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Linux/net/smc/smc_rx.c

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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  */
 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  */
 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_write(&conn->local_tx_ctrl.cons, smc_curs_read(&cons, conn),
 86                        conn);
 87 
 88         /* send consumer cursor update if required */
 89         /* similar to advertising new TCP rcv_wnd if required */
 90         smc_tx_consumer_update(conn, force);
 91 
 92         return rc;
 93 }
 94 
 95 static void smc_rx_update_cons(struct smc_sock *smc, size_t len)
 96 {
 97         struct smc_connection *conn = &smc->conn;
 98         union smc_host_cursor cons;
 99 
100         smc_curs_write(&cons, smc_curs_read(&conn->local_tx_ctrl.cons, conn),
101                        conn);
102         smc_rx_update_consumer(smc, cons, len);
103 }
104 
105 struct smc_spd_priv {
106         struct smc_sock *smc;
107         size_t           len;
108 };
109 
110 static void smc_rx_pipe_buf_release(struct pipe_inode_info *pipe,
111                                     struct pipe_buffer *buf)
112 {
113         struct smc_spd_priv *priv = (struct smc_spd_priv *)buf->private;
114         struct smc_sock *smc = priv->smc;
115         struct smc_connection *conn;
116         struct sock *sk = &smc->sk;
117 
118         if (sk->sk_state == SMC_CLOSED ||
119             sk->sk_state == SMC_PEERFINCLOSEWAIT ||
120             sk->sk_state == SMC_APPFINCLOSEWAIT)
121                 goto out;
122         conn = &smc->conn;
123         lock_sock(sk);
124         smc_rx_update_cons(smc, priv->len);
125         release_sock(sk);
126         if (atomic_sub_and_test(priv->len, &conn->splice_pending))
127                 smc_rx_wake_up(sk);
128 out:
129         kfree(priv);
130         put_page(buf->page);
131         sock_put(sk);
132 }
133 
134 static int smc_rx_pipe_buf_nosteal(struct pipe_inode_info *pipe,
135                                    struct pipe_buffer *buf)
136 {
137         return 1;
138 }
139 
140 static const struct pipe_buf_operations smc_pipe_ops = {
141         .can_merge = 0,
142         .confirm = generic_pipe_buf_confirm,
143         .release = smc_rx_pipe_buf_release,
144         .steal = smc_rx_pipe_buf_nosteal,
145         .get = generic_pipe_buf_get
146 };
147 
148 static void smc_rx_spd_release(struct splice_pipe_desc *spd,
149                                unsigned int i)
150 {
151         put_page(spd->pages[i]);
152 }
153 
154 static int smc_rx_splice(struct pipe_inode_info *pipe, char *src, size_t len,
155                          struct smc_sock *smc)
156 {
157         struct splice_pipe_desc spd;
158         struct partial_page partial;
159         struct smc_spd_priv *priv;
160         struct page *page;
161         int bytes;
162 
163         page = virt_to_page(smc->conn.rmb_desc->cpu_addr);
164         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
165         if (!priv)
166                 return -ENOMEM;
167         priv->len = len;
168         priv->smc = smc;
169         partial.offset = src - (char *)smc->conn.rmb_desc->cpu_addr;
170         partial.len = len;
171         partial.private = (unsigned long)priv;
172 
173         spd.nr_pages_max = 1;
174         spd.nr_pages = 1;
175         spd.pages = &page;
176         spd.partial = &partial;
177         spd.ops = &smc_pipe_ops;
178         spd.spd_release = smc_rx_spd_release;
179 
180         bytes = splice_to_pipe(pipe, &spd);
181         if (bytes > 0) {
182                 sock_hold(&smc->sk);
183                 get_page(smc->conn.rmb_desc->pages);
184                 atomic_add(bytes, &smc->conn.splice_pending);
185         }
186 
187         return bytes;
188 }
189 
190 static int smc_rx_data_available_and_no_splice_pend(struct smc_connection *conn)
191 {
192         return atomic_read(&conn->bytes_to_rcv) &&
193                !atomic_read(&conn->splice_pending);
194 }
195 
196 /* blocks rcvbuf consumer until >=len bytes available or timeout or interrupted
197  *   @smc    smc socket
198  *   @timeo  pointer to max seconds to wait, pointer to value 0 for no timeout
199  *   @fcrit  add'l criterion to evaluate as function pointer
200  * Returns:
201  * 1 if at least 1 byte available in rcvbuf or if socket error/shutdown.
202  * 0 otherwise (nothing in rcvbuf nor timeout, e.g. interrupted).
203  */
204 int smc_rx_wait(struct smc_sock *smc, long *timeo,
205                 int (*fcrit)(struct smc_connection *conn))
206 {
207         DEFINE_WAIT_FUNC(wait, woken_wake_function);
208         struct smc_connection *conn = &smc->conn;
209         struct sock *sk = &smc->sk;
210         int rc;
211 
212         if (fcrit(conn))
213                 return 1;
214         sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
215         add_wait_queue(sk_sleep(sk), &wait);
216         rc = sk_wait_event(sk, timeo,
217                            sk->sk_err ||
218                            sk->sk_shutdown & RCV_SHUTDOWN ||
219                            fcrit(conn) ||
220                            smc_cdc_rxed_any_close_or_senddone(conn),
221                            &wait);
222         remove_wait_queue(sk_sleep(sk), &wait);
223         sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
224         return rc;
225 }
226 
227 static int smc_rx_recv_urg(struct smc_sock *smc, struct msghdr *msg, int len,
228                            int flags)
229 {
230         struct smc_connection *conn = &smc->conn;
231         union smc_host_cursor cons;
232         struct sock *sk = &smc->sk;
233         int rc = 0;
234 
235         if (sock_flag(sk, SOCK_URGINLINE) ||
236             !(conn->urg_state == SMC_URG_VALID) ||
237             conn->urg_state == SMC_URG_READ)
238                 return -EINVAL;
239 
240         if (conn->urg_state == SMC_URG_VALID) {
241                 if (!(flags & MSG_PEEK))
242                         smc->conn.urg_state = SMC_URG_READ;
243                 msg->msg_flags |= MSG_OOB;
244                 if (len > 0) {
245                         if (!(flags & MSG_TRUNC))
246                                 rc = memcpy_to_msg(msg, &conn->urg_rx_byte, 1);
247                         len = 1;
248                         smc_curs_write(&cons,
249                                        smc_curs_read(&conn->local_tx_ctrl.cons,
250                                                      conn),
251                                        conn);
252                         if (smc_curs_diff(conn->rmb_desc->len, &cons,
253                                           &conn->urg_curs) > 1)
254                                 conn->urg_rx_skip_pend = true;
255                         /* Urgent Byte was already accounted for, but trigger
256                          * skipping the urgent byte in non-inline case
257                          */
258                         if (!(flags & MSG_PEEK))
259                                 smc_rx_update_consumer(smc, cons, 0);
260                 } else {
261                         msg->msg_flags |= MSG_TRUNC;
262                 }
263 
264                 return rc ? -EFAULT : len;
265         }
266 
267         if (sk->sk_state == SMC_CLOSED || sk->sk_shutdown & RCV_SHUTDOWN)
268                 return 0;
269 
270         return -EAGAIN;
271 }
272 
273 /* smc_rx_recvmsg - receive data from RMBE
274  * @msg:        copy data to receive buffer
275  * @pipe:       copy data to pipe if set - indicates splice() call
276  *
277  * rcvbuf consumer: main API called by socket layer.
278  * Called under sk lock.
279  */
280 int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg,
281                    struct pipe_inode_info *pipe, size_t len, int flags)
282 {
283         size_t copylen, read_done = 0, read_remaining = len;
284         size_t chunk_len, chunk_off, chunk_len_sum;
285         struct smc_connection *conn = &smc->conn;
286         int (*func)(struct smc_connection *conn);
287         union smc_host_cursor cons;
288         int readable, chunk;
289         char *rcvbuf_base;
290         struct sock *sk;
291         int splbytes;
292         long timeo;
293         int target;             /* Read at least these many bytes */
294         int rc;
295 
296         if (unlikely(flags & MSG_ERRQUEUE))
297                 return -EINVAL; /* future work for sk.sk_family == AF_SMC */
298 
299         sk = &smc->sk;
300         if (sk->sk_state == SMC_LISTEN)
301                 return -ENOTCONN;
302         if (flags & MSG_OOB)
303                 return smc_rx_recv_urg(smc, msg, len, flags);
304         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
305         target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
306 
307         /* we currently use 1 RMBE per RMB, so RMBE == RMB base addr */
308         rcvbuf_base = conn->rmb_desc->cpu_addr;
309 
310         do { /* while (read_remaining) */
311                 if (read_done >= target || (pipe && read_done))
312                         break;
313 
314                 if (atomic_read(&conn->bytes_to_rcv))
315                         goto copy;
316                 else if (conn->urg_state == SMC_URG_VALID)
317                         /* we received a single urgent Byte - skip */
318                         smc_rx_update_cons(smc, 0);
319 
320                 if (sk->sk_shutdown & RCV_SHUTDOWN ||
321                     smc_cdc_rxed_any_close_or_senddone(conn) ||
322                     conn->local_tx_ctrl.conn_state_flags.peer_conn_abort)
323                         break;
324 
325                 if (read_done) {
326                         if (sk->sk_err ||
327                             sk->sk_state == SMC_CLOSED ||
328                             !timeo ||
329                             signal_pending(current))
330                                 break;
331                 } else {
332                         if (sk->sk_err) {
333                                 read_done = sock_error(sk);
334                                 break;
335                         }
336                         if (sk->sk_state == SMC_CLOSED) {
337                                 if (!sock_flag(sk, SOCK_DONE)) {
338                                         /* This occurs when user tries to read
339                                          * from never connected socket.
340                                          */
341                                         read_done = -ENOTCONN;
342                                         break;
343                                 }
344                                 break;
345                         }
346                         if (signal_pending(current)) {
347                                 read_done = sock_intr_errno(timeo);
348                                 break;
349                         }
350                         if (!timeo)
351                                 return -EAGAIN;
352                 }
353 
354                 if (!smc_rx_data_available(conn)) {
355                         smc_rx_wait(smc, &timeo, smc_rx_data_available);
356                         continue;
357                 }
358 
359 copy:
360                 /* initialize variables for 1st iteration of subsequent loop */
361                 /* could be just 1 byte, even after waiting on data above */
362                 readable = atomic_read(&conn->bytes_to_rcv);
363                 splbytes = atomic_read(&conn->splice_pending);
364                 if (!readable || (msg && splbytes)) {
365                         if (splbytes)
366                                 func = smc_rx_data_available_and_no_splice_pend;
367                         else
368                                 func = smc_rx_data_available;
369                         smc_rx_wait(smc, &timeo, func);
370                         continue;
371                 }
372 
373                 smc_curs_write(&cons,
374                                smc_curs_read(&conn->local_tx_ctrl.cons, conn),
375                                conn);
376                 /* subsequent splice() calls pick up where previous left */
377                 if (splbytes)
378                         smc_curs_add(conn->rmb_desc->len, &cons, splbytes);
379                 if (conn->urg_state == SMC_URG_VALID &&
380                     sock_flag(&smc->sk, SOCK_URGINLINE) &&
381                     readable > 1)
382                         readable--;     /* always stop at urgent Byte */
383                 /* not more than what user space asked for */
384                 copylen = min_t(size_t, read_remaining, readable);
385                 /* determine chunks where to read from rcvbuf */
386                 /* either unwrapped case, or 1st chunk of wrapped case */
387                 chunk_len = min_t(size_t, copylen, conn->rmb_desc->len -
388                                   cons.count);
389                 chunk_len_sum = chunk_len;
390                 chunk_off = cons.count;
391                 smc_rmb_sync_sg_for_cpu(conn);
392                 for (chunk = 0; chunk < 2; chunk++) {
393                         if (!(flags & MSG_TRUNC)) {
394                                 if (msg) {
395                                         rc = memcpy_to_msg(msg, rcvbuf_base +
396                                                            chunk_off,
397                                                            chunk_len);
398                                 } else {
399                                         rc = smc_rx_splice(pipe, rcvbuf_base +
400                                                         chunk_off, chunk_len,
401                                                         smc);
402                                 }
403                                 if (rc < 0) {
404                                         if (!read_done)
405                                                 read_done = -EFAULT;
406                                         smc_rmb_sync_sg_for_device(conn);
407                                         goto out;
408                                 }
409                         }
410                         read_remaining -= chunk_len;
411                         read_done += chunk_len;
412 
413                         if (chunk_len_sum == copylen)
414                                 break; /* either on 1st or 2nd iteration */
415                         /* prepare next (== 2nd) iteration */
416                         chunk_len = copylen - chunk_len; /* remainder */
417                         chunk_len_sum += chunk_len;
418                         chunk_off = 0; /* modulo offset in recv ring buffer */
419                 }
420                 smc_rmb_sync_sg_for_device(conn);
421 
422                 /* update cursors */
423                 if (!(flags & MSG_PEEK)) {
424                         /* increased in recv tasklet smc_cdc_msg_rcv() */
425                         smp_mb__before_atomic();
426                         atomic_sub(copylen, &conn->bytes_to_rcv);
427                         /* guarantee 0 <= bytes_to_rcv <= rmb_desc->len */
428                         smp_mb__after_atomic();
429                         if (msg && smc_rx_update_consumer(smc, cons, copylen))
430                                 goto out;
431                 }
432         } while (read_remaining);
433 out:
434         return read_done;
435 }
436 
437 /* Initialize receive properties on connection establishment. NB: not __init! */
438 void smc_rx_init(struct smc_sock *smc)
439 {
440         smc->sk.sk_data_ready = smc_rx_wake_up;
441         atomic_set(&smc->conn.splice_pending, 0);
442         smc->conn.urg_state = SMC_URG_READ;
443 }
444 

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