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Root/net/rds/send.c

1	/*
2	* Copyright (c) 2006 Oracle. All rights reserved.
3	*
4	* This software is available to you under a choice of one of two
5	* licenses. You may choose to be licensed under the terms of the GNU
6	* General Public License (GPL) Version 2, available from the file
7	* COPYING in the main directory of this source tree, or the
8	* OpenIB.org BSD license below:
9	*
10	* Redistribution and use in source and binary forms, with or
11	* without modification, are permitted provided that the following
12	* conditions are met:
13	*
14	* - Redistributions of source code must retain the above
15	* copyright notice, this list of conditions and the following
16	* disclaimer.
17	*
18	* - Redistributions in binary form must reproduce the above
19	* copyright notice, this list of conditions and the following
20	* disclaimer in the documentation and/or other materials
21	* provided with the distribution.
22	*
23	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24	* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25	* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26	* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27	* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28	* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29	* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30	* SOFTWARE.
31	*
32	*/
33	#include <linux/kernel.h>
34	#include <linux/gfp.h>
35	#include <net/sock.h>
36	#include <linux/in.h>
37	#include <linux/list.h>
38
39	#include "rds.h"
40	#include "rdma.h"
41
42	/* When transmitting messages in rds_send_xmit, we need to emerge from
43	* time to time and briefly release the CPU. Otherwise the softlock watchdog
44	* will kick our shin.
45	* Also, it seems fairer to not let one busy connection stall all the
46	* others.
47	*
48	* send_batch_count is the number of times we'll loop in send_xmit. Setting
49	* it to 0 will restore the old behavior (where we looped until we had
50	* drained the queue).
51	*/
52	static int send_batch_count = 64;
53	module_param(send_batch_count, int, 0444);
54	MODULE_PARM_DESC(send_batch_count, " batch factor when working the send queue");
55
56	/*
57	* Reset the send state. Caller must hold c_send_lock when calling here.
58	*/
59	void rds_send_reset(struct rds_connection *conn)
60	{
61	struct rds_message rm, tmp;
62	unsigned long flags;
63
64	if (conn->c_xmit_rm) {
65	/* Tell the user the RDMA op is no longer mapped by the
66	* transport. This isn't entirely true (it's flushed out
67	* independently) but as the connection is down, there's
68	* no ongoing RDMA to/from that memory */
69	rds_message_unmapped(conn->c_xmit_rm);
70	rds_message_put(conn->c_xmit_rm);
71	conn->c_xmit_rm = NULL;
72	}
73	conn->c_xmit_sg = 0;
74	conn->c_xmit_hdr_off = 0;
75	conn->c_xmit_data_off = 0;
76	conn->c_xmit_rdma_sent = 0;
77
78	conn->c_map_queued = 0;
79
80	conn->c_unacked_packets = rds_sysctl_max_unacked_packets;
81	conn->c_unacked_bytes = rds_sysctl_max_unacked_bytes;
82
83	/* Mark messages as retransmissions, and move them to the send q */
84	spin_lock_irqsave(&conn->c_lock, flags);
85	list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
86	set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
87	set_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags);
88	}
89	list_splice_init(&conn->c_retrans, &conn->c_send_queue);
90	spin_unlock_irqrestore(&conn->c_lock, flags);
91	}
92
93	/*
94	* We're making the concious trade-off here to only send one message
95	* down the connection at a time.
96	* Pro:
97	* - tx queueing is a simple fifo list
98	* - reassembly is optional and easily done by transports per conn
99	* - no per flow rx lookup at all, straight to the socket
100	* - less per-frag memory and wire overhead
101	* Con:
102	* - queued acks can be delayed behind large messages
103	* Depends:
104	* - small message latency is higher behind queued large messages
105	* - large message latency isn't starved by intervening small sends
106	*/
107	int rds_send_xmit(struct rds_connection *conn)
108	{
109	struct rds_message *rm;
110	unsigned long flags;
111	unsigned int tmp;
112	unsigned int send_quota = send_batch_count;
113	struct scatterlist *sg;
114	int ret = 0;
115	int was_empty = 0;
116	LIST_HEAD(to_be_dropped);
117
118	/*
119	* sendmsg calls here after having queued its message on the send
120	* queue. We only have one task feeding the connection at a time. If
121	* another thread is already feeding the queue then we back off. This
122	* avoids blocking the caller and trading per-connection data between
123	* caches per message.
124	*
125	* The sem holder will issue a retry if they notice that someone queued
126	* a message after they stopped walking the send queue but before they
127	* dropped the sem.
128	*/
129	if (!mutex_trylock(&conn->c_send_lock)) {
130	rds_stats_inc(s_send_sem_contention);
131	ret = -ENOMEM;
132	goto out;
133	}
134
135	if (conn->c_trans->xmit_prepare)
136	conn->c_trans->xmit_prepare(conn);
137
138	/*
139	* spin trying to push headers and data down the connection until
140	* the connection doens't make forward progress.
141	*/
142	while (--send_quota) {
143	/*
144	* See if need to send a congestion map update if we're
145	* between sending messages. The send_sem protects our sole
146	* use of c_map_offset and _bytes.
147	* Note this is used only by transports that define a special
148	* xmit_cong_map function. For all others, we create allocate
149	* a cong_map message and treat it just like any other send.
150	*/
151	if (conn->c_map_bytes) {
152	ret = conn->c_trans->xmit_cong_map(conn, conn->c_lcong,
153	conn->c_map_offset);
154	if (ret <= 0)
155	break;
156
157	conn->c_map_offset += ret;
158	conn->c_map_bytes -= ret;
159	if (conn->c_map_bytes)
160	continue;
161	}
162
163	/* If we're done sending the current message, clear the
164	* offset and S/G temporaries.
165	*/
166	rm = conn->c_xmit_rm;
167	if (rm != NULL &&
168	conn->c_xmit_hdr_off == sizeof(struct rds_header) &&
169	conn->c_xmit_sg == rm->m_nents) {
170	conn->c_xmit_rm = NULL;
171	conn->c_xmit_sg = 0;
172	conn->c_xmit_hdr_off = 0;
173	conn->c_xmit_data_off = 0;
174	conn->c_xmit_rdma_sent = 0;
175
176	/* Release the reference to the previous message. */
177	rds_message_put(rm);
178	rm = NULL;
179	}
180
181	/* If we're asked to send a cong map update, do so.
182	*/
183	if (rm == NULL && test_and_clear_bit(0, &conn->c_map_queued)) {
184	if (conn->c_trans->xmit_cong_map != NULL) {
185	conn->c_map_offset = 0;
186	conn->c_map_bytes = sizeof(struct rds_header) +
187	RDS_CONG_MAP_BYTES;
188	continue;
189	}
190
191	rm = rds_cong_update_alloc(conn);
192	if (IS_ERR(rm)) {
193	ret = PTR_ERR(rm);
194	break;
195	}
196
197	conn->c_xmit_rm = rm;
198	}
199
200	/*
201	* Grab the next message from the send queue, if there is one.
202	*
203	* c_xmit_rm holds a ref while we're sending this message down
204	* the connction. We can use this ref while holding the
205	* send_sem.. rds_send_reset() is serialized with it.
206	*/
207	if (rm == NULL) {
208	unsigned int len;
209
210	spin_lock_irqsave(&conn->c_lock, flags);
211
212	if (!list_empty(&conn->c_send_queue)) {
213	rm = list_entry(conn->c_send_queue.next,
214	struct rds_message,
215	m_conn_item);
216	rds_message_addref(rm);
217
218	/*
219	* Move the message from the send queue to the retransmit
220	* list right away.
221	*/
222	list_move_tail(&rm->m_conn_item, &conn->c_retrans);
223	}
224
225	spin_unlock_irqrestore(&conn->c_lock, flags);
226
227	if (rm == NULL) {
228	was_empty = 1;
229	break;
230	}
231
232	/* Unfortunately, the way Infiniband deals with
233	* RDMA to a bad MR key is by moving the entire
234	* queue pair to error state. We cold possibly
235	* recover from that, but right now we drop the
236	* connection.
237	* Therefore, we never retransmit messages with RDMA ops.
238	*/
239	if (rm->m_rdma_op &&
240	test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags)) {
241	spin_lock_irqsave(&conn->c_lock, flags);
242	if (test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags))
243	list_move(&rm->m_conn_item, &to_be_dropped);
244	spin_unlock_irqrestore(&conn->c_lock, flags);
245	rds_message_put(rm);
246	continue;
247	}
248
249	/* Require an ACK every once in a while */
250	len = ntohl(rm->m_inc.i_hdr.h_len);
251	if (conn->c_unacked_packets == 0 \|\|
252	conn->c_unacked_bytes < len) {
253	__set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
254
255	conn->c_unacked_packets = rds_sysctl_max_unacked_packets;
256	conn->c_unacked_bytes = rds_sysctl_max_unacked_bytes;
257	rds_stats_inc(s_send_ack_required);
258	} else {
259	conn->c_unacked_bytes -= len;
260	conn->c_unacked_packets--;
261	}
262
263	conn->c_xmit_rm = rm;
264	}
265
266	/*
267	* Try and send an rdma message. Let's see if we can
268	* keep this simple and require that the transport either
269	* send the whole rdma or none of it.
270	*/
271	if (rm->m_rdma_op && !conn->c_xmit_rdma_sent) {
272	ret = conn->c_trans->xmit_rdma(conn, rm->m_rdma_op);
273	if (ret)
274	break;
275	conn->c_xmit_rdma_sent = 1;
276	/* The transport owns the mapped memory for now.
277	* You can't unmap it while it's on the send queue */
278	set_bit(RDS_MSG_MAPPED, &rm->m_flags);
279	}
280
281	if (conn->c_xmit_hdr_off < sizeof(struct rds_header) \|\|
282	conn->c_xmit_sg < rm->m_nents) {
283	ret = conn->c_trans->xmit(conn, rm,
284	conn->c_xmit_hdr_off,
285	conn->c_xmit_sg,
286	conn->c_xmit_data_off);
287	if (ret <= 0)
288	break;
289
290	if (conn->c_xmit_hdr_off < sizeof(struct rds_header)) {
291	tmp = min_t(int, ret,
292	sizeof(struct rds_header) -
293	conn->c_xmit_hdr_off);
294	conn->c_xmit_hdr_off += tmp;
295	ret -= tmp;
296	}
297
298	sg = &rm->m_sg[conn->c_xmit_sg];
299	while (ret) {
300	tmp = min_t(int, ret, sg->length -
301	conn->c_xmit_data_off);
302	conn->c_xmit_data_off += tmp;
303	ret -= tmp;
304	if (conn->c_xmit_data_off == sg->length) {
305	conn->c_xmit_data_off = 0;
306	sg++;
307	conn->c_xmit_sg++;
308	BUG_ON(ret != 0 &&
309	conn->c_xmit_sg == rm->m_nents);
310	}
311	}
312	}
313	}
314
315	/* Nuke any messages we decided not to retransmit. */
316	if (!list_empty(&to_be_dropped))
317	rds_send_remove_from_sock(&to_be_dropped, RDS_RDMA_DROPPED);
318
319	if (conn->c_trans->xmit_complete)
320	conn->c_trans->xmit_complete(conn);
321
322	/*
323	* We might be racing with another sender who queued a message but
324	* backed off on noticing that we held the c_send_lock. If we check
325	* for queued messages after dropping the sem then either we'll
326	* see the queued message or the queuer will get the sem. If we
327	* notice the queued message then we trigger an immediate retry.
328	*
329	* We need to be careful only to do this when we stopped processing
330	* the send queue because it was empty. It's the only way we
331	* stop processing the loop when the transport hasn't taken
332	* responsibility for forward progress.
333	*/
334	mutex_unlock(&conn->c_send_lock);
335
336	if (conn->c_map_bytes \|\| (send_quota == 0 && !was_empty)) {
337	/* We exhausted the send quota, but there's work left to
338	* do. Return and (re-)schedule the send worker.
339	*/
340	ret = -EAGAIN;
341	}
342
343	if (ret == 0 && was_empty) {
344	/* A simple bit test would be way faster than taking the
345	* spin lock */
346	spin_lock_irqsave(&conn->c_lock, flags);
347	if (!list_empty(&conn->c_send_queue)) {
348	rds_stats_inc(s_send_sem_queue_raced);
349	ret = -EAGAIN;
350	}
351	spin_unlock_irqrestore(&conn->c_lock, flags);
352	}
353	out:
354	return ret;
355	}
356
357	static void rds_send_sndbuf_remove(struct rds_sock rs, struct rds_message rm)
358	{
359	u32 len = be32_to_cpu(rm->m_inc.i_hdr.h_len);
360
361	assert_spin_locked(&rs->rs_lock);
362
363	BUG_ON(rs->rs_snd_bytes < len);
364	rs->rs_snd_bytes -= len;
365
366	if (rs->rs_snd_bytes == 0)
367	rds_stats_inc(s_send_queue_empty);
368	}
369
370	static inline int rds_send_is_acked(struct rds_message *rm, u64 ack,
371	is_acked_func is_acked)
372	{
373	if (is_acked)
374	return is_acked(rm, ack);
375	return be64_to_cpu(rm->m_inc.i_hdr.h_sequence) <= ack;
376	}
377
378	/*
379	* Returns true if there are no messages on the send and retransmit queues
380	* which have a sequence number greater than or equal to the given sequence
381	* number.
382	*/
383	int rds_send_acked_before(struct rds_connection *conn, u64 seq)
384	{
385	struct rds_message rm, tmp;
386	int ret = 1;
387
388	spin_lock(&conn->c_lock);
389
390	list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
391	if (be64_to_cpu(rm->m_inc.i_hdr.h_sequence) < seq)
392	ret = 0;
393	break;
394	}
395
396	list_for_each_entry_safe(rm, tmp, &conn->c_send_queue, m_conn_item) {
397	if (be64_to_cpu(rm->m_inc.i_hdr.h_sequence) < seq)
398	ret = 0;
399	break;
400	}
401
402	spin_unlock(&conn->c_lock);
403
404	return ret;
405	}
406
407	/*
408	* This is pretty similar to what happens below in the ACK
409	* handling code - except that we call here as soon as we get
410	* the IB send completion on the RDMA op and the accompanying
411	* message.
412	*/
413	void rds_rdma_send_complete(struct rds_message *rm, int status)
414	{
415	struct rds_sock *rs = NULL;
416	struct rds_rdma_op *ro;
417	struct rds_notifier *notifier;
418
419	spin_lock(&rm->m_rs_lock);
420
421	ro = rm->m_rdma_op;
422	if (test_bit(RDS_MSG_ON_SOCK, &rm->m_flags) &&
423	ro && ro->r_notify && ro->r_notifier) {
424	notifier = ro->r_notifier;
425	rs = rm->m_rs;
426	sock_hold(rds_rs_to_sk(rs));
427
428	notifier->n_status = status;
429	spin_lock(&rs->rs_lock);
430	list_add_tail(&notifier->n_list, &rs->rs_notify_queue);
431	spin_unlock(&rs->rs_lock);
432
433	ro->r_notifier = NULL;
434	}
435
436	spin_unlock(&rm->m_rs_lock);
437
438	if (rs) {
439	rds_wake_sk_sleep(rs);
440	sock_put(rds_rs_to_sk(rs));
441	}
442	}
443	EXPORT_SYMBOL_GPL(rds_rdma_send_complete);
444
445	/*
446	* This is the same as rds_rdma_send_complete except we
447	* don't do any locking - we have all the ingredients (message,
448	* socket, socket lock) and can just move the notifier.
449	*/
450	static inline void
451	__rds_rdma_send_complete(struct rds_sock rs, struct rds_message rm, int status)
452	{
453	struct rds_rdma_op *ro;
454
455	ro = rm->m_rdma_op;
456	if (ro && ro->r_notify && ro->r_notifier) {
457	ro->r_notifier->n_status = status;
458	list_add_tail(&ro->r_notifier->n_list, &rs->rs_notify_queue);
459	ro->r_notifier = NULL;
460	}
461
462	/* No need to wake the app - caller does this */
463	}
464
465	/*
466	* This is called from the IB send completion when we detect
467	* a RDMA operation that failed with remote access error.
468	* So speed is not an issue here.
469	*/
470	struct rds_message rds_send_get_message(struct rds_connection conn,
471	struct rds_rdma_op *op)
472	{
473	struct rds_message rm, tmp, *found = NULL;
474	unsigned long flags;
475
476	spin_lock_irqsave(&conn->c_lock, flags);
477
478	list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
479	if (rm->m_rdma_op == op) {
480	atomic_inc(&rm->m_refcount);
481	found = rm;
482	goto out;
483	}
484	}
485
486	list_for_each_entry_safe(rm, tmp, &conn->c_send_queue, m_conn_item) {
487	if (rm->m_rdma_op == op) {
488	atomic_inc(&rm->m_refcount);
489	found = rm;
490	break;
491	}
492	}
493
494	out:
495	spin_unlock_irqrestore(&conn->c_lock, flags);
496
497	return found;
498	}
499	EXPORT_SYMBOL_GPL(rds_send_get_message);
500
501	/*
502	* This removes messages from the socket's list if they're on it. The list
503	* argument must be private to the caller, we must be able to modify it
504	* without locks. The messages must have a reference held for their
505	* position on the list. This function will drop that reference after
506	* removing the messages from the 'messages' list regardless of if it found
507	* the messages on the socket list or not.
508	*/
509	void rds_send_remove_from_sock(struct list_head *messages, int status)
510	{
511	unsigned long flags = 0; /* silence gcc :P */
512	struct rds_sock *rs = NULL;
513	struct rds_message *rm;
514
515	local_irq_save(flags);
516	while (!list_empty(messages)) {
517	rm = list_entry(messages->next, struct rds_message,
518	m_conn_item);
519	list_del_init(&rm->m_conn_item);
520
521	/*
522	* If we see this flag cleared then we're sure that someone
523	* else beat us to removing it from the sock. If we race
524	* with their flag update we'll get the lock and then really
525	* see that the flag has been cleared.
526	*
527	* The message spinlock makes sure nobody clears rm->m_rs
528	* while we're messing with it. It does not prevent the
529	* message from being removed from the socket, though.
530	*/
531	spin_lock(&rm->m_rs_lock);
532	if (!test_bit(RDS_MSG_ON_SOCK, &rm->m_flags))
533	goto unlock_and_drop;
534
535	if (rs != rm->m_rs) {
536	if (rs) {
537	spin_unlock(&rs->rs_lock);
538	rds_wake_sk_sleep(rs);
539	sock_put(rds_rs_to_sk(rs));
540	}
541	rs = rm->m_rs;
542	spin_lock(&rs->rs_lock);
543	sock_hold(rds_rs_to_sk(rs));
544	}
545
546	if (test_and_clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags)) {
547	struct rds_rdma_op *ro = rm->m_rdma_op;
548	struct rds_notifier *notifier;
549
550	list_del_init(&rm->m_sock_item);
551	rds_send_sndbuf_remove(rs, rm);
552
553	if (ro && ro->r_notifier && (status \|\| ro->r_notify)) {
554	notifier = ro->r_notifier;
555	list_add_tail(&notifier->n_list,
556	&rs->rs_notify_queue);
557	if (!notifier->n_status)
558	notifier->n_status = status;
559	rm->m_rdma_op->r_notifier = NULL;
560	}
561	rds_message_put(rm);
562	rm->m_rs = NULL;
563	}
564
565	unlock_and_drop:
566	spin_unlock(&rm->m_rs_lock);
567	rds_message_put(rm);
568	}
569
570	if (rs) {
571	spin_unlock(&rs->rs_lock);
572	rds_wake_sk_sleep(rs);
573	sock_put(rds_rs_to_sk(rs));
574	}
575	local_irq_restore(flags);
576	}
577
578	/*
579	* Transports call here when they've determined that the receiver queued
580	* messages up to, and including, the given sequence number. Messages are
581	* moved to the retrans queue when rds_send_xmit picks them off the send
582	* queue. This means that in the TCP case, the message may not have been
583	* assigned the m_ack_seq yet - but that's fine as long as tcp_is_acked
584	* checks the RDS_MSG_HAS_ACK_SEQ bit.
585	*
586	* XXX It's not clear to me how this is safely serialized with socket
587	* destruction. Maybe it should bail if it sees SOCK_DEAD.
588	*/
589	void rds_send_drop_acked(struct rds_connection *conn, u64 ack,
590	is_acked_func is_acked)
591	{
592	struct rds_message rm, tmp;
593	unsigned long flags;
594	LIST_HEAD(list);
595
596	spin_lock_irqsave(&conn->c_lock, flags);
597
598	list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
599	if (!rds_send_is_acked(rm, ack, is_acked))
600	break;
601
602	list_move(&rm->m_conn_item, &list);
603	clear_bit(RDS_MSG_ON_CONN, &rm->m_flags);
604	}
605
606	/* order flag updates with spin locks */
607	if (!list_empty(&list))
608	smp_mb__after_clear_bit();
609
610	spin_unlock_irqrestore(&conn->c_lock, flags);
611
612	/* now remove the messages from the sock list as needed */
613	rds_send_remove_from_sock(&list, RDS_RDMA_SUCCESS);
614	}
615	EXPORT_SYMBOL_GPL(rds_send_drop_acked);
616
617	void rds_send_drop_to(struct rds_sock rs, struct sockaddr_in dest)
618	{
619	struct rds_message rm, tmp;
620	struct rds_connection *conn;
621	unsigned long flags, flags2;
622	LIST_HEAD(list);
623	int wake = 0;
624
625	/* get all the messages we're dropping under the rs lock */
626	spin_lock_irqsave(&rs->rs_lock, flags);
627
628	list_for_each_entry_safe(rm, tmp, &rs->rs_send_queue, m_sock_item) {
629	if (dest && (dest->sin_addr.s_addr != rm->m_daddr \|\|
630	dest->sin_port != rm->m_inc.i_hdr.h_dport))
631	continue;
632
633	wake = 1;
634	list_move(&rm->m_sock_item, &list);
635	rds_send_sndbuf_remove(rs, rm);
636	clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags);
637
638	/* If this is a RDMA operation, notify the app. */
639	__rds_rdma_send_complete(rs, rm, RDS_RDMA_CANCELED);
640	}
641
642	/* order flag updates with the rs lock */
643	if (wake)
644	smp_mb__after_clear_bit();
645
646	spin_unlock_irqrestore(&rs->rs_lock, flags);
647
648	if (wake)
649	rds_wake_sk_sleep(rs);
650
651	conn = NULL;
652
653	/* now remove the messages from the conn list as needed */
654	list_for_each_entry(rm, &list, m_sock_item) {
655	/* We do this here rather than in the loop above, so that
656	* we don't have to nest m_rs_lock under rs->rs_lock */
657	spin_lock_irqsave(&rm->m_rs_lock, flags2);
658	rm->m_rs = NULL;
659	spin_unlock_irqrestore(&rm->m_rs_lock, flags2);
660
661	/*
662	* If we see this flag cleared then we're sure that someone
663	* else beat us to removing it from the conn. If we race
664	* with their flag update we'll get the lock and then really
665	* see that the flag has been cleared.
666	*/
667	if (!test_bit(RDS_MSG_ON_CONN, &rm->m_flags))
668	continue;
669
670	if (conn != rm->m_inc.i_conn) {
671	if (conn)
672	spin_unlock_irqrestore(&conn->c_lock, flags);
673	conn = rm->m_inc.i_conn;
674	spin_lock_irqsave(&conn->c_lock, flags);
675	}
676
677	if (test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags)) {
678	list_del_init(&rm->m_conn_item);
679	rds_message_put(rm);
680	}
681	}
682
683	if (conn)
684	spin_unlock_irqrestore(&conn->c_lock, flags);
685
686	while (!list_empty(&list)) {
687	rm = list_entry(list.next, struct rds_message, m_sock_item);
688	list_del_init(&rm->m_sock_item);
689
690	rds_message_wait(rm);
691	rds_message_put(rm);
692	}
693	}
694
695	/*
696	* we only want this to fire once so we use the callers 'queued'. It's
697	* possible that another thread can race with us and remove the
698	* message from the flow with RDS_CANCEL_SENT_TO.
699	*/
700	static int rds_send_queue_rm(struct rds_sock rs, struct rds_connection conn,
701	struct rds_message *rm, __be16 sport,
702	__be16 dport, int *queued)
703	{
704	unsigned long flags;
705	u32 len;
706
707	if (*queued)
708	goto out;
709
710	len = be32_to_cpu(rm->m_inc.i_hdr.h_len);
711
712	/* this is the only place which holds both the socket's rs_lock
713	* and the connection's c_lock */
714	spin_lock_irqsave(&rs->rs_lock, flags);
715
716	/*
717	* If there is a little space in sndbuf, we don't queue anything,
718	* and userspace gets -EAGAIN. But poll() indicates there's send
719	* room. This can lead to bad behavior (spinning) if snd_bytes isn't
720	* freed up by incoming acks. So we check the old value of
721	* rs_snd_bytes here to allow the last msg to exceed the buffer,
722	* and poll() now knows no more data can be sent.
723	*/
724	if (rs->rs_snd_bytes < rds_sk_sndbuf(rs)) {
725	rs->rs_snd_bytes += len;
726
727	/* let recv side know we are close to send space exhaustion.
728	* This is probably not the optimal way to do it, as this
729	* means we set the flag on all messages as soon as our
730	* throughput hits a certain threshold.
731	*/
732	if (rs->rs_snd_bytes >= rds_sk_sndbuf(rs) / 2)
733	__set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
734
735	list_add_tail(&rm->m_sock_item, &rs->rs_send_queue);
736	set_bit(RDS_MSG_ON_SOCK, &rm->m_flags);
737	rds_message_addref(rm);
738	rm->m_rs = rs;
739
740	/* The code ordering is a little weird, but we're
741	trying to minimize the time we hold c_lock */
742	rds_message_populate_header(&rm->m_inc.i_hdr, sport, dport, 0);
743	rm->m_inc.i_conn = conn;
744	rds_message_addref(rm);
745
746	spin_lock(&conn->c_lock);
747	rm->m_inc.i_hdr.h_sequence = cpu_to_be64(conn->c_next_tx_seq++);
748	list_add_tail(&rm->m_conn_item, &conn->c_send_queue);
749	set_bit(RDS_MSG_ON_CONN, &rm->m_flags);
750	spin_unlock(&conn->c_lock);
751
752	rdsdebug("queued msg %p len %d, rs %p bytes %d seq %llu\n",
753	rm, len, rs, rs->rs_snd_bytes,
754	(unsigned long long)be64_to_cpu(rm->m_inc.i_hdr.h_sequence));
755
756	*queued = 1;
757	}
758
759	spin_unlock_irqrestore(&rs->rs_lock, flags);
760	out:
761	return *queued;
762	}
763
764	static int rds_cmsg_send(struct rds_sock rs, struct rds_message rm,
765	struct msghdr msg, int allocated_mr)
766	{
767	struct cmsghdr *cmsg;
768	int ret = 0;
769
770	for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
771	if (!CMSG_OK(msg, cmsg))
772	return -EINVAL;
773
774	if (cmsg->cmsg_level != SOL_RDS)
775	continue;
776
777	/* As a side effect, RDMA_DEST and RDMA_MAP will set
778	* rm->m_rdma_cookie and rm->m_rdma_mr.
779	*/
780	switch (cmsg->cmsg_type) {
781	case RDS_CMSG_RDMA_ARGS:
782	ret = rds_cmsg_rdma_args(rs, rm, cmsg);
783	break;
784
785	case RDS_CMSG_RDMA_DEST:
786	ret = rds_cmsg_rdma_dest(rs, rm, cmsg);
787	break;
788
789	case RDS_CMSG_RDMA_MAP:
790	ret = rds_cmsg_rdma_map(rs, rm, cmsg);
791	if (!ret)
792	*allocated_mr = 1;
793	break;
794
795	default:
796	return -EINVAL;
797	}
798
799	if (ret)
800	break;
801	}
802
803	return ret;
804	}
805
806	int rds_sendmsg(struct kiocb iocb, struct socket sock, struct msghdr *msg,
807	size_t payload_len)
808	{
809	struct sock *sk = sock->sk;
810	struct rds_sock *rs = rds_sk_to_rs(sk);
811	struct sockaddr_in usin = (struct sockaddr_in )msg->msg_name;
812	__be32 daddr;
813	__be16 dport;
814	struct rds_message *rm = NULL;
815	struct rds_connection *conn;
816	int ret = 0;
817	int queued = 0, allocated_mr = 0;
818	int nonblock = msg->msg_flags & MSG_DONTWAIT;
819	long timeo = sock_rcvtimeo(sk, nonblock);
820
821	/* Mirror Linux UDP mirror of BSD error message compatibility */
822	/* XXX: Perhaps MSG_MORE someday */
823	if (msg->msg_flags & ~(MSG_DONTWAIT \| MSG_CMSG_COMPAT)) {
824	printk(KERN_INFO "msg_flags 0x%08X\n", msg->msg_flags);
825	ret = -EOPNOTSUPP;
826	goto out;
827	}
828
829	if (msg->msg_namelen) {
830	/* XXX fail non-unicast destination IPs? */
831	if (msg->msg_namelen < sizeof(*usin) \|\| usin->sin_family != AF_INET) {
832	ret = -EINVAL;
833	goto out;
834	}
835	daddr = usin->sin_addr.s_addr;
836	dport = usin->sin_port;
837	} else {
838	/* We only care about consistency with ->connect() */
839	lock_sock(sk);
840	daddr = rs->rs_conn_addr;
841	dport = rs->rs_conn_port;
842	release_sock(sk);
843	}
844
845	/* racing with another thread binding seems ok here */
846	if (daddr == 0 \|\| rs->rs_bound_addr == 0) {
847	ret = -ENOTCONN; /* XXX not a great errno */
848	goto out;
849	}
850
851	rm = rds_message_copy_from_user(msg->msg_iov, payload_len);
852	if (IS_ERR(rm)) {
853	ret = PTR_ERR(rm);
854	rm = NULL;
855	goto out;
856	}
857
858	rm->m_daddr = daddr;
859
860	/* rds_conn_create has a spinlock that runs with IRQ off.
861	* Caching the conn in the socket helps a lot. */
862	if (rs->rs_conn && rs->rs_conn->c_faddr == daddr)
863	conn = rs->rs_conn;
864	else {
865	conn = rds_conn_create_outgoing(rs->rs_bound_addr, daddr,
866	rs->rs_transport,
867	sock->sk->sk_allocation);
868	if (IS_ERR(conn)) {
869	ret = PTR_ERR(conn);
870	goto out;
871	}
872	rs->rs_conn = conn;
873	}
874
875	/* Parse any control messages the user may have included. */
876	ret = rds_cmsg_send(rs, rm, msg, &allocated_mr);
877	if (ret)
878	goto out;
879
880	if ((rm->m_rdma_cookie \|\| rm->m_rdma_op) &&
881	conn->c_trans->xmit_rdma == NULL) {
882	if (printk_ratelimit())
883	printk(KERN_NOTICE "rdma_op %p conn xmit_rdma %p\n",
884	rm->m_rdma_op, conn->c_trans->xmit_rdma);
885	ret = -EOPNOTSUPP;
886	goto out;
887	}
888
889	/* If the connection is down, trigger a connect. We may
890	* have scheduled a delayed reconnect however - in this case
891	* we should not interfere.
892	*/
893	if (rds_conn_state(conn) == RDS_CONN_DOWN &&
894	!test_and_set_bit(RDS_RECONNECT_PENDING, &conn->c_flags))
895	queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
896
897	ret = rds_cong_wait(conn->c_fcong, dport, nonblock, rs);
898	if (ret)
899	goto out;
900
901	while (!rds_send_queue_rm(rs, conn, rm, rs->rs_bound_port,
902	dport, &queued)) {
903	rds_stats_inc(s_send_queue_full);
904	/* XXX make sure this is reasonable */
905	if (payload_len > rds_sk_sndbuf(rs)) {
906	ret = -EMSGSIZE;
907	goto out;
908	}
909	if (nonblock) {
910	ret = -EAGAIN;
911	goto out;
912	}
913
914	timeo = wait_event_interruptible_timeout(*sk->sk_sleep,
915	rds_send_queue_rm(rs, conn, rm,
916	rs->rs_bound_port,
917	dport,
918	&queued),
919	timeo);
920	rdsdebug("sendmsg woke queued %d timeo %ld\n", queued, timeo);
921	if (timeo > 0 \|\| timeo == MAX_SCHEDULE_TIMEOUT)
922	continue;
923
924	ret = timeo;
925	if (ret == 0)
926	ret = -ETIMEDOUT;
927	goto out;
928	}
929
930	/*
931	* By now we've committed to the send. We reuse rds_send_worker()
932	* to retry sends in the rds thread if the transport asks us to.
933	*/
934	rds_stats_inc(s_send_queued);
935
936	if (!test_bit(RDS_LL_SEND_FULL, &conn->c_flags))
937	rds_send_worker(&conn->c_send_w.work);
938
939	rds_message_put(rm);
940	return payload_len;
941
942	out:
943	/* If the user included a RDMA_MAP cmsg, we allocated a MR on the fly.
944	* If the sendmsg goes through, we keep the MR. If it fails with EAGAIN
945	* or in any other way, we need to destroy the MR again */
946	if (allocated_mr)
947	rds_rdma_unuse(rs, rds_rdma_cookie_key(rm->m_rdma_cookie), 1);
948
949	if (rm)
950	rds_message_put(rm);
951	return ret;
952	}
953
954	/*
955	* Reply to a ping packet.
956	*/
957	int
958	rds_send_pong(struct rds_connection *conn, __be16 dport)
959	{
960	struct rds_message *rm;
961	unsigned long flags;
962	int ret = 0;
963
964	rm = rds_message_alloc(0, GFP_ATOMIC);
965	if (rm == NULL) {
966	ret = -ENOMEM;
967	goto out;
968	}
969
970	rm->m_daddr = conn->c_faddr;
971
972	/* If the connection is down, trigger a connect. We may
973	* have scheduled a delayed reconnect however - in this case
974	* we should not interfere.
975	*/
976	if (rds_conn_state(conn) == RDS_CONN_DOWN &&
977	!test_and_set_bit(RDS_RECONNECT_PENDING, &conn->c_flags))
978	queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
979
980	ret = rds_cong_wait(conn->c_fcong, dport, 1, NULL);
981	if (ret)
982	goto out;
983
984	spin_lock_irqsave(&conn->c_lock, flags);
985	list_add_tail(&rm->m_conn_item, &conn->c_send_queue);
986	set_bit(RDS_MSG_ON_CONN, &rm->m_flags);
987	rds_message_addref(rm);
988	rm->m_inc.i_conn = conn;
989
990	rds_message_populate_header(&rm->m_inc.i_hdr, 0, dport,
991	conn->c_next_tx_seq);
992	conn->c_next_tx_seq++;
993	spin_unlock_irqrestore(&conn->c_lock, flags);
994
995	rds_stats_inc(s_send_queued);
996	rds_stats_inc(s_send_pong);
997
998	queue_delayed_work(rds_wq, &conn->c_send_w, 0);
999	rds_message_put(rm);
1000	return 0;
1001
1002	out:
1003	if (rm)
1004	rds_message_put(rm);
1005	return ret;
1006	}
1007

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