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 /* count can be 0 if only need callback, we can eliminate 88 * overhead of enqueue event */ 89 if (count == 0 && callback == LNET_EQ_HANDLER_NONE) 90 return -EINVAL; 91 92 eq = lnet_eq_alloc(); 93 if (eq == NULL) 94 return -ENOMEM; 95 96 if (count != 0) { 97 LIBCFS_ALLOC(eq->eq_events, count * sizeof(lnet_event_t)); 98 if (eq->eq_events == NULL) 99 goto failed; 100 /* NB allocator has set all event sequence numbers to 0, 101 * so all them should be earlier than eq_deq_seq */ 102 } 103 104 eq->eq_deq_seq = 1; 105 eq->eq_enq_seq = 1; 106 eq->eq_size = count; 107 eq->eq_callback = callback; 108 109 eq->eq_refs = cfs_percpt_alloc(lnet_cpt_table(), 110 sizeof(*eq->eq_refs[0])); 111 if (eq->eq_refs == NULL) 112 goto failed; 113 114 /* MUST hold both exclusive lnet_res_lock */ 115 lnet_res_lock(LNET_LOCK_EX); 116 /* NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do 117 * both EQ lookup and poll event with only lnet_eq_wait_lock */ 118 lnet_eq_wait_lock(); 119 120 lnet_res_lh_initialize(&the_lnet.ln_eq_container, &eq->eq_lh); 121 list_add(&eq->eq_list, &the_lnet.ln_eq_container.rec_active); 122 123 lnet_eq_wait_unlock(); 124 lnet_res_unlock(LNET_LOCK_EX); 125 126 lnet_eq2handle(handle, eq); 127 return 0; 128 129failed: 130 if (eq->eq_events != NULL) 131 LIBCFS_FREE(eq->eq_events, count * sizeof(lnet_event_t)); 132 133 if (eq->eq_refs != NULL) 134 cfs_percpt_free(eq->eq_refs); 135 136 lnet_eq_free(eq); 137 return -ENOMEM; 138} 139EXPORT_SYMBOL(LNetEQAlloc); 140 141/** 142 * Release the resources associated with an event queue if it's idle; 143 * otherwise do nothing and it's up to the user to try again. 144 * 145 * \param eqh A handle for the event queue to be released. 146 * 147 * \retval 0 If the EQ is not in use and freed. 148 * \retval -ENOENT If \a eqh does not point to a valid EQ. 149 * \retval -EBUSY If the EQ is still in use by some MDs. 150 */ 151int 152LNetEQFree(lnet_handle_eq_t eqh) 153{ 154 struct lnet_eq *eq; 155 lnet_event_t *events = NULL; 156 int **refs = NULL; 157 int *ref; 158 int rc = 0; 159 int size = 0; 160 int i; 161 162 LASSERT(the_lnet.ln_init); 163 LASSERT(the_lnet.ln_refcount > 0); 164 165 lnet_res_lock(LNET_LOCK_EX); 166 /* NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do 167 * both EQ lookup and poll event with only lnet_eq_wait_lock */ 168 lnet_eq_wait_lock(); 169 170 eq = lnet_handle2eq(&eqh); 171 if (eq == NULL) { 172 rc = -ENOENT; 173 goto out; 174 } 175 176 cfs_percpt_for_each(ref, i, eq->eq_refs) { 177 LASSERT(*ref >= 0); 178 if (*ref == 0) 179 continue; 180 181 CDEBUG(D_NET, "Event equeue (%d: %d) busy on destroy.\n", 182 i, *ref); 183 rc = -EBUSY; 184 goto out; 185 } 186 187 /* stash for free after lock dropped */ 188 events = eq->eq_events; 189 size = eq->eq_size; 190 refs = eq->eq_refs; 191 192 lnet_res_lh_invalidate(&eq->eq_lh); 193 list_del(&eq->eq_list); 194 lnet_eq_free_locked(eq); 195 out: 196 lnet_eq_wait_unlock(); 197 lnet_res_unlock(LNET_LOCK_EX); 198 199 if (events != NULL) 200 LIBCFS_FREE(events, size * sizeof(lnet_event_t)); 201 if (refs != NULL) 202 cfs_percpt_free(refs); 203 204 return rc; 205} 206EXPORT_SYMBOL(LNetEQFree); 207 208void 209lnet_eq_enqueue_event(lnet_eq_t *eq, lnet_event_t *ev) 210{ 211 /* MUST called with resource lock hold but w/o lnet_eq_wait_lock */ 212 int index; 213 214 if (eq->eq_size == 0) { 215 LASSERT(eq->eq_callback != LNET_EQ_HANDLER_NONE); 216 eq->eq_callback(ev); 217 return; 218 } 219 220 lnet_eq_wait_lock(); 221 ev->sequence = eq->eq_enq_seq++; 222 223 LASSERT(eq->eq_size == LOWEST_BIT_SET(eq->eq_size)); 224 index = ev->sequence & (eq->eq_size - 1); 225 226 eq->eq_events[index] = *ev; 227 228 if (eq->eq_callback != LNET_EQ_HANDLER_NONE) 229 eq->eq_callback(ev); 230 231 /* Wake anyone waiting in LNetEQPoll() */ 232 if (waitqueue_active(&the_lnet.ln_eq_waitq)) 233 wake_up_all(&the_lnet.ln_eq_waitq); 234 lnet_eq_wait_unlock(); 235} 236 237static int 238lnet_eq_dequeue_event(lnet_eq_t *eq, lnet_event_t *ev) 239{ 240 int new_index = eq->eq_deq_seq & (eq->eq_size - 1); 241 lnet_event_t *new_event = &eq->eq_events[new_index]; 242 int rc; 243 244 /* must called with lnet_eq_wait_lock hold */ 245 if (LNET_SEQ_GT(eq->eq_deq_seq, new_event->sequence)) 246 return 0; 247 248 /* We've got a new event... */ 249 *ev = *new_event; 250 251 CDEBUG(D_INFO, "event: %p, sequence: %lu, eq->size: %u\n", 252 new_event, eq->eq_deq_seq, eq->eq_size); 253 254 /* ...but did it overwrite an event we've not seen yet? */ 255 if (eq->eq_deq_seq == new_event->sequence) { 256 rc = 1; 257 } else { 258 /* don't complain with CERROR: some EQs are sized small 259 * anyway; if it's important, the caller should complain */ 260 CDEBUG(D_NET, "Event Queue Overflow: eq seq %lu ev seq %lu\n", 261 eq->eq_deq_seq, new_event->sequence); 262 rc = -EOVERFLOW; 263 } 264 265 eq->eq_deq_seq = new_event->sequence + 1; 266 return rc; 267} 268 269/** 270 * A nonblocking function that can be used to get the next event in an EQ. 271 * If an event handler is associated with the EQ, the handler will run before 272 * this function returns successfully. The event is removed from the queue. 273 * 274 * \param eventq A handle for the event queue. 275 * \param event On successful return (1 or -EOVERFLOW), this location will 276 * hold the next event in the EQ. 277 * 278 * \retval 0 No pending event in the EQ. 279 * \retval 1 Indicates success. 280 * \retval -ENOENT If \a eventq does not point to a valid EQ. 281 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that 282 * at least one event between this event and the last event obtained from the 283 * EQ has been dropped due to limited space in the EQ. 284 */ 285int 286LNetEQGet(lnet_handle_eq_t eventq, lnet_event_t *event) 287{ 288 int which; 289 290 return LNetEQPoll(&eventq, 1, 0, 291 event, &which); 292} 293EXPORT_SYMBOL(LNetEQGet); 294 295/** 296 * Block the calling process until there is an event in the EQ. 297 * If an event handler is associated with the EQ, the handler will run before 298 * this function returns successfully. This function returns the next event 299 * in the EQ and removes it from the EQ. 300 * 301 * \param eventq A handle for the event queue. 302 * \param event On successful return (1 or -EOVERFLOW), this location will 303 * hold the next event in the EQ. 304 * 305 * \retval 1 Indicates success. 306 * \retval -ENOENT If \a eventq does not point to a valid EQ. 307 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that 308 * at least one event between this event and the last event obtained from the 309 * EQ has been dropped due to limited space in the EQ. 310 */ 311int 312LNetEQWait(lnet_handle_eq_t eventq, lnet_event_t *event) 313{ 314 int which; 315 316 return LNetEQPoll(&eventq, 1, LNET_TIME_FOREVER, 317 event, &which); 318} 319EXPORT_SYMBOL(LNetEQWait); 320 321 322static int 323lnet_eq_wait_locked(int *timeout_ms) 324__must_hold(&the_lnet.ln_eq_wait_lock) 325{ 326 int tms = *timeout_ms; 327 int wait; 328 wait_queue_t wl; 329 unsigned long now; 330 331 if (tms == 0) 332 return -1; /* don't want to wait and no new event */ 333 334 init_waitqueue_entry(&wl, current); 335 set_current_state(TASK_INTERRUPTIBLE); 336 add_wait_queue(&the_lnet.ln_eq_waitq, &wl); 337 338 lnet_eq_wait_unlock(); 339 340 if (tms < 0) { 341 schedule(); 342 343 } else { 344 struct timeval tv; 345 346 now = cfs_time_current(); 347 schedule_timeout(cfs_time_seconds(tms) / 1000); 348 cfs_duration_usec(cfs_time_sub(cfs_time_current(), now), &tv); 349 tms -= (int)(tv.tv_sec * 1000 + tv.tv_usec / 1000); 350 if (tms < 0) /* no more wait but may have new event */ 351 tms = 0; 352 } 353 354 wait = tms != 0; /* might need to call here again */ 355 *timeout_ms = tms; 356 357 lnet_eq_wait_lock(); 358 remove_wait_queue(&the_lnet.ln_eq_waitq, &wl); 359 360 return wait; 361} 362 363 364 365/** 366 * Block the calling process until there's an event from a set of EQs or 367 * timeout happens. 368 * 369 * If an event handler is associated with the EQ, the handler will run before 370 * this function returns successfully, in which case the corresponding event 371 * is consumed. 372 * 373 * LNetEQPoll() provides a timeout to allow applications to poll, block for a 374 * fixed period, or block indefinitely. 375 * 376 * \param eventqs,neq An array of EQ handles, and size of the array. 377 * \param timeout_ms Time in milliseconds to wait for an event to occur on 378 * one of the EQs. The constant LNET_TIME_FOREVER can be used to indicate an 379 * infinite timeout. 380 * \param event,which On successful return (1 or -EOVERFLOW), \a event will 381 * hold the next event in the EQs, and \a which will contain the index of the 382 * EQ from which the event was taken. 383 * 384 * \retval 0 No pending event in the EQs after timeout. 385 * \retval 1 Indicates success. 386 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that 387 * at least one event between this event and the last event obtained from the 388 * EQ indicated by \a which has been dropped due to limited space in the EQ. 389 * \retval -ENOENT If there's an invalid handle in \a eventqs. 390 */ 391int 392LNetEQPoll(lnet_handle_eq_t *eventqs, int neq, int timeout_ms, 393 lnet_event_t *event, int *which) 394{ 395 int wait = 1; 396 int rc; 397 int i; 398 399 LASSERT(the_lnet.ln_init); 400 LASSERT(the_lnet.ln_refcount > 0); 401 402 if (neq < 1) 403 return -ENOENT; 404 405 lnet_eq_wait_lock(); 406 407 for (;;) { 408 for (i = 0; i < neq; i++) { 409 lnet_eq_t *eq = lnet_handle2eq(&eventqs[i]); 410 411 if (eq == NULL) { 412 lnet_eq_wait_unlock(); 413 return -ENOENT; 414 } 415 416 rc = lnet_eq_dequeue_event(eq, event); 417 if (rc != 0) { 418 lnet_eq_wait_unlock(); 419 *which = i; 420 return rc; 421 } 422 } 423 424 if (wait == 0) 425 break; 426 427 /* 428 * return value of lnet_eq_wait_locked: 429 * -1 : did nothing and it's sure no new event 430 * 1 : sleep inside and wait until new event 431 * 0 : don't want to wait anymore, but might have new event 432 * so need to call dequeue again 433 */ 434 wait = lnet_eq_wait_locked(&timeout_ms); 435 if (wait < 0) /* no new event */ 436 break; 437 } 438 439 lnet_eq_wait_unlock(); 440 return 0; 441} 442