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Date:   Wed, 19 Apr 2023 11:30:53 +0200
From:   Stefano Garzarella <sgarzare@redhat.com>
To:     Bobby Eshleman <bobby.eshleman@bytedance.com>
Cc:     Stefan Hajnoczi <stefanha@redhat.com>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Jason Wang <jasowang@redhat.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        "K. Y. Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
        Bryan Tan <bryantan@vmware.com>,
        Vishnu Dasa <vdasa@vmware.com>,
        VMware PV-Drivers Reviewers <pv-drivers@vmware.com>,
        kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-hyperv@vger.kernel.org
Subject: Re: [PATCH RFC net-next v2 3/4] vsock: Add lockless sendmsg() support
Message-ID: <bs3elc4lwvvq22y2vq27ewo23qibei2neys4txszi6wybxpuzu@czyq5hb7iv5t>
References: <20230413-b4-vsock-dgram-v2-0-079cc7cee62e@bytedance.com>
 <20230413-b4-vsock-dgram-v2-3-079cc7cee62e@bytedance.com>
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In-Reply-To: <20230413-b4-vsock-dgram-v2-3-079cc7cee62e@bytedance.com>
Precedence: bulk

On Fri, Apr 14, 2023 at 12:25:59AM +0000, Bobby Eshleman wrote:
>Because the dgram sendmsg() path for AF_VSOCK acquires the socket lock
>it does not scale when many senders share a socket.
>
>Prior to this patch the socket lock is used to protect the local_addr,
>remote_addr, transport, and buffer size variables. What follows are the
>new protection schemes for the various protected fields that ensure a
>race-free multi-sender sendmsg() path for vsock dgrams.
>
>- local_addr
>    local_addr changes as a result of binding a socket. The write path
>    for local_addr is bind() and various vsock_auto_bind() call sites.
>    After a socket has been bound via vsock_auto_bind() or bind(), subsequent
>    calls to bind()/vsock_auto_bind() do not write to local_addr again. bind()
>    rejects the user request and vsock_auto_bind() early exits.
>    Therefore, the local addr can not change while a parallel thread is
>    in sendmsg() and lock-free reads of local addr in sendmsg() are safe.
>    Change: only acquire lock for auto-binding as-needed in sendmsg().
>
>- vsk->transport
>    Updated upon socket creation and it doesn't change again until the

This is true only for dgram, right?

How do we decide which transport to assign for dgram?

>    socket is destroyed, which only happens after the socket refcnt reaches
>    zero. This prevents any sendmsg() call from being entered because the
>    sockfd lookup fails beforehand. That is, sendmsg() and vsk->transport
>    writes cannot execute in parallel. Additionally, connect() doesn't
>    update vsk->transport for dgrams as it does for streams. Therefore
>    vsk->transport is also safe to access lock-free in the sendmsg() path.
>    No change.
>
>- buffer size variables
>    Not used by dgram, so they do not need protection. No change.

Is this true because for dgram we use the socket buffer?
Is it the same for VMCI?

>
>- remote_addr
>    Needs additional protection because before this patch the
>    remote_addr (consisting of several fields such as cid, port, and flags)
>    only changed atomically under socket lock context. By acquiring the
>    socket lock to read the structure, the changes made by connect() were
>    always made visible to sendmsg() atomically. Consequently, to retain
>    atomicity of updates but offer lock-free access, this patch
>    redesigns this field as an RCU-protected pointer.
>
>    Writers are still synchronized using the socket lock, but readers
>    only read inside RCU read-side critical sections.
>
>Helpers are introduced for accessing and updating the new pointer.
>
>The remote_addr structure is wrapped together with an rcu_head into a
>sockaddr_vm_rcu structure so that kfree_rcu() can be used. This removes
>the need of writers to use synchronize_rcu() after freeing old structures
>which is simply more efficient and reduces code churn where remote_addr
>is already being updated inside read-side sections.
>
>Only virtio has been tested, but updates were necessary to the VMCI and
>hyperv code. Unfortunately the author does not have access to
>VMCI/hyperv systems so those changes are untested.
>
>Perf Tests
>vCPUS: 16
>Threads: 16
>Payload: 4KB
>Test Runs: 5
>Type: SOCK_DGRAM
>
>Before: 245.2 MB/s
>After: 509.2 MB/s (+107%)
>
>Notably, on the same test system, vsock dgram even outperforms
>multi-threaded UDP over virtio-net with vhost and MQ support enabled.

Cool!

This patch is quite large, so I need to review it carefully in future
versions, but in general it makes sense to me.

Thanks,
Stefano

>
>Throughput metrics for single-threaded SOCK_DGRAM and
>single/multi-threaded SOCK_STREAM showed no statistically signficant
>throughput changes (lowest p-value reaching 0.27), with the range of the
>mean difference ranging between -5% to +1%.
>
>Signed-off-by: Bobby Eshleman <bobby.eshleman@bytedance.com>
>---
> drivers/vhost/vsock.c                   |  12 +-
> include/net/af_vsock.h                  |  19 ++-
> net/vmw_vsock/af_vsock.c                | 261 ++++++++++++++++++++++++++++----
> net/vmw_vsock/diag.c                    |  10 +-
> net/vmw_vsock/hyperv_transport.c        |  15 +-
> net/vmw_vsock/virtio_transport_common.c |  22 ++-
> net/vmw_vsock/vmci_transport.c          |  70 ++++++---
> 7 files changed, 344 insertions(+), 65 deletions(-)
>
>diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
>index 028cf079225e..da105cb856ac 100644
>--- a/drivers/vhost/vsock.c
>+++ b/drivers/vhost/vsock.c
>@@ -296,13 +296,17 @@ static int
> vhost_transport_cancel_pkt(struct vsock_sock *vsk)
> {
> 	struct vhost_vsock *vsock;
>+	unsigned int cid;
> 	int cnt = 0;
> 	int ret = -ENODEV;
>
> 	rcu_read_lock();
>+	ret = vsock_remote_addr_cid(vsk, &cid);
>+	if (ret < 0)
>+		goto out;
>
> 	/* Find the vhost_vsock according to guest context id  */
>-	vsock = vhost_vsock_get(vsk->remote_addr.svm_cid);
>+	vsock = vhost_vsock_get(cid);
> 	if (!vsock)
> 		goto out;
>
>@@ -686,6 +690,10 @@ static void vhost_vsock_flush(struct vhost_vsock *vsock)
> static void vhost_vsock_reset_orphans(struct sock *sk)
> {
> 	struct vsock_sock *vsk = vsock_sk(sk);
>+	unsigned int cid;
>+
>+	if (vsock_remote_addr_cid(vsk, &cid) < 0)
>+		return;
>
> 	/* vmci_transport.c doesn't take sk_lock here either.  At least we're
> 	 * under vsock_table_lock so the sock cannot disappear while we're
>@@ -693,7 +701,7 @@ static void vhost_vsock_reset_orphans(struct sock *sk)
> 	 */
>
> 	/* If the peer is still valid, no need to reset connection */
>-	if (vhost_vsock_get(vsk->remote_addr.svm_cid))
>+	if (vhost_vsock_get(cid))
> 		return;
>
> 	/* If the close timeout is pending, let it expire.  This avoids races
>diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
>index 57af28fede19..c02fd6ad0047 100644
>--- a/include/net/af_vsock.h
>+++ b/include/net/af_vsock.h
>@@ -25,12 +25,17 @@ extern spinlock_t vsock_table_lock;
> #define vsock_sk(__sk)    ((struct vsock_sock *)__sk)
> #define sk_vsock(__vsk)   (&(__vsk)->sk)
>
>+struct sockaddr_vm_rcu {
>+	struct sockaddr_vm addr;
>+	struct rcu_head rcu;
>+};
>+
> struct vsock_sock {
> 	/* sk must be the first member. */
> 	struct sock sk;
> 	const struct vsock_transport *transport;
> 	struct sockaddr_vm local_addr;
>-	struct sockaddr_vm remote_addr;
>+	struct sockaddr_vm_rcu * __rcu remote_addr;
> 	/* Links for the global tables of bound and connected sockets. */
> 	struct list_head bound_table;
> 	struct list_head connected_table;
>@@ -206,7 +211,7 @@ void vsock_release_pending(struct sock *pending);
> void vsock_add_pending(struct sock *listener, struct sock *pending);
> void vsock_remove_pending(struct sock *listener, struct sock *pending);
> void vsock_enqueue_accept(struct sock *listener, struct sock *connected);
>-void vsock_insert_connected(struct vsock_sock *vsk);
>+int vsock_insert_connected(struct vsock_sock *vsk);
> void vsock_remove_bound(struct vsock_sock *vsk);
> void vsock_remove_connected(struct vsock_sock *vsk);
> struct sock *vsock_find_bound_socket(struct sockaddr_vm *addr);
>@@ -244,4 +249,14 @@ static inline void __init vsock_bpf_build_proto(void)
> {}
> #endif
>
>+/* RCU-protected remote addr helpers */
>+int vsock_remote_addr_cid(struct vsock_sock *vsk, unsigned int *cid);
>+int vsock_remote_addr_port(struct vsock_sock *vsk, unsigned int *port);
>+int vsock_remote_addr_cid_port(struct vsock_sock *vsk, unsigned int *cid,
>+			       unsigned int *port);
>+int vsock_remote_addr_copy(struct vsock_sock *vsk, struct sockaddr_vm *dest);
>+bool vsock_remote_addr_bound(struct vsock_sock *vsk);
>+bool vsock_remote_addr_equals(struct vsock_sock *vsk, struct sockaddr_vm *other);
>+int vsock_remote_addr_update_cid_port(struct vsock_sock *vsk, u32 cid, u32 port);
>+
> #endif /* __AF_VSOCK_H__ */
>diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>index 46b3f35e3adc..93b4abbf20b4 100644
>--- a/net/vmw_vsock/af_vsock.c
>+++ b/net/vmw_vsock/af_vsock.c
>@@ -145,6 +145,139 @@ static const struct vsock_transport *transport_local;
> static DEFINE_MUTEX(vsock_register_mutex);
>
> /**** UTILS ****/
>+bool vsock_remote_addr_bound(struct vsock_sock *vsk)
>+{
>+	struct sockaddr_vm_rcu *remote_addr;
>+	bool ret;
>+
>+	rcu_read_lock();
>+	remote_addr = rcu_dereference(vsk->remote_addr);
>+	if (!remote_addr) {
>+		rcu_read_unlock();
>+		return false;
>+	}
>+
>+	ret = vsock_addr_bound(&remote_addr->addr);
>+	rcu_read_unlock();
>+
>+	return ret;
>+}
>+EXPORT_SYMBOL_GPL(vsock_remote_addr_bound);
>+
>+int vsock_remote_addr_copy(struct vsock_sock *vsk, struct sockaddr_vm *dest)
>+{
>+	struct sockaddr_vm_rcu *remote_addr;
>+
>+	rcu_read_lock();
>+	remote_addr = rcu_dereference(vsk->remote_addr);
>+	if (!remote_addr) {
>+		rcu_read_unlock();
>+		return -EINVAL;
>+	}
>+	memcpy(dest, &remote_addr->addr, sizeof(*dest));
>+	rcu_read_unlock();
>+
>+	return 0;
>+}
>+EXPORT_SYMBOL_GPL(vsock_remote_addr_copy);
>+
>+int vsock_remote_addr_cid(struct vsock_sock *vsk, unsigned int *cid)
>+{
>+	return vsock_remote_addr_cid_port(vsk, cid, NULL);
>+}
>+EXPORT_SYMBOL_GPL(vsock_remote_addr_cid);
>+
>+int vsock_remote_addr_port(struct vsock_sock *vsk, unsigned int *port)
>+{
>+	return vsock_remote_addr_cid_port(vsk, NULL, port);
>+}
>+EXPORT_SYMBOL_GPL(vsock_remote_addr_port);
>+
>+int vsock_remote_addr_cid_port(struct vsock_sock *vsk, unsigned int *cid,
>+			       unsigned int *port)
>+{
>+	struct sockaddr_vm_rcu *remote_addr;
>+
>+	rcu_read_lock();
>+	remote_addr = rcu_dereference(vsk->remote_addr);
>+	if (!remote_addr) {
>+		rcu_read_unlock();
>+		return -EINVAL;
>+	}
>+
>+	if (cid)
>+		*cid = remote_addr->addr.svm_cid;
>+	if (port)
>+		*port = remote_addr->addr.svm_port;
>+
>+	rcu_read_unlock();
>+	return 0;
>+}
>+EXPORT_SYMBOL_GPL(vsock_remote_addr_cid_port);
>+
>+/* The socket lock must be held by the caller */
>+int vsock_remote_addr_update_cid_port(struct vsock_sock *vsk, u32 cid, u32 port)
>+{
>+	struct sockaddr_vm_rcu *old, *new;
>+
>+	new = kmalloc(sizeof(*new), GFP_KERNEL);
>+	if (!new)
>+		return -ENOMEM;
>+
>+	rcu_read_lock();
>+	old = rcu_dereference(vsk->remote_addr);
>+	if (!old) {
>+		kfree(new);
>+		return -EINVAL;
>+	}
>+	memcpy(&new->addr, &old->addr, sizeof(new->addr));
>+	rcu_read_unlock();
>+
>+	new->addr.svm_cid = cid;
>+	new->addr.svm_port = port;
>+
>+	old = rcu_replace_pointer(vsk->remote_addr, new, lockdep_sock_is_held(sk_vsock(vsk)));
>+	kfree_rcu(old, rcu);
>+
>+	return 0;
>+}
>+EXPORT_SYMBOL_GPL(vsock_remote_addr_update_cid_port);
>+
>+/* The socket lock must be held by the caller */
>+int vsock_remote_addr_update(struct vsock_sock *vsk, struct sockaddr_vm *src)
>+{
>+	struct sockaddr_vm_rcu *old, *new;
>+
>+	new = kmalloc(sizeof(*new), GFP_KERNEL);
>+	if (!new)
>+		return -ENOMEM;
>+
>+	memcpy(&new->addr, src, sizeof(new->addr));
>+	old = rcu_replace_pointer(vsk->remote_addr, new, lockdep_sock_is_held(sk_vsock(vsk)));
>+	kfree_rcu(old, rcu);
>+
>+	return 0;
>+}
>+
>+bool vsock_remote_addr_equals(struct vsock_sock *vsk,
>+			      struct sockaddr_vm *other)
>+{
>+	struct sockaddr_vm_rcu *remote_addr;
>+	bool equals;
>+
>+	rcu_read_lock();
>+	remote_addr = rcu_dereference(vsk->remote_addr);
>+	if (!remote_addr) {
>+		rcu_read_unlock();
>+		return false;
>+	}
>+
>+	equals = vsock_addr_equals_addr(&remote_addr->addr, other);
>+	rcu_read_unlock();
>+
>+	return equals;
>+}
>+EXPORT_SYMBOL_GPL(vsock_remote_addr_equals);
>
> /* Each bound VSocket is stored in the bind hash table and each connected
>  * VSocket is stored in the connected hash table.
>@@ -254,10 +387,16 @@ static struct sock *__vsock_find_connected_socket(struct sockaddr_vm *src,
>
> 	list_for_each_entry(vsk, vsock_connected_sockets(src, dst),
> 			    connected_table) {
>-		if (vsock_addr_equals_addr(src, &vsk->remote_addr) &&
>+		struct sockaddr_vm_rcu *remote_addr;
>+
>+		rcu_read_lock();
>+		remote_addr = rcu_dereference(vsk->remote_addr);
>+		if (vsock_addr_equals_addr(src, &remote_addr->addr) &&
> 		    dst->svm_port == vsk->local_addr.svm_port) {
>+			rcu_read_unlock();
> 			return sk_vsock(vsk);
> 		}
>+		rcu_read_unlock();
> 	}
>
> 	return NULL;
>@@ -270,14 +409,25 @@ static void vsock_insert_unbound(struct vsock_sock *vsk)
> 	spin_unlock_bh(&vsock_table_lock);
> }
>
>-void vsock_insert_connected(struct vsock_sock *vsk)
>+int vsock_insert_connected(struct vsock_sock *vsk)
> {
>-	struct list_head *list = vsock_connected_sockets(
>-		&vsk->remote_addr, &vsk->local_addr);
>+	struct list_head *list;
>+	struct sockaddr_vm_rcu *remote_addr;
>+
>+	rcu_read_lock();
>+	remote_addr = rcu_dereference(vsk->remote_addr);
>+	if (!remote_addr) {
>+		rcu_read_unlock();
>+		return -EINVAL;
>+	}
>+	list = vsock_connected_sockets(&remote_addr->addr, &vsk->local_addr);
>+	rcu_read_unlock();
>
> 	spin_lock_bh(&vsock_table_lock);
> 	__vsock_insert_connected(list, vsk);
> 	spin_unlock_bh(&vsock_table_lock);
>+
>+	return 0;
> }
> EXPORT_SYMBOL_GPL(vsock_insert_connected);
>
>@@ -438,10 +588,17 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk)
> {
> 	const struct vsock_transport *new_transport;
> 	struct sock *sk = sk_vsock(vsk);
>-	unsigned int remote_cid = vsk->remote_addr.svm_cid;
>+	struct sockaddr_vm remote_addr;
>+	unsigned int remote_cid;
> 	__u8 remote_flags;
> 	int ret;
>
>+	ret = vsock_remote_addr_copy(vsk, &remote_addr);
>+	if (ret < 0)
>+		return ret;
>+
>+	remote_cid = remote_addr.svm_cid;
>+
> 	/* If the packet is coming with the source and destination CIDs higher
> 	 * than VMADDR_CID_HOST, then a vsock channel where all the packets are
> 	 * forwarded to the host should be established. Then the host will
>@@ -451,10 +608,15 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk)
> 	 * the connect path the flag can be set by the user space application.
> 	 */
> 	if (psk && vsk->local_addr.svm_cid > VMADDR_CID_HOST &&
>-	    vsk->remote_addr.svm_cid > VMADDR_CID_HOST)
>-		vsk->remote_addr.svm_flags |= VMADDR_FLAG_TO_HOST;
>+	    remote_addr.svm_cid > VMADDR_CID_HOST) {
>+		remote_addr.svm_flags |= VMADDR_CID_HOST;
>+
>+		ret = vsock_remote_addr_update(vsk, &remote_addr);
>+		if (ret < 0)
>+			return ret;
>+	}
>
>-	remote_flags = vsk->remote_addr.svm_flags;
>+	remote_flags = remote_addr.svm_flags;
>
> 	switch (sk->sk_type) {
> 	case SOCK_DGRAM:
>@@ -742,6 +904,7 @@ static struct sock *__vsock_create(struct net *net,
> 				   unsigned short type,
> 				   int kern)
> {
>+	struct sockaddr_vm *remote_addr;
> 	struct sock *sk;
> 	struct vsock_sock *psk;
> 	struct vsock_sock *vsk;
>@@ -761,7 +924,14 @@ static struct sock *__vsock_create(struct net *net,
>
> 	vsk = vsock_sk(sk);
> 	vsock_addr_init(&vsk->local_addr, VMADDR_CID_ANY, VMADDR_PORT_ANY);
>-	vsock_addr_init(&vsk->remote_addr, VMADDR_CID_ANY, VMADDR_PORT_ANY);
>+
>+	remote_addr = kmalloc(sizeof(*remote_addr), GFP_KERNEL);
>+	if (!remote_addr) {
>+		sk_free(sk);
>+		return NULL;
>+	}
>+	vsock_addr_init(remote_addr, VMADDR_CID_ANY, VMADDR_PORT_ANY);
>+	rcu_assign_pointer(vsk->remote_addr, remote_addr);
>
> 	sk->sk_destruct = vsock_sk_destruct;
> 	sk->sk_backlog_rcv = vsock_queue_rcv_skb;
>@@ -845,6 +1015,7 @@ static void __vsock_release(struct sock *sk, int level)
> static void vsock_sk_destruct(struct sock *sk)
> {
> 	struct vsock_sock *vsk = vsock_sk(sk);
>+	struct sockaddr_vm_rcu *remote_addr;
>
> 	vsock_deassign_transport(vsk);
>
>@@ -852,8 +1023,8 @@ static void vsock_sk_destruct(struct sock *sk)
> 	 * possibly register the address family with the kernel.
> 	 */
> 	vsock_addr_init(&vsk->local_addr, VMADDR_CID_ANY, VMADDR_PORT_ANY);
>-	vsock_addr_init(&vsk->remote_addr, VMADDR_CID_ANY, VMADDR_PORT_ANY);
>-
>+	remote_addr = rcu_replace_pointer(vsk->remote_addr, NULL, 1);
>+	kfree_rcu(remote_addr);
> 	put_cred(vsk->owner);
> }
>
>@@ -943,6 +1114,7 @@ static int vsock_getname(struct socket *sock,
> 	struct sock *sk;
> 	struct vsock_sock *vsk;
> 	struct sockaddr_vm *vm_addr;
>+	struct sockaddr_vm_rcu *rcu_ptr;
>
> 	sk = sock->sk;
> 	vsk = vsock_sk(sk);
>@@ -951,11 +1123,17 @@ static int vsock_getname(struct socket *sock,
> 	lock_sock(sk);
>
> 	if (peer) {
>+		rcu_read_lock();
> 		if (sock->state != SS_CONNECTED) {
> 			err = -ENOTCONN;
> 			goto out;
> 		}
>-		vm_addr = &vsk->remote_addr;
>+		rcu_ptr = rcu_dereference(vsk->remote_addr);
>+		if (!rcu_ptr) {
>+			err = -EINVAL;
>+			goto out;
>+		}
>+		vm_addr = &rcu_ptr->addr;
> 	} else {
> 		vm_addr = &vsk->local_addr;
> 	}
>@@ -975,6 +1153,8 @@ static int vsock_getname(struct socket *sock,
> 	err = sizeof(*vm_addr);
>
> out:
>+	if (peer)
>+		rcu_read_unlock();
> 	release_sock(sk);
> 	return err;
> }
>@@ -1161,7 +1341,7 @@ static int vsock_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
> 	int err;
> 	struct sock *sk;
> 	struct vsock_sock *vsk;
>-	struct sockaddr_vm *remote_addr;
>+	struct sockaddr_vm stack_addr, *remote_addr;
> 	const struct vsock_transport *transport;
>
> 	if (msg->msg_flags & MSG_OOB)
>@@ -1172,15 +1352,26 @@ static int vsock_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
> 	sk = sock->sk;
> 	vsk = vsock_sk(sk);
>
>-	lock_sock(sk);
>+	/* If auto-binding is required, acquire the slock to avoid potential
>+	 * race conditions. Otherwise, do not acquire the lock.
>+	 *
>+	 * We know that the first check of local_addr is racy (indicated by
>+	 * data_race()). By acquiring the lock and then subsequently checking
>+	 * again if local_addr is bound (inside vsock_auto_bind()), we can
>+	 * ensure there are no real data races.
>+	 *
>+	 * This technique is borrowed by inet_send_prepare().
>+	 */
>+	if (data_race(!vsock_addr_bound(&vsk->local_addr))) {
>+		lock_sock(sk);
>+		err = vsock_auto_bind(vsk);
>+		release_sock(sk);
>+		if (err)
>+			return err;
>+	}
>
> 	transport = vsk->transport;
>
>-	err = vsock_auto_bind(vsk);
>-	if (err)
>-		goto out;
>-
>-
> 	/* If the provided message contains an address, use that.  Otherwise
> 	 * fall back on the socket's remote handle (if it has been connected).
> 	 */
>@@ -1199,18 +1390,26 @@ static int vsock_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
> 			goto out;
> 		}
> 	} else if (sock->state == SS_CONNECTED) {
>-		remote_addr = &vsk->remote_addr;
>+		err = vsock_remote_addr_copy(vsk, &stack_addr);
>+		if (err < 0)
>+			goto out;
>
>-		if (remote_addr->svm_cid == VMADDR_CID_ANY)
>-			remote_addr->svm_cid = transport->get_local_cid();
>+		if (stack_addr.svm_cid == VMADDR_CID_ANY) {
>+			stack_addr.svm_cid = transport->get_local_cid();
>+			lock_sock(sk_vsock(vsk));
>+			vsock_remote_addr_update(vsk, &stack_addr);
>+			release_sock(sk_vsock(vsk));
>+		}
>
> 		/* XXX Should connect() or this function ensure remote_addr is
> 		 * bound?
> 		 */
>-		if (!vsock_addr_bound(&vsk->remote_addr)) {
>+		if (!vsock_addr_bound(&stack_addr)) {
> 			err = -EINVAL;
> 			goto out;
> 		}
>+
>+		remote_addr = &stack_addr;
> 	} else {
> 		err = -EINVAL;
> 		goto out;
>@@ -1225,7 +1424,6 @@ static int vsock_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
> 	err = transport->dgram_enqueue(vsk, remote_addr, msg, len);
>
> out:
>-	release_sock(sk);
> 	return err;
> }
>
>@@ -1243,8 +1441,7 @@ static int vsock_dgram_connect(struct socket *sock,
> 	err = vsock_addr_cast(addr, addr_len, &remote_addr);
> 	if (err == -EAFNOSUPPORT && remote_addr->svm_family == AF_UNSPEC) {
> 		lock_sock(sk);
>-		vsock_addr_init(&vsk->remote_addr, VMADDR_CID_ANY,
>-				VMADDR_PORT_ANY);
>+		vsock_remote_addr_update_cid_port(vsk, VMADDR_CID_ANY, VMADDR_PORT_ANY);
> 		sock->state = SS_UNCONNECTED;
> 		release_sock(sk);
> 		return 0;
>@@ -1263,7 +1460,10 @@ static int vsock_dgram_connect(struct socket *sock,
> 		goto out;
> 	}
>
>-	memcpy(&vsk->remote_addr, remote_addr, sizeof(vsk->remote_addr));
>+	err = vsock_remote_addr_update(vsk, remote_addr);
>+	if (err < 0)
>+		goto out;
>+
> 	sock->state = SS_CONNECTED;
>
> 	/* sock map disallows redirection of non-TCP sockets with sk_state !=
>@@ -1399,8 +1599,9 @@ static int vsock_connect(struct socket *sock, struct sockaddr *addr,
> 		}
>
> 		/* Set the remote address that we are connecting to. */
>-		memcpy(&vsk->remote_addr, remote_addr,
>-		       sizeof(vsk->remote_addr));
>+		err = vsock_remote_addr_update(vsk, remote_addr);
>+		if (err)
>+			goto out;
>
> 		err = vsock_assign_transport(vsk, NULL);
> 		if (err)
>@@ -1831,7 +2032,7 @@ static int vsock_connectible_sendmsg(struct socket *sock, struct msghdr *msg,
> 		goto out;
> 	}
>
>-	if (!vsock_addr_bound(&vsk->remote_addr)) {
>+	if (!vsock_remote_addr_bound(vsk)) {
> 		err = -EDESTADDRREQ;
> 		goto out;
> 	}
>diff --git a/net/vmw_vsock/diag.c b/net/vmw_vsock/diag.c
>index a2823b1c5e28..f843bae86b32 100644
>--- a/net/vmw_vsock/diag.c
>+++ b/net/vmw_vsock/diag.c
>@@ -15,8 +15,14 @@ static int sk_diag_fill(struct sock *sk, struct sk_buff *skb,
> 			u32 portid, u32 seq, u32 flags)
> {
> 	struct vsock_sock *vsk = vsock_sk(sk);
>+	struct sockaddr_vm remote_addr;
> 	struct vsock_diag_msg *rep;
> 	struct nlmsghdr *nlh;
>+	int err;
>+
>+	err = vsock_remote_addr_copy(vsk, &remote_addr);
>+	if (err < 0)
>+		return err;
>
> 	nlh = nlmsg_put(skb, portid, seq, SOCK_DIAG_BY_FAMILY, sizeof(*rep),
> 			flags);
>@@ -36,8 +42,8 @@ static int sk_diag_fill(struct sock *sk, struct sk_buff *skb,
> 	rep->vdiag_shutdown = sk->sk_shutdown;
> 	rep->vdiag_src_cid = vsk->local_addr.svm_cid;
> 	rep->vdiag_src_port = vsk->local_addr.svm_port;
>-	rep->vdiag_dst_cid = vsk->remote_addr.svm_cid;
>-	rep->vdiag_dst_port = vsk->remote_addr.svm_port;
>+	rep->vdiag_dst_cid = remote_addr.svm_cid;
>+	rep->vdiag_dst_port = remote_addr.svm_port;
> 	rep->vdiag_ino = sock_i_ino(sk);
>
> 	sock_diag_save_cookie(sk, rep->vdiag_cookie);
>diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c
>index 7cb1a9d2cdb4..462b2ec3e6e9 100644
>--- a/net/vmw_vsock/hyperv_transport.c
>+++ b/net/vmw_vsock/hyperv_transport.c
>@@ -336,9 +336,11 @@ static void hvs_open_connection(struct vmbus_channel *chan)
> 		hvs_addr_init(&vnew->local_addr, if_type);
>
> 		/* Remote peer is always the host */
>-		vsock_addr_init(&vnew->remote_addr,
>-				VMADDR_CID_HOST, VMADDR_PORT_ANY);
>-		vnew->remote_addr.svm_port = get_port_by_srv_id(if_instance);
>+		ret = vsock_remote_addr_update_cid_port(vnew, VMADDR_CID_HOST,
>+							get_port_by_srv_id(if_instance));
>+		if (ret < 0)
>+			goto out;
>+
> 		ret = vsock_assign_transport(vnew, vsock_sk(sk));
> 		/* Transport assigned (looking at remote_addr) must be the
> 		 * same where we received the request.
>@@ -459,13 +461,18 @@ static int hvs_connect(struct vsock_sock *vsk)
> {
> 	union hvs_service_id vm, host;
> 	struct hvsock *h = vsk->trans;
>+	int err;
>
> 	vm.srv_id = srv_id_template;
> 	vm.svm_port = vsk->local_addr.svm_port;
> 	h->vm_srv_id = vm.srv_id;
>
> 	host.srv_id = srv_id_template;
>-	host.svm_port = vsk->remote_addr.svm_port;
>+
>+	err = vsock_remote_addr_port(vsk, &host.svm_port);
>+	if (err < 0)
>+		return err;
>+
> 	h->host_srv_id = host.srv_id;
>
> 	return vmbus_send_tl_connect_request(&h->vm_srv_id, &h->host_srv_id);
>diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>index 925acface893..1b87704e516a 100644
>--- a/net/vmw_vsock/virtio_transport_common.c
>+++ b/net/vmw_vsock/virtio_transport_common.c
>@@ -258,8 +258,9 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
> 	src_cid = t_ops->transport.get_local_cid();
> 	src_port = vsk->local_addr.svm_port;
> 	if (!info->remote_cid) {
>-		dst_cid	= vsk->remote_addr.svm_cid;
>-		dst_port = vsk->remote_addr.svm_port;
>+		ret = vsock_remote_addr_cid_port(vsk, &dst_cid, &dst_port);
>+		if (ret < 0)
>+			return ret;
> 	} else {
> 		dst_cid = info->remote_cid;
> 		dst_port = info->remote_port;
>@@ -1169,7 +1170,9 @@ virtio_transport_recv_connecting(struct sock *sk,
> 	case VIRTIO_VSOCK_OP_RESPONSE:
> 		sk->sk_state = TCP_ESTABLISHED;
> 		sk->sk_socket->state = SS_CONNECTED;
>-		vsock_insert_connected(vsk);
>+		err = vsock_insert_connected(vsk);
>+		if (err)
>+			goto destroy;
> 		sk->sk_state_change(sk);
> 		break;
> 	case VIRTIO_VSOCK_OP_INVALID:
>@@ -1403,9 +1406,8 @@ virtio_transport_recv_listen(struct sock *sk, struct sk_buff *skb,
> 	vchild = vsock_sk(child);
> 	vsock_addr_init(&vchild->local_addr, le64_to_cpu(hdr->dst_cid),
> 			le32_to_cpu(hdr->dst_port));
>-	vsock_addr_init(&vchild->remote_addr, le64_to_cpu(hdr->src_cid),
>-			le32_to_cpu(hdr->src_port));
>-
>+	vsock_remote_addr_update_cid_port(vchild, le64_to_cpu(hdr->src_cid),
>+					  le32_to_cpu(hdr->src_port));
> 	ret = vsock_assign_transport(vchild, vsk);
> 	/* Transport assigned (looking at remote_addr) must be the same
> 	 * where we received the request.
>@@ -1420,7 +1422,13 @@ virtio_transport_recv_listen(struct sock *sk, struct sk_buff *skb,
> 	if (virtio_transport_space_update(child, skb))
> 		child->sk_write_space(child);
>
>-	vsock_insert_connected(vchild);
>+	ret = vsock_insert_connected(vchild);
>+	if (ret) {
>+		release_sock(child);
>+		virtio_transport_reset_no_sock(t, skb);
>+		sock_put(child);
>+		return ret;
>+	}
> 	vsock_enqueue_accept(sk, child);
> 	virtio_transport_send_response(vchild, skb);
>
>diff --git a/net/vmw_vsock/vmci_transport.c b/net/vmw_vsock/vmci_transport.c
>index b370070194fa..c0c445e7d925 100644
>--- a/net/vmw_vsock/vmci_transport.c
>+++ b/net/vmw_vsock/vmci_transport.c
>@@ -283,18 +283,25 @@ vmci_transport_send_control_pkt(struct sock *sk,
> 				u16 proto,
> 				struct vmci_handle handle)
> {
>+	struct sockaddr_vm addr_stack;
>+	struct sockaddr_vm *remote_addr = &addr_stack;
> 	struct vsock_sock *vsk;
>+	int err;
>
> 	vsk = vsock_sk(sk);
>
> 	if (!vsock_addr_bound(&vsk->local_addr))
> 		return -EINVAL;
>
>-	if (!vsock_addr_bound(&vsk->remote_addr))
>+	if (!vsock_remote_addr_bound(vsk))
> 		return -EINVAL;
>
>+	err = vsock_remote_addr_copy(vsk, &addr_stack);
>+	if (err < 0)
>+		return err;
>+
> 	return vmci_transport_alloc_send_control_pkt(&vsk->local_addr,
>-						     &vsk->remote_addr,
>+						     remote_addr,
> 						     type, size, mode,
> 						     wait, proto, handle);
> }
>@@ -317,6 +324,7 @@ static int vmci_transport_send_reset(struct sock *sk,
> 	struct sockaddr_vm *dst_ptr;
> 	struct sockaddr_vm dst;
> 	struct vsock_sock *vsk;
>+	int err;
>
> 	if (pkt->type == VMCI_TRANSPORT_PACKET_TYPE_RST)
> 		return 0;
>@@ -326,13 +334,16 @@ static int vmci_transport_send_reset(struct sock *sk,
> 	if (!vsock_addr_bound(&vsk->local_addr))
> 		return -EINVAL;
>
>-	if (vsock_addr_bound(&vsk->remote_addr)) {
>-		dst_ptr = &vsk->remote_addr;
>+	if (vsock_remote_addr_bound(vsk)) {
>+		err = vsock_remote_addr_copy(vsk, &dst);
>+		if (err < 0)
>+			return err;
> 	} else {
> 		vsock_addr_init(&dst, pkt->dg.src.context,
> 				pkt->src_port);
>-		dst_ptr = &dst;
> 	}
>+	dst_ptr = &dst;
>+
> 	return vmci_transport_alloc_send_control_pkt(&vsk->local_addr, dst_ptr,
> 					     VMCI_TRANSPORT_PACKET_TYPE_RST,
> 					     0, 0, NULL, VSOCK_PROTO_INVALID,
>@@ -490,7 +501,7 @@ static struct sock *vmci_transport_get_pending(
>
> 	list_for_each_entry(vpending, &vlistener->pending_links,
> 			    pending_links) {
>-		if (vsock_addr_equals_addr(&src, &vpending->remote_addr) &&
>+		if (vsock_remote_addr_equals(vpending, &src) &&
> 		    pkt->dst_port == vpending->local_addr.svm_port) {
> 			pending = sk_vsock(vpending);
> 			sock_hold(pending);
>@@ -1015,8 +1026,8 @@ static int vmci_transport_recv_listen(struct sock *sk,
>
> 	vsock_addr_init(&vpending->local_addr, pkt->dg.dst.context,
> 			pkt->dst_port);
>-	vsock_addr_init(&vpending->remote_addr, pkt->dg.src.context,
>-			pkt->src_port);
>+	vsock_remote_addr_update_cid_port(vpending, pkt->dg.src.context,
>+					  pkt->src_port);
>
> 	err = vsock_assign_transport(vpending, vsock_sk(sk));
> 	/* Transport assigned (looking at remote_addr) must be the same
>@@ -1133,6 +1144,7 @@ vmci_transport_recv_connecting_server(struct sock *listener,
> {
> 	struct vsock_sock *vpending;
> 	struct vmci_handle handle;
>+	unsigned int vpending_remote_cid;
> 	struct vmci_qp *qpair;
> 	bool is_local;
> 	u32 flags;
>@@ -1189,8 +1201,13 @@ vmci_transport_recv_connecting_server(struct sock *listener,
> 	/* vpending->local_addr always has a context id so we do not need to
> 	 * worry about VMADDR_CID_ANY in this case.
> 	 */
>-	is_local =
>-	    vpending->remote_addr.svm_cid == vpending->local_addr.svm_cid;
>+	err = vsock_remote_addr_cid(vpending, &vpending_remote_cid);
>+	if (err < 0) {
>+		skerr = EPROTO;
>+		goto destroy;
>+	}
>+
>+	is_local = vpending_remote_cid == vpending->local_addr.svm_cid;
> 	flags = VMCI_QPFLAG_ATTACH_ONLY;
> 	flags |= is_local ? VMCI_QPFLAG_LOCAL : 0;
>
>@@ -1203,7 +1220,7 @@ vmci_transport_recv_connecting_server(struct sock *listener,
> 					flags,
> 					vmci_transport_is_trusted(
> 						vpending,
>-						vpending->remote_addr.svm_cid));
>+						vpending_remote_cid));
> 	if (err < 0) {
> 		vmci_transport_send_reset(pending, pkt);
> 		skerr = -err;
>@@ -1306,9 +1323,20 @@ vmci_transport_recv_connecting_client(struct sock *sk,
> 		break;
> 	case VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE:
> 	case VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE2:
>+		struct sockaddr_vm_rcu *remote_addr;
>+
>+		rcu_read_lock();
>+		remote_addr = rcu_dereference(vsk->remote_addr);
>+		if (!remote_addr) {
>+			skerr = EPROTO;
>+			err = -EINVAL;
>+			rcu_read_unlock();
>+			goto destroy;
>+		}
>+
> 		if (pkt->u.size == 0
>-		    || pkt->dg.src.context != vsk->remote_addr.svm_cid
>-		    || pkt->src_port != vsk->remote_addr.svm_port
>+		    || pkt->dg.src.context != remote_addr->addr.svm_cid
>+		    || pkt->src_port != remote_addr->addr.svm_port
> 		    || !vmci_handle_is_invalid(vmci_trans(vsk)->qp_handle)
> 		    || vmci_trans(vsk)->qpair
> 		    || vmci_trans(vsk)->produce_size != 0
>@@ -1316,9 +1344,10 @@ vmci_transport_recv_connecting_client(struct sock *sk,
> 		    || vmci_trans(vsk)->detach_sub_id != VMCI_INVALID_ID) {
> 			skerr = EPROTO;
> 			err = -EINVAL;
>-
>+			rcu_read_unlock();
> 			goto destroy;
> 		}
>+		rcu_read_unlock();
>
> 		err = vmci_transport_recv_connecting_client_negotiate(sk, pkt);
> 		if (err) {
>@@ -1379,6 +1408,7 @@ static int vmci_transport_recv_connecting_client_negotiate(
> 	int err;
> 	struct vsock_sock *vsk;
> 	struct vmci_handle handle;
>+	unsigned int remote_cid;
> 	struct vmci_qp *qpair;
> 	u32 detach_sub_id;
> 	bool is_local;
>@@ -1449,19 +1479,23 @@ static int vmci_transport_recv_connecting_client_negotiate(
>
> 	/* Make VMCI select the handle for us. */
> 	handle = VMCI_INVALID_HANDLE;
>-	is_local = vsk->remote_addr.svm_cid == vsk->local_addr.svm_cid;
>+
>+	err = vsock_remote_addr_cid(vsk, &remote_cid);
>+	if (err < 0)
>+		goto destroy;
>+
>+	is_local = remote_cid == vsk->local_addr.svm_cid;
> 	flags = is_local ? VMCI_QPFLAG_LOCAL : 0;
>
> 	err = vmci_transport_queue_pair_alloc(&qpair,
> 					      &handle,
> 					      pkt->u.size,
> 					      pkt->u.size,
>-					      vsk->remote_addr.svm_cid,
>+					      remote_cid,
> 					      flags,
> 					      vmci_transport_is_trusted(
> 						  vsk,
>-						  vsk->
>-						  remote_addr.svm_cid));
>+						  remote_cid));
> 	if (err < 0)
> 		goto destroy;
>
>
>-- 
>2.30.2
>