From a9eeb998c28d5506616426bd3a216bd5735a18b8 Mon Sep 17 00:00:00 2001 From: Sunil Muthuswamy Date: Wed, 15 May 2019 00:56:05 +0000 Subject: hv_sock: Add support for delayed close Currently, hvsock does not implement any delayed or background close logic. Whenever the hvsock socket is closed, a FIN is sent to the peer, and the last reference to the socket is dropped, which leads to a call to .destruct where the socket can hang indefinitely waiting for the peer to close it's side. The can cause the user application to hang in the close() call. This change implements proper STREAM(TCP) closing handshake mechanism by sending the FIN to the peer and the waiting for the peer's FIN to arrive for a given timeout. On timeout, it will try to terminate the connection (i.e. a RST). This is in-line with other socket providers such as virtio. This change does not address the hang in the vmbus_hvsock_device_unregister where it waits indefinitely for the host to rescind the channel. That should be taken up as a separate fix. Signed-off-by: Sunil Muthuswamy Reviewed-by: Dexuan Cui Signed-off-by: David S. Miller --- net/vmw_vsock/hyperv_transport.c | 108 ++++++++++++++++++++++++++++----------- 1 file changed, 77 insertions(+), 31 deletions(-) (limited to 'net') diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c index a827547aa102..982a8dc49e03 100644 --- a/net/vmw_vsock/hyperv_transport.c +++ b/net/vmw_vsock/hyperv_transport.c @@ -35,6 +35,9 @@ /* The MTU is 16KB per the host side's design */ #define HVS_MTU_SIZE (1024 * 16) +/* How long to wait for graceful shutdown of a connection */ +#define HVS_CLOSE_TIMEOUT (8 * HZ) + struct vmpipe_proto_header { u32 pkt_type; u32 data_size; @@ -305,19 +308,32 @@ static void hvs_channel_cb(void *ctx) sk->sk_write_space(sk); } -static void hvs_close_connection(struct vmbus_channel *chan) +static void hvs_do_close_lock_held(struct vsock_sock *vsk, + bool cancel_timeout) { - struct sock *sk = get_per_channel_state(chan); - struct vsock_sock *vsk = vsock_sk(sk); - - lock_sock(sk); + struct sock *sk = sk_vsock(vsk); - sk->sk_state = TCP_CLOSE; sock_set_flag(sk, SOCK_DONE); - vsk->peer_shutdown |= SEND_SHUTDOWN | RCV_SHUTDOWN; - + vsk->peer_shutdown = SHUTDOWN_MASK; + if (vsock_stream_has_data(vsk) <= 0) + sk->sk_state = TCP_CLOSING; sk->sk_state_change(sk); + if (vsk->close_work_scheduled && + (!cancel_timeout || cancel_delayed_work(&vsk->close_work))) { + vsk->close_work_scheduled = false; + vsock_remove_sock(vsk); + /* Release the reference taken while scheduling the timeout */ + sock_put(sk); + } +} + +static void hvs_close_connection(struct vmbus_channel *chan) +{ + struct sock *sk = get_per_channel_state(chan); + + lock_sock(sk); + hvs_do_close_lock_held(vsock_sk(sk), true); release_sock(sk); } @@ -452,50 +468,80 @@ static int hvs_connect(struct vsock_sock *vsk) return vmbus_send_tl_connect_request(&h->vm_srv_id, &h->host_srv_id); } +static void hvs_shutdown_lock_held(struct hvsock *hvs, int mode) +{ + struct vmpipe_proto_header hdr; + + if (hvs->fin_sent || !hvs->chan) + return; + + /* It can't fail: see hvs_channel_writable_bytes(). */ + (void)hvs_send_data(hvs->chan, (struct hvs_send_buf *)&hdr, 0); + hvs->fin_sent = true; +} + static int hvs_shutdown(struct vsock_sock *vsk, int mode) { struct sock *sk = sk_vsock(vsk); - struct vmpipe_proto_header hdr; - struct hvs_send_buf *send_buf; - struct hvsock *hvs; if (!(mode & SEND_SHUTDOWN)) return 0; lock_sock(sk); + hvs_shutdown_lock_held(vsk->trans, mode); + release_sock(sk); + return 0; +} - hvs = vsk->trans; - if (hvs->fin_sent) - goto out; - - send_buf = (struct hvs_send_buf *)&hdr; +static void hvs_close_timeout(struct work_struct *work) +{ + struct vsock_sock *vsk = + container_of(work, struct vsock_sock, close_work.work); + struct sock *sk = sk_vsock(vsk); - /* It can't fail: see hvs_channel_writable_bytes(). */ - (void)hvs_send_data(hvs->chan, send_buf, 0); + sock_hold(sk); + lock_sock(sk); + if (!sock_flag(sk, SOCK_DONE)) + hvs_do_close_lock_held(vsk, false); - hvs->fin_sent = true; -out: + vsk->close_work_scheduled = false; release_sock(sk); - return 0; + sock_put(sk); } -static void hvs_release(struct vsock_sock *vsk) +/* Returns true, if it is safe to remove socket; false otherwise */ +static bool hvs_close_lock_held(struct vsock_sock *vsk) { struct sock *sk = sk_vsock(vsk); - struct hvsock *hvs = vsk->trans; - struct vmbus_channel *chan; - lock_sock(sk); + if (!(sk->sk_state == TCP_ESTABLISHED || + sk->sk_state == TCP_CLOSING)) + return true; - sk->sk_state = TCP_CLOSING; - vsock_remove_sock(vsk); + if ((sk->sk_shutdown & SHUTDOWN_MASK) != SHUTDOWN_MASK) + hvs_shutdown_lock_held(vsk->trans, SHUTDOWN_MASK); - release_sock(sk); + if (sock_flag(sk, SOCK_DONE)) + return true; - chan = hvs->chan; - if (chan) - hvs_shutdown(vsk, RCV_SHUTDOWN | SEND_SHUTDOWN); + /* This reference will be dropped by the delayed close routine */ + sock_hold(sk); + INIT_DELAYED_WORK(&vsk->close_work, hvs_close_timeout); + vsk->close_work_scheduled = true; + schedule_delayed_work(&vsk->close_work, HVS_CLOSE_TIMEOUT); + return false; +} +static void hvs_release(struct vsock_sock *vsk) +{ + struct sock *sk = sk_vsock(vsk); + bool remove_sock; + + lock_sock(sk); + remove_sock = hvs_close_lock_held(vsk); + release_sock(sk); + if (remove_sock) + vsock_remove_sock(vsk); } static void hvs_destruct(struct vsock_sock *vsk) -- cgit v1.2.3