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13 * General Public License version 2 for more details (a copy is included
14 * in the LICENSE file that accompanied this code).
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.gnu.org/licenses/gpl-2.0.html
23 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
24 * Use is subject to license terms.
26 * Copyright (c) 2012, Intel Corporation.
29 * This file is part of Lustre, http://www.lustre.org/
30 * Lustre is a trademark of Sun Microsystems, Inc.
34 * Library level Event queue management routines
37 #define DEBUG_SUBSYSTEM S_LNET
39 #include <linux/lnet/lib-lnet.h>
42 * Create an event queue that has room for \a count number of events.
44 * The event queue is circular and older events will be overwritten by new
45 * ones if they are not removed in time by the user using the functions
46 * LNetEQGet(), LNetEQWait(), or LNetEQPoll(). It is up to the user to
47 * determine the appropriate size of the event queue to prevent this loss
48 * of events. Note that when EQ handler is specified in \a callback, no
49 * event loss can happen, since the handler is run for each event deposited
52 * \param count The number of events to be stored in the event queue. It
53 * will be rounded up to the next power of two.
54 * \param callback A handler function that runs when an event is deposited
55 * into the EQ. The constant value LNET_EQ_HANDLER_NONE can be used to
56 * indicate that no event handler is desired.
57 * \param handle On successful return, this location will hold a handle for
58 * the newly created EQ.
60 * \retval 0 On success.
61 * \retval -EINVAL If an parameter is not valid.
62 * \retval -ENOMEM If memory for the EQ can't be allocated.
64 * \see lnet_eq_handler_t for the discussion on EQ handler semantics.
67 LNetEQAlloc(unsigned int count, lnet_eq_handler_t callback,
68 struct lnet_handle_eq *handle)
72 LASSERT(the_lnet.ln_refcount > 0);
75 * We need count to be a power of 2 so that when eq_{enq,deq}_seq
76 * overflow, they don't skip entries, so the queue has the same
77 * apparent capacity at all times
80 count = roundup_pow_of_two(count);
82 if (callback != LNET_EQ_HANDLER_NONE && count)
83 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 * count can be 0 if only need callback, we can eliminate
87 * overhead of enqueue event
89 if (!count && callback == LNET_EQ_HANDLER_NONE)
97 LIBCFS_ALLOC(eq->eq_events, count * sizeof(struct lnet_event));
101 * NB allocator has set all event sequence numbers to 0,
102 * so all them should be earlier than eq_deq_seq
109 eq->eq_callback = callback;
111 eq->eq_refs = cfs_percpt_alloc(lnet_cpt_table(),
112 sizeof(*eq->eq_refs[0]));
116 /* MUST hold both exclusive lnet_res_lock */
117 lnet_res_lock(LNET_LOCK_EX);
119 * NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do
120 * both EQ lookup and poll event with only lnet_eq_wait_lock
124 lnet_res_lh_initialize(&the_lnet.ln_eq_container, &eq->eq_lh);
125 list_add(&eq->eq_list, &the_lnet.ln_eq_container.rec_active);
127 lnet_eq_wait_unlock();
128 lnet_res_unlock(LNET_LOCK_EX);
130 lnet_eq2handle(handle, eq);
135 LIBCFS_FREE(eq->eq_events, count * sizeof(struct lnet_event));
138 cfs_percpt_free(eq->eq_refs);
143 EXPORT_SYMBOL(LNetEQAlloc);
146 * Release the resources associated with an event queue if it's idle;
147 * otherwise do nothing and it's up to the user to try again.
149 * \param eqh A handle for the event queue to be released.
151 * \retval 0 If the EQ is not in use and freed.
152 * \retval -ENOENT If \a eqh does not point to a valid EQ.
153 * \retval -EBUSY If the EQ is still in use by some MDs.
156 LNetEQFree(struct lnet_handle_eq eqh)
159 struct lnet_event *events = NULL;
166 LASSERT(the_lnet.ln_refcount > 0);
168 lnet_res_lock(LNET_LOCK_EX);
170 * NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do
171 * both EQ lookup and poll event with only lnet_eq_wait_lock
175 eq = lnet_handle2eq(&eqh);
181 cfs_percpt_for_each(ref, i, eq->eq_refs) {
186 CDEBUG(D_NET, "Event equeue (%d: %d) busy on destroy.\n",
192 /* stash for free after lock dropped */
193 events = eq->eq_events;
197 lnet_res_lh_invalidate(&eq->eq_lh);
198 list_del(&eq->eq_list);
201 lnet_eq_wait_unlock();
202 lnet_res_unlock(LNET_LOCK_EX);
205 LIBCFS_FREE(events, size * sizeof(struct lnet_event));
207 cfs_percpt_free(refs);
211 EXPORT_SYMBOL(LNetEQFree);
214 lnet_eq_enqueue_event(struct lnet_eq *eq, struct lnet_event *ev)
216 /* MUST called with resource lock hold but w/o lnet_eq_wait_lock */
220 LASSERT(eq->eq_callback != LNET_EQ_HANDLER_NONE);
226 ev->sequence = eq->eq_enq_seq++;
228 LASSERT(eq->eq_size == LOWEST_BIT_SET(eq->eq_size));
229 index = ev->sequence & (eq->eq_size - 1);
231 eq->eq_events[index] = *ev;
233 if (eq->eq_callback != LNET_EQ_HANDLER_NONE)
236 /* Wake anyone waiting in LNetEQPoll() */
237 if (waitqueue_active(&the_lnet.ln_eq_waitq))
238 wake_up_all(&the_lnet.ln_eq_waitq);
239 lnet_eq_wait_unlock();
243 lnet_eq_dequeue_event(struct lnet_eq *eq, struct lnet_event *ev)
245 int new_index = eq->eq_deq_seq & (eq->eq_size - 1);
246 struct lnet_event *new_event = &eq->eq_events[new_index];
249 /* must called with lnet_eq_wait_lock hold */
250 if (LNET_SEQ_GT(eq->eq_deq_seq, new_event->sequence))
253 /* We've got a new event... */
256 CDEBUG(D_INFO, "event: %p, sequence: %lu, eq->size: %u\n",
257 new_event, eq->eq_deq_seq, eq->eq_size);
259 /* ...but did it overwrite an event we've not seen yet? */
260 if (eq->eq_deq_seq == new_event->sequence) {
264 * don't complain with CERROR: some EQs are sized small
265 * anyway; if it's important, the caller should complain
267 CDEBUG(D_NET, "Event Queue Overflow: eq seq %lu ev seq %lu\n",
268 eq->eq_deq_seq, new_event->sequence);
272 eq->eq_deq_seq = new_event->sequence + 1;
277 * A nonblocking function that can be used to get the next event in an EQ.
278 * If an event handler is associated with the EQ, the handler will run before
279 * this function returns successfully. The event is removed from the queue.
281 * \param eventq A handle for the event queue.
282 * \param event On successful return (1 or -EOVERFLOW), this location will
283 * hold the next event in the EQ.
285 * \retval 0 No pending event in the EQ.
286 * \retval 1 Indicates success.
287 * \retval -ENOENT If \a eventq does not point to a valid EQ.
288 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
289 * at least one event between this event and the last event obtained from the
290 * EQ has been dropped due to limited space in the EQ.
294 * Block the calling process until there is an event in the EQ.
295 * If an event handler is associated with the EQ, the handler will run before
296 * this function returns successfully. This function returns the next event
297 * in the EQ and removes it from the EQ.
299 * \param eventq A handle for the event queue.
300 * \param event On successful return (1 or -EOVERFLOW), this location will
301 * hold the next event in the EQ.
303 * \retval 1 Indicates success.
304 * \retval -ENOENT If \a eventq does not point to a valid EQ.
305 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
306 * at least one event between this event and the last event obtained from the
307 * EQ has been dropped due to limited space in the EQ.
311 lnet_eq_wait_locked(int *timeout_ms)
312 __must_hold(&the_lnet.ln_eq_wait_lock)
314 int tms = *timeout_ms;
316 wait_queue_entry_t wl;
320 return -ENXIO; /* don't want to wait and no new event */
322 init_waitqueue_entry(&wl, current);
323 set_current_state(TASK_INTERRUPTIBLE);
324 add_wait_queue(&the_lnet.ln_eq_waitq, &wl);
326 lnet_eq_wait_unlock();
332 schedule_timeout(msecs_to_jiffies(tms));
333 tms -= jiffies_to_msecs(jiffies - now);
334 if (tms < 0) /* no more wait but may have new event */
338 wait = tms; /* might need to call here again */
342 remove_wait_queue(&the_lnet.ln_eq_waitq, &wl);
348 * Block the calling process until there's an event from a set of EQs or
351 * If an event handler is associated with the EQ, the handler will run before
352 * this function returns successfully, in which case the corresponding event
355 * LNetEQPoll() provides a timeout to allow applications to poll, block for a
356 * fixed period, or block indefinitely.
358 * \param eventqs,neq An array of EQ handles, and size of the array.
359 * \param timeout_ms Time in milliseconds to wait for an event to occur on
360 * one of the EQs. The constant LNET_TIME_FOREVER can be used to indicate an
362 * \param event,which On successful return (1 or -EOVERFLOW), \a event will
363 * hold the next event in the EQs, and \a which will contain the index of the
364 * EQ from which the event was taken.
366 * \retval 0 No pending event in the EQs after timeout.
367 * \retval 1 Indicates success.
368 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
369 * at least one event between this event and the last event obtained from the
370 * EQ indicated by \a which has been dropped due to limited space in the EQ.
371 * \retval -ENOENT If there's an invalid handle in \a eventqs.
374 LNetEQPoll(struct lnet_handle_eq *eventqs, int neq, int timeout_ms,
375 struct lnet_event *event, int *which)
381 LASSERT(the_lnet.ln_refcount > 0);
389 for (i = 0; i < neq; i++) {
390 struct lnet_eq *eq = lnet_handle2eq(&eventqs[i]);
393 lnet_eq_wait_unlock();
397 rc = lnet_eq_dequeue_event(eq, event);
399 lnet_eq_wait_unlock();
409 * return value of lnet_eq_wait_locked:
410 * -1 : did nothing and it's sure no new event
411 * 1 : sleep inside and wait until new event
412 * 0 : don't want to wait anymore, but might have new event
413 * so need to call dequeue again
415 wait = lnet_eq_wait_locked(&timeout_ms);
416 if (wait < 0) /* no new event */
420 lnet_eq_wait_unlock();