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 | vsock_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) >= target) { |
165 | *data_ready_now = true; |
166 | } else { |
167 | /* We can't read right now because there is not enough data |
168 | * in the queue. Ask for notifications when there is something |
169 | * to 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 | vsock_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 | }; |
431 | |