Message-ID: <pghfa4vh7vb7sggelop5asuyj6bqtq4rbgm2q3bdslcoeicihj@6arcanemghjo>
Date: Tue, 23 Jul 2024 16:41:29 +0200
From: Stefano Garzarella <sgarzare@...hat.com>
To: Amery Hung <ameryhung@...il.com>
Cc: stefanha@...hat.com, mst@...hat.com, jasowang@...hat.com, 
	xuanzhuo@...ux.alibaba.com, davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org, 
	pabeni@...hat.com, kys@...rosoft.com, haiyangz@...rosoft.com, wei.liu@...nel.org, 
	decui@...rosoft.com, bryantan@...are.com, vdasa@...are.com, pv-drivers@...are.com, 
	dan.carpenter@...aro.org, simon.horman@...igine.com, oxffffaa@...il.com, 
	kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org, linux-hyperv@...r.kernel.org, 
	bpf@...r.kernel.org, bobby.eshleman@...edance.com, jiang.wang@...edance.com, 
	amery.hung@...edance.com, xiyou.wangcong@...il.com
Subject: Re: [RFC PATCH net-next v6 05/14] af_vsock: use a separate dgram
 bind table

On Wed, Jul 10, 2024 at 09:25:46PM GMT, Amery Hung wrote:
>From: Bobby Eshleman <bobby.eshleman@...edance.com>
>
>This commit adds support for bound dgram sockets to be tracked in a
>separate bind table from connectible sockets in order to avoid address
>collisions. With this commit, users can simultaneously bind a dgram
>socket and connectible socket to the same CID and port.
>
>Signed-off-by: Bobby Eshleman <bobby.eshleman@...edance.com>
>---
> net/vmw_vsock/af_vsock.c | 103 +++++++++++++++++++++++++++++----------
> 1 file changed, 76 insertions(+), 27 deletions(-)
>
>diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>index d571be9cdbf0..ab08cd81720e 100644
>--- a/net/vmw_vsock/af_vsock.c
>+++ b/net/vmw_vsock/af_vsock.c
>@@ -10,18 +10,23 @@
>  * - There are two kinds of sockets: those created by user action (such as
>  * calling socket(2)) and those created by incoming connection request packets.
>  *
>- * - There are two "global" tables, one for bound sockets (sockets that have
>- * specified an address that they are responsible for) and one for connected
>- * sockets (sockets that have established a connection with another socket).
>- * These tables are "global" in that all sockets on the system are placed
>- * within them. - Note, though, that the bound table contains an extra entry
>- * for a list of unbound sockets and SOCK_DGRAM sockets will always remain in
>- * that list. The bound table is used solely for lookup of sockets when packets
>- * are received and that's not necessary for SOCK_DGRAM sockets since we create
>- * a datagram handle for each and need not perform a lookup.  Keeping SOCK_DGRAM
>- * sockets out of the bound hash buckets will reduce the chance of collisions
>- * when looking for SOCK_STREAM sockets and prevents us from having to check the
>- * socket type in the hash table lookups.
>+ * - There are three "global" tables, one for bound connectible (stream /
>+ * seqpacket) sockets, one for bound datagram sockets, and one for connected
>+ * sockets. Bound sockets are sockets that have specified an address that
>+ * they are responsible for. Connected sockets are sockets that have
>+ * established a connection with another socket. These tables are "global" in
>+ * that all sockets on the system are placed within them. - Note, though,
>+ * that the bound tables contain an extra entry for a list of unbound
>+ * sockets. The bound tables are used solely for lookup of sockets when packets
>+ * are received.
>+ *
>+ * - There are separate bind tables for connectible and datagram sockets to avoid
>+ * address collisions between stream/seqpacket sockets and datagram sockets.
>+ *
>+ * - Transports may elect to NOT use the global datagram bind table by
>+ * implementing the ->dgram_bind() callback. If that callback is implemented,
>+ * the global bind table is not used and the responsibility of bound datagram
>+ * socket tracking is deferred to the transport.
>  *
>  * - Sockets created by user action will either be "client" sockets that
>  * initiate a connection or "server" sockets that listen for connections; we do
>@@ -116,6 +121,7 @@
> static int __vsock_bind(struct sock *sk, struct sockaddr_vm *addr);
> static void vsock_sk_destruct(struct sock *sk);
> static int vsock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
>+static bool sock_type_connectible(u16 type);
>
> /* Protocol family. */
> struct proto vsock_proto = {
>@@ -152,21 +158,25 @@ static DEFINE_MUTEX(vsock_register_mutex);
>  * VSocket is stored in the connected hash table.
>  *
>  * Unbound sockets are all put on the same list attached to the end of the hash
>- * table (vsock_unbound_sockets).  Bound sockets are added to the hash table in
>- * the bucket that their local address hashes to (vsock_bound_sockets(addr)
>- * represents the list that addr hashes to).
>+ * tables (vsock_unbound_sockets/vsock_unbound_dgram_sockets).  Bound sockets
>+ * are added to the hash table in the bucket that their local address hashes to
>+ * (vsock_bound_sockets(addr) and vsock_bound_dgram_sockets(addr) represents
>+ * the list that addr hashes to).
>  *
>- * Specifically, we initialize the vsock_bind_table array to a size of
>- * VSOCK_HASH_SIZE + 1 so that vsock_bind_table[0] through
>- * vsock_bind_table[VSOCK_HASH_SIZE - 1] are for bound sockets and
>- * vsock_bind_table[VSOCK_HASH_SIZE] is for unbound sockets.  The hash function
>- * mods with VSOCK_HASH_SIZE to ensure this.
>+ * Specifically, taking connectible sockets as an example we initialize the
>+ * vsock_bind_table array to a size of VSOCK_HASH_SIZE + 1 so that
>+ * vsock_bind_table[0] through vsock_bind_table[VSOCK_HASH_SIZE - 1] are for
>+ * bound sockets and vsock_bind_table[VSOCK_HASH_SIZE] is for unbound sockets.
>+ * The hash function mods with VSOCK_HASH_SIZE to ensure this.
>+ * Datagrams and vsock_dgram_bind_table operate in the same way.
>  */
> #define MAX_PORT_RETRIES        24
>
> #define VSOCK_HASH(addr)        ((addr)->svm_port % VSOCK_HASH_SIZE)
> #define vsock_bound_sockets(addr) (&vsock_bind_table[VSOCK_HASH(addr)])
>+#define vsock_bound_dgram_sockets(addr) (&vsock_dgram_bind_table[VSOCK_HASH(addr)])
> #define vsock_unbound_sockets     (&vsock_bind_table[VSOCK_HASH_SIZE])
>+#define vsock_unbound_dgram_sockets     (&vsock_dgram_bind_table[VSOCK_HASH_SIZE])
>
> /* XXX This can probably be implemented in a better way. */
> #define VSOCK_CONN_HASH(src, dst)				\
>@@ -182,6 +192,8 @@ struct list_head vsock_connected_table[VSOCK_HASH_SIZE];
> EXPORT_SYMBOL_GPL(vsock_connected_table);
> DEFINE_SPINLOCK(vsock_table_lock);
> EXPORT_SYMBOL_GPL(vsock_table_lock);
>+static struct list_head vsock_dgram_bind_table[VSOCK_HASH_SIZE + 1];
>+static DEFINE_SPINLOCK(vsock_dgram_table_lock);
>
> /* Autobind this socket to the local address if necessary. */
> static int vsock_auto_bind(struct vsock_sock *vsk)
>@@ -204,6 +216,9 @@ static void vsock_init_tables(void)
>
> 	for (i = 0; i < ARRAY_SIZE(vsock_connected_table); i++)
> 		INIT_LIST_HEAD(&vsock_connected_table[i]);
>+
>+	for (i = 0; i < ARRAY_SIZE(vsock_dgram_bind_table); i++)
>+		INIT_LIST_HEAD(&vsock_dgram_bind_table[i]);
> }
>
> static void __vsock_insert_bound(struct list_head *list,
>@@ -271,13 +286,28 @@ static struct sock *__vsock_find_connected_socket(struct sockaddr_vm *src,
> 	return NULL;
> }
>
>-static void vsock_insert_unbound(struct vsock_sock *vsk)
>+static void __vsock_insert_dgram_unbound(struct vsock_sock *vsk)
>+{
>+	spin_lock_bh(&vsock_dgram_table_lock);
>+	__vsock_insert_bound(vsock_unbound_dgram_sockets, vsk);
>+	spin_unlock_bh(&vsock_dgram_table_lock);
>+}
>+
>+static void __vsock_insert_connectible_unbound(struct vsock_sock *vsk)
> {
> 	spin_lock_bh(&vsock_table_lock);
> 	__vsock_insert_bound(vsock_unbound_sockets, vsk);
> 	spin_unlock_bh(&vsock_table_lock);
> }
>
>+static void vsock_insert_unbound(struct vsock_sock *vsk)
>+{
>+	if (sock_type_connectible(sk_vsock(vsk)->sk_type))
>+		__vsock_insert_connectible_unbound(vsk);
>+	else
>+		__vsock_insert_dgram_unbound(vsk);
>+}
>+
> void vsock_insert_connected(struct vsock_sock *vsk)
> {
> 	struct list_head *list = vsock_connected_sockets(
>@@ -289,6 +319,14 @@ void vsock_insert_connected(struct vsock_sock *vsk)
> }
> EXPORT_SYMBOL_GPL(vsock_insert_connected);
>
>+static void vsock_remove_dgram_bound(struct vsock_sock *vsk)
>+{
>+	spin_lock_bh(&vsock_dgram_table_lock);
>+	if (__vsock_in_bound_table(vsk))
>+		__vsock_remove_bound(vsk);
>+	spin_unlock_bh(&vsock_dgram_table_lock);
>+}
>+
> void vsock_remove_bound(struct vsock_sock *vsk)
> {
> 	spin_lock_bh(&vsock_table_lock);
>@@ -340,7 +378,10 @@ EXPORT_SYMBOL_GPL(vsock_find_connected_socket);
>
> void vsock_remove_sock(struct vsock_sock *vsk)
> {
>-	vsock_remove_bound(vsk);
>+	if (sock_type_connectible(sk_vsock(vsk)->sk_type))
>+		vsock_remove_bound(vsk);
>+	else
>+		vsock_remove_dgram_bound(vsk);

Can we try to be consistent, for example we have vsock_insert_unbound()
which calls internally sock_type_connectible(), while
vsock_remove_bound() is just for connectible sockets. It's a bit
confusing.

> 	vsock_remove_connected(vsk);
> }
> EXPORT_SYMBOL_GPL(vsock_remove_sock);
>@@ -746,11 +787,19 @@ static int __vsock_bind_connectible(struct vsock_sock *vsk,
> 	return vsock_bind_common(vsk, addr, vsock_bind_table, VSOCK_HASH_SIZE + 1);
> }
>
>-static int __vsock_bind_dgram(struct vsock_sock *vsk,
>-			      struct sockaddr_vm *addr)
>+static int vsock_bind_dgram(struct vsock_sock *vsk,
>+			    struct sockaddr_vm *addr)

Why we are renaming this?

> {
>-	if (!vsk->transport || !vsk->transport->dgram_bind)
>-		return -EINVAL;
>+	if (!vsk->transport || !vsk->transport->dgram_bind) {

Why this condition?

Maybe a comment here is needed because I'm lost...

>+		int retval;
>+
>+		spin_lock_bh(&vsock_dgram_table_lock);
>+		retval = vsock_bind_common(vsk, addr, vsock_dgram_bind_table,
>+					   VSOCK_HASH_SIZE);

Should we use VSOCK_HASH_SIZE + 1 here?

Using ARRAY_SIZE(x) should avoid this problem.


>+		spin_unlock_bh(&vsock_dgram_table_lock);
>+
>+		return retval;
>+	}
>
> 	return vsk->transport->dgram_bind(vsk, addr);
> }
>@@ -781,7 +830,7 @@ static int __vsock_bind(struct sock *sk, struct sockaddr_vm *addr)
> 		break;
>
> 	case SOCK_DGRAM:
>-		retval = __vsock_bind_dgram(vsk, addr);
>+		retval = vsock_bind_dgram(vsk, addr);
> 		break;
>
> 	default:
>-- 
>2.20.1
>

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