Merge tag 'v4.16-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux...
[linux-2.6-microblaze.git] / net / rds / tcp.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/slab.h>
35 #include <linux/in.h>
36 #include <linux/module.h>
37 #include <net/tcp.h>
38 #include <net/net_namespace.h>
39 #include <net/netns/generic.h>
40
41 #include "rds.h"
42 #include "tcp.h"
43
44 /* only for info exporting */
45 static DEFINE_SPINLOCK(rds_tcp_tc_list_lock);
46 static LIST_HEAD(rds_tcp_tc_list);
47 static unsigned int rds_tcp_tc_count;
48
49 /* Track rds_tcp_connection structs so they can be cleaned up */
50 static DEFINE_SPINLOCK(rds_tcp_conn_lock);
51 static LIST_HEAD(rds_tcp_conn_list);
52 static atomic_t rds_tcp_unloading = ATOMIC_INIT(0);
53
54 static struct kmem_cache *rds_tcp_conn_slab;
55
56 static int rds_tcp_skbuf_handler(struct ctl_table *ctl, int write,
57                                  void __user *buffer, size_t *lenp,
58                                  loff_t *fpos);
59
60 static int rds_tcp_min_sndbuf = SOCK_MIN_SNDBUF;
61 static int rds_tcp_min_rcvbuf = SOCK_MIN_RCVBUF;
62
63 static struct ctl_table rds_tcp_sysctl_table[] = {
64 #define RDS_TCP_SNDBUF  0
65         {
66                 .procname       = "rds_tcp_sndbuf",
67                 /* data is per-net pointer */
68                 .maxlen         = sizeof(int),
69                 .mode           = 0644,
70                 .proc_handler   = rds_tcp_skbuf_handler,
71                 .extra1         = &rds_tcp_min_sndbuf,
72         },
73 #define RDS_TCP_RCVBUF  1
74         {
75                 .procname       = "rds_tcp_rcvbuf",
76                 /* data is per-net pointer */
77                 .maxlen         = sizeof(int),
78                 .mode           = 0644,
79                 .proc_handler   = rds_tcp_skbuf_handler,
80                 .extra1         = &rds_tcp_min_rcvbuf,
81         },
82         { }
83 };
84
85 /* doing it this way avoids calling tcp_sk() */
86 void rds_tcp_nonagle(struct socket *sock)
87 {
88         int val = 1;
89
90         kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY, (void *)&val,
91                               sizeof(val));
92 }
93
94 u32 rds_tcp_write_seq(struct rds_tcp_connection *tc)
95 {
96         /* seq# of the last byte of data in tcp send buffer */
97         return tcp_sk(tc->t_sock->sk)->write_seq;
98 }
99
100 u32 rds_tcp_snd_una(struct rds_tcp_connection *tc)
101 {
102         return tcp_sk(tc->t_sock->sk)->snd_una;
103 }
104
105 void rds_tcp_restore_callbacks(struct socket *sock,
106                                struct rds_tcp_connection *tc)
107 {
108         rdsdebug("restoring sock %p callbacks from tc %p\n", sock, tc);
109         write_lock_bh(&sock->sk->sk_callback_lock);
110
111         /* done under the callback_lock to serialize with write_space */
112         spin_lock(&rds_tcp_tc_list_lock);
113         list_del_init(&tc->t_list_item);
114         rds_tcp_tc_count--;
115         spin_unlock(&rds_tcp_tc_list_lock);
116
117         tc->t_sock = NULL;
118
119         sock->sk->sk_write_space = tc->t_orig_write_space;
120         sock->sk->sk_data_ready = tc->t_orig_data_ready;
121         sock->sk->sk_state_change = tc->t_orig_state_change;
122         sock->sk->sk_user_data = NULL;
123
124         write_unlock_bh(&sock->sk->sk_callback_lock);
125 }
126
127 /*
128  * rds_tcp_reset_callbacks() switches the to the new sock and
129  * returns the existing tc->t_sock.
130  *
131  * The only functions that set tc->t_sock are rds_tcp_set_callbacks
132  * and rds_tcp_reset_callbacks.  Send and receive trust that
133  * it is set.  The absence of RDS_CONN_UP bit protects those paths
134  * from being called while it isn't set.
135  */
136 void rds_tcp_reset_callbacks(struct socket *sock,
137                              struct rds_conn_path *cp)
138 {
139         struct rds_tcp_connection *tc = cp->cp_transport_data;
140         struct socket *osock = tc->t_sock;
141
142         if (!osock)
143                 goto newsock;
144
145         /* Need to resolve a duelling SYN between peers.
146          * We have an outstanding SYN to this peer, which may
147          * potentially have transitioned to the RDS_CONN_UP state,
148          * so we must quiesce any send threads before resetting
149          * cp_transport_data. We quiesce these threads by setting
150          * cp_state to something other than RDS_CONN_UP, and then
151          * waiting for any existing threads in rds_send_xmit to
152          * complete release_in_xmit(). (Subsequent threads entering
153          * rds_send_xmit() will bail on !rds_conn_up().
154          *
155          * However an incoming syn-ack at this point would end up
156          * marking the conn as RDS_CONN_UP, and would again permit
157          * rds_send_xmi() threads through, so ideally we would
158          * synchronize on RDS_CONN_UP after lock_sock(), but cannot
159          * do that: waiting on !RDS_IN_XMIT after lock_sock() may
160          * end up deadlocking with tcp_sendmsg(), and the RDS_IN_XMIT
161          * would not get set. As a result, we set c_state to
162          * RDS_CONN_RESETTTING, to ensure that rds_tcp_state_change
163          * cannot mark rds_conn_path_up() in the window before lock_sock()
164          */
165         atomic_set(&cp->cp_state, RDS_CONN_RESETTING);
166         wait_event(cp->cp_waitq, !test_bit(RDS_IN_XMIT, &cp->cp_flags));
167         lock_sock(osock->sk);
168         /* reset receive side state for rds_tcp_data_recv() for osock  */
169         cancel_delayed_work_sync(&cp->cp_send_w);
170         cancel_delayed_work_sync(&cp->cp_recv_w);
171         if (tc->t_tinc) {
172                 rds_inc_put(&tc->t_tinc->ti_inc);
173                 tc->t_tinc = NULL;
174         }
175         tc->t_tinc_hdr_rem = sizeof(struct rds_header);
176         tc->t_tinc_data_rem = 0;
177         rds_tcp_restore_callbacks(osock, tc);
178         release_sock(osock->sk);
179         sock_release(osock);
180 newsock:
181         rds_send_path_reset(cp);
182         lock_sock(sock->sk);
183         rds_tcp_set_callbacks(sock, cp);
184         release_sock(sock->sk);
185 }
186
187 /* Add tc to rds_tcp_tc_list and set tc->t_sock. See comments
188  * above rds_tcp_reset_callbacks for notes about synchronization
189  * with data path
190  */
191 void rds_tcp_set_callbacks(struct socket *sock, struct rds_conn_path *cp)
192 {
193         struct rds_tcp_connection *tc = cp->cp_transport_data;
194
195         rdsdebug("setting sock %p callbacks to tc %p\n", sock, tc);
196         write_lock_bh(&sock->sk->sk_callback_lock);
197
198         /* done under the callback_lock to serialize with write_space */
199         spin_lock(&rds_tcp_tc_list_lock);
200         list_add_tail(&tc->t_list_item, &rds_tcp_tc_list);
201         rds_tcp_tc_count++;
202         spin_unlock(&rds_tcp_tc_list_lock);
203
204         /* accepted sockets need our listen data ready undone */
205         if (sock->sk->sk_data_ready == rds_tcp_listen_data_ready)
206                 sock->sk->sk_data_ready = sock->sk->sk_user_data;
207
208         tc->t_sock = sock;
209         tc->t_cpath = cp;
210         tc->t_orig_data_ready = sock->sk->sk_data_ready;
211         tc->t_orig_write_space = sock->sk->sk_write_space;
212         tc->t_orig_state_change = sock->sk->sk_state_change;
213
214         sock->sk->sk_user_data = cp;
215         sock->sk->sk_data_ready = rds_tcp_data_ready;
216         sock->sk->sk_write_space = rds_tcp_write_space;
217         sock->sk->sk_state_change = rds_tcp_state_change;
218
219         write_unlock_bh(&sock->sk->sk_callback_lock);
220 }
221
222 static void rds_tcp_tc_info(struct socket *rds_sock, unsigned int len,
223                             struct rds_info_iterator *iter,
224                             struct rds_info_lengths *lens)
225 {
226         struct rds_info_tcp_socket tsinfo;
227         struct rds_tcp_connection *tc;
228         unsigned long flags;
229         struct sockaddr_in sin;
230         int sinlen;
231         struct socket *sock;
232
233         spin_lock_irqsave(&rds_tcp_tc_list_lock, flags);
234
235         if (len / sizeof(tsinfo) < rds_tcp_tc_count)
236                 goto out;
237
238         list_for_each_entry(tc, &rds_tcp_tc_list, t_list_item) {
239
240                 sock = tc->t_sock;
241                 if (sock) {
242                         sock->ops->getname(sock, (struct sockaddr *)&sin,
243                                            &sinlen, 0);
244                         tsinfo.local_addr = sin.sin_addr.s_addr;
245                         tsinfo.local_port = sin.sin_port;
246                         sock->ops->getname(sock, (struct sockaddr *)&sin,
247                                            &sinlen, 1);
248                         tsinfo.peer_addr = sin.sin_addr.s_addr;
249                         tsinfo.peer_port = sin.sin_port;
250                 }
251
252                 tsinfo.hdr_rem = tc->t_tinc_hdr_rem;
253                 tsinfo.data_rem = tc->t_tinc_data_rem;
254                 tsinfo.last_sent_nxt = tc->t_last_sent_nxt;
255                 tsinfo.last_expected_una = tc->t_last_expected_una;
256                 tsinfo.last_seen_una = tc->t_last_seen_una;
257
258                 rds_info_copy(iter, &tsinfo, sizeof(tsinfo));
259         }
260
261 out:
262         lens->nr = rds_tcp_tc_count;
263         lens->each = sizeof(tsinfo);
264
265         spin_unlock_irqrestore(&rds_tcp_tc_list_lock, flags);
266 }
267
268 static int rds_tcp_laddr_check(struct net *net, __be32 addr)
269 {
270         if (inet_addr_type(net, addr) == RTN_LOCAL)
271                 return 0;
272         return -EADDRNOTAVAIL;
273 }
274
275 static void rds_tcp_conn_free(void *arg)
276 {
277         struct rds_tcp_connection *tc = arg;
278
279         rdsdebug("freeing tc %p\n", tc);
280
281         spin_lock_bh(&rds_tcp_conn_lock);
282         if (!tc->t_tcp_node_detached)
283                 list_del(&tc->t_tcp_node);
284         spin_unlock_bh(&rds_tcp_conn_lock);
285
286         kmem_cache_free(rds_tcp_conn_slab, tc);
287 }
288
289 static int rds_tcp_conn_alloc(struct rds_connection *conn, gfp_t gfp)
290 {
291         struct rds_tcp_connection *tc;
292         int i, j;
293         int ret = 0;
294
295         for (i = 0; i < RDS_MPATH_WORKERS; i++) {
296                 tc = kmem_cache_alloc(rds_tcp_conn_slab, gfp);
297                 if (!tc) {
298                         ret = -ENOMEM;
299                         goto fail;
300                 }
301                 mutex_init(&tc->t_conn_path_lock);
302                 tc->t_sock = NULL;
303                 tc->t_tinc = NULL;
304                 tc->t_tinc_hdr_rem = sizeof(struct rds_header);
305                 tc->t_tinc_data_rem = 0;
306
307                 conn->c_path[i].cp_transport_data = tc;
308                 tc->t_cpath = &conn->c_path[i];
309                 tc->t_tcp_node_detached = true;
310
311                 rdsdebug("rds_conn_path [%d] tc %p\n", i,
312                          conn->c_path[i].cp_transport_data);
313         }
314         spin_lock_bh(&rds_tcp_conn_lock);
315         for (i = 0; i < RDS_MPATH_WORKERS; i++) {
316                 tc = conn->c_path[i].cp_transport_data;
317                 tc->t_tcp_node_detached = false;
318                 list_add_tail(&tc->t_tcp_node, &rds_tcp_conn_list);
319         }
320         spin_unlock_bh(&rds_tcp_conn_lock);
321 fail:
322         if (ret) {
323                 for (j = 0; j < i; j++)
324                         rds_tcp_conn_free(conn->c_path[j].cp_transport_data);
325         }
326         return ret;
327 }
328
329 static bool list_has_conn(struct list_head *list, struct rds_connection *conn)
330 {
331         struct rds_tcp_connection *tc, *_tc;
332
333         list_for_each_entry_safe(tc, _tc, list, t_tcp_node) {
334                 if (tc->t_cpath->cp_conn == conn)
335                         return true;
336         }
337         return false;
338 }
339
340 static void rds_tcp_set_unloading(void)
341 {
342         atomic_set(&rds_tcp_unloading, 1);
343 }
344
345 static bool rds_tcp_is_unloading(struct rds_connection *conn)
346 {
347         return atomic_read(&rds_tcp_unloading) != 0;
348 }
349
350 static void rds_tcp_destroy_conns(void)
351 {
352         struct rds_tcp_connection *tc, *_tc;
353         LIST_HEAD(tmp_list);
354
355         /* avoid calling conn_destroy with irqs off */
356         spin_lock_irq(&rds_tcp_conn_lock);
357         list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
358                 if (!list_has_conn(&tmp_list, tc->t_cpath->cp_conn))
359                         list_move_tail(&tc->t_tcp_node, &tmp_list);
360         }
361         spin_unlock_irq(&rds_tcp_conn_lock);
362
363         list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node)
364                 rds_conn_destroy(tc->t_cpath->cp_conn);
365 }
366
367 static void rds_tcp_exit(void);
368
369 struct rds_transport rds_tcp_transport = {
370         .laddr_check            = rds_tcp_laddr_check,
371         .xmit_path_prepare      = rds_tcp_xmit_path_prepare,
372         .xmit_path_complete     = rds_tcp_xmit_path_complete,
373         .xmit                   = rds_tcp_xmit,
374         .recv_path              = rds_tcp_recv_path,
375         .conn_alloc             = rds_tcp_conn_alloc,
376         .conn_free              = rds_tcp_conn_free,
377         .conn_path_connect      = rds_tcp_conn_path_connect,
378         .conn_path_shutdown     = rds_tcp_conn_path_shutdown,
379         .inc_copy_to_user       = rds_tcp_inc_copy_to_user,
380         .inc_free               = rds_tcp_inc_free,
381         .stats_info_copy        = rds_tcp_stats_info_copy,
382         .exit                   = rds_tcp_exit,
383         .t_owner                = THIS_MODULE,
384         .t_name                 = "tcp",
385         .t_type                 = RDS_TRANS_TCP,
386         .t_prefer_loopback      = 1,
387         .t_mp_capable           = 1,
388         .t_unloading            = rds_tcp_is_unloading,
389 };
390
391 static unsigned int rds_tcp_netid;
392
393 /* per-network namespace private data for this module */
394 struct rds_tcp_net {
395         struct socket *rds_tcp_listen_sock;
396         struct work_struct rds_tcp_accept_w;
397         struct ctl_table_header *rds_tcp_sysctl;
398         struct ctl_table *ctl_table;
399         int sndbuf_size;
400         int rcvbuf_size;
401 };
402
403 /* All module specific customizations to the RDS-TCP socket should be done in
404  * rds_tcp_tune() and applied after socket creation.
405  */
406 void rds_tcp_tune(struct socket *sock)
407 {
408         struct sock *sk = sock->sk;
409         struct net *net = sock_net(sk);
410         struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
411
412         rds_tcp_nonagle(sock);
413         lock_sock(sk);
414         if (rtn->sndbuf_size > 0) {
415                 sk->sk_sndbuf = rtn->sndbuf_size;
416                 sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
417         }
418         if (rtn->rcvbuf_size > 0) {
419                 sk->sk_sndbuf = rtn->rcvbuf_size;
420                 sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
421         }
422         release_sock(sk);
423 }
424
425 static void rds_tcp_accept_worker(struct work_struct *work)
426 {
427         struct rds_tcp_net *rtn = container_of(work,
428                                                struct rds_tcp_net,
429                                                rds_tcp_accept_w);
430
431         while (rds_tcp_accept_one(rtn->rds_tcp_listen_sock) == 0)
432                 cond_resched();
433 }
434
435 void rds_tcp_accept_work(struct sock *sk)
436 {
437         struct net *net = sock_net(sk);
438         struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
439
440         queue_work(rds_wq, &rtn->rds_tcp_accept_w);
441 }
442
443 static __net_init int rds_tcp_init_net(struct net *net)
444 {
445         struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
446         struct ctl_table *tbl;
447         int err = 0;
448
449         memset(rtn, 0, sizeof(*rtn));
450
451         /* {snd, rcv}buf_size default to 0, which implies we let the
452          * stack pick the value, and permit auto-tuning of buffer size.
453          */
454         if (net == &init_net) {
455                 tbl = rds_tcp_sysctl_table;
456         } else {
457                 tbl = kmemdup(rds_tcp_sysctl_table,
458                               sizeof(rds_tcp_sysctl_table), GFP_KERNEL);
459                 if (!tbl) {
460                         pr_warn("could not set allocate syctl table\n");
461                         return -ENOMEM;
462                 }
463                 rtn->ctl_table = tbl;
464         }
465         tbl[RDS_TCP_SNDBUF].data = &rtn->sndbuf_size;
466         tbl[RDS_TCP_RCVBUF].data = &rtn->rcvbuf_size;
467         rtn->rds_tcp_sysctl = register_net_sysctl(net, "net/rds/tcp", tbl);
468         if (!rtn->rds_tcp_sysctl) {
469                 pr_warn("could not register sysctl\n");
470                 err = -ENOMEM;
471                 goto fail;
472         }
473         rtn->rds_tcp_listen_sock = rds_tcp_listen_init(net);
474         if (!rtn->rds_tcp_listen_sock) {
475                 pr_warn("could not set up listen sock\n");
476                 unregister_net_sysctl_table(rtn->rds_tcp_sysctl);
477                 rtn->rds_tcp_sysctl = NULL;
478                 err = -EAFNOSUPPORT;
479                 goto fail;
480         }
481         INIT_WORK(&rtn->rds_tcp_accept_w, rds_tcp_accept_worker);
482         return 0;
483
484 fail:
485         if (net != &init_net)
486                 kfree(tbl);
487         return err;
488 }
489
490 static void __net_exit rds_tcp_exit_net(struct net *net)
491 {
492         struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
493
494         if (rtn->rds_tcp_sysctl)
495                 unregister_net_sysctl_table(rtn->rds_tcp_sysctl);
496
497         if (net != &init_net && rtn->ctl_table)
498                 kfree(rtn->ctl_table);
499
500         /* If rds_tcp_exit_net() is called as a result of netns deletion,
501          * the rds_tcp_kill_sock() device notifier would already have cleaned
502          * up the listen socket, thus there is no work to do in this function.
503          *
504          * If rds_tcp_exit_net() is called as a result of module unload,
505          * i.e., due to rds_tcp_exit() -> unregister_pernet_subsys(), then
506          * we do need to clean up the listen socket here.
507          */
508         if (rtn->rds_tcp_listen_sock) {
509                 struct socket *lsock = rtn->rds_tcp_listen_sock;
510
511                 rtn->rds_tcp_listen_sock = NULL;
512                 rds_tcp_listen_stop(lsock, &rtn->rds_tcp_accept_w);
513         }
514 }
515
516 static struct pernet_operations rds_tcp_net_ops = {
517         .init = rds_tcp_init_net,
518         .exit = rds_tcp_exit_net,
519         .id = &rds_tcp_netid,
520         .size = sizeof(struct rds_tcp_net),
521 };
522
523 static void rds_tcp_kill_sock(struct net *net)
524 {
525         struct rds_tcp_connection *tc, *_tc;
526         LIST_HEAD(tmp_list);
527         struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
528         struct socket *lsock = rtn->rds_tcp_listen_sock;
529
530         rtn->rds_tcp_listen_sock = NULL;
531         rds_tcp_listen_stop(lsock, &rtn->rds_tcp_accept_w);
532         spin_lock_bh(&rds_tcp_conn_lock);
533         list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
534                 struct net *c_net = read_pnet(&tc->t_cpath->cp_conn->c_net);
535
536                 if (net != c_net || !tc->t_sock)
537                         continue;
538                 if (!list_has_conn(&tmp_list, tc->t_cpath->cp_conn)) {
539                         list_move_tail(&tc->t_tcp_node, &tmp_list);
540                 } else {
541                         list_del(&tc->t_tcp_node);
542                         tc->t_tcp_node_detached = true;
543                 }
544         }
545         spin_unlock_bh(&rds_tcp_conn_lock);
546         list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node)
547                 rds_conn_destroy(tc->t_cpath->cp_conn);
548 }
549
550 void *rds_tcp_listen_sock_def_readable(struct net *net)
551 {
552         struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
553         struct socket *lsock = rtn->rds_tcp_listen_sock;
554
555         if (!lsock)
556                 return NULL;
557
558         return lsock->sk->sk_user_data;
559 }
560
561 static int rds_tcp_dev_event(struct notifier_block *this,
562                              unsigned long event, void *ptr)
563 {
564         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
565
566         /* rds-tcp registers as a pernet subys, so the ->exit will only
567          * get invoked after network acitivity has quiesced. We need to
568          * clean up all sockets  to quiesce network activity, and use
569          * the unregistration of the per-net loopback device as a trigger
570          * to start that cleanup.
571          */
572         if (event == NETDEV_UNREGISTER_FINAL &&
573             dev->ifindex == LOOPBACK_IFINDEX)
574                 rds_tcp_kill_sock(dev_net(dev));
575
576         return NOTIFY_DONE;
577 }
578
579 static struct notifier_block rds_tcp_dev_notifier = {
580         .notifier_call        = rds_tcp_dev_event,
581         .priority = -10, /* must be called after other network notifiers */
582 };
583
584 /* when sysctl is used to modify some kernel socket parameters,this
585  * function  resets the RDS connections in that netns  so that we can
586  * restart with new parameters.  The assumption is that such reset
587  * events are few and far-between.
588  */
589 static void rds_tcp_sysctl_reset(struct net *net)
590 {
591         struct rds_tcp_connection *tc, *_tc;
592
593         spin_lock_bh(&rds_tcp_conn_lock);
594         list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
595                 struct net *c_net = read_pnet(&tc->t_cpath->cp_conn->c_net);
596
597                 if (net != c_net || !tc->t_sock)
598                         continue;
599
600                 /* reconnect with new parameters */
601                 rds_conn_path_drop(tc->t_cpath, false);
602         }
603         spin_unlock_bh(&rds_tcp_conn_lock);
604 }
605
606 static int rds_tcp_skbuf_handler(struct ctl_table *ctl, int write,
607                                  void __user *buffer, size_t *lenp,
608                                  loff_t *fpos)
609 {
610         struct net *net = current->nsproxy->net_ns;
611         int err;
612
613         err = proc_dointvec_minmax(ctl, write, buffer, lenp, fpos);
614         if (err < 0) {
615                 pr_warn("Invalid input. Must be >= %d\n",
616                         *(int *)(ctl->extra1));
617                 return err;
618         }
619         if (write)
620                 rds_tcp_sysctl_reset(net);
621         return 0;
622 }
623
624 static void rds_tcp_exit(void)
625 {
626         rds_tcp_set_unloading();
627         synchronize_rcu();
628         rds_info_deregister_func(RDS_INFO_TCP_SOCKETS, rds_tcp_tc_info);
629         unregister_pernet_subsys(&rds_tcp_net_ops);
630         if (unregister_netdevice_notifier(&rds_tcp_dev_notifier))
631                 pr_warn("could not unregister rds_tcp_dev_notifier\n");
632         rds_tcp_destroy_conns();
633         rds_trans_unregister(&rds_tcp_transport);
634         rds_tcp_recv_exit();
635         kmem_cache_destroy(rds_tcp_conn_slab);
636 }
637 module_exit(rds_tcp_exit);
638
639 static int rds_tcp_init(void)
640 {
641         int ret;
642
643         rds_tcp_conn_slab = kmem_cache_create("rds_tcp_connection",
644                                               sizeof(struct rds_tcp_connection),
645                                               0, 0, NULL);
646         if (!rds_tcp_conn_slab) {
647                 ret = -ENOMEM;
648                 goto out;
649         }
650
651         ret = rds_tcp_recv_init();
652         if (ret)
653                 goto out_slab;
654
655         ret = register_pernet_subsys(&rds_tcp_net_ops);
656         if (ret)
657                 goto out_recv;
658
659         ret = register_netdevice_notifier(&rds_tcp_dev_notifier);
660         if (ret) {
661                 pr_warn("could not register rds_tcp_dev_notifier\n");
662                 goto out_pernet;
663         }
664
665         rds_trans_register(&rds_tcp_transport);
666
667         rds_info_register_func(RDS_INFO_TCP_SOCKETS, rds_tcp_tc_info);
668
669         goto out;
670
671 out_pernet:
672         unregister_pernet_subsys(&rds_tcp_net_ops);
673 out_recv:
674         rds_tcp_recv_exit();
675 out_slab:
676         kmem_cache_destroy(rds_tcp_conn_slab);
677 out:
678         return ret;
679 }
680 module_init(rds_tcp_init);
681
682 MODULE_AUTHOR("Oracle Corporation <rds-devel@oss.oracle.com>");
683 MODULE_DESCRIPTION("RDS: TCP transport");
684 MODULE_LICENSE("Dual BSD/GPL");
685