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 */
smc_rx_wake_up(struct sock * sk)28 static 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 */
smc_rx_update_consumer(struct smc_sock * smc,union smc_host_cursor cons,size_t len)53 static 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
smc_rx_update_cons(struct smc_sock * smc,size_t len)94 static 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
103 struct smc_spd_priv {
104 struct smc_sock *smc;
105 size_t len;
106 };
107
smc_rx_pipe_buf_release(struct pipe_inode_info * pipe,struct pipe_buffer * buf)108 static 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);
126 out:
127 kfree(priv);
128 put_page(buf->page);
129 sock_put(sk);
130 }
131
smc_rx_pipe_buf_nosteal(struct pipe_inode_info * pipe,struct pipe_buffer * buf)132 static int smc_rx_pipe_buf_nosteal(struct pipe_inode_info *pipe,
133 struct pipe_buffer *buf)
134 {
135 return 1;
136 }
137
138 static const struct pipe_buf_operations smc_pipe_ops = {
139 .confirm = generic_pipe_buf_confirm,
140 .release = smc_rx_pipe_buf_release,
141 .steal = smc_rx_pipe_buf_nosteal,
142 .get = generic_pipe_buf_get
143 };
144
smc_rx_spd_release(struct splice_pipe_desc * spd,unsigned int i)145 static void smc_rx_spd_release(struct splice_pipe_desc *spd,
146 unsigned int i)
147 {
148 put_page(spd->pages[i]);
149 }
150
smc_rx_splice(struct pipe_inode_info * pipe,char * src,size_t len,struct smc_sock * smc)151 static int smc_rx_splice(struct pipe_inode_info *pipe, char *src, size_t len,
152 struct smc_sock *smc)
153 {
154 struct splice_pipe_desc spd;
155 struct partial_page partial;
156 struct smc_spd_priv *priv;
157 int bytes;
158
159 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
160 if (!priv)
161 return -ENOMEM;
162 priv->len = len;
163 priv->smc = smc;
164 partial.offset = src - (char *)smc->conn.rmb_desc->cpu_addr;
165 partial.len = len;
166 partial.private = (unsigned long)priv;
167
168 spd.nr_pages_max = 1;
169 spd.nr_pages = 1;
170 spd.pages = &smc->conn.rmb_desc->pages;
171 spd.partial = &partial;
172 spd.ops = &smc_pipe_ops;
173 spd.spd_release = smc_rx_spd_release;
174
175 bytes = splice_to_pipe(pipe, &spd);
176 if (bytes > 0) {
177 sock_hold(&smc->sk);
178 get_page(smc->conn.rmb_desc->pages);
179 atomic_add(bytes, &smc->conn.splice_pending);
180 }
181
182 return bytes;
183 }
184
smc_rx_data_available_and_no_splice_pend(struct smc_connection * conn)185 static int smc_rx_data_available_and_no_splice_pend(struct smc_connection *conn)
186 {
187 return atomic_read(&conn->bytes_to_rcv) &&
188 !atomic_read(&conn->splice_pending);
189 }
190
191 /* blocks rcvbuf consumer until >=len bytes available or timeout or interrupted
192 * @smc smc socket
193 * @timeo pointer to max seconds to wait, pointer to value 0 for no timeout
194 * @fcrit add'l criterion to evaluate as function pointer
195 * Returns:
196 * 1 if at least 1 byte available in rcvbuf or if socket error/shutdown.
197 * 0 otherwise (nothing in rcvbuf nor timeout, e.g. interrupted).
198 */
smc_rx_wait(struct smc_sock * smc,long * timeo,int (* fcrit)(struct smc_connection * conn))199 int smc_rx_wait(struct smc_sock *smc, long *timeo,
200 int (*fcrit)(struct smc_connection *conn))
201 {
202 DEFINE_WAIT_FUNC(wait, woken_wake_function);
203 struct smc_connection *conn = &smc->conn;
204 struct sock *sk = &smc->sk;
205 int rc;
206
207 if (fcrit(conn))
208 return 1;
209 sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
210 add_wait_queue(sk_sleep(sk), &wait);
211 rc = sk_wait_event(sk, timeo,
212 sk->sk_err ||
213 sk->sk_shutdown & RCV_SHUTDOWN ||
214 fcrit(conn),
215 &wait);
216 remove_wait_queue(sk_sleep(sk), &wait);
217 sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
218 return rc;
219 }
220
smc_rx_recv_urg(struct smc_sock * smc,struct msghdr * msg,int len,int flags)221 static int smc_rx_recv_urg(struct smc_sock *smc, struct msghdr *msg, int len,
222 int flags)
223 {
224 struct smc_connection *conn = &smc->conn;
225 union smc_host_cursor cons;
226 struct sock *sk = &smc->sk;
227 int rc = 0;
228
229 if (sock_flag(sk, SOCK_URGINLINE) ||
230 !(conn->urg_state == SMC_URG_VALID) ||
231 conn->urg_state == SMC_URG_READ)
232 return -EINVAL;
233
234 if (conn->urg_state == SMC_URG_VALID) {
235 if (!(flags & MSG_PEEK))
236 smc->conn.urg_state = SMC_URG_READ;
237 msg->msg_flags |= MSG_OOB;
238 if (len > 0) {
239 if (!(flags & MSG_TRUNC))
240 rc = memcpy_to_msg(msg, &conn->urg_rx_byte, 1);
241 len = 1;
242 smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
243 if (smc_curs_diff(conn->rmb_desc->len, &cons,
244 &conn->urg_curs) > 1)
245 conn->urg_rx_skip_pend = true;
246 /* Urgent Byte was already accounted for, but trigger
247 * skipping the urgent byte in non-inline case
248 */
249 if (!(flags & MSG_PEEK))
250 smc_rx_update_consumer(smc, cons, 0);
251 } else {
252 msg->msg_flags |= MSG_TRUNC;
253 }
254
255 return rc ? -EFAULT : len;
256 }
257
258 if (sk->sk_state == SMC_CLOSED || sk->sk_shutdown & RCV_SHUTDOWN)
259 return 0;
260
261 return -EAGAIN;
262 }
263
smc_rx_recvmsg_data_available(struct smc_sock * smc)264 static bool smc_rx_recvmsg_data_available(struct smc_sock *smc)
265 {
266 struct smc_connection *conn = &smc->conn;
267
268 if (smc_rx_data_available(conn))
269 return true;
270 else if (conn->urg_state == SMC_URG_VALID)
271 /* we received a single urgent Byte - skip */
272 smc_rx_update_cons(smc, 0);
273 return false;
274 }
275
276 /* smc_rx_recvmsg - receive data from RMBE
277 * @msg: copy data to receive buffer
278 * @pipe: copy data to pipe if set - indicates splice() call
279 *
280 * rcvbuf consumer: main API called by socket layer.
281 * Called under sk lock.
282 */
smc_rx_recvmsg(struct smc_sock * smc,struct msghdr * msg,struct pipe_inode_info * pipe,size_t len,int flags)283 int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg,
284 struct pipe_inode_info *pipe, size_t len, int flags)
285 {
286 size_t copylen, read_done = 0, read_remaining = len;
287 size_t chunk_len, chunk_off, chunk_len_sum;
288 struct smc_connection *conn = &smc->conn;
289 int (*func)(struct smc_connection *conn);
290 union smc_host_cursor cons;
291 int readable, chunk;
292 char *rcvbuf_base;
293 struct sock *sk;
294 int splbytes;
295 long timeo;
296 int target; /* Read at least these many bytes */
297 int rc;
298
299 if (unlikely(flags & MSG_ERRQUEUE))
300 return -EINVAL; /* future work for sk.sk_family == AF_SMC */
301
302 sk = &smc->sk;
303 if (sk->sk_state == SMC_LISTEN)
304 return -ENOTCONN;
305 if (flags & MSG_OOB)
306 return smc_rx_recv_urg(smc, msg, len, flags);
307 timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
308 target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
309
310 /* we currently use 1 RMBE per RMB, so RMBE == RMB base addr */
311 rcvbuf_base = conn->rx_off + conn->rmb_desc->cpu_addr;
312
313 do { /* while (read_remaining) */
314 if (read_done >= target || (pipe && read_done))
315 break;
316
317 if (smc_rx_recvmsg_data_available(smc))
318 goto copy;
319
320 if (sk->sk_shutdown & RCV_SHUTDOWN ||
321 conn->local_tx_ctrl.conn_state_flags.peer_conn_abort) {
322 /* smc_cdc_msg_recv_action() could have run after
323 * above smc_rx_recvmsg_data_available()
324 */
325 if (smc_rx_recvmsg_data_available(smc))
326 goto copy;
327 break;
328 }
329
330 if (read_done) {
331 if (sk->sk_err ||
332 sk->sk_state == SMC_CLOSED ||
333 !timeo ||
334 signal_pending(current))
335 break;
336 } else {
337 if (sk->sk_err) {
338 read_done = sock_error(sk);
339 break;
340 }
341 if (sk->sk_state == SMC_CLOSED) {
342 if (!sock_flag(sk, SOCK_DONE)) {
343 /* This occurs when user tries to read
344 * from never connected socket.
345 */
346 read_done = -ENOTCONN;
347 break;
348 }
349 break;
350 }
351 if (signal_pending(current)) {
352 read_done = sock_intr_errno(timeo);
353 break;
354 }
355 if (!timeo)
356 return -EAGAIN;
357 }
358
359 if (!smc_rx_data_available(conn)) {
360 smc_rx_wait(smc, &timeo, smc_rx_data_available);
361 continue;
362 }
363
364 copy:
365 /* initialize variables for 1st iteration of subsequent loop */
366 /* could be just 1 byte, even after waiting on data above */
367 readable = atomic_read(&conn->bytes_to_rcv);
368 splbytes = atomic_read(&conn->splice_pending);
369 if (!readable || (msg && splbytes)) {
370 if (splbytes)
371 func = smc_rx_data_available_and_no_splice_pend;
372 else
373 func = smc_rx_data_available;
374 smc_rx_wait(smc, &timeo, func);
375 continue;
376 }
377
378 smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
379 /* subsequent splice() calls pick up where previous left */
380 if (splbytes)
381 smc_curs_add(conn->rmb_desc->len, &cons, splbytes);
382 if (conn->urg_state == SMC_URG_VALID &&
383 sock_flag(&smc->sk, SOCK_URGINLINE) &&
384 readable > 1)
385 readable--; /* always stop at urgent Byte */
386 /* not more than what user space asked for */
387 copylen = min_t(size_t, read_remaining, readable);
388 /* determine chunks where to read from rcvbuf */
389 /* either unwrapped case, or 1st chunk of wrapped case */
390 chunk_len = min_t(size_t, copylen, conn->rmb_desc->len -
391 cons.count);
392 chunk_len_sum = chunk_len;
393 chunk_off = cons.count;
394 smc_rmb_sync_sg_for_cpu(conn);
395 for (chunk = 0; chunk < 2; chunk++) {
396 if (!(flags & MSG_TRUNC)) {
397 if (msg) {
398 rc = memcpy_to_msg(msg, rcvbuf_base +
399 chunk_off,
400 chunk_len);
401 } else {
402 rc = smc_rx_splice(pipe, rcvbuf_base +
403 chunk_off, chunk_len,
404 smc);
405 }
406 if (rc < 0) {
407 if (!read_done)
408 read_done = -EFAULT;
409 smc_rmb_sync_sg_for_device(conn);
410 goto out;
411 }
412 }
413 read_remaining -= chunk_len;
414 read_done += chunk_len;
415
416 if (chunk_len_sum == copylen)
417 break; /* either on 1st or 2nd iteration */
418 /* prepare next (== 2nd) iteration */
419 chunk_len = copylen - chunk_len; /* remainder */
420 chunk_len_sum += chunk_len;
421 chunk_off = 0; /* modulo offset in recv ring buffer */
422 }
423 smc_rmb_sync_sg_for_device(conn);
424
425 /* update cursors */
426 if (!(flags & MSG_PEEK)) {
427 /* increased in recv tasklet smc_cdc_msg_rcv() */
428 smp_mb__before_atomic();
429 atomic_sub(copylen, &conn->bytes_to_rcv);
430 /* guarantee 0 <= bytes_to_rcv <= rmb_desc->len */
431 smp_mb__after_atomic();
432 if (msg && smc_rx_update_consumer(smc, cons, copylen))
433 goto out;
434 }
435 } while (read_remaining);
436 out:
437 return read_done;
438 }
439
440 /* Initialize receive properties on connection establishment. NB: not __init! */
smc_rx_init(struct smc_sock * smc)441 void smc_rx_init(struct smc_sock *smc)
442 {
443 smc->sk.sk_data_ready = smc_rx_wake_up;
444 atomic_set(&smc->conn.splice_pending, 0);
445 smc->conn.urg_state = SMC_URG_READ;
446 }
447