Linux 5.1.15

[linux/fpc-iii.git] / net / vmw_vsock / vmci_transport_notify_qstate.c

/*
 * 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 == TCP_ESTABLISHED)
                        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. */
const struct vmci_transport_notify_ops vmci_transport_notify_pkt_q_state_ops = {
        .socket_init = vmci_transport_notify_pkt_socket_init,
        .socket_destruct = vmci_transport_notify_pkt_socket_destruct,
        .poll_in = vmci_transport_notify_pkt_poll_in,
        .poll_out = vmci_transport_notify_pkt_poll_out,
        .handle_notify_pkt = vmci_transport_notify_pkt_handle_pkt,
        .recv_init = vmci_transport_notify_pkt_recv_init,
        .recv_pre_block = vmci_transport_notify_pkt_recv_pre_block,
        .recv_pre_dequeue = vmci_transport_notify_pkt_recv_pre_dequeue,
        .recv_post_dequeue = vmci_transport_notify_pkt_recv_post_dequeue,
        .send_init = vmci_transport_notify_pkt_send_init,
        .send_pre_block = vmci_transport_notify_pkt_send_pre_block,
        .send_pre_enqueue = vmci_transport_notify_pkt_send_pre_enqueue,
        .send_post_enqueue = vmci_transport_notify_pkt_send_post_enqueue,
        .process_request = vmci_transport_notify_pkt_process_request,
        .process_negotiate = vmci_transport_notify_pkt_process_negotiate,
};