/*
* 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, 0);
}
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, 0);
}
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,
};
