1/* 2 * GPL HEADER START 3 * 4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 only, 8 * as published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, but 11 * WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 * General Public License version 2 for more details (a copy is included 14 * in the LICENSE file that accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License 17 * version 2 along with this program; If not, see 18 * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf 19 * 20 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, 21 * CA 95054 USA or visit www.sun.com if you need additional information or 22 * have any questions. 23 * 24 * GPL HEADER END 25 */ 26/* 27 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved. 28 * Use is subject to license terms. 29 * 30 * Copyright (c) 2012, Intel Corporation. 31 */ 32/* 33 * This file is part of Lustre, http://www.lustre.org/ 34 * Lustre is a trademark of Sun Microsystems, Inc. 35 * 36 * lnet/lnet/lib-eq.c 37 * 38 * Library level Event queue management routines 39 */ 40 41#define DEBUG_SUBSYSTEM S_LNET 42#include "../../include/linux/lnet/lib-lnet.h" 43 44/** 45 * Create an event queue that has room for \a count number of events. 46 * 47 * The event queue is circular and older events will be overwritten by new 48 * ones if they are not removed in time by the user using the functions 49 * LNetEQGet(), LNetEQWait(), or LNetEQPoll(). It is up to the user to 50 * determine the appropriate size of the event queue to prevent this loss 51 * of events. Note that when EQ handler is specified in \a callback, no 52 * event loss can happen, since the handler is run for each event deposited 53 * into the EQ. 54 * 55 * \param count The number of events to be stored in the event queue. It 56 * will be rounded up to the next power of two. 57 * \param callback A handler function that runs when an event is deposited 58 * into the EQ. The constant value LNET_EQ_HANDLER_NONE can be used to 59 * indicate that no event handler is desired. 60 * \param handle On successful return, this location will hold a handle for 61 * the newly created EQ. 62 * 63 * \retval 0 On success. 64 * \retval -EINVAL If an parameter is not valid. 65 * \retval -ENOMEM If memory for the EQ can't be allocated. 66 * 67 * \see lnet_eq_handler_t for the discussion on EQ handler semantics. 68 */ 69int 70LNetEQAlloc(unsigned int count, lnet_eq_handler_t callback, 71 lnet_handle_eq_t *handle) 72{ 73 lnet_eq_t *eq; 74 75 LASSERT(the_lnet.ln_init); 76 LASSERT(the_lnet.ln_refcount > 0); 77 78 /* We need count to be a power of 2 so that when eq_{enq,deq}_seq 79 * overflow, they don't skip entries, so the queue has the same 80 * apparent capacity at all times */ 81 82 count = cfs_power2_roundup(count); 83 84 if (callback != LNET_EQ_HANDLER_NONE && count != 0) { 85 CWARN("EQ callback is guaranteed to get every event, do you still want to set eqcount %d for polling event which will have locking overhead? Please contact with developer to confirm\n", count); 86 } 87 88 /* count can be 0 if only need callback, we can eliminate 89 * overhead of enqueue event */ 90 if (count == 0 && callback == LNET_EQ_HANDLER_NONE) 91 return -EINVAL; 92 93 eq = lnet_eq_alloc(); 94 if (eq == NULL) 95 return -ENOMEM; 96 97 if (count != 0) { 98 LIBCFS_ALLOC(eq->eq_events, count * sizeof(lnet_event_t)); 99 if (eq->eq_events == NULL) 100 goto failed; 101 /* NB allocator has set all event sequence numbers to 0, 102 * so all them should be earlier than eq_deq_seq */ 103 } 104 105 eq->eq_deq_seq = 1; 106 eq->eq_enq_seq = 1; 107 eq->eq_size = count; 108 eq->eq_callback = callback; 109 110 eq->eq_refs = cfs_percpt_alloc(lnet_cpt_table(), 111 sizeof(*eq->eq_refs[0])); 112 if (eq->eq_refs == NULL) 113 goto failed; 114 115 /* MUST hold both exclusive lnet_res_lock */ 116 lnet_res_lock(LNET_LOCK_EX); 117 /* NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do 118 * both EQ lookup and poll event with only lnet_eq_wait_lock */ 119 lnet_eq_wait_lock(); 120 121 lnet_res_lh_initialize(&the_lnet.ln_eq_container, &eq->eq_lh); 122 list_add(&eq->eq_list, &the_lnet.ln_eq_container.rec_active); 123 124 lnet_eq_wait_unlock(); 125 lnet_res_unlock(LNET_LOCK_EX); 126 127 lnet_eq2handle(handle, eq); 128 return 0; 129 130failed: 131 if (eq->eq_events != NULL) 132 LIBCFS_FREE(eq->eq_events, count * sizeof(lnet_event_t)); 133 134 if (eq->eq_refs != NULL) 135 cfs_percpt_free(eq->eq_refs); 136 137 lnet_eq_free(eq); 138 return -ENOMEM; 139} 140EXPORT_SYMBOL(LNetEQAlloc); 141 142/** 143 * Release the resources associated with an event queue if it's idle; 144 * otherwise do nothing and it's up to the user to try again. 145 * 146 * \param eqh A handle for the event queue to be released. 147 * 148 * \retval 0 If the EQ is not in use and freed. 149 * \retval -ENOENT If \a eqh does not point to a valid EQ. 150 * \retval -EBUSY If the EQ is still in use by some MDs. 151 */ 152int 153LNetEQFree(lnet_handle_eq_t eqh) 154{ 155 struct lnet_eq *eq; 156 lnet_event_t *events = NULL; 157 int **refs = NULL; 158 int *ref; 159 int rc = 0; 160 int size = 0; 161 int i; 162 163 LASSERT(the_lnet.ln_init); 164 LASSERT(the_lnet.ln_refcount > 0); 165 166 lnet_res_lock(LNET_LOCK_EX); 167 /* NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do 168 * both EQ lookup and poll event with only lnet_eq_wait_lock */ 169 lnet_eq_wait_lock(); 170 171 eq = lnet_handle2eq(&eqh); 172 if (eq == NULL) { 173 rc = -ENOENT; 174 goto out; 175 } 176 177 cfs_percpt_for_each(ref, i, eq->eq_refs) { 178 LASSERT(*ref >= 0); 179 if (*ref == 0) 180 continue; 181 182 CDEBUG(D_NET, "Event equeue (%d: %d) busy on destroy.\n", 183 i, *ref); 184 rc = -EBUSY; 185 goto out; 186 } 187 188 /* stash for free after lock dropped */ 189 events = eq->eq_events; 190 size = eq->eq_size; 191 refs = eq->eq_refs; 192 193 lnet_res_lh_invalidate(&eq->eq_lh); 194 list_del(&eq->eq_list); 195 lnet_eq_free_locked(eq); 196 out: 197 lnet_eq_wait_unlock(); 198 lnet_res_unlock(LNET_LOCK_EX); 199 200 if (events != NULL) 201 LIBCFS_FREE(events, size * sizeof(lnet_event_t)); 202 if (refs != NULL) 203 cfs_percpt_free(refs); 204 205 return rc; 206} 207EXPORT_SYMBOL(LNetEQFree); 208 209void 210lnet_eq_enqueue_event(lnet_eq_t *eq, lnet_event_t *ev) 211{ 212 /* MUST called with resource lock hold but w/o lnet_eq_wait_lock */ 213 int index; 214 215 if (eq->eq_size == 0) { 216 LASSERT(eq->eq_callback != LNET_EQ_HANDLER_NONE); 217 eq->eq_callback(ev); 218 return; 219 } 220 221 lnet_eq_wait_lock(); 222 ev->sequence = eq->eq_enq_seq++; 223 224 LASSERT(eq->eq_size == LOWEST_BIT_SET(eq->eq_size)); 225 index = ev->sequence & (eq->eq_size - 1); 226 227 eq->eq_events[index] = *ev; 228 229 if (eq->eq_callback != LNET_EQ_HANDLER_NONE) 230 eq->eq_callback(ev); 231 232 /* Wake anyone waiting in LNetEQPoll() */ 233 if (waitqueue_active(&the_lnet.ln_eq_waitq)) 234 wake_up_all(&the_lnet.ln_eq_waitq); 235 lnet_eq_wait_unlock(); 236} 237 238static int 239lnet_eq_dequeue_event(lnet_eq_t *eq, lnet_event_t *ev) 240{ 241 int new_index = eq->eq_deq_seq & (eq->eq_size - 1); 242 lnet_event_t *new_event = &eq->eq_events[new_index]; 243 int rc; 244 245 /* must called with lnet_eq_wait_lock hold */ 246 if (LNET_SEQ_GT(eq->eq_deq_seq, new_event->sequence)) 247 return 0; 248 249 /* We've got a new event... */ 250 *ev = *new_event; 251 252 CDEBUG(D_INFO, "event: %p, sequence: %lu, eq->size: %u\n", 253 new_event, eq->eq_deq_seq, eq->eq_size); 254 255 /* ...but did it overwrite an event we've not seen yet? */ 256 if (eq->eq_deq_seq == new_event->sequence) { 257 rc = 1; 258 } else { 259 /* don't complain with CERROR: some EQs are sized small 260 * anyway; if it's important, the caller should complain */ 261 CDEBUG(D_NET, "Event Queue Overflow: eq seq %lu ev seq %lu\n", 262 eq->eq_deq_seq, new_event->sequence); 263 rc = -EOVERFLOW; 264 } 265 266 eq->eq_deq_seq = new_event->sequence + 1; 267 return rc; 268} 269 270/** 271 * A nonblocking function that can be used to get the next event in an EQ. 272 * If an event handler is associated with the EQ, the handler will run before 273 * this function returns successfully. The event is removed from the queue. 274 * 275 * \param eventq A handle for the event queue. 276 * \param event On successful return (1 or -EOVERFLOW), this location will 277 * hold the next event in the EQ. 278 * 279 * \retval 0 No pending event in the EQ. 280 * \retval 1 Indicates success. 281 * \retval -ENOENT If \a eventq does not point to a valid EQ. 282 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that 283 * at least one event between this event and the last event obtained from the 284 * EQ has been dropped due to limited space in the EQ. 285 */ 286int 287LNetEQGet(lnet_handle_eq_t eventq, lnet_event_t *event) 288{ 289 int which; 290 291 return LNetEQPoll(&eventq, 1, 0, 292 event, &which); 293} 294EXPORT_SYMBOL(LNetEQGet); 295 296/** 297 * Block the calling process until there is an event in the EQ. 298 * If an event handler is associated with the EQ, the handler will run before 299 * this function returns successfully. This function returns the next event 300 * in the EQ and removes it from the EQ. 301 * 302 * \param eventq A handle for the event queue. 303 * \param event On successful return (1 or -EOVERFLOW), this location will 304 * hold the next event in the EQ. 305 * 306 * \retval 1 Indicates success. 307 * \retval -ENOENT If \a eventq does not point to a valid EQ. 308 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that 309 * at least one event between this event and the last event obtained from the 310 * EQ has been dropped due to limited space in the EQ. 311 */ 312int 313LNetEQWait(lnet_handle_eq_t eventq, lnet_event_t *event) 314{ 315 int which; 316 317 return LNetEQPoll(&eventq, 1, LNET_TIME_FOREVER, 318 event, &which); 319} 320EXPORT_SYMBOL(LNetEQWait); 321 322 323static int 324lnet_eq_wait_locked(int *timeout_ms) 325__must_hold(&the_lnet.ln_eq_wait_lock) 326{ 327 int tms = *timeout_ms; 328 int wait; 329 wait_queue_t wl; 330 unsigned long now; 331 332 if (tms == 0) 333 return -1; /* don't want to wait and no new event */ 334 335 init_waitqueue_entry(&wl, current); 336 set_current_state(TASK_INTERRUPTIBLE); 337 add_wait_queue(&the_lnet.ln_eq_waitq, &wl); 338 339 lnet_eq_wait_unlock(); 340 341 if (tms < 0) { 342 schedule(); 343 344 } else { 345 struct timeval tv; 346 347 now = cfs_time_current(); 348 schedule_timeout(cfs_time_seconds(tms) / 1000); 349 cfs_duration_usec(cfs_time_sub(cfs_time_current(), now), &tv); 350 tms -= (int)(tv.tv_sec * 1000 + tv.tv_usec / 1000); 351 if (tms < 0) /* no more wait but may have new event */ 352 tms = 0; 353 } 354 355 wait = tms != 0; /* might need to call here again */ 356 *timeout_ms = tms; 357 358 lnet_eq_wait_lock(); 359 remove_wait_queue(&the_lnet.ln_eq_waitq, &wl); 360 361 return wait; 362} 363 364 365 366/** 367 * Block the calling process until there's an event from a set of EQs or 368 * timeout happens. 369 * 370 * If an event handler is associated with the EQ, the handler will run before 371 * this function returns successfully, in which case the corresponding event 372 * is consumed. 373 * 374 * LNetEQPoll() provides a timeout to allow applications to poll, block for a 375 * fixed period, or block indefinitely. 376 * 377 * \param eventqs,neq An array of EQ handles, and size of the array. 378 * \param timeout_ms Time in milliseconds to wait for an event to occur on 379 * one of the EQs. The constant LNET_TIME_FOREVER can be used to indicate an 380 * infinite timeout. 381 * \param event,which On successful return (1 or -EOVERFLOW), \a event will 382 * hold the next event in the EQs, and \a which will contain the index of the 383 * EQ from which the event was taken. 384 * 385 * \retval 0 No pending event in the EQs after timeout. 386 * \retval 1 Indicates success. 387 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that 388 * at least one event between this event and the last event obtained from the 389 * EQ indicated by \a which has been dropped due to limited space in the EQ. 390 * \retval -ENOENT If there's an invalid handle in \a eventqs. 391 */ 392int 393LNetEQPoll(lnet_handle_eq_t *eventqs, int neq, int timeout_ms, 394 lnet_event_t *event, int *which) 395{ 396 int wait = 1; 397 int rc; 398 int i; 399 400 LASSERT(the_lnet.ln_init); 401 LASSERT(the_lnet.ln_refcount > 0); 402 403 if (neq < 1) 404 return -ENOENT; 405 406 lnet_eq_wait_lock(); 407 408 for (;;) { 409 for (i = 0; i < neq; i++) { 410 lnet_eq_t *eq = lnet_handle2eq(&eventqs[i]); 411 412 if (eq == NULL) { 413 lnet_eq_wait_unlock(); 414 return -ENOENT; 415 } 416 417 rc = lnet_eq_dequeue_event(eq, event); 418 if (rc != 0) { 419 lnet_eq_wait_unlock(); 420 *which = i; 421 return rc; 422 } 423 } 424 425 if (wait == 0) 426 break; 427 428 /* 429 * return value of lnet_eq_wait_locked: 430 * -1 : did nothing and it's sure no new event 431 * 1 : sleep inside and wait until new event 432 * 0 : don't want to wait anymore, but might have new event 433 * so need to call dequeue again 434 */ 435 wait = lnet_eq_wait_locked(&timeout_ms); 436 if (wait < 0) /* no new event */ 437 break; 438 } 439 440 lnet_eq_wait_unlock(); 441 return 0; 442} 443