--- /dev/null
+/*
+ * VMware vSockets Driver
+ *
+ * Copyright (C) 2009-2013 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ */
+
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/stddef.h>
+#include <net/sock.h>
+
+#include "vmci_transport_notify.h"
+
+#define PKT_FIELD(vsk, field_name) \
+ (vmci_trans(vsk)->notify.pkt_q_state.field_name)
+
+static bool vmci_transport_notify_waiting_write(struct vsock_sock *vsk)
+{
+ bool retval;
+ u64 notify_limit;
+
+ if (!PKT_FIELD(vsk, peer_waiting_write))
+ return false;
+
+ /* When the sender blocks, we take that as a sign that the sender is
+ * faster than the receiver. To reduce the transmit rate of the sender,
+ * we delay the sending of the read notification by decreasing the
+ * write_notify_window. The notification is delayed until the number of
+ * bytes used in the queue drops below the write_notify_window.
+ */
+
+ if (!PKT_FIELD(vsk, peer_waiting_write_detected)) {
+ PKT_FIELD(vsk, peer_waiting_write_detected) = true;
+ if (PKT_FIELD(vsk, write_notify_window) < PAGE_SIZE) {
+ PKT_FIELD(vsk, write_notify_window) =
+ PKT_FIELD(vsk, write_notify_min_window);
+ } else {
+ PKT_FIELD(vsk, write_notify_window) -= PAGE_SIZE;
+ if (PKT_FIELD(vsk, write_notify_window) <
+ PKT_FIELD(vsk, write_notify_min_window))
+ PKT_FIELD(vsk, write_notify_window) =
+ PKT_FIELD(vsk, write_notify_min_window);
+
+ }
+ }
+ notify_limit = vmci_trans(vsk)->consume_size -
+ PKT_FIELD(vsk, write_notify_window);
+
+ /* The notify_limit is used to delay notifications in the case where
+ * flow control is enabled. Below the test is expressed in terms of
+ * free space in the queue: if free_space > ConsumeSize -
+ * write_notify_window then notify An alternate way of expressing this
+ * is to rewrite the expression to use the data ready in the receive
+ * queue: if write_notify_window > bufferReady then notify as
+ * free_space == ConsumeSize - bufferReady.
+ */
+
+ retval = vmci_qpair_consume_free_space(vmci_trans(vsk)->qpair) >
+ notify_limit;
+
+ if (retval) {
+ /* Once we notify the peer, we reset the detected flag so the
+ * next wait will again cause a decrease in the window size.
+ */
+
+ PKT_FIELD(vsk, peer_waiting_write_detected) = false;
+ }
+ return retval;
+}
+
+static void
+vmci_transport_handle_read(struct sock *sk,
+ struct vmci_transport_packet *pkt,
+ bool bottom_half,
+ struct sockaddr_vm *dst, struct sockaddr_vm *src)
+{
+ sk->sk_write_space(sk);
+}
+
+static void
+vmci_transport_handle_wrote(struct sock *sk,
+ struct vmci_transport_packet *pkt,
+ bool bottom_half,
+ struct sockaddr_vm *dst, struct sockaddr_vm *src)
+{
+ sk->sk_data_ready(sk);
+}
+
+static void vsock_block_update_write_window(struct sock *sk)
+{
+ struct vsock_sock *vsk = vsock_sk(sk);
+
+ if (PKT_FIELD(vsk, write_notify_window) < vmci_trans(vsk)->consume_size)
+ PKT_FIELD(vsk, write_notify_window) =
+ min(PKT_FIELD(vsk, write_notify_window) + PAGE_SIZE,
+ vmci_trans(vsk)->consume_size);
+}
+
+static int vmci_transport_send_read_notification(struct sock *sk)
+{
+ struct vsock_sock *vsk;
+ bool sent_read;
+ unsigned int retries;
+ int err;
+
+ vsk = vsock_sk(sk);
+ sent_read = false;
+ retries = 0;
+ err = 0;
+
+ if (vmci_transport_notify_waiting_write(vsk)) {
+ /* Notify the peer that we have read, retrying the send on
+ * failure up to our maximum value. XXX For now we just log
+ * the failure, but later we should schedule a work item to
+ * handle the resend until it succeeds. That would require
+ * keeping track of work items in the vsk and cleaning them up
+ * upon socket close.
+ */
+ while (!(vsk->peer_shutdown & RCV_SHUTDOWN) &&
+ !sent_read &&
+ retries < VMCI_TRANSPORT_MAX_DGRAM_RESENDS) {
+ err = vmci_transport_send_read(sk);
+ if (err >= 0)
+ sent_read = true;
+
+ retries++;
+ }
+
+ if (retries >= VMCI_TRANSPORT_MAX_DGRAM_RESENDS && !sent_read)
+ pr_err("%p unable to send read notification to peer\n",
+ sk);
+ else
+ PKT_FIELD(vsk, peer_waiting_write) = false;
+
+ }
+ return err;
+}
+
+static void vmci_transport_notify_pkt_socket_init(struct sock *sk)
+{
+ struct vsock_sock *vsk = vsock_sk(sk);
+
+ PKT_FIELD(vsk, write_notify_window) = PAGE_SIZE;
+ PKT_FIELD(vsk, write_notify_min_window) = PAGE_SIZE;
+ PKT_FIELD(vsk, peer_waiting_write) = false;
+ PKT_FIELD(vsk, peer_waiting_write_detected) = false;
+}
+
+static void vmci_transport_notify_pkt_socket_destruct(struct vsock_sock *vsk)
+{
+ PKT_FIELD(vsk, write_notify_window) = PAGE_SIZE;
+ PKT_FIELD(vsk, write_notify_min_window) = PAGE_SIZE;
+ PKT_FIELD(vsk, peer_waiting_write) = false;
+ PKT_FIELD(vsk, peer_waiting_write_detected) = false;
+}
+
+static int
+vmci_transport_notify_pkt_poll_in(struct sock *sk,
+ size_t target, bool *data_ready_now)
+{
+ struct vsock_sock *vsk = vsock_sk(sk);
+
+ if (vsock_stream_has_data(vsk)) {
+ *data_ready_now = true;
+ } else {
+ /* We can't read right now because there is nothing in the
+ * queue. Ask for notifications when there is something to
+ * read.
+ */
+ if (sk->sk_state == SS_CONNECTED)
+ vsock_block_update_write_window(sk);
+ *data_ready_now = false;
+ }
+
+ return 0;
+}
+
+static int
+vmci_transport_notify_pkt_poll_out(struct sock *sk,
+ size_t target, bool *space_avail_now)
+{
+ s64 produce_q_free_space;
+ struct vsock_sock *vsk = vsock_sk(sk);
+
+ produce_q_free_space = vsock_stream_has_space(vsk);
+ if (produce_q_free_space > 0) {
+ *space_avail_now = true;
+ return 0;
+ } else if (produce_q_free_space == 0) {
+ /* This is a connected socket but we can't currently send data.
+ * Nothing else to do.
+ */
+ *space_avail_now = false;
+ }
+
+ return 0;
+}
+
+static int
+vmci_transport_notify_pkt_recv_init(
+ struct sock *sk,
+ size_t target,
+ struct vmci_transport_recv_notify_data *data)
+{
+ struct vsock_sock *vsk = vsock_sk(sk);
+
+ data->consume_head = 0;
+ data->produce_tail = 0;
+ data->notify_on_block = false;
+
+ if (PKT_FIELD(vsk, write_notify_min_window) < target + 1) {
+ PKT_FIELD(vsk, write_notify_min_window) = target + 1;
+ if (PKT_FIELD(vsk, write_notify_window) <
+ PKT_FIELD(vsk, write_notify_min_window)) {
+ /* If the current window is smaller than the new
+ * minimal window size, we need to reevaluate whether
+ * we need to notify the sender. If the number of ready
+ * bytes are smaller than the new window, we need to
+ * send a notification to the sender before we block.
+ */
+
+ PKT_FIELD(vsk, write_notify_window) =
+ PKT_FIELD(vsk, write_notify_min_window);
+ data->notify_on_block = true;
+ }
+ }
+
+ return 0;
+}
+
+static int
+vmci_transport_notify_pkt_recv_pre_block(
+ struct sock *sk,
+ size_t target,
+ struct vmci_transport_recv_notify_data *data)
+{
+ int err = 0;
+
+ vsock_block_update_write_window(sk);
+
+ if (data->notify_on_block) {
+ err = vmci_transport_send_read_notification(sk);
+ if (err < 0)
+ return err;
+ data->notify_on_block = false;
+ }
+
+ return err;
+}
+
+static int
+vmci_transport_notify_pkt_recv_post_dequeue(
+ struct sock *sk,
+ size_t target,
+ ssize_t copied,
+ bool data_read,
+ struct vmci_transport_recv_notify_data *data)
+{
+ struct vsock_sock *vsk;
+ int err;
+ bool was_full = false;
+ u64 free_space;
+
+ vsk = vsock_sk(sk);
+ err = 0;
+
+ if (data_read) {
+ smp_mb();
+
+ free_space =
+ vmci_qpair_consume_free_space(vmci_trans(vsk)->qpair);
+ was_full = free_space == copied;
+
+ if (was_full)
+ PKT_FIELD(vsk, peer_waiting_write) = true;
+
+ err = vmci_transport_send_read_notification(sk);
+ if (err < 0)
+ return err;
+
+ /* See the comment in
+ * vmci_transport_notify_pkt_send_post_enqueue().
+ */
+ sk->sk_data_ready(sk);
+ }
+
+ return err;
+}
+
+static int
+vmci_transport_notify_pkt_send_init(
+ struct sock *sk,
+ struct vmci_transport_send_notify_data *data)
+{
+ data->consume_head = 0;
+ data->produce_tail = 0;
+
+ return 0;
+}
+
+static int
+vmci_transport_notify_pkt_send_post_enqueue(
+ struct sock *sk,
+ ssize_t written,
+ struct vmci_transport_send_notify_data *data)
+{
+ int err = 0;
+ struct vsock_sock *vsk;
+ bool sent_wrote = false;
+ bool was_empty;
+ int retries = 0;
+
+ vsk = vsock_sk(sk);
+
+ smp_mb();
+
+ was_empty =
+ vmci_qpair_produce_buf_ready(vmci_trans(vsk)->qpair) == written;
+ if (was_empty) {
+ while (!(vsk->peer_shutdown & RCV_SHUTDOWN) &&
+ !sent_wrote &&
+ retries < VMCI_TRANSPORT_MAX_DGRAM_RESENDS) {
+ err = vmci_transport_send_wrote(sk);
+ if (err >= 0)
+ sent_wrote = true;
+
+ retries++;
+ }
+ }
+
+ if (retries >= VMCI_TRANSPORT_MAX_DGRAM_RESENDS && !sent_wrote) {
+ pr_err("%p unable to send wrote notification to peer\n",
+ sk);
+ return err;
+ }
+
+ return err;
+}
+
+static void
+vmci_transport_notify_pkt_handle_pkt(
+ struct sock *sk,
+ struct vmci_transport_packet *pkt,
+ bool bottom_half,
+ struct sockaddr_vm *dst,
+ struct sockaddr_vm *src, bool *pkt_processed)
+{
+ bool processed = false;
+
+ switch (pkt->type) {
+ case VMCI_TRANSPORT_PACKET_TYPE_WROTE:
+ vmci_transport_handle_wrote(sk, pkt, bottom_half, dst, src);
+ processed = true;
+ break;
+ case VMCI_TRANSPORT_PACKET_TYPE_READ:
+ vmci_transport_handle_read(sk, pkt, bottom_half, dst, src);
+ processed = true;
+ break;
+ }
+
+ if (pkt_processed)
+ *pkt_processed = processed;
+}
+
+static void vmci_transport_notify_pkt_process_request(struct sock *sk)
+{
+ struct vsock_sock *vsk = vsock_sk(sk);
+
+ PKT_FIELD(vsk, write_notify_window) = vmci_trans(vsk)->consume_size;
+ if (vmci_trans(vsk)->consume_size <
+ PKT_FIELD(vsk, write_notify_min_window))
+ PKT_FIELD(vsk, write_notify_min_window) =
+ vmci_trans(vsk)->consume_size;
+}
+
+static void vmci_transport_notify_pkt_process_negotiate(struct sock *sk)
+{
+ struct vsock_sock *vsk = vsock_sk(sk);
+
+ PKT_FIELD(vsk, write_notify_window) = vmci_trans(vsk)->consume_size;
+ if (vmci_trans(vsk)->consume_size <
+ PKT_FIELD(vsk, write_notify_min_window))
+ PKT_FIELD(vsk, write_notify_min_window) =
+ vmci_trans(vsk)->consume_size;
+}
+
+static int
+vmci_transport_notify_pkt_recv_pre_dequeue(
+ struct sock *sk,
+ size_t target,
+ struct vmci_transport_recv_notify_data *data)
+{
+ return 0; /* NOP for QState. */
+}
+
+static int
+vmci_transport_notify_pkt_send_pre_block(
+ struct sock *sk,
+ struct vmci_transport_send_notify_data *data)
+{
+ return 0; /* NOP for QState. */
+}
+
+static int
+vmci_transport_notify_pkt_send_pre_enqueue(
+ struct sock *sk,
+ struct vmci_transport_send_notify_data *data)
+{
+ return 0; /* NOP for QState. */
+}
+
+/* Socket always on control packet based operations. */
+struct vmci_transport_notify_ops vmci_transport_notify_pkt_q_state_ops = {
+ vmci_transport_notify_pkt_socket_init,
+ vmci_transport_notify_pkt_socket_destruct,
+ vmci_transport_notify_pkt_poll_in,
+ vmci_transport_notify_pkt_poll_out,
+ vmci_transport_notify_pkt_handle_pkt,
+ vmci_transport_notify_pkt_recv_init,
+ vmci_transport_notify_pkt_recv_pre_block,
+ vmci_transport_notify_pkt_recv_pre_dequeue,
+ vmci_transport_notify_pkt_recv_post_dequeue,
+ vmci_transport_notify_pkt_send_init,
+ vmci_transport_notify_pkt_send_pre_block,
+ vmci_transport_notify_pkt_send_pre_enqueue,
+ vmci_transport_notify_pkt_send_post_enqueue,
+ vmci_transport_notify_pkt_process_request,
+ vmci_transport_notify_pkt_process_negotiate,
+};
Code Review / kvmfornfv.git / blobdiff