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18 * http://www.gnu.org/licenses/gpl-2.0.html
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 lnet_handle_eq_t *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(lnet_event_t));
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(lnet_event_t));
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(lnet_handle_eq_t eqh)
155 lnet_event_t *events = NULL;
162 LASSERT(the_lnet.ln_refcount > 0);
164 lnet_res_lock(LNET_LOCK_EX);
165 /* NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do
166 * both EQ lookup and poll event with only lnet_eq_wait_lock */
169 eq = lnet_handle2eq(&eqh);
175 cfs_percpt_for_each(ref, i, eq->eq_refs) {
180 CDEBUG(D_NET, "Event equeue (%d: %d) busy on destroy.\n",
186 /* stash for free after lock dropped */
187 events = eq->eq_events;
191 lnet_res_lh_invalidate(&eq->eq_lh);
192 list_del(&eq->eq_list);
195 lnet_eq_wait_unlock();
196 lnet_res_unlock(LNET_LOCK_EX);
199 LIBCFS_FREE(events, size * sizeof(lnet_event_t));
201 cfs_percpt_free(refs);
205 EXPORT_SYMBOL(LNetEQFree);
208 lnet_eq_enqueue_event(lnet_eq_t *eq, lnet_event_t *ev)
210 /* MUST called with resource lock hold but w/o lnet_eq_wait_lock */
213 if (eq->eq_size == 0) {
214 LASSERT(eq->eq_callback != LNET_EQ_HANDLER_NONE);
220 ev->sequence = eq->eq_enq_seq++;
222 LASSERT(eq->eq_size == LOWEST_BIT_SET(eq->eq_size));
223 index = ev->sequence & (eq->eq_size - 1);
225 eq->eq_events[index] = *ev;
227 if (eq->eq_callback != LNET_EQ_HANDLER_NONE)
230 /* Wake anyone waiting in LNetEQPoll() */
231 if (waitqueue_active(&the_lnet.ln_eq_waitq))
232 wake_up_all(&the_lnet.ln_eq_waitq);
233 lnet_eq_wait_unlock();
237 lnet_eq_dequeue_event(lnet_eq_t *eq, lnet_event_t *ev)
239 int new_index = eq->eq_deq_seq & (eq->eq_size - 1);
240 lnet_event_t *new_event = &eq->eq_events[new_index];
244 /* must called with lnet_eq_wait_lock hold */
245 if (LNET_SEQ_GT(eq->eq_deq_seq, new_event->sequence))
248 /* We've got a new event... */
251 CDEBUG(D_INFO, "event: %p, sequence: %lu, eq->size: %u\n",
252 new_event, eq->eq_deq_seq, eq->eq_size);
254 /* ...but did it overwrite an event we've not seen yet? */
255 if (eq->eq_deq_seq == new_event->sequence) {
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);
265 eq->eq_deq_seq = new_event->sequence + 1;
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.
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.
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.
286 LNetEQGet (lnet_handle_eq_t eventq, lnet_event_t *event)
290 return LNetEQPoll(&eventq, 1, 0,
293 EXPORT_SYMBOL(LNetEQGet);
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.
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.
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.
312 LNetEQWait (lnet_handle_eq_t eventq, lnet_event_t *event)
316 return LNetEQPoll(&eventq, 1, MAX_SCHEDULE_TIMEOUT,
319 EXPORT_SYMBOL(LNetEQWait);
322 lnet_eq_wait_locked(signed long *timeout)
323 __must_hold(&the_lnet.ln_eq_wait_lock)
325 signed long tms = *timeout;
330 return -ENXIO; /* don't want to wait and no new event */
332 init_waitqueue_entry(&wl, current);
333 add_wait_queue(&the_lnet.ln_eq_waitq, &wl);
335 lnet_eq_wait_unlock();
337 tms = schedule_timeout_interruptible(tms);
338 wait = tms != 0; /* 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 Time in jiffies to wait for an event to occur on
360 * one of the EQs. The constant MAX_SCHEDULE_TIMEOUT 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(lnet_handle_eq_t *eventqs, int neq, signed long timeout,
375 lnet_event_t *event, int *which)
382 LASSERT(the_lnet.ln_refcount > 0);
390 for (i = 0; i < neq; i++) {
391 lnet_eq_t *eq = lnet_handle2eq(&eventqs[i]);
394 lnet_eq_wait_unlock();
398 rc = lnet_eq_dequeue_event(eq, event);
400 lnet_eq_wait_unlock();
410 * return value of lnet_eq_wait_locked:
411 * -1 : did nothing and it's sure no new event
412 * 1 : sleep inside and wait until new event
413 * 0 : don't want to wait anymore, but might have new event
414 * so need to call dequeue again
416 wait = lnet_eq_wait_locked(&timeout);
417 if (wait < 0) /* no new event */
421 lnet_eq_wait_unlock();