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27 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
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30 * Copyright (c) 2012, Intel Corporation.
33 * This file is part of Lustre, http://www.lustre.org/
34 * Lustre is a trademark of Sun Microsystems, Inc.
38 * Library level Event queue management routines
41 #define DEBUG_SUBSYSTEM S_LNET
42 #include <lnet/lib-lnet.h>
45 * Create an event queue that has room for \a count number of events.
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
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.
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.
67 * \see lnet_eq_handler_t for the discussion on EQ handler semantics.
70 LNetEQAlloc(unsigned int count, lnet_eq_handler_t callback,
71 lnet_handle_eq_t *handle)
75 LASSERT (the_lnet.ln_refcount > 0);
77 /* We need count to be a power of 2 so that when eq_{enq,deq}_seq
78 * overflow, they don't skip entries, so the queue has the same
79 * apparent capacity at all times */
82 count = roundup_pow_of_two(count);
84 if (callback != LNET_EQ_HANDLER_NONE && count != 0) {
85 CWARN("EQ callback is guaranteed to get every event, "
86 "do you still want to set eqcount %d for polling "
87 "event which will have locking overhead? "
88 "Please contact with developer to confirm\n", count);
91 /* count can be 0 if only need callback, we can eliminate
92 * overhead of enqueue event */
93 if (count == 0 && callback == LNET_EQ_HANDLER_NONE)
101 LIBCFS_ALLOC(eq->eq_events, count * sizeof(lnet_event_t));
102 if (eq->eq_events == NULL)
104 /* NB allocator has set all event sequence numbers to 0,
105 * so all them should be earlier than eq_deq_seq */
111 eq->eq_callback = callback;
113 eq->eq_refs = cfs_percpt_alloc(lnet_cpt_table(),
114 sizeof(*eq->eq_refs[0]));
115 if (eq->eq_refs == NULL)
118 /* MUST hold both exclusive lnet_res_lock */
119 lnet_res_lock(LNET_LOCK_EX);
120 /* NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do
121 * 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);
134 if (eq->eq_events != NULL)
135 LIBCFS_FREE(eq->eq_events, count * sizeof(lnet_event_t));
137 if (eq->eq_refs != NULL)
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(lnet_handle_eq_t eqh)
159 lnet_event_t *events = NULL;
166 LASSERT(the_lnet.ln_refcount > 0);
168 lnet_res_lock(LNET_LOCK_EX);
169 /* NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do
170 * both EQ lookup and poll event with only lnet_eq_wait_lock */
173 eq = lnet_handle2eq(&eqh);
179 cfs_percpt_for_each(ref, i, eq->eq_refs) {
184 CDEBUG(D_NET, "Event equeue (%d: %d) busy on destroy.\n",
190 /* stash for free after lock dropped */
191 events = eq->eq_events;
195 lnet_res_lh_invalidate(&eq->eq_lh);
196 list_del(&eq->eq_list);
199 lnet_eq_wait_unlock();
200 lnet_res_unlock(LNET_LOCK_EX);
203 LIBCFS_FREE(events, size * sizeof(lnet_event_t));
205 cfs_percpt_free(refs);
209 EXPORT_SYMBOL(LNetEQFree);
212 lnet_eq_enqueue_event(lnet_eq_t *eq, lnet_event_t *ev)
214 /* MUST called with resource lock hold but w/o lnet_eq_wait_lock */
217 if (eq->eq_size == 0) {
218 LASSERT(eq->eq_callback != LNET_EQ_HANDLER_NONE);
224 ev->sequence = eq->eq_enq_seq++;
226 LASSERT(eq->eq_size == LOWEST_BIT_SET(eq->eq_size));
227 index = ev->sequence & (eq->eq_size - 1);
229 eq->eq_events[index] = *ev;
231 if (eq->eq_callback != LNET_EQ_HANDLER_NONE)
234 /* Wake anyone waiting in LNetEQPoll() */
235 if (waitqueue_active(&the_lnet.ln_eq_waitq))
236 wake_up_all(&the_lnet.ln_eq_waitq);
237 lnet_eq_wait_unlock();
241 lnet_eq_dequeue_event(lnet_eq_t *eq, lnet_event_t *ev)
243 int new_index = eq->eq_deq_seq & (eq->eq_size - 1);
244 lnet_event_t *new_event = &eq->eq_events[new_index];
248 /* must called with lnet_eq_wait_lock hold */
249 if (LNET_SEQ_GT(eq->eq_deq_seq, new_event->sequence))
252 /* We've got a new event... */
255 CDEBUG(D_INFO, "event: %p, sequence: %lu, eq->size: %u\n",
256 new_event, eq->eq_deq_seq, eq->eq_size);
258 /* ...but did it overwrite an event we've not seen yet? */
259 if (eq->eq_deq_seq == new_event->sequence) {
262 /* don't complain with CERROR: some EQs are sized small
263 * anyway; if it's important, the caller should complain */
264 CDEBUG(D_NET, "Event Queue Overflow: eq seq %lu ev seq %lu\n",
265 eq->eq_deq_seq, new_event->sequence);
269 eq->eq_deq_seq = new_event->sequence + 1;
274 * A nonblocking function that can be used to get the next event in an EQ.
275 * If an event handler is associated with the EQ, the handler will run before
276 * this function returns successfully. The event is removed from the queue.
278 * \param eventq A handle for the event queue.
279 * \param event On successful return (1 or -EOVERFLOW), this location will
280 * hold the next event in the EQ.
282 * \retval 0 No pending event in the EQ.
283 * \retval 1 Indicates success.
284 * \retval -ENOENT If \a eventq does not point to a valid EQ.
285 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
286 * at least one event between this event and the last event obtained from the
287 * EQ has been dropped due to limited space in the EQ.
290 LNetEQGet (lnet_handle_eq_t eventq, lnet_event_t *event)
294 return LNetEQPoll(&eventq, 1, 0,
297 EXPORT_SYMBOL(LNetEQGet);
300 * Block the calling process until there is an event in the EQ.
301 * If an event handler is associated with the EQ, the handler will run before
302 * this function returns successfully. This function returns the next event
303 * in the EQ and removes it from the EQ.
305 * \param eventq A handle for the event queue.
306 * \param event On successful return (1 or -EOVERFLOW), this location will
307 * hold the next event in the EQ.
309 * \retval 1 Indicates success.
310 * \retval -ENOENT If \a eventq does not point to a valid EQ.
311 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
312 * at least one event between this event and the last event obtained from the
313 * EQ has been dropped due to limited space in the EQ.
316 LNetEQWait (lnet_handle_eq_t eventq, lnet_event_t *event)
320 return LNetEQPoll(&eventq, 1, LNET_TIME_FOREVER,
323 EXPORT_SYMBOL(LNetEQWait);
326 lnet_eq_wait_locked(int *timeout_ms)
327 __must_hold(&the_lnet.ln_eq_wait_lock)
329 int tms = *timeout_ms;
335 return -ENXIO; /* don't want to wait and no new event */
337 init_waitqueue_entry(&wl, current);
338 set_current_state(TASK_INTERRUPTIBLE);
339 add_wait_queue(&the_lnet.ln_eq_waitq, &wl);
341 lnet_eq_wait_unlock();
348 now = cfs_time_current();
349 schedule_timeout(cfs_time_seconds(tms) / 1000);
350 cfs_duration_usec(cfs_time_sub(cfs_time_current(), now), &tv);
351 tms -= (int)(tv.tv_sec * 1000 + tv.tv_usec / 1000);
352 if (tms < 0) /* no more wait but may have new event */
356 wait = tms != 0; /* might need to call here again */
360 remove_wait_queue(&the_lnet.ln_eq_waitq, &wl);
366 * Block the calling process until there's an event from a set of EQs or
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
373 * LNetEQPoll() provides a timeout to allow applications to poll, block for a
374 * fixed period, or block indefinitely.
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
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.
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.
392 LNetEQPoll(lnet_handle_eq_t *eventqs, int neq, int timeout_ms,
393 lnet_event_t *event, int *which)
400 LASSERT (the_lnet.ln_refcount > 0);
408 for (i = 0; i < neq; i++) {
409 lnet_eq_t *eq = lnet_handle2eq(&eventqs[i]);
412 lnet_eq_wait_unlock();
416 rc = lnet_eq_dequeue_event(eq, event);
418 lnet_eq_wait_unlock();
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
434 wait = lnet_eq_wait_locked(&timeout_ms);
435 if (wait < 0) /* no new event */
439 lnet_eq_wait_unlock();