net/udp: Add 4-tuple hash list basis

Add a new hash list, hash4, in udp table. It will be used to implement
4-tuple hash for connected udp sockets. This patch adds the hlist to
table, and implements helpers and the initialization. 4-tuple hash is
implemented in the following patch.

hash4 uses hlist_nulls to avoid moving wrongly onto another hlist due to
concurrent rehash, because rehash() can happen with lookup().

Co-developed-by: Cambda Zhu <cambda@linux.alibaba.com>
Signed-off-by: Cambda Zhu <cambda@linux.alibaba.com>
Co-developed-by: Fred Chen <fred.cc@alibaba-inc.com>
Signed-off-by: Fred Chen <fred.cc@alibaba-inc.com>
Co-developed-by: Yubing Qiu <yubing.qiuyubing@alibaba-inc.com>
Signed-off-by: Yubing Qiu <yubing.qiuyubing@alibaba-inc.com>
Signed-off-by: Philo Lu <lulie@linux.alibaba.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 82 insertions, 3 deletions

diff --git a/include/net/udp.h b/include/net/udp.h
index 62a7207e65f2..edb669967130 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -50,14 +50,21 @@ struct udp_skb_cb {
 #define UDP_SKB_CB(__skb)	((struct udp_skb_cb *)((__skb)->cb))
 
 /**
- *	struct udp_hslot - UDP hash slot used by udp_table.hash
+ *	struct udp_hslot - UDP hash slot used by udp_table.hash/hash4
  *
  *	@head:	head of list of sockets
+ *	@nulls_head:	head of list of sockets, only used by hash4
  *	@count:	number of sockets in 'head' list
  *	@lock:	spinlock protecting changes to head/count
  */
 struct udp_hslot {
-	struct hlist_head	head;
+	union {
+		struct hlist_head	head;
+		/* hash4 uses hlist_nulls to avoid moving wrongly onto another
+		 * hlist, because rehash() can happen with lookup().
+		 */
+		struct hlist_nulls_head	nulls_head;
+	};
 	int			count;
 	spinlock_t		lock;
 } __aligned(2 * sizeof(long));
@@ -82,12 +89,17 @@ struct udp_hslot_main {
  *
  *	@hash:	hash table, sockets are hashed on (local port)
  *	@hash2:	hash table, sockets are hashed on (local port, local address)
+ *	@hash4:	hash table, connected sockets are hashed on
+ *		(local port, local address, remote port, remote address)
  *	@mask:	number of slots in hash tables, minus 1
  *	@log:	log2(number of slots in hash table)
  */
 struct udp_table {
 	struct udp_hslot	*hash;
 	struct udp_hslot_main	*hash2;
+#if !IS_ENABLED(CONFIG_BASE_SMALL)
+	struct udp_hslot	*hash4;
+#endif
 	unsigned int		mask;
 	unsigned int		log;
 };
@@ -114,13 +126,80 @@ static inline struct udp_hslot *udp_hashslot2(struct udp_table *table,
 static inline void udp_table_hash4_init(struct udp_table *table)
 {
 }
+
+static inline struct udp_hslot *udp_hashslot4(struct udp_table *table,
+					      unsigned int hash)
+{
+	BUILD_BUG();
+	return NULL;
+}
+
+static inline bool udp_hashed4(const struct sock *sk)
+{
+	return false;
+}
+
+static inline unsigned int udp_hash4_slot_size(void)
+{
+	return 0;
+}
+
+static inline bool udp_has_hash4(const struct udp_hslot *hslot2)
+{
+	return false;
+}
+
+static inline void udp_hash4_inc(struct udp_hslot *hslot2)
+{
+}
+
+static inline void udp_hash4_dec(struct udp_hslot *hslot2)
+{
+}
 #else /* !CONFIG_BASE_SMALL */
 
 /* Must be called with table->hash2 initialized */
 static inline void udp_table_hash4_init(struct udp_table *table)
 {
-	for (int i = 0; i <= table->mask; i++)
+	table->hash4 = (void *)(table->hash2 + (table->mask + 1));
+	for (int i = 0; i <= table->mask; i++) {
 		table->hash2[i].hash4_cnt = 0;
+
+		INIT_HLIST_NULLS_HEAD(&table->hash4[i].nulls_head, i);
+		table->hash4[i].count = 0;
+		spin_lock_init(&table->hash4[i].lock);
+	}
+}
+
+static inline struct udp_hslot *udp_hashslot4(struct udp_table *table,
+					      unsigned int hash)
+{
+	return &table->hash4[hash & table->mask];
+}
+
+static inline bool udp_hashed4(const struct sock *sk)
+{
+	return !hlist_nulls_unhashed(&udp_sk(sk)->udp_lrpa_node);
+}
+
+static inline unsigned int udp_hash4_slot_size(void)
+{
+	return sizeof(struct udp_hslot);
+}
+
+static inline bool udp_has_hash4(const struct udp_hslot *hslot2)
+{
+	return UDP_HSLOT_MAIN(hslot2)->hash4_cnt;
+}
+
+static inline void udp_hash4_inc(struct udp_hslot *hslot2)
+{
+	UDP_HSLOT_MAIN(hslot2)->hash4_cnt++;
+}
+
+static inline void udp_hash4_dec(struct udp_hslot *hslot2)
+{
+	UDP_HSLOT_MAIN(hslot2)->hash4_cnt--;
 }
 #endif /* CONFIG_BASE_SMALL */