smc_tx.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Shared Memory Communications over RDMA (SMC-R) and RoCE
  4 *
  5 * Manage send buffer.
  6 * Producer:
  7 * Copy user space data into send buffer, if send buffer space available.
  8 * Consumer:
  9 * Trigger RDMA write into RMBE of peer and send CDC, if RMBE space available.
 10 *
 11 * Copyright IBM Corp. 2016
 12 *
 13 * Author(s):  Ursula Braun <ubraun@linux.vnet.ibm.com>
 14 */
 15
 16#include <linux/net.h>
 17#include <linux/rcupdate.h>
 18#include <linux/workqueue.h>
 19#include <linux/sched/signal.h>
 20
 21#include <net/sock.h>
 22#include <net/tcp.h>
 23
 24#include "smc.h"
 25#include "smc_wr.h"
 26#include "smc_cdc.h"
 27#include "smc_close.h"
 28#include "smc_ism.h"
 29#include "smc_tx.h"
 30#include "smc_stats.h"
 31#include "smc_tracepoint.h"
 32
 33#define SMC_TX_WORK_DELAY	0
 34
 35/***************************** sndbuf producer *******************************/
 36
 37/* callback implementation for sk.sk_write_space()
 38 * to wakeup sndbuf producers that blocked with smc_tx_wait().
 39 * called under sk_socket lock.
 40 */
 41static void smc_tx_write_space(struct sock *sk)
 42{
 43	struct socket *sock = sk->sk_socket;
 44	struct smc_sock *smc = smc_sk(sk);
 45	struct socket_wq *wq;
 46
 47	/* similar to sk_stream_write_space */
 48	if (atomic_read(&smc->conn.sndbuf_space) && sock) {
 49		if (test_bit(SOCK_NOSPACE, &sock->flags))
 50			SMC_STAT_RMB_TX_FULL(smc, !smc->conn.lnk);
 51		clear_bit(SOCK_NOSPACE, &sock->flags);
 52		rcu_read_lock();
 53		wq = rcu_dereference(sk->sk_wq);
 54		if (skwq_has_sleeper(wq))
 55			wake_up_interruptible_poll(&wq->wait,
 56						   EPOLLOUT | EPOLLWRNORM |
 57						   EPOLLWRBAND);
 58		if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
 59			sock_wake_async(wq, SOCK_WAKE_SPACE, POLL_OUT);
 60		rcu_read_unlock();
 61	}
 62}
 63
 64/* Wakeup sndbuf producers that blocked with smc_tx_wait().
 65 * Cf. tcp_data_snd_check()=>tcp_check_space()=>tcp_new_space().
 66 */
 67void smc_tx_sndbuf_nonfull(struct smc_sock *smc)
 68{
 69	if (smc->sk.sk_socket &&
 70	    test_bit(SOCK_NOSPACE, &smc->sk.sk_socket->flags))
 71		smc->sk.sk_write_space(&smc->sk);
 72}
 73
 74/* blocks sndbuf producer until at least one byte of free space available
 75 * or urgent Byte was consumed
 76 */
 77static int smc_tx_wait(struct smc_sock *smc, int flags)
 78{
 79	DEFINE_WAIT_FUNC(wait, woken_wake_function);
 80	struct smc_connection *conn = &smc->conn;
 81	struct sock *sk = &smc->sk;
 82	long timeo;
 83	int rc = 0;
 84
 85	/* similar to sk_stream_wait_memory */
 86	timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 87	add_wait_queue(sk_sleep(sk), &wait);
 88	while (1) {
 89		sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 90		if (sk->sk_err ||
 91		    (sk->sk_shutdown & SEND_SHUTDOWN) ||
 92		    conn->killed ||
 93		    conn->local_tx_ctrl.conn_state_flags.peer_done_writing) {
 94			rc = -EPIPE;
 95			break;
 96		}
 97		if (smc_cdc_rxed_any_close(conn)) {
 98			rc = -ECONNRESET;
 99			break;
100		}
101		if (!timeo) {
102			/* ensure EPOLLOUT is subsequently generated */
103			set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
104			rc = -EAGAIN;
105			break;
106		}
107		if (signal_pending(current)) {
108			rc = sock_intr_errno(timeo);
109			break;
110		}
111		sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
112		if (atomic_read(&conn->sndbuf_space) && !conn->urg_tx_pend)
113			break; /* at least 1 byte of free & no urgent data */
114		set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
115		sk_wait_event(sk, &timeo,
116			      READ_ONCE(sk->sk_err) ||
117			      (READ_ONCE(sk->sk_shutdown) & SEND_SHUTDOWN) ||
118			      smc_cdc_rxed_any_close(conn) ||
119			      (atomic_read(&conn->sndbuf_space) &&
120			       !conn->urg_tx_pend),
121			      &wait);
122	}
123	remove_wait_queue(sk_sleep(sk), &wait);
124	return rc;
125}
126
127static bool smc_tx_is_corked(struct smc_sock *smc)
128{
129	struct tcp_sock *tp = tcp_sk(smc->clcsock->sk);
130
131	return (tp->nonagle & TCP_NAGLE_CORK) ? true : false;
132}
133
134/* If we have pending CDC messages, do not send:
135 * Because CQE of this CDC message will happen shortly, it gives
136 * a chance to coalesce future sendmsg() payload in to one RDMA Write,
137 * without need for a timer, and with no latency trade off.
138 * Algorithm here:
139 *  1. First message should never cork
140 *  2. If we have pending Tx CDC messages, wait for the first CDC
141 *     message's completion
142 *  3. Don't cork to much data in a single RDMA Write to prevent burst
143 *     traffic, total corked message should not exceed sendbuf/2
144 */
145static bool smc_should_autocork(struct smc_sock *smc)
146{
147	struct smc_connection *conn = &smc->conn;
148	int corking_size;
149
150	corking_size = min_t(unsigned int, conn->sndbuf_desc->len >> 1,
151			     sock_net(&smc->sk)->smc.sysctl_autocorking_size);
152
153	if (atomic_read(&conn->cdc_pend_tx_wr) == 0 ||
154	    smc_tx_prepared_sends(conn) > corking_size)
155		return false;
156	return true;
157}
158
159static bool smc_tx_should_cork(struct smc_sock *smc, struct msghdr *msg)
160{
161	struct smc_connection *conn = &smc->conn;
162
163	if (smc_should_autocork(smc))
164		return true;
165
166	/* for a corked socket defer the RDMA writes if
167	 * sndbuf_space is still available. The applications
168	 * should known how/when to uncork it.
169	 */
170	if ((msg->msg_flags & MSG_MORE ||
171	     smc_tx_is_corked(smc)) &&
172	    atomic_read(&conn->sndbuf_space))
173		return true;
174
175	return false;
176}
177
178/* sndbuf producer: main API called by socket layer.
179 * called under sock lock.
180 */
181int smc_tx_sendmsg(struct smc_sock *smc, struct msghdr *msg, size_t len)
182{
183	size_t copylen, send_done = 0, send_remaining = len;
184	size_t chunk_len, chunk_off, chunk_len_sum;
185	struct smc_connection *conn = &smc->conn;
186	union smc_host_cursor prep;
187	struct sock *sk = &smc->sk;
188	char *sndbuf_base;
189	int tx_cnt_prep;
190	int writespace;
191	int rc, chunk;
192
193	/* This should be in poll */
194	sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
195
196	if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) {
197		rc = -EPIPE;
198		goto out_err;
199	}
200
201	if (sk->sk_state == SMC_INIT)
202		return -ENOTCONN;
203
204	if (len > conn->sndbuf_desc->len)
205		SMC_STAT_RMB_TX_SIZE_SMALL(smc, !conn->lnk);
206
207	if (len > conn->peer_rmbe_size)
208		SMC_STAT_RMB_TX_PEER_SIZE_SMALL(smc, !conn->lnk);
209
210	if (msg->msg_flags & MSG_OOB)
211		SMC_STAT_INC(smc, urg_data_cnt);
212
213	while (msg_data_left(msg)) {
214		if (smc->sk.sk_shutdown & SEND_SHUTDOWN ||
215		    (smc->sk.sk_err == ECONNABORTED) ||
216		    conn->killed)
217			return -EPIPE;
218		if (smc_cdc_rxed_any_close(conn))
219			return send_done ?: -ECONNRESET;
220
221		if (msg->msg_flags & MSG_OOB)
222			conn->local_tx_ctrl.prod_flags.urg_data_pending = 1;
223
224		if (!atomic_read(&conn->sndbuf_space) || conn->urg_tx_pend) {
225			if (send_done)
226				return send_done;
227			rc = smc_tx_wait(smc, msg->msg_flags);
228			if (rc)
229				goto out_err;
230			continue;
231		}
232
233		/* initialize variables for 1st iteration of subsequent loop */
234		/* could be just 1 byte, even after smc_tx_wait above */
235		writespace = atomic_read(&conn->sndbuf_space);
236		/* not more than what user space asked for */
237		copylen = min_t(size_t, send_remaining, writespace);
238		/* determine start of sndbuf */
239		sndbuf_base = conn->sndbuf_desc->cpu_addr;
240		smc_curs_copy(&prep, &conn->tx_curs_prep, conn);
241		tx_cnt_prep = prep.count;
242		/* determine chunks where to write into sndbuf */
243		/* either unwrapped case, or 1st chunk of wrapped case */
244		chunk_len = min_t(size_t, copylen, conn->sndbuf_desc->len -
245				  tx_cnt_prep);
246		chunk_len_sum = chunk_len;
247		chunk_off = tx_cnt_prep;
248		for (chunk = 0; chunk < 2; chunk++) {
249			rc = memcpy_from_msg(sndbuf_base + chunk_off,
250					     msg, chunk_len);
251			if (rc) {
252				smc_sndbuf_sync_sg_for_device(conn);
253				if (send_done)
254					return send_done;
255				goto out_err;
256			}
257			send_done += chunk_len;
258			send_remaining -= chunk_len;
259
260			if (chunk_len_sum == copylen)
261				break; /* either on 1st or 2nd iteration */
262			/* prepare next (== 2nd) iteration */
263			chunk_len = copylen - chunk_len; /* remainder */
264			chunk_len_sum += chunk_len;
265			chunk_off = 0; /* modulo offset in send ring buffer */
266		}
267		smc_sndbuf_sync_sg_for_device(conn);
268		/* update cursors */
269		smc_curs_add(conn->sndbuf_desc->len, &prep, copylen);
270		smc_curs_copy(&conn->tx_curs_prep, &prep, conn);
271		/* increased in send tasklet smc_cdc_tx_handler() */
272		smp_mb__before_atomic();
273		atomic_sub(copylen, &conn->sndbuf_space);
274		/* guarantee 0 <= sndbuf_space <= sndbuf_desc->len */
275		smp_mb__after_atomic();
276		/* since we just produced more new data into sndbuf,
277		 * trigger sndbuf consumer: RDMA write into peer RMBE and CDC
278		 */
279		if ((msg->msg_flags & MSG_OOB) && !send_remaining)
280			conn->urg_tx_pend = true;
281		/* If we need to cork, do nothing and wait for the next
282		 * sendmsg() call or push on tx completion
283		 */
284		if (!smc_tx_should_cork(smc, msg))
285			smc_tx_sndbuf_nonempty(conn);
286
287		trace_smc_tx_sendmsg(smc, copylen);
288	} /* while (msg_data_left(msg)) */
289
290	return send_done;
291
292out_err:
293	rc = sk_stream_error(sk, msg->msg_flags, rc);
294	/* make sure we wake any epoll edge trigger waiter */
295	if (unlikely(rc == -EAGAIN))
296		sk->sk_write_space(sk);
297	return rc;
298}
299
300/***************************** sndbuf consumer *******************************/
301
302/* sndbuf consumer: actual data transfer of one target chunk with ISM write */
303int smcd_tx_ism_write(struct smc_connection *conn, void *data, size_t len,
304		      u32 offset, int signal)
305{
306	int rc;
307
308	rc = smc_ism_write(conn->lgr->smcd, conn->peer_token,
309			   conn->peer_rmbe_idx, signal, conn->tx_off + offset,
310			   data, len);
311	if (rc)
312		conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
313	return rc;
314}
315
316/* sndbuf consumer: actual data transfer of one target chunk with RDMA write */
317static int smc_tx_rdma_write(struct smc_connection *conn, int peer_rmbe_offset,
318			     int num_sges, struct ib_rdma_wr *rdma_wr)
319{
320	struct smc_link_group *lgr = conn->lgr;
321	struct smc_link *link = conn->lnk;
322	int rc;
323
324	rdma_wr->wr.wr_id = smc_wr_tx_get_next_wr_id(link);
325	rdma_wr->wr.num_sge = num_sges;
326	rdma_wr->remote_addr =
327		lgr->rtokens[conn->rtoken_idx][link->link_idx].dma_addr +
328		/* RMBE within RMB */
329		conn->tx_off +
330		/* offset within RMBE */
331		peer_rmbe_offset;
332	rdma_wr->rkey = lgr->rtokens[conn->rtoken_idx][link->link_idx].rkey;
333	rc = ib_post_send(link->roce_qp, &rdma_wr->wr, NULL);
334	if (rc)
335		smcr_link_down_cond_sched(link);
336	return rc;
337}
338
339/* sndbuf consumer */
340static inline void smc_tx_advance_cursors(struct smc_connection *conn,
341					  union smc_host_cursor *prod,
342					  union smc_host_cursor *sent,
343					  size_t len)
344{
345	smc_curs_add(conn->peer_rmbe_size, prod, len);
346	/* increased in recv tasklet smc_cdc_msg_rcv() */
347	smp_mb__before_atomic();
348	/* data in flight reduces usable snd_wnd */
349	atomic_sub(len, &conn->peer_rmbe_space);
350	/* guarantee 0 <= peer_rmbe_space <= peer_rmbe_size */
351	smp_mb__after_atomic();
352	smc_curs_add(conn->sndbuf_desc->len, sent, len);
353}
354
355/* SMC-R helper for smc_tx_rdma_writes() */
356static int smcr_tx_rdma_writes(struct smc_connection *conn, size_t len,
357			       size_t src_off, size_t src_len,
358			       size_t dst_off, size_t dst_len,
359			       struct smc_rdma_wr *wr_rdma_buf)
360{
361	struct smc_link *link = conn->lnk;
362
363	dma_addr_t dma_addr =
364		sg_dma_address(conn->sndbuf_desc->sgt[link->link_idx].sgl);
365	u64 virt_addr = (uintptr_t)conn->sndbuf_desc->cpu_addr;
366	int src_len_sum = src_len, dst_len_sum = dst_len;
367	int sent_count = src_off;
368	int srcchunk, dstchunk;
369	int num_sges;
370	int rc;
371
372	for (dstchunk = 0; dstchunk < 2; dstchunk++) {
373		struct ib_rdma_wr *wr = &wr_rdma_buf->wr_tx_rdma[dstchunk];
374		struct ib_sge *sge = wr->wr.sg_list;
375		u64 base_addr = dma_addr;
376
377		if (dst_len < link->qp_attr.cap.max_inline_data) {
378			base_addr = virt_addr;
379			wr->wr.send_flags |= IB_SEND_INLINE;
380		} else {
381			wr->wr.send_flags &= ~IB_SEND_INLINE;
382		}
383
384		num_sges = 0;
385		for (srcchunk = 0; srcchunk < 2; srcchunk++) {
386			sge[srcchunk].addr = conn->sndbuf_desc->is_vm ?
387				(virt_addr + src_off) : (base_addr + src_off);
388			sge[srcchunk].length = src_len;
389			if (conn->sndbuf_desc->is_vm)
390				sge[srcchunk].lkey =
391					conn->sndbuf_desc->mr[link->link_idx]->lkey;
392			num_sges++;
393
394			src_off += src_len;
395			if (src_off >= conn->sndbuf_desc->len)
396				src_off -= conn->sndbuf_desc->len;
397						/* modulo in send ring */
398			if (src_len_sum == dst_len)
399				break; /* either on 1st or 2nd iteration */
400			/* prepare next (== 2nd) iteration */
401			src_len = dst_len - src_len; /* remainder */
402			src_len_sum += src_len;
403		}
404		rc = smc_tx_rdma_write(conn, dst_off, num_sges, wr);
405		if (rc)
406			return rc;
407		if (dst_len_sum == len)
408			break; /* either on 1st or 2nd iteration */
409		/* prepare next (== 2nd) iteration */
410		dst_off = 0; /* modulo offset in RMBE ring buffer */
411		dst_len = len - dst_len; /* remainder */
412		dst_len_sum += dst_len;
413		src_len = min_t(int, dst_len, conn->sndbuf_desc->len -
414				sent_count);
415		src_len_sum = src_len;
416	}
417	return 0;
418}
419
420/* SMC-D helper for smc_tx_rdma_writes() */
421static int smcd_tx_rdma_writes(struct smc_connection *conn, size_t len,
422			       size_t src_off, size_t src_len,
423			       size_t dst_off, size_t dst_len)
424{
425	int src_len_sum = src_len, dst_len_sum = dst_len;
426	int srcchunk, dstchunk;
427	int rc;
428
429	if (conn->sndbuf_desc->is_attached)
430		return 0;
431
432	for (dstchunk = 0; dstchunk < 2; dstchunk++) {
433		for (srcchunk = 0; srcchunk < 2; srcchunk++) {
434			void *data = conn->sndbuf_desc->cpu_addr + src_off;
435
436			rc = smcd_tx_ism_write(conn, data, src_len, dst_off +
437					       sizeof(struct smcd_cdc_msg), 0);
438			if (rc)
439				return rc;
440			dst_off += src_len;
441			src_off += src_len;
442			if (src_off >= conn->sndbuf_desc->len)
443				src_off -= conn->sndbuf_desc->len;
444						/* modulo in send ring */
445			if (src_len_sum == dst_len)
446				break; /* either on 1st or 2nd iteration */
447			/* prepare next (== 2nd) iteration */
448			src_len = dst_len - src_len; /* remainder */
449			src_len_sum += src_len;
450		}
451		if (dst_len_sum == len)
452			break; /* either on 1st or 2nd iteration */
453		/* prepare next (== 2nd) iteration */
454		dst_off = 0; /* modulo offset in RMBE ring buffer */
455		dst_len = len - dst_len; /* remainder */
456		dst_len_sum += dst_len;
457		src_len = min_t(int, dst_len, conn->sndbuf_desc->len - src_off);
458		src_len_sum = src_len;
459	}
460	return 0;
461}
462
463/* sndbuf consumer: prepare all necessary (src&dst) chunks of data transmit;
464 * usable snd_wnd as max transmit
465 */
466static int smc_tx_rdma_writes(struct smc_connection *conn,
467			      struct smc_rdma_wr *wr_rdma_buf)
468{
469	size_t len, src_len, dst_off, dst_len; /* current chunk values */
470	union smc_host_cursor sent, prep, prod, cons;
471	struct smc_cdc_producer_flags *pflags;
472	int to_send, rmbespace;
473	int rc;
474
475	/* source: sndbuf */
476	smc_curs_copy(&sent, &conn->tx_curs_sent, conn);
477	smc_curs_copy(&prep, &conn->tx_curs_prep, conn);
478	/* cf. wmem_alloc - (snd_max - snd_una) */
479	to_send = smc_curs_diff(conn->sndbuf_desc->len, &sent, &prep);
480	if (to_send <= 0)
481		return 0;
482
483	/* destination: RMBE */
484	/* cf. snd_wnd */
485	rmbespace = atomic_read(&conn->peer_rmbe_space);
486	if (rmbespace <= 0) {
487		struct smc_sock *smc = container_of(conn, struct smc_sock,
488						    conn);
489		SMC_STAT_RMB_TX_PEER_FULL(smc, !conn->lnk);
490		return 0;
491	}
492	smc_curs_copy(&prod, &conn->local_tx_ctrl.prod, conn);
493	smc_curs_copy(&cons, &conn->local_rx_ctrl.cons, conn);
494
495	/* if usable snd_wnd closes ask peer to advertise once it opens again */
496	pflags = &conn->local_tx_ctrl.prod_flags;
497	pflags->write_blocked = (to_send >= rmbespace);
498	/* cf. usable snd_wnd */
499	len = min(to_send, rmbespace);
500
501	/* initialize variables for first iteration of subsequent nested loop */
502	dst_off = prod.count;
503	if (prod.wrap == cons.wrap) {
504		/* the filled destination area is unwrapped,
505		 * hence the available free destination space is wrapped
506		 * and we need 2 destination chunks of sum len; start with 1st
507		 * which is limited by what's available in sndbuf
508		 */
509		dst_len = min_t(size_t,
510				conn->peer_rmbe_size - prod.count, len);
511	} else {
512		/* the filled destination area is wrapped,
513		 * hence the available free destination space is unwrapped
514		 * and we need a single destination chunk of entire len
515		 */
516		dst_len = len;
517	}
518	/* dst_len determines the maximum src_len */
519	if (sent.count + dst_len <= conn->sndbuf_desc->len) {
520		/* unwrapped src case: single chunk of entire dst_len */
521		src_len = dst_len;
522	} else {
523		/* wrapped src case: 2 chunks of sum dst_len; start with 1st: */
524		src_len = conn->sndbuf_desc->len - sent.count;
525	}
526
527	if (conn->lgr->is_smcd)
528		rc = smcd_tx_rdma_writes(conn, len, sent.count, src_len,
529					 dst_off, dst_len);
530	else
531		rc = smcr_tx_rdma_writes(conn, len, sent.count, src_len,
532					 dst_off, dst_len, wr_rdma_buf);
533	if (rc)
534		return rc;
535
536	if (conn->urg_tx_pend && len == to_send)
537		pflags->urg_data_present = 1;
538	smc_tx_advance_cursors(conn, &prod, &sent, len);
539	/* update connection's cursors with advanced local cursors */
540	smc_curs_copy(&conn->local_tx_ctrl.prod, &prod, conn);
541							/* dst: peer RMBE */
542	smc_curs_copy(&conn->tx_curs_sent, &sent, conn);/* src: local sndbuf */
543
544	return 0;
545}
546
547/* Wakeup sndbuf consumers from any context (IRQ or process)
548 * since there is more data to transmit; usable snd_wnd as max transmit
549 */
550static int smcr_tx_sndbuf_nonempty(struct smc_connection *conn)
551{
552	struct smc_cdc_producer_flags *pflags = &conn->local_tx_ctrl.prod_flags;
553	struct smc_link *link = conn->lnk;
554	struct smc_rdma_wr *wr_rdma_buf;
555	struct smc_cdc_tx_pend *pend;
556	struct smc_wr_buf *wr_buf;
557	int rc;
558
559	if (!link || !smc_wr_tx_link_hold(link))
560		return -ENOLINK;
561	rc = smc_cdc_get_free_slot(conn, link, &wr_buf, &wr_rdma_buf, &pend);
562	if (rc < 0) {
563		smc_wr_tx_link_put(link);
564		if (rc == -EBUSY) {
565			struct smc_sock *smc =
566				container_of(conn, struct smc_sock, conn);
567
568			if (smc->sk.sk_err == ECONNABORTED)
569				return sock_error(&smc->sk);
570			if (conn->killed)
571				return -EPIPE;
572			rc = 0;
573			mod_delayed_work(conn->lgr->tx_wq, &conn->tx_work,
574					 SMC_TX_WORK_DELAY);
575		}
576		return rc;
577	}
578
579	spin_lock_bh(&conn->send_lock);
580	if (link != conn->lnk) {
581		/* link of connection changed, tx_work will restart */
582		smc_wr_tx_put_slot(link,
583				   (struct smc_wr_tx_pend_priv *)pend);
584		rc = -ENOLINK;
585		goto out_unlock;
586	}
587	if (!pflags->urg_data_present) {
588		rc = smc_tx_rdma_writes(conn, wr_rdma_buf);
589		if (rc) {
590			smc_wr_tx_put_slot(link,
591					   (struct smc_wr_tx_pend_priv *)pend);
592			goto out_unlock;
593		}
594	}
595
596	rc = smc_cdc_msg_send(conn, wr_buf, pend);
597	if (!rc && pflags->urg_data_present) {
598		pflags->urg_data_pending = 0;
599		pflags->urg_data_present = 0;
600	}
601
602out_unlock:
603	spin_unlock_bh(&conn->send_lock);
604	smc_wr_tx_link_put(link);
605	return rc;
606}
607
608static int smcd_tx_sndbuf_nonempty(struct smc_connection *conn)
609{
610	struct smc_cdc_producer_flags *pflags = &conn->local_tx_ctrl.prod_flags;
611	int rc = 0;
612
613	spin_lock_bh(&conn->send_lock);
614	if (!pflags->urg_data_present)
615		rc = smc_tx_rdma_writes(conn, NULL);
616	if (!rc)
617		rc = smcd_cdc_msg_send(conn);
618
619	if (!rc && pflags->urg_data_present) {
620		pflags->urg_data_pending = 0;
621		pflags->urg_data_present = 0;
622	}
623	spin_unlock_bh(&conn->send_lock);
624	return rc;
625}
626
627int smc_tx_sndbuf_nonempty(struct smc_connection *conn)
628{
629	struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
630	int rc = 0;
631
632	/* No data in the send queue */
633	if (unlikely(smc_tx_prepared_sends(conn) <= 0))
634		goto out;
635
636	/* Peer don't have RMBE space */
637	if (unlikely(atomic_read(&conn->peer_rmbe_space) <= 0)) {
638		SMC_STAT_RMB_TX_PEER_FULL(smc, !conn->lnk);
639		goto out;
640	}
641
642	if (conn->killed ||
643	    conn->local_rx_ctrl.conn_state_flags.peer_conn_abort) {
644		rc = -EPIPE;    /* connection being aborted */
645		goto out;
646	}
647	if (conn->lgr->is_smcd)
648		rc = smcd_tx_sndbuf_nonempty(conn);
649	else
650		rc = smcr_tx_sndbuf_nonempty(conn);
651
652	if (!rc) {
653		/* trigger socket release if connection is closing */
654		smc_close_wake_tx_prepared(smc);
655	}
656
657out:
658	return rc;
659}
660
661/* Wakeup sndbuf consumers from process context
662 * since there is more data to transmit. The caller
663 * must hold sock lock.
664 */
665void smc_tx_pending(struct smc_connection *conn)
666{
667	struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
668	int rc;
669
670	if (smc->sk.sk_err)
671		return;
672
673	rc = smc_tx_sndbuf_nonempty(conn);
674	if (!rc && conn->local_rx_ctrl.prod_flags.write_blocked &&
675	    !atomic_read(&conn->bytes_to_rcv))
676		conn->local_rx_ctrl.prod_flags.write_blocked = 0;
677}
678
679/* Wakeup sndbuf consumers from process context
680 * since there is more data to transmit in locked
681 * sock.
682 */
683void smc_tx_work(struct work_struct *work)
684{
685	struct smc_connection *conn = container_of(to_delayed_work(work),
686						   struct smc_connection,
687						   tx_work);
688	struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
689
690	lock_sock(&smc->sk);
691	smc_tx_pending(conn);
692	release_sock(&smc->sk);
693}
694
695void smc_tx_consumer_update(struct smc_connection *conn, bool force)
696{
697	union smc_host_cursor cfed, cons, prod;
698	int sender_free = conn->rmb_desc->len;
699	int to_confirm;
700
701	smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
702	smc_curs_copy(&cfed, &conn->rx_curs_confirmed, conn);
703	to_confirm = smc_curs_diff(conn->rmb_desc->len, &cfed, &cons);
704	if (to_confirm > conn->rmbe_update_limit) {
705		smc_curs_copy(&prod, &conn->local_rx_ctrl.prod, conn);
706		sender_free = conn->rmb_desc->len -
707			      smc_curs_diff_large(conn->rmb_desc->len,
708						  &cfed, &prod);
709	}
710
711	if (conn->local_rx_ctrl.prod_flags.cons_curs_upd_req ||
712	    force ||
713	    ((to_confirm > conn->rmbe_update_limit) &&
714	     ((sender_free <= (conn->rmb_desc->len / 2)) ||
715	      conn->local_rx_ctrl.prod_flags.write_blocked))) {
716		if (conn->killed ||
717		    conn->local_rx_ctrl.conn_state_flags.peer_conn_abort)
718			return;
719		if ((smc_cdc_get_slot_and_msg_send(conn) < 0) &&
720		    !conn->killed) {
721			queue_delayed_work(conn->lgr->tx_wq, &conn->tx_work,
722					   SMC_TX_WORK_DELAY);
723			return;
724		}
725	}
726	if (conn->local_rx_ctrl.prod_flags.write_blocked &&
727	    !atomic_read(&conn->bytes_to_rcv))
728		conn->local_rx_ctrl.prod_flags.write_blocked = 0;
729}
730
731/***************************** send initialize *******************************/
732
733/* Initialize send properties on connection establishment. NB: not __init! */
734void smc_tx_init(struct smc_sock *smc)
735{
736	smc->sk.sk_write_space = smc_tx_write_space;
737}