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

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