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922cb17a | 1 | /* |
eee2fa6a | 2 | * Copyright (c) 2007, 2017 Oracle and/or its affiliates. All rights reserved. |
922cb17a AG |
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 | */ | |
5a0e3ad6 | 33 | #include <linux/slab.h> |
922cb17a AG |
34 | #include <linux/types.h> |
35 | #include <linux/rbtree.h> | |
12ce2242 | 36 | #include <linux/bitops.h> |
bc3b2d7f | 37 | #include <linux/export.h> |
c3b32404 | 38 | |
922cb17a AG |
39 | #include "rds.h" |
40 | ||
41 | /* | |
42 | * This file implements the receive side of the unconventional congestion | |
43 | * management in RDS. | |
44 | * | |
45 | * Messages waiting in the receive queue on the receiving socket are accounted | |
46 | * against the sockets SO_RCVBUF option value. Only the payload bytes in the | |
47 | * message are accounted for. If the number of bytes queued equals or exceeds | |
48 | * rcvbuf then the socket is congested. All sends attempted to this socket's | |
49 | * address should return block or return -EWOULDBLOCK. | |
50 | * | |
51 | * Applications are expected to be reasonably tuned such that this situation | |
52 | * very rarely occurs. An application encountering this "back-pressure" is | |
53 | * considered a bug. | |
54 | * | |
55 | * This is implemented by having each node maintain bitmaps which indicate | |
56 | * which ports on bound addresses are congested. As the bitmap changes it is | |
57 | * sent through all the connections which terminate in the local address of the | |
58 | * bitmap which changed. | |
59 | * | |
60 | * The bitmaps are allocated as connections are brought up. This avoids | |
61 | * allocation in the interrupt handling path which queues messages on sockets. | |
62 | * The dense bitmaps let transports send the entire bitmap on any bitmap change | |
63 | * reasonably efficiently. This is much easier to implement than some | |
64 | * finer-grained communication of per-port congestion. The sender does a very | |
65 | * inexpensive bit test to test if the port it's about to send to is congested | |
66 | * or not. | |
67 | */ | |
68 | ||
69 | /* | |
70 | * Interaction with poll is a tad tricky. We want all processes stuck in | |
71 | * poll to wake up and check whether a congested destination became uncongested. | |
72 | * The really sad thing is we have no idea which destinations the application | |
73 | * wants to send to - we don't even know which rds_connections are involved. | |
74 | * So until we implement a more flexible rds poll interface, we have to make | |
75 | * do with this: | |
76 | * We maintain a global counter that is incremented each time a congestion map | |
77 | * update is received. Each rds socket tracks this value, and if rds_poll | |
78 | * finds that the saved generation number is smaller than the global generation | |
79 | * number, it wakes up the process. | |
80 | */ | |
81 | static atomic_t rds_cong_generation = ATOMIC_INIT(0); | |
82 | ||
83 | /* | |
84 | * Congestion monitoring | |
85 | */ | |
86 | static LIST_HEAD(rds_cong_monitor); | |
87 | static DEFINE_RWLOCK(rds_cong_monitor_lock); | |
88 | ||
89 | /* | |
90 | * Yes, a global lock. It's used so infrequently that it's worth keeping it | |
91 | * global to simplify the locking. It's only used in the following | |
92 | * circumstances: | |
93 | * | |
94 | * - on connection buildup to associate a conn with its maps | |
95 | * - on map changes to inform conns of a new map to send | |
96 | * | |
97 | * It's sadly ordered under the socket callback lock and the connection lock. | |
98 | * Receive paths can mark ports congested from interrupt context so the | |
99 | * lock masks interrupts. | |
100 | */ | |
101 | static DEFINE_SPINLOCK(rds_cong_lock); | |
102 | static struct rb_root rds_cong_tree = RB_ROOT; | |
103 | ||
eee2fa6a | 104 | static struct rds_cong_map *rds_cong_tree_walk(const struct in6_addr *addr, |
922cb17a AG |
105 | struct rds_cong_map *insert) |
106 | { | |
107 | struct rb_node **p = &rds_cong_tree.rb_node; | |
108 | struct rb_node *parent = NULL; | |
109 | struct rds_cong_map *map; | |
110 | ||
111 | while (*p) { | |
eee2fa6a KCP |
112 | int diff; |
113 | ||
922cb17a AG |
114 | parent = *p; |
115 | map = rb_entry(parent, struct rds_cong_map, m_rb_node); | |
116 | ||
eee2fa6a KCP |
117 | diff = rds_addr_cmp(addr, &map->m_addr); |
118 | if (diff < 0) | |
922cb17a | 119 | p = &(*p)->rb_left; |
eee2fa6a | 120 | else if (diff > 0) |
922cb17a AG |
121 | p = &(*p)->rb_right; |
122 | else | |
123 | return map; | |
124 | } | |
125 | ||
126 | if (insert) { | |
127 | rb_link_node(&insert->m_rb_node, parent, p); | |
128 | rb_insert_color(&insert->m_rb_node, &rds_cong_tree); | |
129 | } | |
130 | return NULL; | |
131 | } | |
132 | ||
133 | /* | |
134 | * There is only ever one bitmap for any address. Connections try and allocate | |
135 | * these bitmaps in the process getting pointers to them. The bitmaps are only | |
136 | * ever freed as the module is removed after all connections have been freed. | |
137 | */ | |
eee2fa6a | 138 | static struct rds_cong_map *rds_cong_from_addr(const struct in6_addr *addr) |
922cb17a AG |
139 | { |
140 | struct rds_cong_map *map; | |
141 | struct rds_cong_map *ret = NULL; | |
142 | unsigned long zp; | |
143 | unsigned long i; | |
144 | unsigned long flags; | |
145 | ||
146 | map = kzalloc(sizeof(struct rds_cong_map), GFP_KERNEL); | |
8690bfa1 | 147 | if (!map) |
922cb17a AG |
148 | return NULL; |
149 | ||
eee2fa6a | 150 | map->m_addr = *addr; |
922cb17a AG |
151 | init_waitqueue_head(&map->m_waitq); |
152 | INIT_LIST_HEAD(&map->m_conn_list); | |
153 | ||
154 | for (i = 0; i < RDS_CONG_MAP_PAGES; i++) { | |
155 | zp = get_zeroed_page(GFP_KERNEL); | |
156 | if (zp == 0) | |
157 | goto out; | |
158 | map->m_page_addrs[i] = zp; | |
159 | } | |
160 | ||
161 | spin_lock_irqsave(&rds_cong_lock, flags); | |
162 | ret = rds_cong_tree_walk(addr, map); | |
163 | spin_unlock_irqrestore(&rds_cong_lock, flags); | |
164 | ||
8690bfa1 | 165 | if (!ret) { |
922cb17a AG |
166 | ret = map; |
167 | map = NULL; | |
168 | } | |
169 | ||
170 | out: | |
171 | if (map) { | |
172 | for (i = 0; i < RDS_CONG_MAP_PAGES && map->m_page_addrs[i]; i++) | |
173 | free_page(map->m_page_addrs[i]); | |
174 | kfree(map); | |
175 | } | |
176 | ||
eee2fa6a | 177 | rdsdebug("map %p for addr %pI6c\n", ret, addr); |
922cb17a AG |
178 | |
179 | return ret; | |
180 | } | |
181 | ||
182 | /* | |
183 | * Put the conn on its local map's list. This is called when the conn is | |
184 | * really added to the hash. It's nested under the rds_conn_lock, sadly. | |
185 | */ | |
186 | void rds_cong_add_conn(struct rds_connection *conn) | |
187 | { | |
188 | unsigned long flags; | |
189 | ||
190 | rdsdebug("conn %p now on map %p\n", conn, conn->c_lcong); | |
191 | spin_lock_irqsave(&rds_cong_lock, flags); | |
192 | list_add_tail(&conn->c_map_item, &conn->c_lcong->m_conn_list); | |
193 | spin_unlock_irqrestore(&rds_cong_lock, flags); | |
194 | } | |
195 | ||
196 | void rds_cong_remove_conn(struct rds_connection *conn) | |
197 | { | |
198 | unsigned long flags; | |
199 | ||
200 | rdsdebug("removing conn %p from map %p\n", conn, conn->c_lcong); | |
201 | spin_lock_irqsave(&rds_cong_lock, flags); | |
202 | list_del_init(&conn->c_map_item); | |
203 | spin_unlock_irqrestore(&rds_cong_lock, flags); | |
204 | } | |
205 | ||
206 | int rds_cong_get_maps(struct rds_connection *conn) | |
207 | { | |
eee2fa6a KCP |
208 | conn->c_lcong = rds_cong_from_addr(&conn->c_laddr); |
209 | conn->c_fcong = rds_cong_from_addr(&conn->c_faddr); | |
922cb17a | 210 | |
8690bfa1 | 211 | if (!(conn->c_lcong && conn->c_fcong)) |
922cb17a AG |
212 | return -ENOMEM; |
213 | ||
214 | return 0; | |
215 | } | |
216 | ||
217 | void rds_cong_queue_updates(struct rds_cong_map *map) | |
218 | { | |
219 | struct rds_connection *conn; | |
220 | unsigned long flags; | |
221 | ||
222 | spin_lock_irqsave(&rds_cong_lock, flags); | |
223 | ||
224 | list_for_each_entry(conn, &map->m_conn_list, c_map_item) { | |
3db6e0d1 SV |
225 | struct rds_conn_path *cp = &conn->c_path[0]; |
226 | ||
227 | rcu_read_lock(); | |
228 | if (!test_and_set_bit(0, &conn->c_map_queued) && | |
ebeeb1ad | 229 | !rds_destroy_pending(cp->cp_conn)) { |
922cb17a | 230 | rds_stats_inc(s_cong_update_queued); |
80ad0d4a SV |
231 | /* We cannot inline the call to rds_send_xmit() here |
232 | * for two reasons (both pertaining to a TCP transport): | |
233 | * 1. When we get here from the receive path, we | |
234 | * are already holding the sock_lock (held by | |
235 | * tcp_v4_rcv()). So inlining calls to | |
236 | * tcp_setsockopt and/or tcp_sendmsg will deadlock | |
237 | * when it tries to get the sock_lock()) | |
238 | * 2. Interrupts are masked so that we can mark the | |
d936b1d5 | 239 | * port congested from both send and recv paths. |
80ad0d4a SV |
240 | * (See comment around declaration of rdc_cong_lock). |
241 | * An attempt to get the sock_lock() here will | |
242 | * therefore trigger warnings. | |
243 | * Defer the xmit to rds_send_worker() instead. | |
244 | */ | |
3db6e0d1 | 245 | queue_delayed_work(rds_wq, &cp->cp_send_w, 0); |
922cb17a | 246 | } |
3db6e0d1 | 247 | rcu_read_unlock(); |
922cb17a AG |
248 | } |
249 | ||
250 | spin_unlock_irqrestore(&rds_cong_lock, flags); | |
251 | } | |
252 | ||
253 | void rds_cong_map_updated(struct rds_cong_map *map, uint64_t portmask) | |
254 | { | |
255 | rdsdebug("waking map %p for %pI4\n", | |
256 | map, &map->m_addr); | |
257 | rds_stats_inc(s_cong_update_received); | |
258 | atomic_inc(&rds_cong_generation); | |
259 | if (waitqueue_active(&map->m_waitq)) | |
260 | wake_up(&map->m_waitq); | |
261 | if (waitqueue_active(&rds_poll_waitq)) | |
262 | wake_up_all(&rds_poll_waitq); | |
263 | ||
264 | if (portmask && !list_empty(&rds_cong_monitor)) { | |
265 | unsigned long flags; | |
266 | struct rds_sock *rs; | |
267 | ||
268 | read_lock_irqsave(&rds_cong_monitor_lock, flags); | |
269 | list_for_each_entry(rs, &rds_cong_monitor, rs_cong_list) { | |
270 | spin_lock(&rs->rs_lock); | |
271 | rs->rs_cong_notify |= (rs->rs_cong_mask & portmask); | |
272 | rs->rs_cong_mask &= ~portmask; | |
273 | spin_unlock(&rs->rs_lock); | |
274 | if (rs->rs_cong_notify) | |
275 | rds_wake_sk_sleep(rs); | |
276 | } | |
277 | read_unlock_irqrestore(&rds_cong_monitor_lock, flags); | |
278 | } | |
279 | } | |
616b757a | 280 | EXPORT_SYMBOL_GPL(rds_cong_map_updated); |
922cb17a AG |
281 | |
282 | int rds_cong_updated_since(unsigned long *recent) | |
283 | { | |
284 | unsigned long gen = atomic_read(&rds_cong_generation); | |
285 | ||
286 | if (likely(*recent == gen)) | |
287 | return 0; | |
288 | *recent = gen; | |
289 | return 1; | |
290 | } | |
291 | ||
292 | /* | |
293 | * We're called under the locking that protects the sockets receive buffer | |
294 | * consumption. This makes it a lot easier for the caller to only call us | |
295 | * when it knows that an existing set bit needs to be cleared, and vice versa. | |
296 | * We can't block and we need to deal with concurrent sockets working against | |
297 | * the same per-address map. | |
298 | */ | |
299 | void rds_cong_set_bit(struct rds_cong_map *map, __be16 port) | |
300 | { | |
301 | unsigned long i; | |
302 | unsigned long off; | |
303 | ||
304 | rdsdebug("setting congestion for %pI4:%u in map %p\n", | |
305 | &map->m_addr, ntohs(port), map); | |
306 | ||
307 | i = be16_to_cpu(port) / RDS_CONG_MAP_PAGE_BITS; | |
308 | off = be16_to_cpu(port) % RDS_CONG_MAP_PAGE_BITS; | |
309 | ||
e47db94e | 310 | set_bit_le(off, (void *)map->m_page_addrs[i]); |
922cb17a AG |
311 | } |
312 | ||
313 | void rds_cong_clear_bit(struct rds_cong_map *map, __be16 port) | |
314 | { | |
315 | unsigned long i; | |
316 | unsigned long off; | |
317 | ||
318 | rdsdebug("clearing congestion for %pI4:%u in map %p\n", | |
319 | &map->m_addr, ntohs(port), map); | |
320 | ||
321 | i = be16_to_cpu(port) / RDS_CONG_MAP_PAGE_BITS; | |
322 | off = be16_to_cpu(port) % RDS_CONG_MAP_PAGE_BITS; | |
323 | ||
e47db94e | 324 | clear_bit_le(off, (void *)map->m_page_addrs[i]); |
922cb17a AG |
325 | } |
326 | ||
327 | static int rds_cong_test_bit(struct rds_cong_map *map, __be16 port) | |
328 | { | |
329 | unsigned long i; | |
330 | unsigned long off; | |
331 | ||
332 | i = be16_to_cpu(port) / RDS_CONG_MAP_PAGE_BITS; | |
333 | off = be16_to_cpu(port) % RDS_CONG_MAP_PAGE_BITS; | |
334 | ||
e1dc1c81 | 335 | return test_bit_le(off, (void *)map->m_page_addrs[i]); |
922cb17a AG |
336 | } |
337 | ||
338 | void rds_cong_add_socket(struct rds_sock *rs) | |
339 | { | |
340 | unsigned long flags; | |
341 | ||
342 | write_lock_irqsave(&rds_cong_monitor_lock, flags); | |
343 | if (list_empty(&rs->rs_cong_list)) | |
344 | list_add(&rs->rs_cong_list, &rds_cong_monitor); | |
345 | write_unlock_irqrestore(&rds_cong_monitor_lock, flags); | |
346 | } | |
347 | ||
348 | void rds_cong_remove_socket(struct rds_sock *rs) | |
349 | { | |
350 | unsigned long flags; | |
351 | struct rds_cong_map *map; | |
352 | ||
353 | write_lock_irqsave(&rds_cong_monitor_lock, flags); | |
354 | list_del_init(&rs->rs_cong_list); | |
355 | write_unlock_irqrestore(&rds_cong_monitor_lock, flags); | |
356 | ||
357 | /* update congestion map for now-closed port */ | |
358 | spin_lock_irqsave(&rds_cong_lock, flags); | |
eee2fa6a | 359 | map = rds_cong_tree_walk(&rs->rs_bound_addr, NULL); |
922cb17a AG |
360 | spin_unlock_irqrestore(&rds_cong_lock, flags); |
361 | ||
362 | if (map && rds_cong_test_bit(map, rs->rs_bound_port)) { | |
363 | rds_cong_clear_bit(map, rs->rs_bound_port); | |
364 | rds_cong_queue_updates(map); | |
365 | } | |
366 | } | |
367 | ||
368 | int rds_cong_wait(struct rds_cong_map *map, __be16 port, int nonblock, | |
369 | struct rds_sock *rs) | |
370 | { | |
371 | if (!rds_cong_test_bit(map, port)) | |
372 | return 0; | |
373 | if (nonblock) { | |
374 | if (rs && rs->rs_cong_monitor) { | |
375 | unsigned long flags; | |
376 | ||
377 | /* It would have been nice to have an atomic set_bit on | |
378 | * a uint64_t. */ | |
379 | spin_lock_irqsave(&rs->rs_lock, flags); | |
380 | rs->rs_cong_mask |= RDS_CONG_MONITOR_MASK(ntohs(port)); | |
381 | spin_unlock_irqrestore(&rs->rs_lock, flags); | |
382 | ||
383 | /* Test again - a congestion update may have arrived in | |
384 | * the meantime. */ | |
385 | if (!rds_cong_test_bit(map, port)) | |
386 | return 0; | |
387 | } | |
388 | rds_stats_inc(s_cong_send_error); | |
389 | return -ENOBUFS; | |
390 | } | |
391 | ||
392 | rds_stats_inc(s_cong_send_blocked); | |
393 | rdsdebug("waiting on map %p for port %u\n", map, be16_to_cpu(port)); | |
394 | ||
395 | return wait_event_interruptible(map->m_waitq, | |
396 | !rds_cong_test_bit(map, port)); | |
397 | } | |
398 | ||
399 | void rds_cong_exit(void) | |
400 | { | |
401 | struct rb_node *node; | |
402 | struct rds_cong_map *map; | |
403 | unsigned long i; | |
404 | ||
405 | while ((node = rb_first(&rds_cong_tree))) { | |
406 | map = rb_entry(node, struct rds_cong_map, m_rb_node); | |
407 | rdsdebug("freeing map %p\n", map); | |
408 | rb_erase(&map->m_rb_node, &rds_cong_tree); | |
409 | for (i = 0; i < RDS_CONG_MAP_PAGES && map->m_page_addrs[i]; i++) | |
410 | free_page(map->m_page_addrs[i]); | |
411 | kfree(map); | |
412 | } | |
413 | } | |
414 | ||
415 | /* | |
416 | * Allocate a RDS message containing a congestion update. | |
417 | */ | |
418 | struct rds_message *rds_cong_update_alloc(struct rds_connection *conn) | |
419 | { | |
420 | struct rds_cong_map *map = conn->c_lcong; | |
421 | struct rds_message *rm; | |
422 | ||
423 | rm = rds_message_map_pages(map->m_page_addrs, RDS_CONG_MAP_BYTES); | |
424 | if (!IS_ERR(rm)) | |
425 | rm->m_inc.i_hdr.h_flags = RDS_FLAG_CONG_BITMAP; | |
426 | ||
427 | return rm; | |
428 | } |