/* * 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. */ 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, };