David Howells | 4a3388c | 2016-04-04 14:00:37 +0100 | [diff] [blame] | 1 | /* Client connection-specific management code. |
| 2 | * |
| 3 | * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved. |
| 4 | * Written by David Howells (dhowells@redhat.com) |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or |
| 7 | * modify it under the terms of the GNU General Public Licence |
| 8 | * as published by the Free Software Foundation; either version |
| 9 | * 2 of the Licence, or (at your option) any later version. |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 10 | * |
| 11 | * |
| 12 | * Client connections need to be cached for a little while after they've made a |
| 13 | * call so as to handle retransmitted DATA packets in case the server didn't |
| 14 | * receive the final ACK or terminating ABORT we sent it. |
| 15 | * |
| 16 | * Client connections can be in one of a number of cache states: |
| 17 | * |
| 18 | * (1) INACTIVE - The connection is not held in any list and may not have been |
| 19 | * exposed to the world. If it has been previously exposed, it was |
| 20 | * discarded from the idle list after expiring. |
| 21 | * |
| 22 | * (2) WAITING - The connection is waiting for the number of client conns to |
| 23 | * drop below the maximum capacity. Calls may be in progress upon it from |
| 24 | * when it was active and got culled. |
| 25 | * |
| 26 | * The connection is on the rxrpc_waiting_client_conns list which is kept |
| 27 | * in to-be-granted order. Culled conns with waiters go to the back of |
| 28 | * the queue just like new conns. |
| 29 | * |
| 30 | * (3) ACTIVE - The connection has at least one call in progress upon it, it |
| 31 | * may freely grant available channels to new calls and calls may be |
| 32 | * waiting on it for channels to become available. |
| 33 | * |
| 34 | * The connection is on the rxrpc_active_client_conns list which is kept |
| 35 | * in activation order for culling purposes. |
| 36 | * |
| 37 | * rxrpc_nr_active_client_conns is held incremented also. |
| 38 | * |
| 39 | * (4) CULLED - The connection got summarily culled to try and free up |
| 40 | * capacity. Calls currently in progress on the connection are allowed to |
| 41 | * continue, but new calls will have to wait. There can be no waiters in |
| 42 | * this state - the conn would have to go to the WAITING state instead. |
| 43 | * |
| 44 | * (5) IDLE - The connection has no calls in progress upon it and must have |
| 45 | * been exposed to the world (ie. the EXPOSED flag must be set). When it |
| 46 | * expires, the EXPOSED flag is cleared and the connection transitions to |
| 47 | * the INACTIVE state. |
| 48 | * |
| 49 | * The connection is on the rxrpc_idle_client_conns list which is kept in |
| 50 | * order of how soon they'll expire. |
| 51 | * |
| 52 | * There are flags of relevance to the cache: |
| 53 | * |
| 54 | * (1) EXPOSED - The connection ID got exposed to the world. If this flag is |
| 55 | * set, an extra ref is added to the connection preventing it from being |
| 56 | * reaped when it has no calls outstanding. This flag is cleared and the |
| 57 | * ref dropped when a conn is discarded from the idle list. |
| 58 | * |
| 59 | * This allows us to move terminal call state retransmission to the |
| 60 | * connection and to discard the call immediately we think it is done |
| 61 | * with. It also give us a chance to reuse the connection. |
| 62 | * |
| 63 | * (2) DONT_REUSE - The connection should be discarded as soon as possible and |
| 64 | * should not be reused. This is set when an exclusive connection is used |
| 65 | * or a call ID counter overflows. |
| 66 | * |
| 67 | * The caching state may only be changed if the cache lock is held. |
| 68 | * |
| 69 | * There are two idle client connection expiry durations. If the total number |
| 70 | * of connections is below the reap threshold, we use the normal duration; if |
| 71 | * it's above, we use the fast duration. |
David Howells | 4a3388c | 2016-04-04 14:00:37 +0100 | [diff] [blame] | 72 | */ |
| 73 | |
| 74 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| 75 | |
| 76 | #include <linux/slab.h> |
| 77 | #include <linux/idr.h> |
| 78 | #include <linux/timer.h> |
| 79 | #include "ar-internal.h" |
| 80 | |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 81 | __read_mostly unsigned int rxrpc_max_client_connections = 1000; |
| 82 | __read_mostly unsigned int rxrpc_reap_client_connections = 900; |
| 83 | __read_mostly unsigned int rxrpc_conn_idle_client_expiry = 2 * 60 * HZ; |
| 84 | __read_mostly unsigned int rxrpc_conn_idle_client_fast_expiry = 2 * HZ; |
| 85 | |
| 86 | static unsigned int rxrpc_nr_client_conns; |
| 87 | static unsigned int rxrpc_nr_active_client_conns; |
| 88 | static __read_mostly bool rxrpc_kill_all_client_conns; |
| 89 | |
| 90 | static DEFINE_SPINLOCK(rxrpc_client_conn_cache_lock); |
| 91 | static DEFINE_SPINLOCK(rxrpc_client_conn_discard_mutex); |
| 92 | static LIST_HEAD(rxrpc_waiting_client_conns); |
| 93 | static LIST_HEAD(rxrpc_active_client_conns); |
| 94 | static LIST_HEAD(rxrpc_idle_client_conns); |
| 95 | |
David Howells | 4a3388c | 2016-04-04 14:00:37 +0100 | [diff] [blame] | 96 | /* |
| 97 | * We use machine-unique IDs for our client connections. |
| 98 | */ |
| 99 | DEFINE_IDR(rxrpc_client_conn_ids); |
| 100 | static DEFINE_SPINLOCK(rxrpc_conn_id_lock); |
| 101 | |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 102 | static void rxrpc_cull_active_client_conns(void); |
| 103 | static void rxrpc_discard_expired_client_conns(struct work_struct *); |
| 104 | |
| 105 | static DECLARE_DELAYED_WORK(rxrpc_client_conn_reap, |
| 106 | rxrpc_discard_expired_client_conns); |
| 107 | |
David Howells | 4a3388c | 2016-04-04 14:00:37 +0100 | [diff] [blame] | 108 | /* |
| 109 | * Get a connection ID and epoch for a client connection from the global pool. |
| 110 | * The connection struct pointer is then recorded in the idr radix tree. The |
David Howells | 090f85d | 2016-09-04 13:14:46 +0100 | [diff] [blame^] | 111 | * epoch doesn't change until the client is rebooted (or, at least, unless the |
| 112 | * module is unloaded). |
David Howells | 4a3388c | 2016-04-04 14:00:37 +0100 | [diff] [blame] | 113 | */ |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 114 | static int rxrpc_get_client_connection_id(struct rxrpc_connection *conn, |
| 115 | gfp_t gfp) |
David Howells | 4a3388c | 2016-04-04 14:00:37 +0100 | [diff] [blame] | 116 | { |
David Howells | 4a3388c | 2016-04-04 14:00:37 +0100 | [diff] [blame] | 117 | int id; |
| 118 | |
| 119 | _enter(""); |
| 120 | |
| 121 | idr_preload(gfp); |
David Howells | 4a3388c | 2016-04-04 14:00:37 +0100 | [diff] [blame] | 122 | spin_lock(&rxrpc_conn_id_lock); |
| 123 | |
David Howells | 090f85d | 2016-09-04 13:14:46 +0100 | [diff] [blame^] | 124 | id = idr_alloc_cyclic(&rxrpc_client_conn_ids, conn, |
| 125 | 1, 0x40000000, GFP_NOWAIT); |
| 126 | if (id < 0) |
| 127 | goto error; |
David Howells | 4a3388c | 2016-04-04 14:00:37 +0100 | [diff] [blame] | 128 | |
| 129 | spin_unlock(&rxrpc_conn_id_lock); |
David Howells | 4a3388c | 2016-04-04 14:00:37 +0100 | [diff] [blame] | 130 | idr_preload_end(); |
| 131 | |
David Howells | 090f85d | 2016-09-04 13:14:46 +0100 | [diff] [blame^] | 132 | conn->proto.epoch = rxrpc_epoch; |
David Howells | 4a3388c | 2016-04-04 14:00:37 +0100 | [diff] [blame] | 133 | conn->proto.cid = id << RXRPC_CIDSHIFT; |
| 134 | set_bit(RXRPC_CONN_HAS_IDR, &conn->flags); |
David Howells | 090f85d | 2016-09-04 13:14:46 +0100 | [diff] [blame^] | 135 | _leave(" [CID %x]", conn->proto.cid); |
David Howells | 4a3388c | 2016-04-04 14:00:37 +0100 | [diff] [blame] | 136 | return 0; |
| 137 | |
| 138 | error: |
| 139 | spin_unlock(&rxrpc_conn_id_lock); |
David Howells | 4a3388c | 2016-04-04 14:00:37 +0100 | [diff] [blame] | 140 | idr_preload_end(); |
| 141 | _leave(" = %d", id); |
| 142 | return id; |
| 143 | } |
| 144 | |
| 145 | /* |
| 146 | * Release a connection ID for a client connection from the global pool. |
| 147 | */ |
David Howells | 001c112 | 2016-06-30 10:45:22 +0100 | [diff] [blame] | 148 | static void rxrpc_put_client_connection_id(struct rxrpc_connection *conn) |
David Howells | 4a3388c | 2016-04-04 14:00:37 +0100 | [diff] [blame] | 149 | { |
| 150 | if (test_bit(RXRPC_CONN_HAS_IDR, &conn->flags)) { |
| 151 | spin_lock(&rxrpc_conn_id_lock); |
| 152 | idr_remove(&rxrpc_client_conn_ids, |
| 153 | conn->proto.cid >> RXRPC_CIDSHIFT); |
| 154 | spin_unlock(&rxrpc_conn_id_lock); |
| 155 | } |
| 156 | } |
David Howells | eb9b9d2 | 2016-06-27 10:32:02 +0100 | [diff] [blame] | 157 | |
| 158 | /* |
| 159 | * Destroy the client connection ID tree. |
| 160 | */ |
| 161 | void rxrpc_destroy_client_conn_ids(void) |
| 162 | { |
| 163 | struct rxrpc_connection *conn; |
| 164 | int id; |
| 165 | |
| 166 | if (!idr_is_empty(&rxrpc_client_conn_ids)) { |
| 167 | idr_for_each_entry(&rxrpc_client_conn_ids, conn, id) { |
| 168 | pr_err("AF_RXRPC: Leaked client conn %p {%d}\n", |
| 169 | conn, atomic_read(&conn->usage)); |
| 170 | } |
| 171 | BUG(); |
| 172 | } |
| 173 | |
| 174 | idr_destroy(&rxrpc_client_conn_ids); |
| 175 | } |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 176 | |
| 177 | /* |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 178 | * Allocate a client connection. |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 179 | */ |
| 180 | static struct rxrpc_connection * |
| 181 | rxrpc_alloc_client_connection(struct rxrpc_conn_parameters *cp, gfp_t gfp) |
| 182 | { |
| 183 | struct rxrpc_connection *conn; |
| 184 | int ret; |
| 185 | |
| 186 | _enter(""); |
| 187 | |
| 188 | conn = rxrpc_alloc_connection(gfp); |
| 189 | if (!conn) { |
| 190 | _leave(" = -ENOMEM"); |
| 191 | return ERR_PTR(-ENOMEM); |
| 192 | } |
| 193 | |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 194 | atomic_set(&conn->usage, 1); |
| 195 | if (conn->params.exclusive) |
| 196 | __set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags); |
| 197 | |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 198 | conn->params = *cp; |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 199 | conn->out_clientflag = RXRPC_CLIENT_INITIATED; |
| 200 | conn->state = RXRPC_CONN_CLIENT; |
| 201 | |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 202 | ret = rxrpc_get_client_connection_id(conn, gfp); |
| 203 | if (ret < 0) |
| 204 | goto error_0; |
| 205 | |
| 206 | ret = rxrpc_init_client_conn_security(conn); |
| 207 | if (ret < 0) |
| 208 | goto error_1; |
| 209 | |
| 210 | ret = conn->security->prime_packet_security(conn); |
| 211 | if (ret < 0) |
| 212 | goto error_2; |
| 213 | |
| 214 | write_lock(&rxrpc_connection_lock); |
David Howells | 4d028b2 | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 215 | list_add_tail(&conn->proc_link, &rxrpc_connection_proc_list); |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 216 | write_unlock(&rxrpc_connection_lock); |
| 217 | |
| 218 | /* We steal the caller's peer ref. */ |
| 219 | cp->peer = NULL; |
| 220 | rxrpc_get_local(conn->params.local); |
| 221 | key_get(conn->params.key); |
| 222 | |
| 223 | _leave(" = %p", conn); |
| 224 | return conn; |
| 225 | |
| 226 | error_2: |
| 227 | conn->security->clear(conn); |
| 228 | error_1: |
| 229 | rxrpc_put_client_connection_id(conn); |
| 230 | error_0: |
| 231 | kfree(conn); |
| 232 | _leave(" = %d", ret); |
| 233 | return ERR_PTR(ret); |
| 234 | } |
| 235 | |
| 236 | /* |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 237 | * Determine if a connection may be reused. |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 238 | */ |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 239 | static bool rxrpc_may_reuse_conn(struct rxrpc_connection *conn) |
| 240 | { |
| 241 | int id_cursor, id, distance, limit; |
| 242 | |
| 243 | if (test_bit(RXRPC_CONN_DONT_REUSE, &conn->flags)) |
| 244 | goto dont_reuse; |
| 245 | |
| 246 | if (conn->proto.epoch != rxrpc_epoch) |
| 247 | goto mark_dont_reuse; |
| 248 | |
| 249 | /* The IDR tree gets very expensive on memory if the connection IDs are |
| 250 | * widely scattered throughout the number space, so we shall want to |
| 251 | * kill off connections that, say, have an ID more than about four |
| 252 | * times the maximum number of client conns away from the current |
| 253 | * allocation point to try and keep the IDs concentrated. |
| 254 | */ |
| 255 | id_cursor = READ_ONCE(rxrpc_client_conn_ids.cur); |
| 256 | id = conn->proto.cid >> RXRPC_CIDSHIFT; |
| 257 | distance = id - id_cursor; |
| 258 | if (distance < 0) |
| 259 | distance = -distance; |
| 260 | limit = round_up(rxrpc_max_client_connections, IDR_SIZE) * 4; |
| 261 | if (distance > limit) |
| 262 | goto mark_dont_reuse; |
| 263 | |
| 264 | return true; |
| 265 | |
| 266 | mark_dont_reuse: |
| 267 | set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags); |
| 268 | dont_reuse: |
| 269 | return false; |
| 270 | } |
| 271 | |
| 272 | /* |
| 273 | * Create or find a client connection to use for a call. |
| 274 | * |
| 275 | * If we return with a connection, the call will be on its waiting list. It's |
| 276 | * left to the caller to assign a channel and wake up the call. |
| 277 | */ |
| 278 | static int rxrpc_get_client_conn(struct rxrpc_call *call, |
| 279 | struct rxrpc_conn_parameters *cp, |
| 280 | struct sockaddr_rxrpc *srx, |
| 281 | gfp_t gfp) |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 282 | { |
| 283 | struct rxrpc_connection *conn, *candidate = NULL; |
| 284 | struct rxrpc_local *local = cp->local; |
| 285 | struct rb_node *p, **pp, *parent; |
| 286 | long diff; |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 287 | int ret = -ENOMEM; |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 288 | |
| 289 | _enter("{%d,%lx},", call->debug_id, call->user_call_ID); |
| 290 | |
| 291 | cp->peer = rxrpc_lookup_peer(cp->local, srx, gfp); |
| 292 | if (!cp->peer) |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 293 | goto error; |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 294 | |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 295 | /* If the connection is not meant to be exclusive, search the available |
| 296 | * connections to see if the connection we want to use already exists. |
| 297 | */ |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 298 | if (!cp->exclusive) { |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 299 | _debug("search 1"); |
| 300 | spin_lock(&local->client_conns_lock); |
| 301 | p = local->client_conns.rb_node; |
| 302 | while (p) { |
| 303 | conn = rb_entry(p, struct rxrpc_connection, client_node); |
| 304 | |
| 305 | #define cmp(X) ((long)conn->params.X - (long)cp->X) |
| 306 | diff = (cmp(peer) ?: |
| 307 | cmp(key) ?: |
| 308 | cmp(security_level)); |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 309 | #undef cmp |
| 310 | if (diff < 0) { |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 311 | p = p->rb_left; |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 312 | } else if (diff > 0) { |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 313 | p = p->rb_right; |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 314 | } else { |
| 315 | if (rxrpc_may_reuse_conn(conn) && |
| 316 | rxrpc_get_connection_maybe(conn)) |
| 317 | goto found_extant_conn; |
| 318 | /* The connection needs replacing. It's better |
| 319 | * to effect that when we have something to |
| 320 | * replace it with so that we don't have to |
| 321 | * rebalance the tree twice. |
| 322 | */ |
| 323 | break; |
| 324 | } |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 325 | } |
| 326 | spin_unlock(&local->client_conns_lock); |
| 327 | } |
| 328 | |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 329 | /* There wasn't a connection yet or we need an exclusive connection. |
| 330 | * We need to create a candidate and then potentially redo the search |
| 331 | * in case we're racing with another thread also trying to connect on a |
| 332 | * shareable connection. |
| 333 | */ |
| 334 | _debug("new conn"); |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 335 | candidate = rxrpc_alloc_client_connection(cp, gfp); |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 336 | if (IS_ERR(candidate)) { |
| 337 | ret = PTR_ERR(candidate); |
| 338 | goto error_peer; |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 339 | } |
| 340 | |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 341 | /* Add the call to the new connection's waiting list in case we're |
| 342 | * going to have to wait for the connection to come live. It's our |
| 343 | * connection, so we want first dibs on the channel slots. We would |
| 344 | * normally have to take channel_lock but we do this before anyone else |
| 345 | * can see the connection. |
| 346 | */ |
| 347 | list_add_tail(&call->chan_wait_link, &candidate->waiting_calls); |
| 348 | |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 349 | if (cp->exclusive) { |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 350 | call->conn = candidate; |
| 351 | _leave(" = 0 [exclusive %d]", candidate->debug_id); |
| 352 | return 0; |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 353 | } |
| 354 | |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 355 | /* Publish the new connection for userspace to find. We need to redo |
| 356 | * the search before doing this lest we race with someone else adding a |
| 357 | * conflicting instance. |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 358 | */ |
| 359 | _debug("search 2"); |
| 360 | spin_lock(&local->client_conns_lock); |
| 361 | |
| 362 | pp = &local->client_conns.rb_node; |
| 363 | parent = NULL; |
| 364 | while (*pp) { |
| 365 | parent = *pp; |
| 366 | conn = rb_entry(parent, struct rxrpc_connection, client_node); |
| 367 | |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 368 | #define cmp(X) ((long)conn->params.X - (long)candidate->params.X) |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 369 | diff = (cmp(peer) ?: |
| 370 | cmp(key) ?: |
| 371 | cmp(security_level)); |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 372 | #undef cmp |
| 373 | if (diff < 0) { |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 374 | pp = &(*pp)->rb_left; |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 375 | } else if (diff > 0) { |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 376 | pp = &(*pp)->rb_right; |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 377 | } else { |
| 378 | if (rxrpc_may_reuse_conn(conn) && |
| 379 | rxrpc_get_connection_maybe(conn)) |
| 380 | goto found_extant_conn; |
| 381 | /* The old connection is from an outdated epoch. */ |
| 382 | _debug("replace conn"); |
| 383 | clear_bit(RXRPC_CONN_IN_CLIENT_CONNS, &conn->flags); |
| 384 | rb_replace_node(&conn->client_node, |
| 385 | &candidate->client_node, |
| 386 | &local->client_conns); |
| 387 | goto candidate_published; |
| 388 | } |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 389 | } |
| 390 | |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 391 | _debug("new conn"); |
David Howells | 001c112 | 2016-06-30 10:45:22 +0100 | [diff] [blame] | 392 | rb_link_node(&candidate->client_node, parent, pp); |
| 393 | rb_insert_color(&candidate->client_node, &local->client_conns); |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 394 | |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 395 | candidate_published: |
| 396 | set_bit(RXRPC_CONN_IN_CLIENT_CONNS, &candidate->flags); |
| 397 | call->conn = candidate; |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 398 | spin_unlock(&local->client_conns_lock); |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 399 | _leave(" = 0 [new %d]", candidate->debug_id); |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 400 | return 0; |
| 401 | |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 402 | /* We come here if we found a suitable connection already in existence. |
| 403 | * Discard any candidate we may have allocated, and try to get a |
| 404 | * channel on this one. |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 405 | */ |
| 406 | found_extant_conn: |
| 407 | _debug("found conn"); |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 408 | spin_unlock(&local->client_conns_lock); |
| 409 | |
| 410 | rxrpc_put_connection(candidate); |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 411 | candidate = NULL; |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 412 | |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 413 | spin_lock(&conn->channel_lock); |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 414 | call->conn = conn; |
| 415 | list_add(&call->chan_wait_link, &conn->waiting_calls); |
| 416 | spin_unlock(&conn->channel_lock); |
| 417 | _leave(" = 0 [extant %d]", conn->debug_id); |
| 418 | return 0; |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 419 | |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 420 | error_peer: |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 421 | rxrpc_put_peer(cp->peer); |
| 422 | cp->peer = NULL; |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 423 | error: |
| 424 | _leave(" = %d", ret); |
| 425 | return ret; |
David Howells | c6d2b8d | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 426 | } |
David Howells | 001c112 | 2016-06-30 10:45:22 +0100 | [diff] [blame] | 427 | |
| 428 | /* |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 429 | * Activate a connection. |
David Howells | 001c112 | 2016-06-30 10:45:22 +0100 | [diff] [blame] | 430 | */ |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 431 | static void rxrpc_activate_conn(struct rxrpc_connection *conn) |
David Howells | 001c112 | 2016-06-30 10:45:22 +0100 | [diff] [blame] | 432 | { |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 433 | conn->cache_state = RXRPC_CONN_CLIENT_ACTIVE; |
| 434 | rxrpc_nr_active_client_conns++; |
| 435 | list_move_tail(&conn->cache_link, &rxrpc_active_client_conns); |
| 436 | } |
David Howells | 001c112 | 2016-06-30 10:45:22 +0100 | [diff] [blame] | 437 | |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 438 | /* |
| 439 | * Attempt to animate a connection for a new call. |
| 440 | * |
| 441 | * If it's not exclusive, the connection is in the endpoint tree, and we're in |
| 442 | * the conn's list of those waiting to grab a channel. There is, however, a |
| 443 | * limit on the number of live connections allowed at any one time, so we may |
| 444 | * have to wait for capacity to become available. |
| 445 | * |
| 446 | * Note that a connection on the waiting queue might *also* have active |
| 447 | * channels if it has been culled to make space and then re-requested by a new |
| 448 | * call. |
| 449 | */ |
| 450 | static void rxrpc_animate_client_conn(struct rxrpc_connection *conn) |
| 451 | { |
| 452 | unsigned int nr_conns; |
| 453 | |
| 454 | _enter("%d,%d", conn->debug_id, conn->cache_state); |
| 455 | |
| 456 | if (conn->cache_state == RXRPC_CONN_CLIENT_ACTIVE) |
| 457 | goto out; |
| 458 | |
| 459 | spin_lock(&rxrpc_client_conn_cache_lock); |
| 460 | |
| 461 | nr_conns = rxrpc_nr_client_conns; |
| 462 | if (!test_and_set_bit(RXRPC_CONN_COUNTED, &conn->flags)) |
| 463 | rxrpc_nr_client_conns = nr_conns + 1; |
| 464 | |
| 465 | switch (conn->cache_state) { |
| 466 | case RXRPC_CONN_CLIENT_ACTIVE: |
| 467 | case RXRPC_CONN_CLIENT_WAITING: |
| 468 | break; |
| 469 | |
| 470 | case RXRPC_CONN_CLIENT_INACTIVE: |
| 471 | case RXRPC_CONN_CLIENT_CULLED: |
| 472 | case RXRPC_CONN_CLIENT_IDLE: |
| 473 | if (nr_conns >= rxrpc_max_client_connections) |
| 474 | goto wait_for_capacity; |
| 475 | goto activate_conn; |
| 476 | |
| 477 | default: |
| 478 | BUG(); |
| 479 | } |
| 480 | |
| 481 | out_unlock: |
| 482 | spin_unlock(&rxrpc_client_conn_cache_lock); |
| 483 | out: |
| 484 | _leave(" [%d]", conn->cache_state); |
| 485 | return; |
| 486 | |
| 487 | activate_conn: |
| 488 | _debug("activate"); |
| 489 | rxrpc_activate_conn(conn); |
| 490 | goto out_unlock; |
| 491 | |
| 492 | wait_for_capacity: |
| 493 | _debug("wait"); |
| 494 | conn->cache_state = RXRPC_CONN_CLIENT_WAITING; |
| 495 | list_move_tail(&conn->cache_link, &rxrpc_waiting_client_conns); |
| 496 | goto out_unlock; |
| 497 | } |
| 498 | |
| 499 | /* |
| 500 | * Deactivate a channel. |
| 501 | */ |
| 502 | static void rxrpc_deactivate_one_channel(struct rxrpc_connection *conn, |
| 503 | unsigned int channel) |
| 504 | { |
| 505 | struct rxrpc_channel *chan = &conn->channels[channel]; |
| 506 | |
| 507 | rcu_assign_pointer(chan->call, NULL); |
| 508 | conn->active_chans &= ~(1 << channel); |
| 509 | } |
| 510 | |
| 511 | /* |
| 512 | * Assign a channel to the call at the front of the queue and wake the call up. |
| 513 | * We don't increment the callNumber counter until this number has been exposed |
| 514 | * to the world. |
| 515 | */ |
| 516 | static void rxrpc_activate_one_channel(struct rxrpc_connection *conn, |
| 517 | unsigned int channel) |
| 518 | { |
| 519 | struct rxrpc_channel *chan = &conn->channels[channel]; |
| 520 | struct rxrpc_call *call = list_entry(conn->waiting_calls.next, |
| 521 | struct rxrpc_call, chan_wait_link); |
| 522 | u32 call_id = chan->call_counter + 1; |
| 523 | |
David Howells | af338a9 | 2016-09-04 13:10:10 +0100 | [diff] [blame] | 524 | write_lock_bh(&call->state_lock); |
| 525 | call->state = RXRPC_CALL_CLIENT_SEND_REQUEST; |
| 526 | write_unlock_bh(&call->state_lock); |
| 527 | |
David Howells | e34d423 | 2016-08-30 09:49:29 +0100 | [diff] [blame] | 528 | rxrpc_see_call(call); |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 529 | list_del_init(&call->chan_wait_link); |
| 530 | conn->active_chans |= 1 << channel; |
| 531 | call->peer = rxrpc_get_peer(conn->params.peer); |
| 532 | call->cid = conn->proto.cid | channel; |
| 533 | call->call_id = call_id; |
| 534 | |
| 535 | _net("CONNECT call %08x:%08x as call %d on conn %d", |
| 536 | call->cid, call->call_id, call->debug_id, conn->debug_id); |
| 537 | |
| 538 | /* Paired with the read barrier in rxrpc_wait_for_channel(). This |
| 539 | * orders cid and epoch in the connection wrt to call_id without the |
| 540 | * need to take the channel_lock. |
| 541 | * |
| 542 | * We provisionally assign a callNumber at this point, but we don't |
| 543 | * confirm it until the call is about to be exposed. |
| 544 | * |
| 545 | * TODO: Pair with a barrier in the data_ready handler when that looks |
| 546 | * at the call ID through a connection channel. |
| 547 | */ |
| 548 | smp_wmb(); |
| 549 | chan->call_id = call_id; |
| 550 | rcu_assign_pointer(chan->call, call); |
| 551 | wake_up(&call->waitq); |
| 552 | } |
| 553 | |
| 554 | /* |
| 555 | * Assign channels and callNumbers to waiting calls. |
| 556 | */ |
| 557 | static void rxrpc_activate_channels(struct rxrpc_connection *conn) |
| 558 | { |
| 559 | unsigned char mask; |
| 560 | |
| 561 | _enter("%d", conn->debug_id); |
| 562 | |
| 563 | if (conn->cache_state != RXRPC_CONN_CLIENT_ACTIVE || |
| 564 | conn->active_chans == RXRPC_ACTIVE_CHANS_MASK) |
| 565 | return; |
| 566 | |
| 567 | spin_lock(&conn->channel_lock); |
| 568 | |
| 569 | while (!list_empty(&conn->waiting_calls) && |
| 570 | (mask = ~conn->active_chans, |
| 571 | mask &= RXRPC_ACTIVE_CHANS_MASK, |
| 572 | mask != 0)) |
| 573 | rxrpc_activate_one_channel(conn, __ffs(mask)); |
| 574 | |
| 575 | spin_unlock(&conn->channel_lock); |
| 576 | _leave(""); |
| 577 | } |
| 578 | |
| 579 | /* |
| 580 | * Wait for a callNumber and a channel to be granted to a call. |
| 581 | */ |
| 582 | static int rxrpc_wait_for_channel(struct rxrpc_call *call, gfp_t gfp) |
| 583 | { |
| 584 | int ret = 0; |
| 585 | |
| 586 | _enter("%d", call->debug_id); |
| 587 | |
| 588 | if (!call->call_id) { |
| 589 | DECLARE_WAITQUEUE(myself, current); |
| 590 | |
| 591 | if (!gfpflags_allow_blocking(gfp)) { |
| 592 | ret = -EAGAIN; |
| 593 | goto out; |
| 594 | } |
| 595 | |
| 596 | add_wait_queue_exclusive(&call->waitq, &myself); |
| 597 | for (;;) { |
| 598 | set_current_state(TASK_INTERRUPTIBLE); |
| 599 | if (call->call_id) |
| 600 | break; |
| 601 | if (signal_pending(current)) { |
| 602 | ret = -ERESTARTSYS; |
| 603 | break; |
| 604 | } |
| 605 | schedule(); |
| 606 | } |
| 607 | remove_wait_queue(&call->waitq, &myself); |
| 608 | __set_current_state(TASK_RUNNING); |
| 609 | } |
| 610 | |
| 611 | /* Paired with the write barrier in rxrpc_activate_one_channel(). */ |
| 612 | smp_rmb(); |
| 613 | |
| 614 | out: |
| 615 | _leave(" = %d", ret); |
| 616 | return ret; |
| 617 | } |
| 618 | |
| 619 | /* |
| 620 | * find a connection for a call |
| 621 | * - called in process context with IRQs enabled |
| 622 | */ |
| 623 | int rxrpc_connect_call(struct rxrpc_call *call, |
| 624 | struct rxrpc_conn_parameters *cp, |
| 625 | struct sockaddr_rxrpc *srx, |
| 626 | gfp_t gfp) |
| 627 | { |
| 628 | int ret; |
| 629 | |
| 630 | _enter("{%d,%lx},", call->debug_id, call->user_call_ID); |
| 631 | |
| 632 | rxrpc_discard_expired_client_conns(NULL); |
| 633 | rxrpc_cull_active_client_conns(); |
| 634 | |
| 635 | ret = rxrpc_get_client_conn(call, cp, srx, gfp); |
| 636 | if (ret < 0) |
| 637 | return ret; |
| 638 | |
| 639 | rxrpc_animate_client_conn(call->conn); |
| 640 | rxrpc_activate_channels(call->conn); |
| 641 | |
| 642 | ret = rxrpc_wait_for_channel(call, gfp); |
| 643 | if (ret < 0) |
| 644 | rxrpc_disconnect_client_call(call); |
| 645 | |
| 646 | _leave(" = %d", ret); |
| 647 | return ret; |
| 648 | } |
| 649 | |
| 650 | /* |
| 651 | * Note that a connection is about to be exposed to the world. Once it is |
| 652 | * exposed, we maintain an extra ref on it that stops it from being summarily |
| 653 | * discarded before it's (a) had a chance to deal with retransmission and (b) |
| 654 | * had a chance at re-use (the per-connection security negotiation is |
| 655 | * expensive). |
| 656 | */ |
| 657 | static void rxrpc_expose_client_conn(struct rxrpc_connection *conn) |
| 658 | { |
| 659 | if (!test_and_set_bit(RXRPC_CONN_EXPOSED, &conn->flags)) |
| 660 | rxrpc_get_connection(conn); |
| 661 | } |
| 662 | |
| 663 | /* |
| 664 | * Note that a call, and thus a connection, is about to be exposed to the |
| 665 | * world. |
| 666 | */ |
| 667 | void rxrpc_expose_client_call(struct rxrpc_call *call) |
| 668 | { |
| 669 | struct rxrpc_connection *conn = call->conn; |
| 670 | struct rxrpc_channel *chan = |
| 671 | &conn->channels[call->cid & RXRPC_CHANNELMASK]; |
| 672 | |
| 673 | if (!test_and_set_bit(RXRPC_CALL_EXPOSED, &call->flags)) { |
| 674 | /* Mark the call ID as being used. If the callNumber counter |
| 675 | * exceeds ~2 billion, we kill the connection after its |
| 676 | * outstanding calls have finished so that the counter doesn't |
| 677 | * wrap. |
| 678 | */ |
| 679 | chan->call_counter++; |
| 680 | if (chan->call_counter >= INT_MAX) |
| 681 | set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags); |
| 682 | rxrpc_expose_client_conn(conn); |
| 683 | } |
| 684 | } |
| 685 | |
| 686 | /* |
| 687 | * Disconnect a client call. |
| 688 | */ |
| 689 | void rxrpc_disconnect_client_call(struct rxrpc_call *call) |
| 690 | { |
| 691 | unsigned int channel = call->cid & RXRPC_CHANNELMASK; |
| 692 | struct rxrpc_connection *conn = call->conn; |
| 693 | struct rxrpc_channel *chan = &conn->channels[channel]; |
| 694 | |
| 695 | call->conn = NULL; |
| 696 | |
| 697 | spin_lock(&conn->channel_lock); |
| 698 | |
| 699 | /* Calls that have never actually been assigned a channel can simply be |
| 700 | * discarded. If the conn didn't get used either, it will follow |
| 701 | * immediately unless someone else grabs it in the meantime. |
| 702 | */ |
| 703 | if (!list_empty(&call->chan_wait_link)) { |
| 704 | _debug("call is waiting"); |
| 705 | ASSERTCMP(call->call_id, ==, 0); |
| 706 | ASSERT(!test_bit(RXRPC_CALL_EXPOSED, &call->flags)); |
| 707 | list_del_init(&call->chan_wait_link); |
| 708 | |
| 709 | /* We must deactivate or idle the connection if it's now |
| 710 | * waiting for nothing. |
| 711 | */ |
| 712 | spin_lock(&rxrpc_client_conn_cache_lock); |
| 713 | if (conn->cache_state == RXRPC_CONN_CLIENT_WAITING && |
| 714 | list_empty(&conn->waiting_calls) && |
| 715 | !conn->active_chans) |
| 716 | goto idle_connection; |
| 717 | goto out; |
| 718 | } |
| 719 | |
| 720 | ASSERTCMP(rcu_access_pointer(chan->call), ==, call); |
| 721 | ASSERTCMP(atomic_read(&conn->usage), >=, 2); |
| 722 | |
| 723 | /* If a client call was exposed to the world, we save the result for |
| 724 | * retransmission. |
| 725 | * |
| 726 | * We use a barrier here so that the call number and abort code can be |
| 727 | * read without needing to take a lock. |
| 728 | * |
| 729 | * TODO: Make the incoming packet handler check this and handle |
| 730 | * terminal retransmission without requiring access to the call. |
| 731 | */ |
| 732 | if (test_bit(RXRPC_CALL_EXPOSED, &call->flags)) { |
David Howells | f5c17aa | 2016-08-30 09:49:28 +0100 | [diff] [blame] | 733 | _debug("exposed %u,%u", call->call_id, call->abort_code); |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 734 | __rxrpc_disconnect_call(conn, call); |
| 735 | } |
| 736 | |
| 737 | /* See if we can pass the channel directly to another call. */ |
| 738 | if (conn->cache_state == RXRPC_CONN_CLIENT_ACTIVE && |
| 739 | !list_empty(&conn->waiting_calls)) { |
| 740 | _debug("pass chan"); |
| 741 | rxrpc_activate_one_channel(conn, channel); |
| 742 | goto out_2; |
| 743 | } |
| 744 | |
| 745 | /* Things are more complex and we need the cache lock. We might be |
| 746 | * able to simply idle the conn or it might now be lurking on the wait |
| 747 | * list. It might even get moved back to the active list whilst we're |
| 748 | * waiting for the lock. |
| 749 | */ |
| 750 | spin_lock(&rxrpc_client_conn_cache_lock); |
| 751 | |
| 752 | switch (conn->cache_state) { |
| 753 | case RXRPC_CONN_CLIENT_ACTIVE: |
| 754 | if (list_empty(&conn->waiting_calls)) { |
| 755 | rxrpc_deactivate_one_channel(conn, channel); |
| 756 | if (!conn->active_chans) { |
| 757 | rxrpc_nr_active_client_conns--; |
| 758 | goto idle_connection; |
| 759 | } |
| 760 | goto out; |
| 761 | } |
| 762 | |
| 763 | _debug("pass chan 2"); |
| 764 | rxrpc_activate_one_channel(conn, channel); |
| 765 | goto out; |
| 766 | |
| 767 | case RXRPC_CONN_CLIENT_CULLED: |
| 768 | rxrpc_deactivate_one_channel(conn, channel); |
| 769 | ASSERT(list_empty(&conn->waiting_calls)); |
| 770 | if (!conn->active_chans) |
| 771 | goto idle_connection; |
| 772 | goto out; |
| 773 | |
| 774 | case RXRPC_CONN_CLIENT_WAITING: |
| 775 | rxrpc_deactivate_one_channel(conn, channel); |
| 776 | goto out; |
| 777 | |
| 778 | default: |
| 779 | BUG(); |
| 780 | } |
| 781 | |
| 782 | out: |
| 783 | spin_unlock(&rxrpc_client_conn_cache_lock); |
| 784 | out_2: |
| 785 | spin_unlock(&conn->channel_lock); |
| 786 | rxrpc_put_connection(conn); |
| 787 | _leave(""); |
| 788 | return; |
| 789 | |
| 790 | idle_connection: |
| 791 | /* As no channels remain active, the connection gets deactivated |
| 792 | * immediately or moved to the idle list for a short while. |
| 793 | */ |
| 794 | if (test_bit(RXRPC_CONN_EXPOSED, &conn->flags)) { |
| 795 | _debug("make idle"); |
| 796 | conn->idle_timestamp = jiffies; |
| 797 | conn->cache_state = RXRPC_CONN_CLIENT_IDLE; |
| 798 | list_move_tail(&conn->cache_link, &rxrpc_idle_client_conns); |
| 799 | if (rxrpc_idle_client_conns.next == &conn->cache_link && |
| 800 | !rxrpc_kill_all_client_conns) |
| 801 | queue_delayed_work(rxrpc_workqueue, |
| 802 | &rxrpc_client_conn_reap, |
| 803 | rxrpc_conn_idle_client_expiry); |
| 804 | } else { |
| 805 | _debug("make inactive"); |
| 806 | conn->cache_state = RXRPC_CONN_CLIENT_INACTIVE; |
| 807 | list_del_init(&conn->cache_link); |
| 808 | } |
| 809 | goto out; |
| 810 | } |
| 811 | |
| 812 | /* |
| 813 | * Clean up a dead client connection. |
| 814 | */ |
| 815 | static struct rxrpc_connection * |
| 816 | rxrpc_put_one_client_conn(struct rxrpc_connection *conn) |
| 817 | { |
| 818 | struct rxrpc_connection *next; |
| 819 | struct rxrpc_local *local = conn->params.local; |
| 820 | unsigned int nr_conns; |
| 821 | |
| 822 | if (test_bit(RXRPC_CONN_IN_CLIENT_CONNS, &conn->flags)) { |
| 823 | spin_lock(&local->client_conns_lock); |
| 824 | if (test_and_clear_bit(RXRPC_CONN_IN_CLIENT_CONNS, |
| 825 | &conn->flags)) |
| 826 | rb_erase(&conn->client_node, &local->client_conns); |
| 827 | spin_unlock(&local->client_conns_lock); |
| 828 | } |
David Howells | 001c112 | 2016-06-30 10:45:22 +0100 | [diff] [blame] | 829 | |
| 830 | rxrpc_put_client_connection_id(conn); |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 831 | |
| 832 | ASSERTCMP(conn->cache_state, ==, RXRPC_CONN_CLIENT_INACTIVE); |
| 833 | |
| 834 | if (!test_bit(RXRPC_CONN_COUNTED, &conn->flags)) |
| 835 | return NULL; |
| 836 | |
| 837 | spin_lock(&rxrpc_client_conn_cache_lock); |
| 838 | nr_conns = --rxrpc_nr_client_conns; |
| 839 | |
| 840 | next = NULL; |
| 841 | if (nr_conns < rxrpc_max_client_connections && |
| 842 | !list_empty(&rxrpc_waiting_client_conns)) { |
| 843 | next = list_entry(rxrpc_waiting_client_conns.next, |
| 844 | struct rxrpc_connection, cache_link); |
| 845 | rxrpc_get_connection(next); |
| 846 | rxrpc_activate_conn(next); |
| 847 | } |
| 848 | |
| 849 | spin_unlock(&rxrpc_client_conn_cache_lock); |
| 850 | rxrpc_kill_connection(conn); |
| 851 | |
| 852 | if (next) |
| 853 | rxrpc_activate_channels(next); |
| 854 | |
| 855 | /* We need to get rid of the temporary ref we took upon next, but we |
| 856 | * can't call rxrpc_put_connection() recursively. |
| 857 | */ |
| 858 | return next; |
| 859 | } |
| 860 | |
| 861 | /* |
| 862 | * Clean up a dead client connections. |
| 863 | */ |
| 864 | void rxrpc_put_client_conn(struct rxrpc_connection *conn) |
| 865 | { |
| 866 | struct rxrpc_connection *next; |
| 867 | |
| 868 | do { |
| 869 | _enter("%p{u=%d,d=%d}", |
| 870 | conn, atomic_read(&conn->usage), conn->debug_id); |
| 871 | |
| 872 | next = rxrpc_put_one_client_conn(conn); |
| 873 | |
| 874 | if (!next) |
| 875 | break; |
| 876 | conn = next; |
| 877 | } while (atomic_dec_and_test(&conn->usage)); |
| 878 | |
| 879 | _leave(""); |
| 880 | } |
| 881 | |
| 882 | /* |
| 883 | * Kill the longest-active client connections to make room for new ones. |
| 884 | */ |
| 885 | static void rxrpc_cull_active_client_conns(void) |
| 886 | { |
| 887 | struct rxrpc_connection *conn; |
| 888 | unsigned int nr_conns = rxrpc_nr_client_conns; |
| 889 | unsigned int nr_active, limit; |
| 890 | |
| 891 | _enter(""); |
| 892 | |
| 893 | ASSERTCMP(nr_conns, >=, 0); |
| 894 | if (nr_conns < rxrpc_max_client_connections) { |
| 895 | _leave(" [ok]"); |
| 896 | return; |
| 897 | } |
| 898 | limit = rxrpc_reap_client_connections; |
| 899 | |
| 900 | spin_lock(&rxrpc_client_conn_cache_lock); |
| 901 | nr_active = rxrpc_nr_active_client_conns; |
| 902 | |
| 903 | while (nr_active > limit) { |
| 904 | ASSERT(!list_empty(&rxrpc_active_client_conns)); |
| 905 | conn = list_entry(rxrpc_active_client_conns.next, |
| 906 | struct rxrpc_connection, cache_link); |
| 907 | ASSERTCMP(conn->cache_state, ==, RXRPC_CONN_CLIENT_ACTIVE); |
| 908 | |
| 909 | if (list_empty(&conn->waiting_calls)) { |
| 910 | conn->cache_state = RXRPC_CONN_CLIENT_CULLED; |
| 911 | list_del_init(&conn->cache_link); |
| 912 | } else { |
| 913 | conn->cache_state = RXRPC_CONN_CLIENT_WAITING; |
| 914 | list_move_tail(&conn->cache_link, |
| 915 | &rxrpc_waiting_client_conns); |
| 916 | } |
| 917 | |
| 918 | nr_active--; |
| 919 | } |
| 920 | |
| 921 | rxrpc_nr_active_client_conns = nr_active; |
| 922 | spin_unlock(&rxrpc_client_conn_cache_lock); |
| 923 | ASSERTCMP(nr_active, >=, 0); |
| 924 | _leave(" [culled]"); |
| 925 | } |
| 926 | |
| 927 | /* |
| 928 | * Discard expired client connections from the idle list. Each conn in the |
| 929 | * idle list has been exposed and holds an extra ref because of that. |
| 930 | * |
| 931 | * This may be called from conn setup or from a work item so cannot be |
| 932 | * considered non-reentrant. |
| 933 | */ |
| 934 | static void rxrpc_discard_expired_client_conns(struct work_struct *work) |
| 935 | { |
| 936 | struct rxrpc_connection *conn; |
| 937 | unsigned long expiry, conn_expires_at, now; |
| 938 | unsigned int nr_conns; |
| 939 | bool did_discard = false; |
| 940 | |
| 941 | _enter("%c", work ? 'w' : 'n'); |
| 942 | |
| 943 | if (list_empty(&rxrpc_idle_client_conns)) { |
| 944 | _leave(" [empty]"); |
| 945 | return; |
| 946 | } |
| 947 | |
| 948 | /* Don't double up on the discarding */ |
| 949 | if (!spin_trylock(&rxrpc_client_conn_discard_mutex)) { |
| 950 | _leave(" [already]"); |
| 951 | return; |
| 952 | } |
| 953 | |
| 954 | /* We keep an estimate of what the number of conns ought to be after |
| 955 | * we've discarded some so that we don't overdo the discarding. |
| 956 | */ |
| 957 | nr_conns = rxrpc_nr_client_conns; |
| 958 | |
| 959 | next: |
| 960 | spin_lock(&rxrpc_client_conn_cache_lock); |
| 961 | |
| 962 | if (list_empty(&rxrpc_idle_client_conns)) |
| 963 | goto out; |
| 964 | |
| 965 | conn = list_entry(rxrpc_idle_client_conns.next, |
| 966 | struct rxrpc_connection, cache_link); |
| 967 | ASSERT(test_bit(RXRPC_CONN_EXPOSED, &conn->flags)); |
| 968 | |
| 969 | if (!rxrpc_kill_all_client_conns) { |
| 970 | /* If the number of connections is over the reap limit, we |
| 971 | * expedite discard by reducing the expiry timeout. We must, |
| 972 | * however, have at least a short grace period to be able to do |
| 973 | * final-ACK or ABORT retransmission. |
| 974 | */ |
| 975 | expiry = rxrpc_conn_idle_client_expiry; |
| 976 | if (nr_conns > rxrpc_reap_client_connections) |
| 977 | expiry = rxrpc_conn_idle_client_fast_expiry; |
| 978 | |
| 979 | conn_expires_at = conn->idle_timestamp + expiry; |
| 980 | |
| 981 | now = READ_ONCE(jiffies); |
| 982 | if (time_after(conn_expires_at, now)) |
| 983 | goto not_yet_expired; |
| 984 | } |
| 985 | |
| 986 | _debug("discard conn %d", conn->debug_id); |
| 987 | if (!test_and_clear_bit(RXRPC_CONN_EXPOSED, &conn->flags)) |
| 988 | BUG(); |
| 989 | conn->cache_state = RXRPC_CONN_CLIENT_INACTIVE; |
| 990 | list_del_init(&conn->cache_link); |
| 991 | |
| 992 | spin_unlock(&rxrpc_client_conn_cache_lock); |
| 993 | |
| 994 | /* When we cleared the EXPOSED flag, we took on responsibility for the |
| 995 | * reference that that had on the usage count. We deal with that here. |
| 996 | * If someone re-sets the flag and re-gets the ref, that's fine. |
| 997 | */ |
| 998 | rxrpc_put_connection(conn); |
| 999 | did_discard = true; |
| 1000 | nr_conns--; |
| 1001 | goto next; |
| 1002 | |
| 1003 | not_yet_expired: |
| 1004 | /* The connection at the front of the queue hasn't yet expired, so |
| 1005 | * schedule the work item for that point if we discarded something. |
| 1006 | * |
| 1007 | * We don't worry if the work item is already scheduled - it can look |
| 1008 | * after rescheduling itself at a later time. We could cancel it, but |
| 1009 | * then things get messier. |
| 1010 | */ |
| 1011 | _debug("not yet"); |
| 1012 | if (!rxrpc_kill_all_client_conns) |
| 1013 | queue_delayed_work(rxrpc_workqueue, |
| 1014 | &rxrpc_client_conn_reap, |
| 1015 | conn_expires_at - now); |
| 1016 | |
| 1017 | out: |
| 1018 | spin_unlock(&rxrpc_client_conn_cache_lock); |
| 1019 | spin_unlock(&rxrpc_client_conn_discard_mutex); |
| 1020 | _leave(""); |
| 1021 | } |
| 1022 | |
| 1023 | /* |
| 1024 | * Preemptively destroy all the client connection records rather than waiting |
| 1025 | * for them to time out |
| 1026 | */ |
| 1027 | void __exit rxrpc_destroy_all_client_connections(void) |
| 1028 | { |
| 1029 | _enter(""); |
| 1030 | |
| 1031 | spin_lock(&rxrpc_client_conn_cache_lock); |
| 1032 | rxrpc_kill_all_client_conns = true; |
| 1033 | spin_unlock(&rxrpc_client_conn_cache_lock); |
| 1034 | |
| 1035 | cancel_delayed_work(&rxrpc_client_conn_reap); |
| 1036 | |
| 1037 | if (!queue_delayed_work(rxrpc_workqueue, &rxrpc_client_conn_reap, 0)) |
| 1038 | _debug("destroy: queue failed"); |
| 1039 | |
| 1040 | _leave(""); |
David Howells | 001c112 | 2016-06-30 10:45:22 +0100 | [diff] [blame] | 1041 | } |