// SPDX-License-Identifier: GPL-2.0-only
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/*
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* VMware vSockets Driver
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*
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* Copyright (C) 2009-2013 VMware, Inc. All rights reserved.
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*/
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#include <linux/types.h>
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#include <linux/socket.h>
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#include <linux/stddef.h>
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#include <net/sock.h>
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#include "vmci_transport_notify.h"
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#define PKT_FIELD(vsk, field_name) \
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(vmci_trans(vsk)->notify.pkt_q_state.field_name)
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static bool vmci_transport_notify_waiting_write(struct vsock_sock *vsk)
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{
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bool retval;
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u64 notify_limit;
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if (!PKT_FIELD(vsk, peer_waiting_write))
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return false;
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/* When the sender blocks, we take that as a sign that the sender is
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* faster than the receiver. To reduce the transmit rate of the sender,
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* we delay the sending of the read notification by decreasing the
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* write_notify_window. The notification is delayed until the number of
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* bytes used in the queue drops below the write_notify_window.
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*/
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if (!PKT_FIELD(vsk, peer_waiting_write_detected)) {
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PKT_FIELD(vsk, peer_waiting_write_detected) = true;
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if (PKT_FIELD(vsk, write_notify_window) < PAGE_SIZE) {
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PKT_FIELD(vsk, write_notify_window) =
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PKT_FIELD(vsk, write_notify_min_window);
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} else {
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PKT_FIELD(vsk, write_notify_window) -= PAGE_SIZE;
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if (PKT_FIELD(vsk, write_notify_window) <
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PKT_FIELD(vsk, write_notify_min_window))
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PKT_FIELD(vsk, write_notify_window) =
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PKT_FIELD(vsk, write_notify_min_window);
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}
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}
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notify_limit = vmci_trans(vsk)->consume_size -
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PKT_FIELD(vsk, write_notify_window);
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/* The notify_limit is used to delay notifications in the case where
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* flow control is enabled. Below the test is expressed in terms of
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* free space in the queue: if free_space > ConsumeSize -
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* write_notify_window then notify An alternate way of expressing this
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* is to rewrite the expression to use the data ready in the receive
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* queue: if write_notify_window > bufferReady then notify as
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* free_space == ConsumeSize - bufferReady.
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*/
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retval = vmci_qpair_consume_free_space(vmci_trans(vsk)->qpair) >
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notify_limit;
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if (retval) {
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/* Once we notify the peer, we reset the detected flag so the
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* next wait will again cause a decrease in the window size.
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*/
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PKT_FIELD(vsk, peer_waiting_write_detected) = false;
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}
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return retval;
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}
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static void
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vmci_transport_handle_read(struct sock *sk,
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struct vmci_transport_packet *pkt,
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bool bottom_half,
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struct sockaddr_vm *dst, struct sockaddr_vm *src)
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{
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sk->sk_write_space(sk);
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}
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static void
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vmci_transport_handle_wrote(struct sock *sk,
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struct vmci_transport_packet *pkt,
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bool bottom_half,
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struct sockaddr_vm *dst, struct sockaddr_vm *src)
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{
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sk->sk_data_ready(sk);
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}
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static void vsock_block_update_write_window(struct sock *sk)
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{
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struct vsock_sock *vsk = vsock_sk(sk);
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if (PKT_FIELD(vsk, write_notify_window) < vmci_trans(vsk)->consume_size)
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PKT_FIELD(vsk, write_notify_window) =
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min(PKT_FIELD(vsk, write_notify_window) + PAGE_SIZE,
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vmci_trans(vsk)->consume_size);
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}
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static int vmci_transport_send_read_notification(struct sock *sk)
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{
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struct vsock_sock *vsk;
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bool sent_read;
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unsigned int retries;
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int err;
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vsk = vsock_sk(sk);
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sent_read = false;
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retries = 0;
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err = 0;
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if (vmci_transport_notify_waiting_write(vsk)) {
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/* Notify the peer that we have read, retrying the send on
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* failure up to our maximum value. XXX For now we just log
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* the failure, but later we should schedule a work item to
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* handle the resend until it succeeds. That would require
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* keeping track of work items in the vsk and cleaning them up
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* upon socket close.
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*/
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while (!(vsk->peer_shutdown & RCV_SHUTDOWN) &&
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!sent_read &&
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retries < VMCI_TRANSPORT_MAX_DGRAM_RESENDS) {
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err = vmci_transport_send_read(sk);
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if (err >= 0)
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sent_read = true;
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retries++;
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}
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if (retries >= VMCI_TRANSPORT_MAX_DGRAM_RESENDS && !sent_read)
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pr_err("%p unable to send read notification to peer\n",
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sk);
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else
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PKT_FIELD(vsk, peer_waiting_write) = false;
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}
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return err;
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}
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static void vmci_transport_notify_pkt_socket_init(struct sock *sk)
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{
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struct vsock_sock *vsk = vsock_sk(sk);
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PKT_FIELD(vsk, write_notify_window) = PAGE_SIZE;
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PKT_FIELD(vsk, write_notify_min_window) = PAGE_SIZE;
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PKT_FIELD(vsk, peer_waiting_write) = false;
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PKT_FIELD(vsk, peer_waiting_write_detected) = false;
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}
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static void vmci_transport_notify_pkt_socket_destruct(struct vsock_sock *vsk)
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{
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PKT_FIELD(vsk, write_notify_window) = PAGE_SIZE;
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PKT_FIELD(vsk, write_notify_min_window) = PAGE_SIZE;
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PKT_FIELD(vsk, peer_waiting_write) = false;
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PKT_FIELD(vsk, peer_waiting_write_detected) = false;
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}
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static int
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vmci_transport_notify_pkt_poll_in(struct sock *sk,
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size_t target, bool *data_ready_now)
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{
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struct vsock_sock *vsk = vsock_sk(sk);
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if (vsock_stream_has_data(vsk)) {
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*data_ready_now = true;
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} else {
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/* We can't read right now because there is nothing in the
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* queue. Ask for notifications when there is something to
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* read.
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*/
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if (sk->sk_state == TCP_ESTABLISHED)
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vsock_block_update_write_window(sk);
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*data_ready_now = false;
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}
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return 0;
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}
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static int
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vmci_transport_notify_pkt_poll_out(struct sock *sk,
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size_t target, bool *space_avail_now)
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{
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s64 produce_q_free_space;
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struct vsock_sock *vsk = vsock_sk(sk);
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produce_q_free_space = vsock_stream_has_space(vsk);
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if (produce_q_free_space > 0) {
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*space_avail_now = true;
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return 0;
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} else if (produce_q_free_space == 0) {
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/* This is a connected socket but we can't currently send data.
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* Nothing else to do.
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*/
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*space_avail_now = false;
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}
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return 0;
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}
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static int
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vmci_transport_notify_pkt_recv_init(
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struct sock *sk,
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size_t target,
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struct vmci_transport_recv_notify_data *data)
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{
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struct vsock_sock *vsk = vsock_sk(sk);
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data->consume_head = 0;
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data->produce_tail = 0;
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data->notify_on_block = false;
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if (PKT_FIELD(vsk, write_notify_min_window) < target + 1) {
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PKT_FIELD(vsk, write_notify_min_window) = target + 1;
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if (PKT_FIELD(vsk, write_notify_window) <
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PKT_FIELD(vsk, write_notify_min_window)) {
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/* If the current window is smaller than the new
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* minimal window size, we need to reevaluate whether
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* we need to notify the sender. If the number of ready
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* bytes are smaller than the new window, we need to
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* send a notification to the sender before we block.
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*/
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PKT_FIELD(vsk, write_notify_window) =
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PKT_FIELD(vsk, write_notify_min_window);
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data->notify_on_block = true;
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}
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}
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return 0;
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}
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static int
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vmci_transport_notify_pkt_recv_pre_block(
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struct sock *sk,
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size_t target,
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struct vmci_transport_recv_notify_data *data)
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{
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int err = 0;
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vsock_block_update_write_window(sk);
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if (data->notify_on_block) {
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err = vmci_transport_send_read_notification(sk);
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if (err < 0)
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return err;
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data->notify_on_block = false;
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}
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return err;
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}
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static int
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vmci_transport_notify_pkt_recv_post_dequeue(
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struct sock *sk,
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size_t target,
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ssize_t copied,
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bool data_read,
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struct vmci_transport_recv_notify_data *data)
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{
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struct vsock_sock *vsk;
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int err;
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bool was_full = false;
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u64 free_space;
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vsk = vsock_sk(sk);
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err = 0;
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if (data_read) {
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smp_mb();
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free_space =
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vmci_qpair_consume_free_space(vmci_trans(vsk)->qpair);
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was_full = free_space == copied;
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if (was_full)
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PKT_FIELD(vsk, peer_waiting_write) = true;
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err = vmci_transport_send_read_notification(sk);
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if (err < 0)
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return err;
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/* See the comment in
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* vmci_transport_notify_pkt_send_post_enqueue().
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*/
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sk->sk_data_ready(sk);
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}
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return err;
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}
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static int
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vmci_transport_notify_pkt_send_init(
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struct sock *sk,
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struct vmci_transport_send_notify_data *data)
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{
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data->consume_head = 0;
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data->produce_tail = 0;
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return 0;
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}
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static int
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vmci_transport_notify_pkt_send_post_enqueue(
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struct sock *sk,
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ssize_t written,
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struct vmci_transport_send_notify_data *data)
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{
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int err = 0;
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struct vsock_sock *vsk;
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bool sent_wrote = false;
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bool was_empty;
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int retries = 0;
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vsk = vsock_sk(sk);
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smp_mb();
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was_empty =
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vmci_qpair_produce_buf_ready(vmci_trans(vsk)->qpair) == written;
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if (was_empty) {
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while (!(vsk->peer_shutdown & RCV_SHUTDOWN) &&
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!sent_wrote &&
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retries < VMCI_TRANSPORT_MAX_DGRAM_RESENDS) {
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err = vmci_transport_send_wrote(sk);
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if (err >= 0)
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sent_wrote = true;
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retries++;
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}
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}
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if (retries >= VMCI_TRANSPORT_MAX_DGRAM_RESENDS && !sent_wrote) {
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pr_err("%p unable to send wrote notification to peer\n",
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sk);
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return err;
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}
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return err;
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}
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static void
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vmci_transport_notify_pkt_handle_pkt(
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struct sock *sk,
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struct vmci_transport_packet *pkt,
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bool bottom_half,
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struct sockaddr_vm *dst,
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struct sockaddr_vm *src, bool *pkt_processed)
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{
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bool processed = false;
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switch (pkt->type) {
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case VMCI_TRANSPORT_PACKET_TYPE_WROTE:
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vmci_transport_handle_wrote(sk, pkt, bottom_half, dst, src);
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processed = true;
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break;
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case VMCI_TRANSPORT_PACKET_TYPE_READ:
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vmci_transport_handle_read(sk, pkt, bottom_half, dst, src);
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processed = true;
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break;
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}
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if (pkt_processed)
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*pkt_processed = processed;
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}
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static void vmci_transport_notify_pkt_process_request(struct sock *sk)
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{
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struct vsock_sock *vsk = vsock_sk(sk);
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PKT_FIELD(vsk, write_notify_window) = vmci_trans(vsk)->consume_size;
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if (vmci_trans(vsk)->consume_size <
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PKT_FIELD(vsk, write_notify_min_window))
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PKT_FIELD(vsk, write_notify_min_window) =
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vmci_trans(vsk)->consume_size;
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}
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static void vmci_transport_notify_pkt_process_negotiate(struct sock *sk)
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{
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struct vsock_sock *vsk = vsock_sk(sk);
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PKT_FIELD(vsk, write_notify_window) = vmci_trans(vsk)->consume_size;
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if (vmci_trans(vsk)->consume_size <
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PKT_FIELD(vsk, write_notify_min_window))
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PKT_FIELD(vsk, write_notify_min_window) =
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vmci_trans(vsk)->consume_size;
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}
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static int
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vmci_transport_notify_pkt_recv_pre_dequeue(
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struct sock *sk,
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size_t target,
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struct vmci_transport_recv_notify_data *data)
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{
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return 0; /* NOP for QState. */
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}
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static int
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vmci_transport_notify_pkt_send_pre_block(
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struct sock *sk,
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struct vmci_transport_send_notify_data *data)
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{
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return 0; /* NOP for QState. */
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}
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static int
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vmci_transport_notify_pkt_send_pre_enqueue(
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struct sock *sk,
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struct vmci_transport_send_notify_data *data)
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{
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return 0; /* NOP for QState. */
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}
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/* Socket always on control packet based operations. */
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const struct vmci_transport_notify_ops vmci_transport_notify_pkt_q_state_ops = {
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.socket_init = vmci_transport_notify_pkt_socket_init,
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.socket_destruct = vmci_transport_notify_pkt_socket_destruct,
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.poll_in = vmci_transport_notify_pkt_poll_in,
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.poll_out = vmci_transport_notify_pkt_poll_out,
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.handle_notify_pkt = vmci_transport_notify_pkt_handle_pkt,
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.recv_init = vmci_transport_notify_pkt_recv_init,
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.recv_pre_block = vmci_transport_notify_pkt_recv_pre_block,
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.recv_pre_dequeue = vmci_transport_notify_pkt_recv_pre_dequeue,
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.recv_post_dequeue = vmci_transport_notify_pkt_recv_post_dequeue,
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.send_init = vmci_transport_notify_pkt_send_init,
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.send_pre_block = vmci_transport_notify_pkt_send_pre_block,
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.send_pre_enqueue = vmci_transport_notify_pkt_send_pre_enqueue,
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.send_post_enqueue = vmci_transport_notify_pkt_send_post_enqueue,
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.process_request = vmci_transport_notify_pkt_process_request,
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.process_negotiate = vmci_transport_notify_pkt_process_negotiate,
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};
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