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23 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
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26 * Copyright (c) 2012, 2016, 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
38 #include <lnet/lib-lnet.h>
41 * Create an event queue that has room for \a count number of events.
43 * The event queue is circular and older events will be overwritten by new
44 * ones if they are not removed in time by the user using the functions
45 * LNetEQGet(), LNetEQWait(), or LNetEQPoll(). It is up to the user to
46 * determine the appropriate size of the event queue to prevent this loss
47 * of events. Note that when EQ handler is specified in \a callback, no
48 * event loss can happen, since the handler is run for each event deposited
51 * \param count The number of events to be stored in the event queue. It
52 * will be rounded up to the next power of two.
53 * \param callback A handler function that runs when an event is deposited
54 * into the EQ. The constant value LNET_EQ_HANDLER_NONE can be used to
55 * indicate that no event handler is desired.
56 * \param handle On successful return, this location will hold a handle for
57 * the newly created EQ.
59 * \retval 0 On success.
60 * \retval -EINVAL If an parameter is not valid.
61 * \retval -ENOMEM If memory for the EQ can't be allocated.
63 * \see lnet_eq_handler_t for the discussion on EQ handler semantics.
66 LNetEQAlloc(unsigned int count, lnet_eq_handler_t callback,
67 struct lnet_handle_eq *handle)
71 LASSERT(the_lnet.ln_refcount > 0);
73 /* We need count to be a power of 2 so that when eq_{enq,deq}_seq
74 * overflow, they don't skip entries, so the queue has the same
75 * apparent capacity at all times */
78 count = roundup_pow_of_two(count);
80 if (callback != LNET_EQ_HANDLER_NONE && count != 0) {
81 CWARN("EQ callback is guaranteed to get every event, "
82 "do you still want to set eqcount %d for polling "
83 "event which will have locking overhead? "
84 "Please contact with developer to confirm\n", count);
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)
97 LIBCFS_ALLOC(eq->eq_events, count * sizeof(*eq->eq_events));
98 if (eq->eq_events == NULL)
100 /* NB allocator has set all event sequence numbers to 0,
101 * so all them should be earlier than eq_deq_seq */
107 eq->eq_callback = callback;
109 eq->eq_refs = cfs_percpt_alloc(lnet_cpt_table(),
110 sizeof(*eq->eq_refs[0]));
111 if (eq->eq_refs == NULL)
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 */
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);
123 lnet_eq_wait_unlock();
124 lnet_res_unlock(LNET_LOCK_EX);
126 lnet_eq2handle(handle, eq);
130 if (eq->eq_events != NULL)
131 LIBCFS_FREE(eq->eq_events, count * sizeof(*eq->eq_events));
133 if (eq->eq_refs != NULL)
134 cfs_percpt_free(eq->eq_refs);
139 EXPORT_SYMBOL(LNetEQAlloc);
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.
145 * \param eqh A handle for the event queue to be released.
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.
152 LNetEQFree(struct lnet_handle_eq eqh)
155 struct lnet_event *events = NULL;
162 lnet_res_lock(LNET_LOCK_EX);
163 /* NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do
164 * both EQ lookup and poll event with only lnet_eq_wait_lock */
167 eq = lnet_handle2eq(&eqh);
173 cfs_percpt_for_each(ref, i, eq->eq_refs) {
178 CDEBUG(D_NET, "Event equeue (%d: %d) busy on destroy.\n",
184 /* stash for free after lock dropped */
185 events = eq->eq_events;
189 lnet_res_lh_invalidate(&eq->eq_lh);
190 list_del(&eq->eq_list);
193 lnet_eq_wait_unlock();
194 lnet_res_unlock(LNET_LOCK_EX);
197 LIBCFS_FREE(events, size * sizeof(*events));
199 cfs_percpt_free(refs);
203 EXPORT_SYMBOL(LNetEQFree);
206 lnet_eq_enqueue_event(struct lnet_eq *eq, struct lnet_event *ev)
208 /* MUST called with resource lock hold but w/o lnet_eq_wait_lock */
211 if (eq->eq_size == 0) {
212 LASSERT(eq->eq_callback != LNET_EQ_HANDLER_NONE);
218 ev->sequence = eq->eq_enq_seq++;
220 LASSERT(eq->eq_size == LOWEST_BIT_SET(eq->eq_size));
221 index = ev->sequence & (eq->eq_size - 1);
223 eq->eq_events[index] = *ev;
225 if (eq->eq_callback != LNET_EQ_HANDLER_NONE)
228 /* Wake anyone waiting in LNetEQPoll() */
229 if (waitqueue_active(&the_lnet.ln_eq_waitq))
230 wake_up_all(&the_lnet.ln_eq_waitq);
231 lnet_eq_wait_unlock();
235 lnet_eq_dequeue_event(struct lnet_eq *eq, struct lnet_event *ev)
237 int new_index = eq->eq_deq_seq & (eq->eq_size - 1);
238 struct lnet_event *new_event = &eq->eq_events[new_index];
242 /* must called with lnet_eq_wait_lock hold */
243 if (LNET_SEQ_GT(eq->eq_deq_seq, new_event->sequence))
246 /* We've got a new event... */
249 CDEBUG(D_INFO, "event: %p, sequence: %lu, eq->size: %u\n",
250 new_event, eq->eq_deq_seq, eq->eq_size);
252 /* ...but did it overwrite an event we've not seen yet? */
253 if (eq->eq_deq_seq == new_event->sequence) {
256 /* don't complain with CERROR: some EQs are sized small
257 * anyway; if it's important, the caller should complain */
258 CDEBUG(D_NET, "Event Queue Overflow: eq seq %lu ev seq %lu\n",
259 eq->eq_deq_seq, new_event->sequence);
263 eq->eq_deq_seq = new_event->sequence + 1;
268 * A nonblocking function that can be used to get the next event in an EQ.
269 * If an event handler is associated with the EQ, the handler will run before
270 * this function returns successfully. The event is removed from the queue.
272 * \param eventq A handle for the event queue.
273 * \param event On successful return (1 or -EOVERFLOW), this location will
274 * hold the next event in the EQ.
276 * \retval 0 No pending event in the EQ.
277 * \retval 1 Indicates success.
278 * \retval -ENOENT If \a eventq does not point to a valid EQ.
279 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
280 * at least one event between this event and the last event obtained from the
281 * EQ has been dropped due to limited space in the EQ.
284 LNetEQGet(struct lnet_handle_eq eventq, struct lnet_event *event)
288 return LNetEQPoll(&eventq, 1, 0,
291 EXPORT_SYMBOL(LNetEQGet);
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.
310 LNetEQWait(struct lnet_handle_eq eventq, struct lnet_event *event)
314 return LNetEQPoll(&eventq, 1, MAX_SCHEDULE_TIMEOUT,
317 EXPORT_SYMBOL(LNetEQWait);
320 lnet_eq_wait_locked(signed long *timeout)
321 __must_hold(&the_lnet.ln_eq_wait_lock)
323 signed long tms = *timeout;
324 wait_queue_entry_t wl;
328 return -ENXIO; /* don't want to wait and no new event */
330 init_waitqueue_entry(&wl, current);
331 add_wait_queue(&the_lnet.ln_eq_waitq, &wl);
333 lnet_eq_wait_unlock();
335 tms = schedule_timeout_interruptible(tms);
336 wait = tms != 0; /* might need to call here again */
340 remove_wait_queue(&the_lnet.ln_eq_waitq, &wl);
346 * Block the calling process until there's an event from a set of EQs or
349 * If an event handler is associated with the EQ, the handler will run before
350 * this function returns successfully, in which case the corresponding event
353 * LNetEQPoll() provides a timeout to allow applications to poll, block for a
354 * fixed period, or block indefinitely.
356 * \param eventqs,neq An array of EQ handles, and size of the array.
357 * \param timeout Time in jiffies to wait for an event to occur on
358 * one of the EQs. The constant MAX_SCHEDULE_TIMEOUT can be used to indicate an
360 * \param event,which On successful return (1 or -EOVERFLOW), \a event will
361 * hold the next event in the EQs, and \a which will contain the index of the
362 * EQ from which the event was taken.
364 * \retval 0 No pending event in the EQs after timeout.
365 * \retval 1 Indicates success.
366 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
367 * at least one event between this event and the last event obtained from the
368 * EQ indicated by \a which has been dropped due to limited space in the EQ.
369 * \retval -ENOENT If there's an invalid handle in \a eventqs.
372 LNetEQPoll(struct lnet_handle_eq *eventqs, int neq, signed long timeout,
373 struct lnet_event *event, int *which)
380 LASSERT(the_lnet.ln_refcount > 0);
388 for (i = 0; i < neq; i++) {
389 struct lnet_eq *eq = lnet_handle2eq(&eventqs[i]);
392 lnet_eq_wait_unlock();
396 rc = lnet_eq_dequeue_event(eq, event);
398 lnet_eq_wait_unlock();
408 * return value of lnet_eq_wait_locked:
409 * -1 : did nothing and it's sure no new event
410 * 1 : sleep inside and wait until new event
411 * 0 : don't want to wait anymore, but might have new event
412 * so need to call dequeue again
414 wait = lnet_eq_wait_locked(&timeout);
415 if (wait < 0) /* no new event */
419 lnet_eq_wait_unlock();