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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Shared Memory Communications over RDMA (SMC-R) and RoCE
4 *
5 * Manage RMBE
6 * copy new RMBE data into user space
7 *
8 * Copyright IBM Corp. 2016
9 *
10 * Author(s): Ursula Braun <ubraun@linux.vnet.ibm.com>
11 */
12
13#include <linux/net.h>
14#include <linux/rcupdate.h>
15#include <linux/sched/signal.h>
16
17#include <net/sock.h>
18
19#include "smc.h"
20#include "smc_core.h"
21#include "smc_cdc.h"
22#include "smc_tx.h" /* smc_tx_consumer_update() */
23#include "smc_rx.h"
24
25/* callback implementation to wakeup consumers blocked with smc_rx_wait().
26 * indirectly called by smc_cdc_msg_recv_action().
27 */
28static void smc_rx_wake_up(struct sock *sk)
29{
30 struct socket_wq *wq;
31
32 /* derived from sock_def_readable() */
33 /* called already in smc_listen_work() */
34 rcu_read_lock();
35 wq = rcu_dereference(sk->sk_wq);
36 if (skwq_has_sleeper(wq))
37 wake_up_interruptible_sync_poll(&wq->wait, EPOLLIN | EPOLLPRI |
38 EPOLLRDNORM | EPOLLRDBAND);
39 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
40 if ((sk->sk_shutdown == SHUTDOWN_MASK) ||
41 (sk->sk_state == SMC_CLOSED))
42 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
43 rcu_read_unlock();
44}
45
46/* Update consumer cursor
47 * @conn connection to update
48 * @cons consumer cursor
49 * @len number of Bytes consumed
50 * Returns:
51 * 1 if we should end our receive, 0 otherwise
52 */
53static int smc_rx_update_consumer(struct smc_sock *smc,
54 union smc_host_cursor cons, size_t len)
55{
56 struct smc_connection *conn = &smc->conn;
57 struct sock *sk = &smc->sk;
58 bool force = false;
59 int diff, rc = 0;
60
61 smc_curs_add(conn->rmb_desc->len, &cons, len);
62
63 /* did we process urgent data? */
64 if (conn->urg_state == SMC_URG_VALID || conn->urg_rx_skip_pend) {
65 diff = smc_curs_comp(conn->rmb_desc->len, &cons,
66 &conn->urg_curs);
67 if (sock_flag(sk, SOCK_URGINLINE)) {
68 if (diff == 0) {
69 force = true;
70 rc = 1;
71 conn->urg_state = SMC_URG_READ;
72 }
73 } else {
74 if (diff == 1) {
75 /* skip urgent byte */
76 force = true;
77 smc_curs_add(conn->rmb_desc->len, &cons, 1);
78 conn->urg_rx_skip_pend = false;
79 } else if (diff < -1)
80 /* we read past urgent byte */
81 conn->urg_state = SMC_URG_READ;
82 }
83 }
84
85 smc_curs_copy(&conn->local_tx_ctrl.cons, &cons, conn);
86
87 /* send consumer cursor update if required */
88 /* similar to advertising new TCP rcv_wnd if required */
89 smc_tx_consumer_update(conn, force);
90
91 return rc;
92}
93
94static void smc_rx_update_cons(struct smc_sock *smc, size_t len)
95{
96 struct smc_connection *conn = &smc->conn;
97 union smc_host_cursor cons;
98
99 smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
100 smc_rx_update_consumer(smc, cons, len);
101}
102
103struct smc_spd_priv {
104 struct smc_sock *smc;
105 size_t len;
106};
107
108static void smc_rx_pipe_buf_release(struct pipe_inode_info *pipe,
109 struct pipe_buffer *buf)
110{
111 struct smc_spd_priv *priv = (struct smc_spd_priv *)buf->private;
112 struct smc_sock *smc = priv->smc;
113 struct smc_connection *conn;
114 struct sock *sk = &smc->sk;
115
116 if (sk->sk_state == SMC_CLOSED ||
117 sk->sk_state == SMC_PEERFINCLOSEWAIT ||
118 sk->sk_state == SMC_APPFINCLOSEWAIT)
119 goto out;
120 conn = &smc->conn;
121 lock_sock(sk);
122 smc_rx_update_cons(smc, priv->len);
123 release_sock(sk);
124 if (atomic_sub_and_test(priv->len, &conn->splice_pending))
125 smc_rx_wake_up(sk);
126out:
127 kfree(priv);
128 put_page(buf->page);
129 sock_put(sk);
130}
131
132static const struct pipe_buf_operations smc_pipe_ops = {
133 .release = smc_rx_pipe_buf_release,
134 .get = generic_pipe_buf_get
135};
136
137static void smc_rx_spd_release(struct splice_pipe_desc *spd,
138 unsigned int i)
139{
140 put_page(spd->pages[i]);
141}
142
143static int smc_rx_splice(struct pipe_inode_info *pipe, char *src, size_t len,
144 struct smc_sock *smc)
145{
146 struct splice_pipe_desc spd;
147 struct partial_page partial;
148 struct smc_spd_priv *priv;
149 int bytes;
150
151 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
152 if (!priv)
153 return -ENOMEM;
154 priv->len = len;
155 priv->smc = smc;
156 partial.offset = src - (char *)smc->conn.rmb_desc->cpu_addr;
157 partial.len = len;
158 partial.private = (unsigned long)priv;
159
160 spd.nr_pages_max = 1;
161 spd.nr_pages = 1;
162 spd.pages = &smc->conn.rmb_desc->pages;
163 spd.partial = &partial;
164 spd.ops = &smc_pipe_ops;
165 spd.spd_release = smc_rx_spd_release;
166
167 bytes = splice_to_pipe(pipe, &spd);
168 if (bytes > 0) {
169 sock_hold(&smc->sk);
170 get_page(smc->conn.rmb_desc->pages);
171 atomic_add(bytes, &smc->conn.splice_pending);
172 }
173
174 return bytes;
175}
176
177static int smc_rx_data_available_and_no_splice_pend(struct smc_connection *conn)
178{
179 return atomic_read(&conn->bytes_to_rcv) &&
180 !atomic_read(&conn->splice_pending);
181}
182
183/* blocks rcvbuf consumer until >=len bytes available or timeout or interrupted
184 * @smc smc socket
185 * @timeo pointer to max seconds to wait, pointer to value 0 for no timeout
186 * @fcrit add'l criterion to evaluate as function pointer
187 * Returns:
188 * 1 if at least 1 byte available in rcvbuf or if socket error/shutdown.
189 * 0 otherwise (nothing in rcvbuf nor timeout, e.g. interrupted).
190 */
191int smc_rx_wait(struct smc_sock *smc, long *timeo,
192 int (*fcrit)(struct smc_connection *conn))
193{
194 DEFINE_WAIT_FUNC(wait, woken_wake_function);
195 struct smc_connection *conn = &smc->conn;
196 struct smc_cdc_conn_state_flags *cflags =
197 &conn->local_tx_ctrl.conn_state_flags;
198 struct sock *sk = &smc->sk;
199 int rc;
200
201 if (fcrit(conn))
202 return 1;
203 sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
204 add_wait_queue(sk_sleep(sk), &wait);
205 rc = sk_wait_event(sk, timeo,
206 sk->sk_err ||
207 cflags->peer_conn_abort ||
208 sk->sk_shutdown & RCV_SHUTDOWN ||
209 conn->killed ||
210 fcrit(conn),
211 &wait);
212 remove_wait_queue(sk_sleep(sk), &wait);
213 sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
214 return rc;
215}
216
217static int smc_rx_recv_urg(struct smc_sock *smc, struct msghdr *msg, int len,
218 int flags)
219{
220 struct smc_connection *conn = &smc->conn;
221 union smc_host_cursor cons;
222 struct sock *sk = &smc->sk;
223 int rc = 0;
224
225 if (sock_flag(sk, SOCK_URGINLINE) ||
226 !(conn->urg_state == SMC_URG_VALID) ||
227 conn->urg_state == SMC_URG_READ)
228 return -EINVAL;
229
230 if (conn->urg_state == SMC_URG_VALID) {
231 if (!(flags & MSG_PEEK))
232 smc->conn.urg_state = SMC_URG_READ;
233 msg->msg_flags |= MSG_OOB;
234 if (len > 0) {
235 if (!(flags & MSG_TRUNC))
236 rc = memcpy_to_msg(msg, &conn->urg_rx_byte, 1);
237 len = 1;
238 smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
239 if (smc_curs_diff(conn->rmb_desc->len, &cons,
240 &conn->urg_curs) > 1)
241 conn->urg_rx_skip_pend = true;
242 /* Urgent Byte was already accounted for, but trigger
243 * skipping the urgent byte in non-inline case
244 */
245 if (!(flags & MSG_PEEK))
246 smc_rx_update_consumer(smc, cons, 0);
247 } else {
248 msg->msg_flags |= MSG_TRUNC;
249 }
250
251 return rc ? -EFAULT : len;
252 }
253
254 if (sk->sk_state == SMC_CLOSED || sk->sk_shutdown & RCV_SHUTDOWN)
255 return 0;
256
257 return -EAGAIN;
258}
259
260static bool smc_rx_recvmsg_data_available(struct smc_sock *smc)
261{
262 struct smc_connection *conn = &smc->conn;
263
264 if (smc_rx_data_available(conn))
265 return true;
266 else if (conn->urg_state == SMC_URG_VALID)
267 /* we received a single urgent Byte - skip */
268 smc_rx_update_cons(smc, 0);
269 return false;
270}
271
272/* smc_rx_recvmsg - receive data from RMBE
273 * @msg: copy data to receive buffer
274 * @pipe: copy data to pipe if set - indicates splice() call
275 *
276 * rcvbuf consumer: main API called by socket layer.
277 * Called under sk lock.
278 */
279int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg,
280 struct pipe_inode_info *pipe, size_t len, int flags)
281{
282 size_t copylen, read_done = 0, read_remaining = len;
283 size_t chunk_len, chunk_off, chunk_len_sum;
284 struct smc_connection *conn = &smc->conn;
285 int (*func)(struct smc_connection *conn);
286 union smc_host_cursor cons;
287 int readable, chunk;
288 char *rcvbuf_base;
289 struct sock *sk;
290 int splbytes;
291 long timeo;
292 int target; /* Read at least these many bytes */
293 int rc;
294
295 if (unlikely(flags & MSG_ERRQUEUE))
296 return -EINVAL; /* future work for sk.sk_family == AF_SMC */
297
298 sk = &smc->sk;
299 if (sk->sk_state == SMC_LISTEN)
300 return -ENOTCONN;
301 if (flags & MSG_OOB)
302 return smc_rx_recv_urg(smc, msg, len, flags);
303 timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
304 target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
305
306 /* we currently use 1 RMBE per RMB, so RMBE == RMB base addr */
307 rcvbuf_base = conn->rx_off + conn->rmb_desc->cpu_addr;
308
309 do { /* while (read_remaining) */
310 if (read_done >= target || (pipe && read_done))
311 break;
312
313 if (conn->killed)
314 break;
315
316 if (smc_rx_recvmsg_data_available(smc))
317 goto copy;
318
319 if (sk->sk_shutdown & RCV_SHUTDOWN) {
320 /* smc_cdc_msg_recv_action() could have run after
321 * above smc_rx_recvmsg_data_available()
322 */
323 if (smc_rx_recvmsg_data_available(smc))
324 goto copy;
325 break;
326 }
327
328 if (read_done) {
329 if (sk->sk_err ||
330 sk->sk_state == SMC_CLOSED ||
331 !timeo ||
332 signal_pending(current))
333 break;
334 } else {
335 if (sk->sk_err) {
336 read_done = sock_error(sk);
337 break;
338 }
339 if (sk->sk_state == SMC_CLOSED) {
340 if (!sock_flag(sk, SOCK_DONE)) {
341 /* This occurs when user tries to read
342 * from never connected socket.
343 */
344 read_done = -ENOTCONN;
345 break;
346 }
347 break;
348 }
349 if (signal_pending(current)) {
350 read_done = sock_intr_errno(timeo);
351 break;
352 }
353 if (!timeo)
354 return -EAGAIN;
355 }
356
357 if (!smc_rx_data_available(conn)) {
358 smc_rx_wait(smc, &timeo, smc_rx_data_available);
359 continue;
360 }
361
362copy:
363 /* initialize variables for 1st iteration of subsequent loop */
364 /* could be just 1 byte, even after waiting on data above */
365 readable = atomic_read(&conn->bytes_to_rcv);
366 splbytes = atomic_read(&conn->splice_pending);
367 if (!readable || (msg && splbytes)) {
368 if (splbytes)
369 func = smc_rx_data_available_and_no_splice_pend;
370 else
371 func = smc_rx_data_available;
372 smc_rx_wait(smc, &timeo, func);
373 continue;
374 }
375
376 smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
377 /* subsequent splice() calls pick up where previous left */
378 if (splbytes)
379 smc_curs_add(conn->rmb_desc->len, &cons, splbytes);
380 if (conn->urg_state == SMC_URG_VALID &&
381 sock_flag(&smc->sk, SOCK_URGINLINE) &&
382 readable > 1)
383 readable--; /* always stop at urgent Byte */
384 /* not more than what user space asked for */
385 copylen = min_t(size_t, read_remaining, readable);
386 /* determine chunks where to read from rcvbuf */
387 /* either unwrapped case, or 1st chunk of wrapped case */
388 chunk_len = min_t(size_t, copylen, conn->rmb_desc->len -
389 cons.count);
390 chunk_len_sum = chunk_len;
391 chunk_off = cons.count;
392 smc_rmb_sync_sg_for_cpu(conn);
393 for (chunk = 0; chunk < 2; chunk++) {
394 if (!(flags & MSG_TRUNC)) {
395 if (msg) {
396 rc = memcpy_to_msg(msg, rcvbuf_base +
397 chunk_off,
398 chunk_len);
399 } else {
400 rc = smc_rx_splice(pipe, rcvbuf_base +
401 chunk_off, chunk_len,
402 smc);
403 }
404 if (rc < 0) {
405 if (!read_done)
406 read_done = -EFAULT;
407 smc_rmb_sync_sg_for_device(conn);
408 goto out;
409 }
410 }
411 read_remaining -= chunk_len;
412 read_done += chunk_len;
413
414 if (chunk_len_sum == copylen)
415 break; /* either on 1st or 2nd iteration */
416 /* prepare next (== 2nd) iteration */
417 chunk_len = copylen - chunk_len; /* remainder */
418 chunk_len_sum += chunk_len;
419 chunk_off = 0; /* modulo offset in recv ring buffer */
420 }
421 smc_rmb_sync_sg_for_device(conn);
422
423 /* update cursors */
424 if (!(flags & MSG_PEEK)) {
425 /* increased in recv tasklet smc_cdc_msg_rcv() */
426 smp_mb__before_atomic();
427 atomic_sub(copylen, &conn->bytes_to_rcv);
428 /* guarantee 0 <= bytes_to_rcv <= rmb_desc->len */
429 smp_mb__after_atomic();
430 if (msg && smc_rx_update_consumer(smc, cons, copylen))
431 goto out;
432 }
433 } while (read_remaining);
434out:
435 return read_done;
436}
437
438/* Initialize receive properties on connection establishment. NB: not __init! */
439void smc_rx_init(struct smc_sock *smc)
440{
441 smc->sk.sk_data_ready = smc_rx_wake_up;
442 atomic_set(&smc->conn.splice_pending, 0);
443 smc->conn.urg_state = SMC_URG_READ;
444}