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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 "../../include/linux/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_init);
76 LASSERT(the_lnet.ln_refcount > 0);
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 */
82 count = cfs_power2_roundup(count);
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);
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_init);
163 LASSERT(the_lnet.ln_refcount > 0);
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 */
170 eq = lnet_handle2eq(&eqh);
176 cfs_percpt_for_each(ref, i, eq->eq_refs) {
181 CDEBUG(D_NET, "Event equeue (%d: %d) busy on destroy.\n",
187 /* stash for free after lock dropped */
188 events = eq->eq_events;
192 lnet_res_lh_invalidate(&eq->eq_lh);
193 list_del(&eq->eq_list);
194 lnet_eq_free_locked(eq);
196 lnet_eq_wait_unlock();
197 lnet_res_unlock(LNET_LOCK_EX);
200 LIBCFS_FREE(events, size * sizeof(lnet_event_t));
202 cfs_percpt_free(refs);
206 EXPORT_SYMBOL(LNetEQFree);
209 lnet_eq_enqueue_event(lnet_eq_t *eq, lnet_event_t *ev)
211 /* MUST called with resource lock hold but w/o lnet_eq_wait_lock */
214 if (eq->eq_size == 0) {
215 LASSERT(eq->eq_callback != LNET_EQ_HANDLER_NONE);
221 ev->sequence = eq->eq_enq_seq++;
223 LASSERT(eq->eq_size == LOWEST_BIT_SET(eq->eq_size));
224 index = ev->sequence & (eq->eq_size - 1);
226 eq->eq_events[index] = *ev;
228 if (eq->eq_callback != LNET_EQ_HANDLER_NONE)
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();
238 lnet_eq_dequeue_event(lnet_eq_t *eq, lnet_event_t *ev)
240 int new_index = eq->eq_deq_seq & (eq->eq_size - 1);
241 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, LNET_TIME_FOREVER,
319 EXPORT_SYMBOL(LNetEQWait);
323 lnet_eq_wait_locked(int *timeout_ms)
324 __must_hold(&the_lnet.ln_eq_wait_lock)
326 int tms = *timeout_ms;
332 return -1; /* don't want to wait and no new event */
334 init_waitqueue_entry(&wl, current);
335 set_current_state(TASK_INTERRUPTIBLE);
336 add_wait_queue(&the_lnet.ln_eq_waitq, &wl);
338 lnet_eq_wait_unlock();
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 */
354 wait = tms != 0; /* might need to call here again */
358 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)
399 LASSERT(the_lnet.ln_init);
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();