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TOMOYO Linux Cross Reference
Linux/net/rds/recv.c

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  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/slab.h>
 35 #include <net/sock.h>
 36 #include <linux/in.h>
 37 #include <linux/export.h>
 38 
 39 #include "rds.h"
 40 
 41 void rds_inc_init(struct rds_incoming *inc, struct rds_connection *conn,
 42                   __be32 saddr)
 43 {
 44         atomic_set(&inc->i_refcount, 1);
 45         INIT_LIST_HEAD(&inc->i_item);
 46         inc->i_conn = conn;
 47         inc->i_saddr = saddr;
 48         inc->i_rdma_cookie = 0;
 49 }
 50 EXPORT_SYMBOL_GPL(rds_inc_init);
 51 
 52 static void rds_inc_addref(struct rds_incoming *inc)
 53 {
 54         rdsdebug("addref inc %p ref %d\n", inc, atomic_read(&inc->i_refcount));
 55         atomic_inc(&inc->i_refcount);
 56 }
 57 
 58 void rds_inc_put(struct rds_incoming *inc)
 59 {
 60         rdsdebug("put inc %p ref %d\n", inc, atomic_read(&inc->i_refcount));
 61         if (atomic_dec_and_test(&inc->i_refcount)) {
 62                 BUG_ON(!list_empty(&inc->i_item));
 63 
 64                 inc->i_conn->c_trans->inc_free(inc);
 65         }
 66 }
 67 EXPORT_SYMBOL_GPL(rds_inc_put);
 68 
 69 static void rds_recv_rcvbuf_delta(struct rds_sock *rs, struct sock *sk,
 70                                   struct rds_cong_map *map,
 71                                   int delta, __be16 port)
 72 {
 73         int now_congested;
 74 
 75         if (delta == 0)
 76                 return;
 77 
 78         rs->rs_rcv_bytes += delta;
 79         now_congested = rs->rs_rcv_bytes > rds_sk_rcvbuf(rs);
 80 
 81         rdsdebug("rs %p (%pI4:%u) recv bytes %d buf %d "
 82           "now_cong %d delta %d\n",
 83           rs, &rs->rs_bound_addr,
 84           ntohs(rs->rs_bound_port), rs->rs_rcv_bytes,
 85           rds_sk_rcvbuf(rs), now_congested, delta);
 86 
 87         /* wasn't -> am congested */
 88         if (!rs->rs_congested && now_congested) {
 89                 rs->rs_congested = 1;
 90                 rds_cong_set_bit(map, port);
 91                 rds_cong_queue_updates(map);
 92         }
 93         /* was -> aren't congested */
 94         /* Require more free space before reporting uncongested to prevent
 95            bouncing cong/uncong state too often */
 96         else if (rs->rs_congested && (rs->rs_rcv_bytes < (rds_sk_rcvbuf(rs)/2))) {
 97                 rs->rs_congested = 0;
 98                 rds_cong_clear_bit(map, port);
 99                 rds_cong_queue_updates(map);
100         }
101 
102         /* do nothing if no change in cong state */
103 }
104 
105 /*
106  * Process all extension headers that come with this message.
107  */
108 static void rds_recv_incoming_exthdrs(struct rds_incoming *inc, struct rds_sock *rs)
109 {
110         struct rds_header *hdr = &inc->i_hdr;
111         unsigned int pos = 0, type, len;
112         union {
113                 struct rds_ext_header_version version;
114                 struct rds_ext_header_rdma rdma;
115                 struct rds_ext_header_rdma_dest rdma_dest;
116         } buffer;
117 
118         while (1) {
119                 len = sizeof(buffer);
120                 type = rds_message_next_extension(hdr, &pos, &buffer, &len);
121                 if (type == RDS_EXTHDR_NONE)
122                         break;
123                 /* Process extension header here */
124                 switch (type) {
125                 case RDS_EXTHDR_RDMA:
126                         rds_rdma_unuse(rs, be32_to_cpu(buffer.rdma.h_rdma_rkey), 0);
127                         break;
128 
129                 case RDS_EXTHDR_RDMA_DEST:
130                         /* We ignore the size for now. We could stash it
131                          * somewhere and use it for error checking. */
132                         inc->i_rdma_cookie = rds_rdma_make_cookie(
133                                         be32_to_cpu(buffer.rdma_dest.h_rdma_rkey),
134                                         be32_to_cpu(buffer.rdma_dest.h_rdma_offset));
135 
136                         break;
137                 }
138         }
139 }
140 
141 /*
142  * The transport must make sure that this is serialized against other
143  * rx and conn reset on this specific conn.
144  *
145  * We currently assert that only one fragmented message will be sent
146  * down a connection at a time.  This lets us reassemble in the conn
147  * instead of per-flow which means that we don't have to go digging through
148  * flows to tear down partial reassembly progress on conn failure and
149  * we save flow lookup and locking for each frag arrival.  It does mean
150  * that small messages will wait behind large ones.  Fragmenting at all
151  * is only to reduce the memory consumption of pre-posted buffers.
152  *
153  * The caller passes in saddr and daddr instead of us getting it from the
154  * conn.  This lets loopback, who only has one conn for both directions,
155  * tell us which roles the addrs in the conn are playing for this message.
156  */
157 void rds_recv_incoming(struct rds_connection *conn, __be32 saddr, __be32 daddr,
158                        struct rds_incoming *inc, gfp_t gfp)
159 {
160         struct rds_sock *rs = NULL;
161         struct sock *sk;
162         unsigned long flags;
163 
164         inc->i_conn = conn;
165         inc->i_rx_jiffies = jiffies;
166 
167         rdsdebug("conn %p next %llu inc %p seq %llu len %u sport %u dport %u "
168                  "flags 0x%x rx_jiffies %lu\n", conn,
169                  (unsigned long long)conn->c_next_rx_seq,
170                  inc,
171                  (unsigned long long)be64_to_cpu(inc->i_hdr.h_sequence),
172                  be32_to_cpu(inc->i_hdr.h_len),
173                  be16_to_cpu(inc->i_hdr.h_sport),
174                  be16_to_cpu(inc->i_hdr.h_dport),
175                  inc->i_hdr.h_flags,
176                  inc->i_rx_jiffies);
177 
178         /*
179          * Sequence numbers should only increase.  Messages get their
180          * sequence number as they're queued in a sending conn.  They
181          * can be dropped, though, if the sending socket is closed before
182          * they hit the wire.  So sequence numbers can skip forward
183          * under normal operation.  They can also drop back in the conn
184          * failover case as previously sent messages are resent down the
185          * new instance of a conn.  We drop those, otherwise we have
186          * to assume that the next valid seq does not come after a
187          * hole in the fragment stream.
188          *
189          * The headers don't give us a way to realize if fragments of
190          * a message have been dropped.  We assume that frags that arrive
191          * to a flow are part of the current message on the flow that is
192          * being reassembled.  This means that senders can't drop messages
193          * from the sending conn until all their frags are sent.
194          *
195          * XXX we could spend more on the wire to get more robust failure
196          * detection, arguably worth it to avoid data corruption.
197          */
198         if (be64_to_cpu(inc->i_hdr.h_sequence) < conn->c_next_rx_seq &&
199             (inc->i_hdr.h_flags & RDS_FLAG_RETRANSMITTED)) {
200                 rds_stats_inc(s_recv_drop_old_seq);
201                 goto out;
202         }
203         conn->c_next_rx_seq = be64_to_cpu(inc->i_hdr.h_sequence) + 1;
204 
205         if (rds_sysctl_ping_enable && inc->i_hdr.h_dport == 0) {
206                 rds_stats_inc(s_recv_ping);
207                 rds_send_pong(conn, inc->i_hdr.h_sport);
208                 goto out;
209         }
210 
211         rs = rds_find_bound(daddr, inc->i_hdr.h_dport);
212         if (!rs) {
213                 rds_stats_inc(s_recv_drop_no_sock);
214                 goto out;
215         }
216 
217         /* Process extension headers */
218         rds_recv_incoming_exthdrs(inc, rs);
219 
220         /* We can be racing with rds_release() which marks the socket dead. */
221         sk = rds_rs_to_sk(rs);
222 
223         /* serialize with rds_release -> sock_orphan */
224         write_lock_irqsave(&rs->rs_recv_lock, flags);
225         if (!sock_flag(sk, SOCK_DEAD)) {
226                 rdsdebug("adding inc %p to rs %p's recv queue\n", inc, rs);
227                 rds_stats_inc(s_recv_queued);
228                 rds_recv_rcvbuf_delta(rs, sk, inc->i_conn->c_lcong,
229                                       be32_to_cpu(inc->i_hdr.h_len),
230                                       inc->i_hdr.h_dport);
231                 rds_inc_addref(inc);
232                 list_add_tail(&inc->i_item, &rs->rs_recv_queue);
233                 __rds_wake_sk_sleep(sk);
234         } else {
235                 rds_stats_inc(s_recv_drop_dead_sock);
236         }
237         write_unlock_irqrestore(&rs->rs_recv_lock, flags);
238 
239 out:
240         if (rs)
241                 rds_sock_put(rs);
242 }
243 EXPORT_SYMBOL_GPL(rds_recv_incoming);
244 
245 /*
246  * be very careful here.  This is being called as the condition in
247  * wait_event_*() needs to cope with being called many times.
248  */
249 static int rds_next_incoming(struct rds_sock *rs, struct rds_incoming **inc)
250 {
251         unsigned long flags;
252 
253         if (!*inc) {
254                 read_lock_irqsave(&rs->rs_recv_lock, flags);
255                 if (!list_empty(&rs->rs_recv_queue)) {
256                         *inc = list_entry(rs->rs_recv_queue.next,
257                                           struct rds_incoming,
258                                           i_item);
259                         rds_inc_addref(*inc);
260                 }
261                 read_unlock_irqrestore(&rs->rs_recv_lock, flags);
262         }
263 
264         return *inc != NULL;
265 }
266 
267 static int rds_still_queued(struct rds_sock *rs, struct rds_incoming *inc,
268                             int drop)
269 {
270         struct sock *sk = rds_rs_to_sk(rs);
271         int ret = 0;
272         unsigned long flags;
273 
274         write_lock_irqsave(&rs->rs_recv_lock, flags);
275         if (!list_empty(&inc->i_item)) {
276                 ret = 1;
277                 if (drop) {
278                         /* XXX make sure this i_conn is reliable */
279                         rds_recv_rcvbuf_delta(rs, sk, inc->i_conn->c_lcong,
280                                               -be32_to_cpu(inc->i_hdr.h_len),
281                                               inc->i_hdr.h_dport);
282                         list_del_init(&inc->i_item);
283                         rds_inc_put(inc);
284                 }
285         }
286         write_unlock_irqrestore(&rs->rs_recv_lock, flags);
287 
288         rdsdebug("inc %p rs %p still %d dropped %d\n", inc, rs, ret, drop);
289         return ret;
290 }
291 
292 /*
293  * Pull errors off the error queue.
294  * If msghdr is NULL, we will just purge the error queue.
295  */
296 int rds_notify_queue_get(struct rds_sock *rs, struct msghdr *msghdr)
297 {
298         struct rds_notifier *notifier;
299         struct rds_rdma_notify cmsg = { 0 }; /* fill holes with zero */
300         unsigned int count = 0, max_messages = ~0U;
301         unsigned long flags;
302         LIST_HEAD(copy);
303         int err = 0;
304 
305 
306         /* put_cmsg copies to user space and thus may sleep. We can't do this
307          * with rs_lock held, so first grab as many notifications as we can stuff
308          * in the user provided cmsg buffer. We don't try to copy more, to avoid
309          * losing notifications - except when the buffer is so small that it wouldn't
310          * even hold a single notification. Then we give him as much of this single
311          * msg as we can squeeze in, and set MSG_CTRUNC.
312          */
313         if (msghdr) {
314                 max_messages = msghdr->msg_controllen / CMSG_SPACE(sizeof(cmsg));
315                 if (!max_messages)
316                         max_messages = 1;
317         }
318 
319         spin_lock_irqsave(&rs->rs_lock, flags);
320         while (!list_empty(&rs->rs_notify_queue) && count < max_messages) {
321                 notifier = list_entry(rs->rs_notify_queue.next,
322                                 struct rds_notifier, n_list);
323                 list_move(&notifier->n_list, &copy);
324                 count++;
325         }
326         spin_unlock_irqrestore(&rs->rs_lock, flags);
327 
328         if (!count)
329                 return 0;
330 
331         while (!list_empty(&copy)) {
332                 notifier = list_entry(copy.next, struct rds_notifier, n_list);
333 
334                 if (msghdr) {
335                         cmsg.user_token = notifier->n_user_token;
336                         cmsg.status = notifier->n_status;
337 
338                         err = put_cmsg(msghdr, SOL_RDS, RDS_CMSG_RDMA_STATUS,
339                                        sizeof(cmsg), &cmsg);
340                         if (err)
341                                 break;
342                 }
343 
344                 list_del_init(&notifier->n_list);
345                 kfree(notifier);
346         }
347 
348         /* If we bailed out because of an error in put_cmsg,
349          * we may be left with one or more notifications that we
350          * didn't process. Return them to the head of the list. */
351         if (!list_empty(&copy)) {
352                 spin_lock_irqsave(&rs->rs_lock, flags);
353                 list_splice(&copy, &rs->rs_notify_queue);
354                 spin_unlock_irqrestore(&rs->rs_lock, flags);
355         }
356 
357         return err;
358 }
359 
360 /*
361  * Queue a congestion notification
362  */
363 static int rds_notify_cong(struct rds_sock *rs, struct msghdr *msghdr)
364 {
365         uint64_t notify = rs->rs_cong_notify;
366         unsigned long flags;
367         int err;
368 
369         err = put_cmsg(msghdr, SOL_RDS, RDS_CMSG_CONG_UPDATE,
370                         sizeof(notify), &notify);
371         if (err)
372                 return err;
373 
374         spin_lock_irqsave(&rs->rs_lock, flags);
375         rs->rs_cong_notify &= ~notify;
376         spin_unlock_irqrestore(&rs->rs_lock, flags);
377 
378         return 0;
379 }
380 
381 /*
382  * Receive any control messages.
383  */
384 static int rds_cmsg_recv(struct rds_incoming *inc, struct msghdr *msg)
385 {
386         int ret = 0;
387 
388         if (inc->i_rdma_cookie) {
389                 ret = put_cmsg(msg, SOL_RDS, RDS_CMSG_RDMA_DEST,
390                                 sizeof(inc->i_rdma_cookie), &inc->i_rdma_cookie);
391                 if (ret)
392                         return ret;
393         }
394 
395         return 0;
396 }
397 
398 int rds_recvmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
399                 size_t size, int msg_flags)
400 {
401         struct sock *sk = sock->sk;
402         struct rds_sock *rs = rds_sk_to_rs(sk);
403         long timeo;
404         int ret = 0, nonblock = msg_flags & MSG_DONTWAIT;
405         struct sockaddr_in *sin;
406         struct rds_incoming *inc = NULL;
407 
408         /* udp_recvmsg()->sock_recvtimeo() gets away without locking too.. */
409         timeo = sock_rcvtimeo(sk, nonblock);
410 
411         rdsdebug("size %zu flags 0x%x timeo %ld\n", size, msg_flags, timeo);
412 
413         if (msg_flags & MSG_OOB)
414                 goto out;
415 
416         while (1) {
417                 /* If there are pending notifications, do those - and nothing else */
418                 if (!list_empty(&rs->rs_notify_queue)) {
419                         ret = rds_notify_queue_get(rs, msg);
420                         break;
421                 }
422 
423                 if (rs->rs_cong_notify) {
424                         ret = rds_notify_cong(rs, msg);
425                         break;
426                 }
427 
428                 if (!rds_next_incoming(rs, &inc)) {
429                         if (nonblock) {
430                                 ret = -EAGAIN;
431                                 break;
432                         }
433 
434                         timeo = wait_event_interruptible_timeout(*sk_sleep(sk),
435                                         (!list_empty(&rs->rs_notify_queue) ||
436                                          rs->rs_cong_notify ||
437                                          rds_next_incoming(rs, &inc)), timeo);
438                         rdsdebug("recvmsg woke inc %p timeo %ld\n", inc,
439                                  timeo);
440                         if (timeo > 0 || timeo == MAX_SCHEDULE_TIMEOUT)
441                                 continue;
442 
443                         ret = timeo;
444                         if (ret == 0)
445                                 ret = -ETIMEDOUT;
446                         break;
447                 }
448 
449                 rdsdebug("copying inc %p from %pI4:%u to user\n", inc,
450                          &inc->i_conn->c_faddr,
451                          ntohs(inc->i_hdr.h_sport));
452                 ret = inc->i_conn->c_trans->inc_copy_to_user(inc, msg->msg_iov,
453                                                              size);
454                 if (ret < 0)
455                         break;
456 
457                 /*
458                  * if the message we just copied isn't at the head of the
459                  * recv queue then someone else raced us to return it, try
460                  * to get the next message.
461                  */
462                 if (!rds_still_queued(rs, inc, !(msg_flags & MSG_PEEK))) {
463                         rds_inc_put(inc);
464                         inc = NULL;
465                         rds_stats_inc(s_recv_deliver_raced);
466                         continue;
467                 }
468 
469                 if (ret < be32_to_cpu(inc->i_hdr.h_len)) {
470                         if (msg_flags & MSG_TRUNC)
471                                 ret = be32_to_cpu(inc->i_hdr.h_len);
472                         msg->msg_flags |= MSG_TRUNC;
473                 }
474 
475                 if (rds_cmsg_recv(inc, msg)) {
476                         ret = -EFAULT;
477                         goto out;
478                 }
479 
480                 rds_stats_inc(s_recv_delivered);
481 
482                 sin = (struct sockaddr_in *)msg->msg_name;
483                 if (sin) {
484                         sin->sin_family = AF_INET;
485                         sin->sin_port = inc->i_hdr.h_sport;
486                         sin->sin_addr.s_addr = inc->i_saddr;
487                         memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
488                         msg->msg_namelen = sizeof(*sin);
489                 }
490                 break;
491         }
492 
493         if (inc)
494                 rds_inc_put(inc);
495 
496 out:
497         return ret;
498 }
499 
500 /*
501  * The socket is being shut down and we're asked to drop messages that were
502  * queued for recvmsg.  The caller has unbound the socket so the receive path
503  * won't queue any more incoming fragments or messages on the socket.
504  */
505 void rds_clear_recv_queue(struct rds_sock *rs)
506 {
507         struct sock *sk = rds_rs_to_sk(rs);
508         struct rds_incoming *inc, *tmp;
509         unsigned long flags;
510 
511         write_lock_irqsave(&rs->rs_recv_lock, flags);
512         list_for_each_entry_safe(inc, tmp, &rs->rs_recv_queue, i_item) {
513                 rds_recv_rcvbuf_delta(rs, sk, inc->i_conn->c_lcong,
514                                       -be32_to_cpu(inc->i_hdr.h_len),
515                                       inc->i_hdr.h_dport);
516                 list_del_init(&inc->i_item);
517                 rds_inc_put(inc);
518         }
519         write_unlock_irqrestore(&rs->rs_recv_lock, flags);
520 }
521 
522 /*
523  * inc->i_saddr isn't used here because it is only set in the receive
524  * path.
525  */
526 void rds_inc_info_copy(struct rds_incoming *inc,
527                        struct rds_info_iterator *iter,
528                        __be32 saddr, __be32 daddr, int flip)
529 {
530         struct rds_info_message minfo;
531 
532         minfo.seq = be64_to_cpu(inc->i_hdr.h_sequence);
533         minfo.len = be32_to_cpu(inc->i_hdr.h_len);
534 
535         if (flip) {
536                 minfo.laddr = daddr;
537                 minfo.faddr = saddr;
538                 minfo.lport = inc->i_hdr.h_dport;
539                 minfo.fport = inc->i_hdr.h_sport;
540         } else {
541                 minfo.laddr = saddr;
542                 minfo.faddr = daddr;
543                 minfo.lport = inc->i_hdr.h_sport;
544                 minfo.fport = inc->i_hdr.h_dport;
545         }
546 
547         rds_info_copy(iter, &minfo, sizeof(minfo));
548 }
549 

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