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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_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 
 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 
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 
132 static const struct pipe_buf_operations smc_pipe_ops = {
133         .release = smc_rx_pipe_buf_release,
134         .get = generic_pipe_buf_get
135 };
136 
137 static void smc_rx_spd_release(struct splice_pipe_desc *spd,
138                                unsigned int i)
139 {
140         put_page(spd->pages[i]);
141 }
142 
143 static 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 
177 static 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  */
191 int 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 
217 static 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 
260 static 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  */
279 int 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 
362 copy:
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);
434 out:
435         return read_done;
436 }
437 
438 /* Initialize receive properties on connection establishment. NB: not __init! */
439 void 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 }
445 

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