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 */
69 int
LNetEQAlloc(unsigned int count,lnet_eq_handler_t callback,lnet_handle_eq_t * handle)70 LNetEQAlloc(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
129 failed:
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 }
139 EXPORT_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 */
151 int
LNetEQFree(lnet_handle_eq_t eqh)152 LNetEQFree(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 }
206 EXPORT_SYMBOL(LNetEQFree);
207
208 void
lnet_eq_enqueue_event(lnet_eq_t * eq,lnet_event_t * ev)209 lnet_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
237 static int
lnet_eq_dequeue_event(lnet_eq_t * eq,lnet_event_t * ev)238 lnet_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 */
285 int
LNetEQGet(lnet_handle_eq_t eventq,lnet_event_t * event)286 LNetEQGet(lnet_handle_eq_t eventq, lnet_event_t *event)
287 {
288 int which;
289
290 return LNetEQPoll(&eventq, 1, 0,
291 event, &which);
292 }
293 EXPORT_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 */
311 int
LNetEQWait(lnet_handle_eq_t eventq,lnet_event_t * event)312 LNetEQWait(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 }
319 EXPORT_SYMBOL(LNetEQWait);
320
321
322 static int
lnet_eq_wait_locked(int * timeout_ms)323 lnet_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 */
391 int
LNetEQPoll(lnet_handle_eq_t * eventqs,int neq,int timeout_ms,lnet_event_t * event,int * which)392 LNetEQPoll(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