ht_down);
 		rcu_assign_pointer(n->ht_down, ht_down);

 		if (ht_old)
-			ht_old->refcnt--;
+			refcount_dec(&ht_old->refcnt);
 	}

 	if (ifindex >= 0)
@@ -852,7 +852,7 @@ static struct tc_u_knode *u32_init_knode(struct net *net, struct tcf_proto *tp,

 	/* bump reference count as long as we hold pointer to structure */
 	if (ht)
-		ht->refcnt++;
+		refcount_inc(&ht->refcnt);

 	return new;
 }
@@ -932,7 +932,7 @@ static int u32_change(struct net *net, struct sk_buff *in_skb,

 				ht_old = rtnl_dereference(n->ht_down);
 				if (ht_old)
-					ht_old->refcnt++;
+					refcount_inc(&ht_old->refcnt);
 			}
 			__u32_destroy_key(new);
 			return err;
@@ -980,7 +980,7 @@ static int u32_change(struct net *net, struct sk_buff *in_skb,
 				return err;
 			}
 		}
-		ht->refcnt = 1;
+		refcount_set(&ht->refcnt, 1);
 		ht->divisor = divisor;
 		ht->handle = handle;
 		ht->prio = tp->prio;
--- a/tools/testing/selftests/tc-testing/tc-tests/filters/u32.json
+++ b/tools/testing/selftests/tc-testing/tc-tests/filters/u32.json
@@ -272,5 +272,62 @@
        "teardown": [
            "$TC qdisc del dev $DEV1 parent root drr"
        ]
+    },
+    {
+        "id": "bd32",
+        "name": "Try to delete hashtable referenced by another u32 filter",
+        "category": [
+            "filter",
+            "u32"
+        ],
+        "plugins": {
+            "requires": "nsPlugin"
+        },
+        "setup": [
+            "$TC qdisc add dev $DEV1 parent root handle 10: drr",
+            "$TC filter add dev $DEV1 parent 10:0 protocol ip prio 2 handle 1: u32 divisor 1",
+            "$TC filter add dev $DEV1 parent 10:0 protocol ip prio 2 u32 ht 800: match ip src any link 1:"
+        ],
+        "cmdUnderTest": "$TC filter delete dev $DEV1 parent 10: prio 2 handle 1: u32",
+        "expExitCode": "2",
+        "verifyCmd": "$TC filter show dev $DEV1",
+        "matchPattern": "protocol ip pref 2 u32 chain 0 fh 1:",
+        "matchCount": "1",
+        "teardown": [
+            "$TC qdisc del dev $DEV1 parent root drr"
+        ]
+    },
+    {
+        "id": "4585",
+        "name": "Delete small tree of u32 hashtables and filters",
+        "category": [
+            "filter",
+            "u32"
+        ],
+        "plugins": {
+            "requires": "nsPlugin"
+        },
+        "setup": [
+            "$TC qdisc add dev $DEV1 parent root handle 10: drr",
+            "$TC filter add dev $DEV1 parent 10:0 protocol ip prio 2 handle 1: u32 divisor 1",
+            "$TC filter add dev $DEV1 parent 10:0 protocol ip prio 2 handle 2: u32 divisor 1",
+            "$TC filter add dev $DEV1 parent 10:0 protocol ip prio 2 handle 3: u32 divisor 2",
+            "$TC filter add dev $DEV1 parent 10:0 protocol ip prio 2 handle 4: u32 divisor 1",
+            "$TC filter add dev $DEV1 parent 10:0 protocol ip prio 2 u32 ht 1: match ip src any action drop",
+            "$TC filter add dev $DEV1 parent 10:0 protocol ip prio 2 u32 ht 2: match ip src any action drop",
+            "$TC filter add dev $DEV1 parent 10:0 protocol ip prio 2 u32 ht 3: match ip src any link 2:",
+            "$TC filter add dev $DEV1 parent 10:0 protocol ip prio 2 u32 ht 3: match ip src any link 1:",
+            "$TC filter add dev $DEV1 parent 10:0 protocol ip prio 2 u32 ht 4: match ip src any action drop",
+            "$TC filter add dev $DEV1 parent 10:0 protocol ip prio 2 u32 ht 800: match ip src any link 3:",
+            "$TC filter add dev $DEV1 parent 10:0 protocol ip prio 2 u32 ht 800: match ip src any link 4:"
+        ],
+        "cmdUnderTest": "$TC filter delete dev $DEV1 parent 10:",
+        "expExitCode": "0",
+        "verifyCmd": "$TC filter show dev $DEV1",
+        "matchPattern": "protocol ip pref 2 u32",
+        "matchCount": "0",
+        "teardown": [
+            "$TC qdisc del dev $DEV1 parent root drr"
+        ]
    }
 ]