net/vmw_vsock/vmci_transport_notify_qstate.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * VMware vSockets Driver
   4  *
   5  * Copyright (C) 2009-2013 VMware, Inc. All rights reserved.
   6  */
   7
   8 #include <linux/types.h>
   9 #include <linux/socket.h>
  10 #include <linux/stddef.h>
  11 #include <net/sock.h>
  12
  13 #include "vmci_transport_notify.h"
  14
  15 #define PKT_FIELD(vsk, field_name) \
  16         (vmci_trans(vsk)->notify.pkt_q_state.field_name)
  17
  18 static bool vmci_transport_notify_waiting_write(struct vsock_sock *vsk)
  19 {
  20         bool retval;
  21         u64 notify_limit;
  22
  23         if (!PKT_FIELD(vsk, peer_waiting_write))
  24                 return false;
  25
  26         /* When the sender blocks, we take that as a sign that the sender is
  27          * faster than the receiver. To reduce the transmit rate of the sender,
  28          * we delay the sending of the read notification by decreasing the
  29          * write_notify_window. The notification is delayed until the number of
  30          * bytes used in the queue drops below the write_notify_window.
  31          */
  32
  33         if (!PKT_FIELD(vsk, peer_waiting_write_detected)) {
  34                 PKT_FIELD(vsk, peer_waiting_write_detected) = true;
  35                 if (PKT_FIELD(vsk, write_notify_window) < PAGE_SIZE) {
  36                         PKT_FIELD(vsk, write_notify_window) =
  37                             PKT_FIELD(vsk, write_notify_min_window);
  38                 } else {
  39                         PKT_FIELD(vsk, write_notify_window) -= PAGE_SIZE;
  40                         if (PKT_FIELD(vsk, write_notify_window) <
  41                             PKT_FIELD(vsk, write_notify_min_window))
  42                                 PKT_FIELD(vsk, write_notify_window) =
  43                                     PKT_FIELD(vsk, write_notify_min_window);
  44
  45                 }
  46         }
  47         notify_limit = vmci_trans(vsk)->consume_size -
  48                 PKT_FIELD(vsk, write_notify_window);
  49
  50         /* The notify_limit is used to delay notifications in the case where
  51          * flow control is enabled. Below the test is expressed in terms of
  52          * free space in the queue: if free_space > ConsumeSize -
  53          * write_notify_window then notify An alternate way of expressing this
  54          * is to rewrite the expression to use the data ready in the receive
  55          * queue: if write_notify_window > bufferReady then notify as
  56          * free_space == ConsumeSize - bufferReady.
  57          */
  58
  59         retval = vmci_qpair_consume_free_space(vmci_trans(vsk)->qpair) >
  60                 notify_limit;
  61
  62         if (retval) {
  63                 /* Once we notify the peer, we reset the detected flag so the
  64                  * next wait will again cause a decrease in the window size.
  65                  */
  66
  67                 PKT_FIELD(vsk, peer_waiting_write_detected) = false;
  68         }
  69         return retval;
  70 }
  71
  72 static void
  73 vmci_transport_handle_read(struct sock *sk,
  74                            struct vmci_transport_packet *pkt,
  75                            bool bottom_half,
  76                            struct sockaddr_vm *dst, struct sockaddr_vm *src)
  77 {
  78         sk->sk_write_space(sk);
  79 }
  80
  81 static void
  82 vmci_transport_handle_wrote(struct sock *sk,
  83                             struct vmci_transport_packet *pkt,
  84                             bool bottom_half,
  85                             struct sockaddr_vm *dst, struct sockaddr_vm *src)
  86 {
  87         sk->sk_data_ready(sk);
  88 }
  89
  90 static void vsock_block_update_write_window(struct sock *sk)
  91 {
  92         struct vsock_sock *vsk = vsock_sk(sk);
  93
  94         if (PKT_FIELD(vsk, write_notify_window) < vmci_trans(vsk)->consume_size)
  95                 PKT_FIELD(vsk, write_notify_window) =
  96                     min(PKT_FIELD(vsk, write_notify_window) + PAGE_SIZE,
  97                         vmci_trans(vsk)->consume_size);
  98 }
  99
 100 static int vmci_transport_send_read_notification(struct sock *sk)
 101 {
 102         struct vsock_sock *vsk;
 103         bool sent_read;
 104         unsigned int retries;
 105         int err;
 106
 107         vsk = vsock_sk(sk);
 108         sent_read = false;
 109         retries = 0;
 110         err = 0;
 111
 112         if (vmci_transport_notify_waiting_write(vsk)) {
 113                 /* Notify the peer that we have read, retrying the send on
 114                  * failure up to our maximum value.  XXX For now we just log
 115                  * the failure, but later we should schedule a work item to
 116                  * handle the resend until it succeeds.  That would require
 117                  * keeping track of work items in the vsk and cleaning them up
 118                  * upon socket close.
 119                  */
 120                 while (!(vsk->peer_shutdown & RCV_SHUTDOWN) &&
 121                        !sent_read &&
 122                        retries < VMCI_TRANSPORT_MAX_DGRAM_RESENDS) {
 123                         err = vmci_transport_send_read(sk);
 124                         if (err >= 0)
 125                                 sent_read = true;
 126
 127                         retries++;
 128                 }
 129
 130                 if (retries >= VMCI_TRANSPORT_MAX_DGRAM_RESENDS && !sent_read)
 131                         pr_err("%p unable to send read notification to peer\n",
 132                                sk);
 133                 else
 134                         PKT_FIELD(vsk, peer_waiting_write) = false;
 135
 136         }
 137         return err;
 138 }
 139
 140 static void vmci_transport_notify_pkt_socket_init(struct sock *sk)
 141 {
 142         struct vsock_sock *vsk = vsock_sk(sk);
 143
 144         PKT_FIELD(vsk, write_notify_window) = PAGE_SIZE;
 145         PKT_FIELD(vsk, write_notify_min_window) = PAGE_SIZE;
 146         PKT_FIELD(vsk, peer_waiting_write) = false;
 147         PKT_FIELD(vsk, peer_waiting_write_detected) = false;
 148 }
 149
 150 static void vmci_transport_notify_pkt_socket_destruct(struct vsock_sock *vsk)
 151 {
 152         PKT_FIELD(vsk, write_notify_window) = PAGE_SIZE;
 153         PKT_FIELD(vsk, write_notify_min_window) = PAGE_SIZE;
 154         PKT_FIELD(vsk, peer_waiting_write) = false;
 155         PKT_FIELD(vsk, peer_waiting_write_detected) = false;
 156 }
 157
 158 static int
 159 vmci_transport_notify_pkt_poll_in(struct sock *sk,
 160                                   size_t target, bool *data_ready_now)
 161 {
 162         struct vsock_sock *vsk = vsock_sk(sk);
 163
 164         if (vsock_stream_has_data(vsk)) {
 165                 *data_ready_now = true;
 166         } else {
 167                 /* We can't read right now because there is nothing in the
 168                  * queue. Ask for notifications when there is something to
 169                  * read.
 170                  */
 171                 if (sk->sk_state == TCP_ESTABLISHED)
 172                         vsock_block_update_write_window(sk);
 173                 *data_ready_now = false;
 174         }
 175
 176         return 0;
 177 }
 178
 179 static int
 180 vmci_transport_notify_pkt_poll_out(struct sock *sk,
 181                                    size_t target, bool *space_avail_now)
 182 {
 183         s64 produce_q_free_space;
 184         struct vsock_sock *vsk = vsock_sk(sk);
 185
 186         produce_q_free_space = vsock_stream_has_space(vsk);
 187         if (produce_q_free_space > 0) {
 188                 *space_avail_now = true;
 189                 return 0;
 190         } else if (produce_q_free_space == 0) {
 191                 /* This is a connected socket but we can't currently send data.
 192                  * Nothing else to do.
 193                  */
 194                 *space_avail_now = false;
 195         }
 196
 197         return 0;
 198 }
 199
 200 static int
 201 vmci_transport_notify_pkt_recv_init(
 202                                 struct sock *sk,
 203                                 size_t target,
 204                                 struct vmci_transport_recv_notify_data *data)
 205 {
 206         struct vsock_sock *vsk = vsock_sk(sk);
 207
 208         data->consume_head = 0;
 209         data->produce_tail = 0;
 210         data->notify_on_block = false;
 211
 212         if (PKT_FIELD(vsk, write_notify_min_window) < target + 1) {
 213                 PKT_FIELD(vsk, write_notify_min_window) = target + 1;
 214                 if (PKT_FIELD(vsk, write_notify_window) <
 215                     PKT_FIELD(vsk, write_notify_min_window)) {
 216                         /* If the current window is smaller than the new
 217                          * minimal window size, we need to reevaluate whether
 218                          * we need to notify the sender. If the number of ready
 219                          * bytes are smaller than the new window, we need to
 220                          * send a notification to the sender before we block.
 221                          */
 222
 223                         PKT_FIELD(vsk, write_notify_window) =
 224                             PKT_FIELD(vsk, write_notify_min_window);
 225                         data->notify_on_block = true;
 226                 }
 227         }
 228
 229         return 0;
 230 }
 231
 232 static int
 233 vmci_transport_notify_pkt_recv_pre_block(
 234                                 struct sock *sk,
 235                                 size_t target,
 236                                 struct vmci_transport_recv_notify_data *data)
 237 {
 238         int err = 0;
 239
 240         vsock_block_update_write_window(sk);
 241
 242         if (data->notify_on_block) {
 243                 err = vmci_transport_send_read_notification(sk);
 244                 if (err < 0)
 245                         return err;
 246                 data->notify_on_block = false;
 247         }
 248
 249         return err;
 250 }
 251
 252 static int
 253 vmci_transport_notify_pkt_recv_post_dequeue(
 254                                 struct sock *sk,
 255                                 size_t target,
 256                                 ssize_t copied,
 257                                 bool data_read,
 258                                 struct vmci_transport_recv_notify_data *data)
 259 {
 260         struct vsock_sock *vsk;
 261         int err;
 262         bool was_full = false;
 263         u64 free_space;
 264
 265         vsk = vsock_sk(sk);
 266         err = 0;
 267
 268         if (data_read) {
 269                 smp_mb();
 270
 271                 free_space =
 272                         vmci_qpair_consume_free_space(vmci_trans(vsk)->qpair);
 273                 was_full = free_space == copied;
 274
 275                 if (was_full)
 276                         PKT_FIELD(vsk, peer_waiting_write) = true;
 277
 278                 err = vmci_transport_send_read_notification(sk);
 279                 if (err < 0)
 280                         return err;
 281
 282                 /* See the comment in
 283                  * vmci_transport_notify_pkt_send_post_enqueue().
 284                  */
 285                 sk->sk_data_ready(sk);
 286         }
 287
 288         return err;
 289 }
 290
 291 static int
 292 vmci_transport_notify_pkt_send_init(
 293                                 struct sock *sk,
 294                                 struct vmci_transport_send_notify_data *data)
 295 {
 296         data->consume_head = 0;
 297         data->produce_tail = 0;
 298
 299         return 0;
 300 }
 301
 302 static int
 303 vmci_transport_notify_pkt_send_post_enqueue(
 304                                 struct sock *sk,
 305                                 ssize_t written,
 306                                 struct vmci_transport_send_notify_data *data)
 307 {
 308         int err = 0;
 309         struct vsock_sock *vsk;
 310         bool sent_wrote = false;
 311         bool was_empty;
 312         int retries = 0;
 313
 314         vsk = vsock_sk(sk);
 315
 316         smp_mb();
 317
 318         was_empty =
 319                 vmci_qpair_produce_buf_ready(vmci_trans(vsk)->qpair) == written;
 320         if (was_empty) {
 321                 while (!(vsk->peer_shutdown & RCV_SHUTDOWN) &&
 322                        !sent_wrote &&
 323                        retries < VMCI_TRANSPORT_MAX_DGRAM_RESENDS) {
 324                         err = vmci_transport_send_wrote(sk);
 325                         if (err >= 0)
 326                                 sent_wrote = true;
 327
 328                         retries++;
 329                 }
 330         }
 331
 332         if (retries >= VMCI_TRANSPORT_MAX_DGRAM_RESENDS && !sent_wrote) {
 333                 pr_err("%p unable to send wrote notification to peer\n",
 334                        sk);
 335                 return err;
 336         }
 337
 338         return err;
 339 }
 340
 341 static void
 342 vmci_transport_notify_pkt_handle_pkt(
 343                                 struct sock *sk,
 344                                 struct vmci_transport_packet *pkt,
 345                                 bool bottom_half,
 346                                 struct sockaddr_vm *dst,
 347                                 struct sockaddr_vm *src, bool *pkt_processed)
 348 {
 349         bool processed = false;
 350
 351         switch (pkt->type) {
 352         case VMCI_TRANSPORT_PACKET_TYPE_WROTE:
 353                 vmci_transport_handle_wrote(sk, pkt, bottom_half, dst, src);
 354                 processed = true;
 355                 break;
 356         case VMCI_TRANSPORT_PACKET_TYPE_READ:
 357                 vmci_transport_handle_read(sk, pkt, bottom_half, dst, src);
 358                 processed = true;
 359                 break;
 360         }
 361
 362         if (pkt_processed)
 363                 *pkt_processed = processed;
 364 }
 365
 366 static void vmci_transport_notify_pkt_process_request(struct sock *sk)
 367 {
 368         struct vsock_sock *vsk = vsock_sk(sk);
 369
 370         PKT_FIELD(vsk, write_notify_window) = vmci_trans(vsk)->consume_size;
 371         if (vmci_trans(vsk)->consume_size <
 372                 PKT_FIELD(vsk, write_notify_min_window))
 373                 PKT_FIELD(vsk, write_notify_min_window) =
 374                         vmci_trans(vsk)->consume_size;
 375 }
 376
 377 static void vmci_transport_notify_pkt_process_negotiate(struct sock *sk)
 378 {
 379         struct vsock_sock *vsk = vsock_sk(sk);
 380
 381         PKT_FIELD(vsk, write_notify_window) = vmci_trans(vsk)->consume_size;
 382         if (vmci_trans(vsk)->consume_size <
 383                 PKT_FIELD(vsk, write_notify_min_window))
 384                 PKT_FIELD(vsk, write_notify_min_window) =
 385                         vmci_trans(vsk)->consume_size;
 386 }
 387
 388 static int
 389 vmci_transport_notify_pkt_recv_pre_dequeue(
 390                                 struct sock *sk,
 391                                 size_t target,
 392                                 struct vmci_transport_recv_notify_data *data)
 393 {
 394         return 0; /* NOP for QState. */
 395 }
 396
 397 static int
 398 vmci_transport_notify_pkt_send_pre_block(
 399                                 struct sock *sk,
 400                                 struct vmci_transport_send_notify_data *data)
 401 {
 402         return 0; /* NOP for QState. */
 403 }
 404
 405 static int
 406 vmci_transport_notify_pkt_send_pre_enqueue(
 407                                 struct sock *sk,
 408                                 struct vmci_transport_send_notify_data *data)
 409 {
 410         return 0; /* NOP for QState. */
 411 }
 412
 413 /* Socket always on control packet based operations. */
 414 const struct vmci_transport_notify_ops vmci_transport_notify_pkt_q_state_ops = {
 415         .socket_init = vmci_transport_notify_pkt_socket_init,
 416         .socket_destruct = vmci_transport_notify_pkt_socket_destruct,
 417         .poll_in = vmci_transport_notify_pkt_poll_in,
 418         .poll_out = vmci_transport_notify_pkt_poll_out,
 419         .handle_notify_pkt = vmci_transport_notify_pkt_handle_pkt,
 420         .recv_init = vmci_transport_notify_pkt_recv_init,
 421         .recv_pre_block = vmci_transport_notify_pkt_recv_pre_block,
 422         .recv_pre_dequeue = vmci_transport_notify_pkt_recv_pre_dequeue,
 423         .recv_post_dequeue = vmci_transport_notify_pkt_recv_post_dequeue,
 424         .send_init = vmci_transport_notify_pkt_send_init,
 425         .send_pre_block = vmci_transport_notify_pkt_send_pre_block,
 426         .send_pre_enqueue = vmci_transport_notify_pkt_send_pre_enqueue,
 427         .send_post_enqueue = vmci_transport_notify_pkt_send_post_enqueue,
 428         .process_request = vmci_transport_notify_pkt_process_request,
 429         .process_negotiate = vmci_transport_notify_pkt_process_negotiate,
 430 };