Andy King | d021c34 | 2013-02-06 14:23:56 +0000 | [diff] [blame] | 1 | /* |
| 2 | * VMware vSockets Driver |
| 3 | * |
| 4 | * Copyright (C) 2009-2013 VMware, Inc. All rights reserved. |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify it |
| 7 | * under the terms of the GNU General Public License as published by the Free |
| 8 | * Software Foundation version 2 and no later version. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, but WITHOUT |
| 11 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 12 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
| 13 | * more details. |
| 14 | */ |
| 15 | |
| 16 | #include <linux/types.h> |
| 17 | #include <linux/socket.h> |
| 18 | #include <linux/stddef.h> |
| 19 | #include <net/sock.h> |
| 20 | |
| 21 | #include "vmci_transport_notify.h" |
| 22 | |
| 23 | #define PKT_FIELD(vsk, field_name) \ |
| 24 | (vmci_trans(vsk)->notify.pkt_q_state.field_name) |
| 25 | |
| 26 | static bool vmci_transport_notify_waiting_write(struct vsock_sock *vsk) |
| 27 | { |
| 28 | bool retval; |
| 29 | u64 notify_limit; |
| 30 | |
| 31 | if (!PKT_FIELD(vsk, peer_waiting_write)) |
| 32 | return false; |
| 33 | |
| 34 | /* When the sender blocks, we take that as a sign that the sender is |
| 35 | * faster than the receiver. To reduce the transmit rate of the sender, |
| 36 | * we delay the sending of the read notification by decreasing the |
| 37 | * write_notify_window. The notification is delayed until the number of |
| 38 | * bytes used in the queue drops below the write_notify_window. |
| 39 | */ |
| 40 | |
| 41 | if (!PKT_FIELD(vsk, peer_waiting_write_detected)) { |
| 42 | PKT_FIELD(vsk, peer_waiting_write_detected) = true; |
| 43 | if (PKT_FIELD(vsk, write_notify_window) < PAGE_SIZE) { |
| 44 | PKT_FIELD(vsk, write_notify_window) = |
| 45 | PKT_FIELD(vsk, write_notify_min_window); |
| 46 | } else { |
| 47 | PKT_FIELD(vsk, write_notify_window) -= PAGE_SIZE; |
| 48 | if (PKT_FIELD(vsk, write_notify_window) < |
| 49 | PKT_FIELD(vsk, write_notify_min_window)) |
| 50 | PKT_FIELD(vsk, write_notify_window) = |
| 51 | PKT_FIELD(vsk, write_notify_min_window); |
| 52 | |
| 53 | } |
| 54 | } |
| 55 | notify_limit = vmci_trans(vsk)->consume_size - |
| 56 | PKT_FIELD(vsk, write_notify_window); |
| 57 | |
| 58 | /* The notify_limit is used to delay notifications in the case where |
| 59 | * flow control is enabled. Below the test is expressed in terms of |
| 60 | * free space in the queue: if free_space > ConsumeSize - |
| 61 | * write_notify_window then notify An alternate way of expressing this |
| 62 | * is to rewrite the expression to use the data ready in the receive |
| 63 | * queue: if write_notify_window > bufferReady then notify as |
| 64 | * free_space == ConsumeSize - bufferReady. |
| 65 | */ |
| 66 | |
| 67 | retval = vmci_qpair_consume_free_space(vmci_trans(vsk)->qpair) > |
| 68 | notify_limit; |
| 69 | |
| 70 | if (retval) { |
| 71 | /* Once we notify the peer, we reset the detected flag so the |
| 72 | * next wait will again cause a decrease in the window size. |
| 73 | */ |
| 74 | |
| 75 | PKT_FIELD(vsk, peer_waiting_write_detected) = false; |
| 76 | } |
| 77 | return retval; |
| 78 | } |
| 79 | |
| 80 | static void |
| 81 | vmci_transport_handle_read(struct sock *sk, |
| 82 | struct vmci_transport_packet *pkt, |
| 83 | bool bottom_half, |
| 84 | struct sockaddr_vm *dst, struct sockaddr_vm *src) |
| 85 | { |
| 86 | sk->sk_write_space(sk); |
| 87 | } |
| 88 | |
| 89 | static void |
| 90 | vmci_transport_handle_wrote(struct sock *sk, |
| 91 | struct vmci_transport_packet *pkt, |
| 92 | bool bottom_half, |
| 93 | struct sockaddr_vm *dst, struct sockaddr_vm *src) |
| 94 | { |
| 95 | sk->sk_data_ready(sk, 0); |
| 96 | } |
| 97 | |
| 98 | static void vsock_block_update_write_window(struct sock *sk) |
| 99 | { |
| 100 | struct vsock_sock *vsk = vsock_sk(sk); |
| 101 | |
| 102 | if (PKT_FIELD(vsk, write_notify_window) < vmci_trans(vsk)->consume_size) |
| 103 | PKT_FIELD(vsk, write_notify_window) = |
| 104 | min(PKT_FIELD(vsk, write_notify_window) + PAGE_SIZE, |
| 105 | vmci_trans(vsk)->consume_size); |
| 106 | } |
| 107 | |
| 108 | static int vmci_transport_send_read_notification(struct sock *sk) |
| 109 | { |
| 110 | struct vsock_sock *vsk; |
| 111 | bool sent_read; |
| 112 | unsigned int retries; |
| 113 | int err; |
| 114 | |
| 115 | vsk = vsock_sk(sk); |
| 116 | sent_read = false; |
| 117 | retries = 0; |
| 118 | err = 0; |
| 119 | |
| 120 | if (vmci_transport_notify_waiting_write(vsk)) { |
| 121 | /* Notify the peer that we have read, retrying the send on |
| 122 | * failure up to our maximum value. XXX For now we just log |
| 123 | * the failure, but later we should schedule a work item to |
| 124 | * handle the resend until it succeeds. That would require |
| 125 | * keeping track of work items in the vsk and cleaning them up |
| 126 | * upon socket close. |
| 127 | */ |
| 128 | while (!(vsk->peer_shutdown & RCV_SHUTDOWN) && |
| 129 | !sent_read && |
| 130 | retries < VMCI_TRANSPORT_MAX_DGRAM_RESENDS) { |
| 131 | err = vmci_transport_send_read(sk); |
| 132 | if (err >= 0) |
| 133 | sent_read = true; |
| 134 | |
| 135 | retries++; |
| 136 | } |
| 137 | |
| 138 | if (retries >= VMCI_TRANSPORT_MAX_DGRAM_RESENDS && !sent_read) |
| 139 | pr_err("%p unable to send read notification to peer\n", |
| 140 | sk); |
| 141 | else |
| 142 | PKT_FIELD(vsk, peer_waiting_write) = false; |
| 143 | |
| 144 | } |
| 145 | return err; |
| 146 | } |
| 147 | |
| 148 | static void vmci_transport_notify_pkt_socket_init(struct sock *sk) |
| 149 | { |
| 150 | struct vsock_sock *vsk = vsock_sk(sk); |
| 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 void vmci_transport_notify_pkt_socket_destruct(struct vsock_sock *vsk) |
| 159 | { |
| 160 | PKT_FIELD(vsk, write_notify_window) = PAGE_SIZE; |
| 161 | PKT_FIELD(vsk, write_notify_min_window) = PAGE_SIZE; |
| 162 | PKT_FIELD(vsk, peer_waiting_write) = false; |
| 163 | PKT_FIELD(vsk, peer_waiting_write_detected) = false; |
| 164 | } |
| 165 | |
| 166 | static int |
| 167 | vmci_transport_notify_pkt_poll_in(struct sock *sk, |
| 168 | size_t target, bool *data_ready_now) |
| 169 | { |
| 170 | struct vsock_sock *vsk = vsock_sk(sk); |
| 171 | |
| 172 | if (vsock_stream_has_data(vsk)) { |
| 173 | *data_ready_now = true; |
| 174 | } else { |
| 175 | /* We can't read right now because there is nothing in the |
| 176 | * queue. Ask for notifications when there is something to |
| 177 | * read. |
| 178 | */ |
| 179 | if (sk->sk_state == SS_CONNECTED) |
| 180 | vsock_block_update_write_window(sk); |
| 181 | *data_ready_now = false; |
| 182 | } |
| 183 | |
| 184 | return 0; |
| 185 | } |
| 186 | |
| 187 | static int |
| 188 | vmci_transport_notify_pkt_poll_out(struct sock *sk, |
| 189 | size_t target, bool *space_avail_now) |
| 190 | { |
| 191 | s64 produce_q_free_space; |
| 192 | struct vsock_sock *vsk = vsock_sk(sk); |
| 193 | |
| 194 | produce_q_free_space = vsock_stream_has_space(vsk); |
| 195 | if (produce_q_free_space > 0) { |
| 196 | *space_avail_now = true; |
| 197 | return 0; |
| 198 | } else if (produce_q_free_space == 0) { |
| 199 | /* This is a connected socket but we can't currently send data. |
| 200 | * Nothing else to do. |
| 201 | */ |
| 202 | *space_avail_now = false; |
| 203 | } |
| 204 | |
| 205 | return 0; |
| 206 | } |
| 207 | |
| 208 | static int |
| 209 | vmci_transport_notify_pkt_recv_init( |
| 210 | struct sock *sk, |
| 211 | size_t target, |
| 212 | struct vmci_transport_recv_notify_data *data) |
| 213 | { |
| 214 | struct vsock_sock *vsk = vsock_sk(sk); |
| 215 | |
| 216 | data->consume_head = 0; |
| 217 | data->produce_tail = 0; |
| 218 | data->notify_on_block = false; |
| 219 | |
| 220 | if (PKT_FIELD(vsk, write_notify_min_window) < target + 1) { |
| 221 | PKT_FIELD(vsk, write_notify_min_window) = target + 1; |
| 222 | if (PKT_FIELD(vsk, write_notify_window) < |
| 223 | PKT_FIELD(vsk, write_notify_min_window)) { |
| 224 | /* If the current window is smaller than the new |
| 225 | * minimal window size, we need to reevaluate whether |
| 226 | * we need to notify the sender. If the number of ready |
| 227 | * bytes are smaller than the new window, we need to |
| 228 | * send a notification to the sender before we block. |
| 229 | */ |
| 230 | |
| 231 | PKT_FIELD(vsk, write_notify_window) = |
| 232 | PKT_FIELD(vsk, write_notify_min_window); |
| 233 | data->notify_on_block = true; |
| 234 | } |
| 235 | } |
| 236 | |
| 237 | return 0; |
| 238 | } |
| 239 | |
| 240 | static int |
| 241 | vmci_transport_notify_pkt_recv_pre_block( |
| 242 | struct sock *sk, |
| 243 | size_t target, |
| 244 | struct vmci_transport_recv_notify_data *data) |
| 245 | { |
| 246 | int err = 0; |
| 247 | |
| 248 | vsock_block_update_write_window(sk); |
| 249 | |
| 250 | if (data->notify_on_block) { |
| 251 | err = vmci_transport_send_read_notification(sk); |
| 252 | if (err < 0) |
| 253 | return err; |
| 254 | data->notify_on_block = false; |
| 255 | } |
| 256 | |
| 257 | return err; |
| 258 | } |
| 259 | |
| 260 | static int |
| 261 | vmci_transport_notify_pkt_recv_post_dequeue( |
| 262 | struct sock *sk, |
| 263 | size_t target, |
| 264 | ssize_t copied, |
| 265 | bool data_read, |
| 266 | struct vmci_transport_recv_notify_data *data) |
| 267 | { |
| 268 | struct vsock_sock *vsk; |
| 269 | int err; |
| 270 | bool was_full = false; |
| 271 | u64 free_space; |
| 272 | |
| 273 | vsk = vsock_sk(sk); |
| 274 | err = 0; |
| 275 | |
| 276 | if (data_read) { |
| 277 | smp_mb(); |
| 278 | |
| 279 | free_space = |
| 280 | vmci_qpair_consume_free_space(vmci_trans(vsk)->qpair); |
| 281 | was_full = free_space == copied; |
| 282 | |
| 283 | if (was_full) |
| 284 | PKT_FIELD(vsk, peer_waiting_write) = true; |
| 285 | |
| 286 | err = vmci_transport_send_read_notification(sk); |
| 287 | if (err < 0) |
| 288 | return err; |
| 289 | |
| 290 | /* See the comment in |
| 291 | * vmci_transport_notify_pkt_send_post_enqueue(). |
| 292 | */ |
| 293 | sk->sk_data_ready(sk, 0); |
| 294 | } |
| 295 | |
| 296 | return err; |
| 297 | } |
| 298 | |
| 299 | static int |
| 300 | vmci_transport_notify_pkt_send_init( |
| 301 | struct sock *sk, |
| 302 | struct vmci_transport_send_notify_data *data) |
| 303 | { |
| 304 | data->consume_head = 0; |
| 305 | data->produce_tail = 0; |
| 306 | |
| 307 | return 0; |
| 308 | } |
| 309 | |
| 310 | static int |
| 311 | vmci_transport_notify_pkt_send_post_enqueue( |
| 312 | struct sock *sk, |
| 313 | ssize_t written, |
| 314 | struct vmci_transport_send_notify_data *data) |
| 315 | { |
| 316 | int err = 0; |
| 317 | struct vsock_sock *vsk; |
| 318 | bool sent_wrote = false; |
| 319 | bool was_empty; |
| 320 | int retries = 0; |
| 321 | |
| 322 | vsk = vsock_sk(sk); |
| 323 | |
| 324 | smp_mb(); |
| 325 | |
| 326 | was_empty = |
| 327 | vmci_qpair_produce_buf_ready(vmci_trans(vsk)->qpair) == written; |
| 328 | if (was_empty) { |
| 329 | while (!(vsk->peer_shutdown & RCV_SHUTDOWN) && |
| 330 | !sent_wrote && |
| 331 | retries < VMCI_TRANSPORT_MAX_DGRAM_RESENDS) { |
| 332 | err = vmci_transport_send_wrote(sk); |
| 333 | if (err >= 0) |
| 334 | sent_wrote = true; |
| 335 | |
| 336 | retries++; |
| 337 | } |
| 338 | } |
| 339 | |
| 340 | if (retries >= VMCI_TRANSPORT_MAX_DGRAM_RESENDS && !sent_wrote) { |
| 341 | pr_err("%p unable to send wrote notification to peer\n", |
| 342 | sk); |
| 343 | return err; |
| 344 | } |
| 345 | |
| 346 | return err; |
| 347 | } |
| 348 | |
| 349 | static void |
| 350 | vmci_transport_notify_pkt_handle_pkt( |
| 351 | struct sock *sk, |
| 352 | struct vmci_transport_packet *pkt, |
| 353 | bool bottom_half, |
| 354 | struct sockaddr_vm *dst, |
| 355 | struct sockaddr_vm *src, bool *pkt_processed) |
| 356 | { |
| 357 | bool processed = false; |
| 358 | |
| 359 | switch (pkt->type) { |
| 360 | case VMCI_TRANSPORT_PACKET_TYPE_WROTE: |
| 361 | vmci_transport_handle_wrote(sk, pkt, bottom_half, dst, src); |
| 362 | processed = true; |
| 363 | break; |
| 364 | case VMCI_TRANSPORT_PACKET_TYPE_READ: |
| 365 | vmci_transport_handle_read(sk, pkt, bottom_half, dst, src); |
| 366 | processed = true; |
| 367 | break; |
| 368 | } |
| 369 | |
| 370 | if (pkt_processed) |
| 371 | *pkt_processed = processed; |
| 372 | } |
| 373 | |
| 374 | static void vmci_transport_notify_pkt_process_request(struct sock *sk) |
| 375 | { |
| 376 | struct vsock_sock *vsk = vsock_sk(sk); |
| 377 | |
| 378 | PKT_FIELD(vsk, write_notify_window) = vmci_trans(vsk)->consume_size; |
| 379 | if (vmci_trans(vsk)->consume_size < |
| 380 | PKT_FIELD(vsk, write_notify_min_window)) |
| 381 | PKT_FIELD(vsk, write_notify_min_window) = |
| 382 | vmci_trans(vsk)->consume_size; |
| 383 | } |
| 384 | |
| 385 | static void vmci_transport_notify_pkt_process_negotiate(struct sock *sk) |
| 386 | { |
| 387 | struct vsock_sock *vsk = vsock_sk(sk); |
| 388 | |
| 389 | PKT_FIELD(vsk, write_notify_window) = vmci_trans(vsk)->consume_size; |
| 390 | if (vmci_trans(vsk)->consume_size < |
| 391 | PKT_FIELD(vsk, write_notify_min_window)) |
| 392 | PKT_FIELD(vsk, write_notify_min_window) = |
| 393 | vmci_trans(vsk)->consume_size; |
| 394 | } |
| 395 | |
| 396 | static int |
| 397 | vmci_transport_notify_pkt_recv_pre_dequeue( |
| 398 | struct sock *sk, |
| 399 | size_t target, |
| 400 | struct vmci_transport_recv_notify_data *data) |
| 401 | { |
| 402 | return 0; /* NOP for QState. */ |
| 403 | } |
| 404 | |
| 405 | static int |
| 406 | vmci_transport_notify_pkt_send_pre_block( |
| 407 | struct sock *sk, |
| 408 | struct vmci_transport_send_notify_data *data) |
| 409 | { |
| 410 | return 0; /* NOP for QState. */ |
| 411 | } |
| 412 | |
| 413 | static int |
| 414 | vmci_transport_notify_pkt_send_pre_enqueue( |
| 415 | struct sock *sk, |
| 416 | struct vmci_transport_send_notify_data *data) |
| 417 | { |
| 418 | return 0; /* NOP for QState. */ |
| 419 | } |
| 420 | |
| 421 | /* Socket always on control packet based operations. */ |
| 422 | struct vmci_transport_notify_ops vmci_transport_notify_pkt_q_state_ops = { |
| 423 | vmci_transport_notify_pkt_socket_init, |
| 424 | vmci_transport_notify_pkt_socket_destruct, |
| 425 | vmci_transport_notify_pkt_poll_in, |
| 426 | vmci_transport_notify_pkt_poll_out, |
| 427 | vmci_transport_notify_pkt_handle_pkt, |
| 428 | vmci_transport_notify_pkt_recv_init, |
| 429 | vmci_transport_notify_pkt_recv_pre_block, |
| 430 | vmci_transport_notify_pkt_recv_pre_dequeue, |
| 431 | vmci_transport_notify_pkt_recv_post_dequeue, |
| 432 | vmci_transport_notify_pkt_send_init, |
| 433 | vmci_transport_notify_pkt_send_pre_block, |
| 434 | vmci_transport_notify_pkt_send_pre_enqueue, |
| 435 | vmci_transport_notify_pkt_send_post_enqueue, |
| 436 | vmci_transport_notify_pkt_process_request, |
| 437 | vmci_transport_notify_pkt_process_negotiate, |
| 438 | }; |