smc_rx.c

  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#include <linux/splice.h>
 17
 18#include <net/sock.h>
 19#include <trace/events/sock.h>
 20
 21#include "smc.h"
 22#include "smc_core.h"
 23#include "smc_cdc.h"
 24#include "smc_tx.h" /* smc_tx_consumer_update() */
 25#include "smc_rx.h"
 26#include "smc_stats.h"
 27#include "smc_tracepoint.h"
 28
 29/* callback implementation to wakeup consumers blocked with smc_rx_wait().
 30 * indirectly called by smc_cdc_msg_recv_action().
 31 */
 32static void smc_rx_wake_up(struct sock *sk)
 33{
 34	struct socket_wq *wq;
 35
 36	trace_sk_data_ready(sk);
 37
 38	/* derived from sock_def_readable() */
 39	/* called already in smc_listen_work() */
 40	rcu_read_lock();
 41	wq = rcu_dereference(sk->sk_wq);
 42	if (skwq_has_sleeper(wq))
 43		wake_up_interruptible_sync_poll(&wq->wait, EPOLLIN | EPOLLPRI |
 44						EPOLLRDNORM | EPOLLRDBAND);
 45	sk_wake_async_rcu(sk, SOCK_WAKE_WAITD, POLL_IN);
 46	if ((sk->sk_shutdown == SHUTDOWN_MASK) ||
 47	    (sk->sk_state == SMC_CLOSED))
 48		sk_wake_async_rcu(sk, SOCK_WAKE_WAITD, POLL_HUP);
 49	rcu_read_unlock();
 50}
 51
 52/* Update consumer cursor
 53 *   @conn   connection to update
 54 *   @cons   consumer cursor
 55 *   @len    number of Bytes consumed
 56 *   Returns:
 57 *   1 if we should end our receive, 0 otherwise
 58 */
 59static int smc_rx_update_consumer(struct smc_sock *smc,
 60				  union smc_host_cursor cons, size_t len)
 61{
 62	struct smc_connection *conn = &smc->conn;
 63	struct sock *sk = &smc->sk;
 64	bool force = false;
 65	int diff, rc = 0;
 66
 67	smc_curs_add(conn->rmb_desc->len, &cons, len);
 68
 69	/* did we process urgent data? */
 70	if (conn->urg_state == SMC_URG_VALID || conn->urg_rx_skip_pend) {
 71		diff = smc_curs_comp(conn->rmb_desc->len, &cons,
 72				     &conn->urg_curs);
 73		if (sock_flag(sk, SOCK_URGINLINE)) {
 74			if (diff == 0) {
 75				force = true;
 76				rc = 1;
 77				conn->urg_state = SMC_URG_READ;
 78			}
 79		} else {
 80			if (diff == 1) {
 81				/* skip urgent byte */
 82				force = true;
 83				smc_curs_add(conn->rmb_desc->len, &cons, 1);
 84				conn->urg_rx_skip_pend = false;
 85			} else if (diff < -1)
 86				/* we read past urgent byte */
 87				conn->urg_state = SMC_URG_READ;
 88		}
 89	}
 90
 91	smc_curs_copy(&conn->local_tx_ctrl.cons, &cons, conn);
 92
 93	/* send consumer cursor update if required */
 94	/* similar to advertising new TCP rcv_wnd if required */
 95	smc_tx_consumer_update(conn, force);
 96
 97	return rc;
 98}
 99
100static void smc_rx_update_cons(struct smc_sock *smc, size_t len)
101{
102	struct smc_connection *conn = &smc->conn;
103	union smc_host_cursor cons;
104
105	smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
106	smc_rx_update_consumer(smc, cons, len);
107}
108
109struct smc_spd_priv {
110	struct smc_sock *smc;
111	size_t		 len;
112};
113
114static void smc_rx_pipe_buf_release(struct pipe_inode_info *pipe,
115				    struct pipe_buffer *buf)
116{
117	struct smc_spd_priv *priv = (struct smc_spd_priv *)buf->private;
118	struct smc_sock *smc = priv->smc;
119	struct smc_connection *conn;
120	struct sock *sk = &smc->sk;
121
122	if (sk->sk_state == SMC_CLOSED ||
123	    sk->sk_state == SMC_PEERFINCLOSEWAIT ||
124	    sk->sk_state == SMC_APPFINCLOSEWAIT)
125		goto out;
126	conn = &smc->conn;
127	lock_sock(sk);
128	smc_rx_update_cons(smc, priv->len);
129	release_sock(sk);
130	if (atomic_sub_and_test(priv->len, &conn->splice_pending))
131		smc_rx_wake_up(sk);
132out:
133	kfree(priv);
134	put_page(buf->page);
135	sock_put(sk);
136}
137
138static bool smc_rx_pipe_buf_get(struct pipe_inode_info *pipe,
139				struct pipe_buffer *buf)
140{
141	/* smc_spd_priv in buf->private is not shareable; disallow cloning. */
142	return false;
143}
144
145static const struct pipe_buf_operations smc_pipe_ops = {
146	.release = smc_rx_pipe_buf_release,
147	.get	 = smc_rx_pipe_buf_get,
148};
149
150static void smc_rx_spd_release(struct splice_pipe_desc *spd,
151			       unsigned int i)
152{
153	put_page(spd->pages[i]);
154}
155
156static int smc_rx_splice(struct pipe_inode_info *pipe, char *src, size_t len,
157			 struct smc_sock *smc)
158{
159	struct smc_link_group *lgr = smc->conn.lgr;
160	int offset = offset_in_page(src);
161	struct partial_page *partial;
162	struct splice_pipe_desc spd;
163	struct smc_spd_priv **priv;
164	struct page **pages;
165	int bytes, nr_pages;
166	int i;
167
168	nr_pages = !lgr->is_smcd && smc->conn.rmb_desc->is_vm ?
169		   PAGE_ALIGN(len + offset) / PAGE_SIZE : 1;
170
171	pages = kcalloc(nr_pages, sizeof(*pages), GFP_KERNEL);
172	if (!pages)
173		goto out;
174	partial = kcalloc(nr_pages, sizeof(*partial), GFP_KERNEL);
175	if (!partial)
176		goto out_page;
177	priv = kcalloc(nr_pages, sizeof(*priv), GFP_KERNEL);
178	if (!priv)
179		goto out_part;
180	for (i = 0; i < nr_pages; i++) {
181		priv[i] = kzalloc(sizeof(**priv), GFP_KERNEL);
182		if (!priv[i])
183			goto out_priv;
184	}
185
186	if (lgr->is_smcd ||
187	    (!lgr->is_smcd && !smc->conn.rmb_desc->is_vm)) {
188		/* smcd or smcr that uses physically contiguous RMBs */
189		priv[0]->len = len;
190		priv[0]->smc = smc;
191		partial[0].offset = src - (char *)smc->conn.rmb_desc->cpu_addr;
192		partial[0].len = len;
193		partial[0].private = (unsigned long)priv[0];
194		pages[0] = smc->conn.rmb_desc->pages;
195	} else {
196		int size, left = len;
197		void *buf = src;
198		/* smcr that uses virtually contiguous RMBs*/
199		for (i = 0; i < nr_pages; i++) {
200			size = min_t(int, PAGE_SIZE - offset, left);
201			priv[i]->len = size;
202			priv[i]->smc = smc;
203			pages[i] = vmalloc_to_page(buf);
204			partial[i].offset = offset;
205			partial[i].len = size;
206			partial[i].private = (unsigned long)priv[i];
207			buf += size;
208			left -= size;
209			offset = 0;
210		}
211	}
212	spd.nr_pages_max = nr_pages;
213	spd.nr_pages = nr_pages;
214	spd.pages = pages;
215	spd.partial = partial;
216	spd.ops = &smc_pipe_ops;
217	spd.spd_release = smc_rx_spd_release;
218
219	bytes = splice_to_pipe(pipe, &spd);
220	if (bytes > 0) {
221		sock_hold(&smc->sk);
222		if (!lgr->is_smcd && smc->conn.rmb_desc->is_vm) {
223			for (i = 0; i < PAGE_ALIGN(bytes + offset) / PAGE_SIZE; i++)
224				get_page(pages[i]);
225		} else {
226			get_page(smc->conn.rmb_desc->pages);
227		}
228		atomic_add(bytes, &smc->conn.splice_pending);
229	}
230	kfree(priv);
231	kfree(partial);
232	kfree(pages);
233
234	return bytes;
235
236out_priv:
237	for (i = (i - 1); i >= 0; i--)
238		kfree(priv[i]);
239	kfree(priv);
240out_part:
241	kfree(partial);
242out_page:
243	kfree(pages);
244out:
245	return -ENOMEM;
246}
247
248static int smc_rx_data_available_and_no_splice_pend(struct smc_connection *conn, size_t peeked)
249{
250	return smc_rx_data_available(conn, peeked) &&
251	       !atomic_read(&conn->splice_pending);
252}
253
254/* blocks rcvbuf consumer until >=len bytes available or timeout or interrupted
255 *   @smc    smc socket
256 *   @timeo  pointer to max seconds to wait, pointer to value 0 for no timeout
257 *   @peeked  number of bytes already peeked
258 *   @fcrit  add'l criterion to evaluate as function pointer
259 * Returns:
260 * 1 if at least 1 byte available in rcvbuf or if socket error/shutdown.
261 * 0 otherwise (nothing in rcvbuf nor timeout, e.g. interrupted).
262 */
263int smc_rx_wait(struct smc_sock *smc, long *timeo, size_t peeked,
264		int (*fcrit)(struct smc_connection *conn, size_t baseline))
265{
266	DEFINE_WAIT_FUNC(wait, woken_wake_function);
267	struct smc_connection *conn = &smc->conn;
268	struct smc_cdc_conn_state_flags *cflags =
269					&conn->local_tx_ctrl.conn_state_flags;
270	struct sock *sk = &smc->sk;
271	int rc;
272
273	if (fcrit(conn, peeked))
274		return 1;
275	sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
276	add_wait_queue(sk_sleep(sk), &wait);
277	rc = sk_wait_event(sk, timeo,
278			   READ_ONCE(sk->sk_err) ||
279			   cflags->peer_conn_abort ||
280			   READ_ONCE(sk->sk_shutdown) & RCV_SHUTDOWN ||
281			   conn->killed ||
282			   fcrit(conn, peeked),
283			   &wait);
284	remove_wait_queue(sk_sleep(sk), &wait);
285	sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
286	return rc;
287}
288
289static int smc_rx_recv_urg(struct smc_sock *smc, struct msghdr *msg, int len,
290			   int flags)
291{
292	struct smc_connection *conn = &smc->conn;
293	union smc_host_cursor cons;
294	struct sock *sk = &smc->sk;
295	int rc = 0;
296
297	if (sock_flag(sk, SOCK_URGINLINE) ||
298	    !(conn->urg_state == SMC_URG_VALID) ||
299	    conn->urg_state == SMC_URG_READ)
300		return -EINVAL;
301
302	SMC_STAT_INC(smc, urg_data_cnt);
303	if (conn->urg_state == SMC_URG_VALID) {
304		if (!(flags & MSG_PEEK))
305			smc->conn.urg_state = SMC_URG_READ;
306		msg->msg_flags |= MSG_OOB;
307		if (len > 0) {
308			if (!(flags & MSG_TRUNC))
309				rc = memcpy_to_msg(msg, &conn->urg_rx_byte, 1);
310			len = 1;
311			smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
312			if (smc_curs_diff(conn->rmb_desc->len, &cons,
313					  &conn->urg_curs) > 1)
314				conn->urg_rx_skip_pend = true;
315			/* Urgent Byte was already accounted for, but trigger
316			 * skipping the urgent byte in non-inline case
317			 */
318			if (!(flags & MSG_PEEK))
319				smc_rx_update_consumer(smc, cons, 0);
320		} else {
321			msg->msg_flags |= MSG_TRUNC;
322		}
323
324		return rc ? -EFAULT : len;
325	}
326
327	if (sk->sk_state == SMC_CLOSED || sk->sk_shutdown & RCV_SHUTDOWN)
328		return 0;
329
330	return -EAGAIN;
331}
332
333static bool smc_rx_recvmsg_data_available(struct smc_sock *smc, size_t peeked)
334{
335	struct smc_connection *conn = &smc->conn;
336
337	if (smc_rx_data_available(conn, peeked))
338		return true;
339	else if (conn->urg_state == SMC_URG_VALID)
340		/* we received a single urgent Byte - skip */
341		smc_rx_update_cons(smc, 0);
342	return false;
343}
344
345/* smc_rx_recvmsg - receive data from RMBE
346 * @msg:	copy data to receive buffer
347 * @pipe:	copy data to pipe if set - indicates splice() call
348 *
349 * rcvbuf consumer: main API called by socket layer.
350 * Called under sk lock.
351 */
352int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg,
353		   struct pipe_inode_info *pipe, size_t len, int flags)
354{
355	size_t copylen, read_done = 0, read_remaining = len, peeked_bytes = 0;
356	size_t chunk_len, chunk_off, chunk_len_sum;
357	struct smc_connection *conn = &smc->conn;
358	int (*func)(struct smc_connection *conn, size_t baseline);
359	union smc_host_cursor cons;
360	int readable, chunk;
361	char *rcvbuf_base;
362	struct sock *sk;
363	int splbytes;
364	long timeo;
365	int target;		/* Read at least these many bytes */
366	int rc;
367
368	if (unlikely(flags & MSG_ERRQUEUE))
369		return -EINVAL; /* future work for sk.sk_family == AF_SMC */
370
371	sk = &smc->sk;
372	if (sk->sk_state == SMC_LISTEN)
373		return -ENOTCONN;
374	if (flags & MSG_OOB)
375		return smc_rx_recv_urg(smc, msg, len, flags);
376	timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
377	target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
378
379	readable = atomic_read(&conn->bytes_to_rcv);
380	if (readable >= conn->rmb_desc->len)
381		SMC_STAT_RMB_RX_FULL(smc, !conn->lnk);
382
383	if (len < readable)
384		SMC_STAT_RMB_RX_SIZE_SMALL(smc, !conn->lnk);
385	/* we currently use 1 RMBE per RMB, so RMBE == RMB base addr */
386	rcvbuf_base = conn->rx_off + conn->rmb_desc->cpu_addr;
387
388	do { /* while (read_remaining) */
389		if (read_done >= target || (pipe && read_done))
390			break;
391
392		if (conn->killed)
393			break;
394
395		if (smc_rx_recvmsg_data_available(smc, peeked_bytes))
396			goto copy;
397
398		if (sk->sk_shutdown & RCV_SHUTDOWN) {
399			/* smc_cdc_msg_recv_action() could have run after
400			 * above smc_rx_recvmsg_data_available()
401			 */
402			if (smc_rx_recvmsg_data_available(smc, peeked_bytes))
403				goto copy;
404			break;
405		}
406
407		if (read_done) {
408			if (sk->sk_err ||
409			    sk->sk_state == SMC_CLOSED ||
410			    !timeo ||
411			    signal_pending(current))
412				break;
413		} else {
414			if (sk->sk_err) {
415				read_done = sock_error(sk);
416				break;
417			}
418			if (sk->sk_state == SMC_CLOSED) {
419				if (!sock_flag(sk, SOCK_DONE)) {
420					/* This occurs when user tries to read
421					 * from never connected socket.
422					 */
423					read_done = -ENOTCONN;
424					break;
425				}
426				break;
427			}
428			if (!timeo)
429				return -EAGAIN;
430			if (signal_pending(current)) {
431				read_done = sock_intr_errno(timeo);
432				break;
433			}
434		}
435
436		if (!smc_rx_data_available(conn, peeked_bytes)) {
437			smc_rx_wait(smc, &timeo, peeked_bytes, smc_rx_data_available);
438			continue;
439		}
440
441copy:
442		/* initialize variables for 1st iteration of subsequent loop */
443		/* could be just 1 byte, even after waiting on data above */
444		readable = smc_rx_data_available(conn, peeked_bytes);
445		splbytes = atomic_read(&conn->splice_pending);
446		if (!readable || (msg && splbytes)) {
447			if (splbytes)
448				func = smc_rx_data_available_and_no_splice_pend;
449			else
450				func = smc_rx_data_available;
451			smc_rx_wait(smc, &timeo, peeked_bytes, func);
452			continue;
453		}
454
455		smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
456		if ((flags & MSG_PEEK) && peeked_bytes)
457			smc_curs_add(conn->rmb_desc->len, &cons, peeked_bytes);
458		/* subsequent splice() calls pick up where previous left */
459		if (splbytes)
460			smc_curs_add(conn->rmb_desc->len, &cons, splbytes);
461		if (conn->urg_state == SMC_URG_VALID &&
462		    sock_flag(&smc->sk, SOCK_URGINLINE) &&
463		    readable > 1)
464			readable--;	/* always stop at urgent Byte */
465		/* not more than what user space asked for */
466		copylen = min_t(size_t, read_remaining, readable);
467		/* determine chunks where to read from rcvbuf */
468		/* either unwrapped case, or 1st chunk of wrapped case */
469		chunk_len = min_t(size_t, copylen, conn->rmb_desc->len -
470				  cons.count);
471		chunk_len_sum = chunk_len;
472		chunk_off = cons.count;
473		smc_rmb_sync_sg_for_cpu(conn);
474		for (chunk = 0; chunk < 2; chunk++) {
475			if (!(flags & MSG_TRUNC)) {
476				if (msg) {
477					rc = memcpy_to_msg(msg, rcvbuf_base +
478							   chunk_off,
479							   chunk_len);
480				} else {
481					rc = smc_rx_splice(pipe, rcvbuf_base +
482							chunk_off, chunk_len,
483							smc);
484				}
485				if (rc < 0) {
486					if (!read_done)
487						read_done = -EFAULT;
488					goto out;
489				}
490			}
491			read_remaining -= chunk_len;
492			read_done += chunk_len;
493			if (flags & MSG_PEEK)
494				peeked_bytes += chunk_len;
495
496			if (chunk_len_sum == copylen)
497				break; /* either on 1st or 2nd iteration */
498			/* prepare next (== 2nd) iteration */
499			chunk_len = copylen - chunk_len; /* remainder */
500			chunk_len_sum += chunk_len;
501			chunk_off = 0; /* modulo offset in recv ring buffer */
502		}
503
504		/* update cursors */
505		if (!(flags & MSG_PEEK)) {
506			/* increased in recv tasklet smc_cdc_msg_rcv() */
507			smp_mb__before_atomic();
508			atomic_sub(copylen, &conn->bytes_to_rcv);
509			/* guarantee 0 <= bytes_to_rcv <= rmb_desc->len */
510			smp_mb__after_atomic();
511			if (msg && smc_rx_update_consumer(smc, cons, copylen))
512				goto out;
513		}
514
515		trace_smc_rx_recvmsg(smc, copylen);
516	} while (read_remaining);
517out:
518	return read_done;
519}
520
521/* Initialize receive properties on connection establishment. NB: not __init! */
522void smc_rx_init(struct smc_sock *smc)
523{
524	smc->sk.sk_data_ready = smc_rx_wake_up;
525	atomic_set(&smc->conn.splice_pending, 0);
526	smc->conn.urg_state = SMC_URG_READ;
527}