[deliverable/linux.git] / drivers / staging / lustre / lnet / lnet / lib-eq.c

/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License version 2 for more details (a copy is included
 * in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; If not, see
 * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2012, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 *
 * lnet/lnet/lib-eq.c
 *
 * Library level Event queue management routines
 */

#define DEBUG_SUBSYSTEM S_LNET
#include "../../include/linux/lnet/lib-lnet.h"

/**
 * Create an event queue that has room for \a count number of events.
 *
 * The event queue is circular and older events will be overwritten by new
 * ones if they are not removed in time by the user using the functions
 * LNetEQGet(), LNetEQWait(), or LNetEQPoll(). It is up to the user to
 * determine the appropriate size of the event queue to prevent this loss
 * of events. Note that when EQ handler is specified in \a callback, no
 * event loss can happen, since the handler is run for each event deposited
 * into the EQ.
 *
 * \param count The number of events to be stored in the event queue. It
 * will be rounded up to the next power of two.
 * \param callback A handler function that runs when an event is deposited
 * into the EQ. The constant value LNET_EQ_HANDLER_NONE can be used to
 * indicate that no event handler is desired.
 * \param handle On successful return, this location will hold a handle for
 * the newly created EQ.
 *
 * \retval 0       On success.
 * \retval -EINVAL If an parameter is not valid.
 * \retval -ENOMEM If memory for the EQ can't be allocated.
 *
 * \see lnet_eq_handler_t for the discussion on EQ handler semantics.
 */
int
LNetEQAlloc(unsigned int count, lnet_eq_handler_t callback,
	    lnet_handle_eq_t *handle)
{
	lnet_eq_t *eq;

	LASSERT(the_lnet.ln_init);
	LASSERT(the_lnet.ln_refcount > 0);

	/*
	 * We need count to be a power of 2 so that when eq_{enq,deq}_seq
	 * overflow, they don't skip entries, so the queue has the same
	 * apparent capacity at all times
	 */
	if (count)
		count = roundup_pow_of_two(count);

	if (callback != LNET_EQ_HANDLER_NONE && count != 0)
		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);

	/*
	 * count can be 0 if only need callback, we can eliminate
	 * overhead of enqueue event
	 */
	if (count == 0 && callback == LNET_EQ_HANDLER_NONE)
		return -EINVAL;

	eq = lnet_eq_alloc();
	if (!eq)
		return -ENOMEM;

	if (count != 0) {
		LIBCFS_ALLOC(eq->eq_events, count * sizeof(lnet_event_t));
		if (!eq->eq_events)
			goto failed;
		/*
		 * NB allocator has set all event sequence numbers to 0,
		 * so all them should be earlier than eq_deq_seq
		 */
	}

	eq->eq_deq_seq = 1;
	eq->eq_enq_seq = 1;
	eq->eq_size = count;
	eq->eq_callback = callback;

	eq->eq_refs = cfs_percpt_alloc(lnet_cpt_table(),
				       sizeof(*eq->eq_refs[0]));
	if (!eq->eq_refs)
		goto failed;

	/* MUST hold both exclusive lnet_res_lock */
	lnet_res_lock(LNET_LOCK_EX);
	/*
	 * NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do
	 * both EQ lookup and poll event with only lnet_eq_wait_lock
	 */
	lnet_eq_wait_lock();

	lnet_res_lh_initialize(&the_lnet.ln_eq_container, &eq->eq_lh);
	list_add(&eq->eq_list, &the_lnet.ln_eq_container.rec_active);

	lnet_eq_wait_unlock();
	lnet_res_unlock(LNET_LOCK_EX);

	lnet_eq2handle(handle, eq);
	return 0;

failed:
	if (eq->eq_events)
		LIBCFS_FREE(eq->eq_events, count * sizeof(lnet_event_t));

	if (eq->eq_refs)
		cfs_percpt_free(eq->eq_refs);

	lnet_eq_free(eq);
	return -ENOMEM;
}
EXPORT_SYMBOL(LNetEQAlloc);

/**
 * Release the resources associated with an event queue if it's idle;
 * otherwise do nothing and it's up to the user to try again.
 *
 * \param eqh A handle for the event queue to be released.
 *
 * \retval 0 If the EQ is not in use and freed.
 * \retval -ENOENT If \a eqh does not point to a valid EQ.
 * \retval -EBUSY  If the EQ is still in use by some MDs.
 */
int
LNetEQFree(lnet_handle_eq_t eqh)
{
	struct lnet_eq *eq;
	lnet_event_t *events = NULL;
	int **refs = NULL;
	int *ref;
	int rc = 0;
	int size = 0;
	int i;

	LASSERT(the_lnet.ln_init);
	LASSERT(the_lnet.ln_refcount > 0);

	lnet_res_lock(LNET_LOCK_EX);
	/*
	 * NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do
	 * both EQ lookup and poll event with only lnet_eq_wait_lock
	 */
	lnet_eq_wait_lock();

	eq = lnet_handle2eq(&eqh);
	if (!eq) {
		rc = -ENOENT;
		goto out;
	}

	cfs_percpt_for_each(ref, i, eq->eq_refs) {
		LASSERT(*ref >= 0);
		if (*ref == 0)
			continue;

		CDEBUG(D_NET, "Event equeue (%d: %d) busy on destroy.\n",
		       i, *ref);
		rc = -EBUSY;
		goto out;
	}

	/* stash for free after lock dropped */
	events = eq->eq_events;
	size = eq->eq_size;
	refs = eq->eq_refs;

	lnet_res_lh_invalidate(&eq->eq_lh);
	list_del(&eq->eq_list);
	lnet_eq_free(eq);
 out:
	lnet_eq_wait_unlock();
	lnet_res_unlock(LNET_LOCK_EX);

	if (events)
		LIBCFS_FREE(events, size * sizeof(lnet_event_t));
	if (refs)
		cfs_percpt_free(refs);

	return rc;
}
EXPORT_SYMBOL(LNetEQFree);

void
lnet_eq_enqueue_event(lnet_eq_t *eq, lnet_event_t *ev)
{
	/* MUST called with resource lock hold but w/o lnet_eq_wait_lock */
	int index;

	if (eq->eq_size == 0) {
		LASSERT(eq->eq_callback != LNET_EQ_HANDLER_NONE);
		eq->eq_callback(ev);
		return;
	}

	lnet_eq_wait_lock();
	ev->sequence = eq->eq_enq_seq++;

	LASSERT(eq->eq_size == LOWEST_BIT_SET(eq->eq_size));
	index = ev->sequence & (eq->eq_size - 1);

	eq->eq_events[index] = *ev;

	if (eq->eq_callback != LNET_EQ_HANDLER_NONE)
		eq->eq_callback(ev);

	/* Wake anyone waiting in LNetEQPoll() */
	if (waitqueue_active(&the_lnet.ln_eq_waitq))
		wake_up_all(&the_lnet.ln_eq_waitq);
	lnet_eq_wait_unlock();
}

static int
lnet_eq_dequeue_event(lnet_eq_t *eq, lnet_event_t *ev)
{
	int new_index = eq->eq_deq_seq & (eq->eq_size - 1);
	lnet_event_t *new_event = &eq->eq_events[new_index];
	int rc;

	/* must called with lnet_eq_wait_lock hold */
	if (LNET_SEQ_GT(eq->eq_deq_seq, new_event->sequence))
		return 0;

	/* We've got a new event... */
	*ev = *new_event;

	CDEBUG(D_INFO, "event: %p, sequence: %lu, eq->size: %u\n",
	       new_event, eq->eq_deq_seq, eq->eq_size);

	/* ...but did it overwrite an event we've not seen yet? */
	if (eq->eq_deq_seq == new_event->sequence) {
		rc = 1;
	} else {
		/*
		 * don't complain with CERROR: some EQs are sized small
		 * anyway; if it's important, the caller should complain
		 */
		CDEBUG(D_NET, "Event Queue Overflow: eq seq %lu ev seq %lu\n",
		       eq->eq_deq_seq, new_event->sequence);
		rc = -EOVERFLOW;
	}

	eq->eq_deq_seq = new_event->sequence + 1;
	return rc;
}

/**
 * A nonblocking function that can be used to get the next event in an EQ.
 * If an event handler is associated with the EQ, the handler will run before
 * this function returns successfully. The event is removed from the queue.
 *
 * \param eventq A handle for the event queue.
 * \param event On successful return (1 or -EOVERFLOW), this location will
 * hold the next event in the EQ.
 *
 * \retval 0	  No pending event in the EQ.
 * \retval 1	  Indicates success.
 * \retval -ENOENT    If \a eventq does not point to a valid EQ.
 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
 * at least one event between this event and the last event obtained from the
 * EQ has been dropped due to limited space in the EQ.
 */

/**
 * Block the calling process until there is an event in the EQ.
 * If an event handler is associated with the EQ, the handler will run before
 * this function returns successfully. This function returns the next event
 * in the EQ and removes it from the EQ.
 *
 * \param eventq A handle for the event queue.
 * \param event On successful return (1 or -EOVERFLOW), this location will
 * hold the next event in the EQ.
 *
 * \retval 1	  Indicates success.
 * \retval -ENOENT    If \a eventq does not point to a valid EQ.
 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
 * at least one event between this event and the last event obtained from the
 * EQ has been dropped due to limited space in the EQ.
 */

static int
lnet_eq_wait_locked(int *timeout_ms)
__must_hold(&the_lnet.ln_eq_wait_lock)
{
	int tms = *timeout_ms;
	int wait;
	wait_queue_t wl;
	unsigned long now;

	if (tms == 0)
		return -1; /* don't want to wait and no new event */

	init_waitqueue_entry(&wl, current);
	set_current_state(TASK_INTERRUPTIBLE);
	add_wait_queue(&the_lnet.ln_eq_waitq, &wl);

	lnet_eq_wait_unlock();

	if (tms < 0) {
		schedule();
	} else {
		now = jiffies;
		schedule_timeout(msecs_to_jiffies(tms));
		tms -= jiffies_to_msecs(jiffies - now);
		if (tms < 0) /* no more wait but may have new event */
			tms = 0;
	}

	wait = tms != 0; /* might need to call here again */
	*timeout_ms = tms;

	lnet_eq_wait_lock();
	remove_wait_queue(&the_lnet.ln_eq_waitq, &wl);

	return wait;
}

/**
 * Block the calling process until there's an event from a set of EQs or
 * timeout happens.
 *
 * If an event handler is associated with the EQ, the handler will run before
 * this function returns successfully, in which case the corresponding event
 * is consumed.
 *
 * LNetEQPoll() provides a timeout to allow applications to poll, block for a
 * fixed period, or block indefinitely.
 *
 * \param eventqs,neq An array of EQ handles, and size of the array.
 * \param timeout_ms Time in milliseconds to wait for an event to occur on
 * one of the EQs. The constant LNET_TIME_FOREVER can be used to indicate an
 * infinite timeout.
 * \param event,which On successful return (1 or -EOVERFLOW), \a event will
 * hold the next event in the EQs, and \a which will contain the index of the
 * EQ from which the event was taken.
 *
 * \retval 0	  No pending event in the EQs after timeout.
 * \retval 1	  Indicates success.
 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
 * at least one event between this event and the last event obtained from the
 * EQ indicated by \a which has been dropped due to limited space in the EQ.
 * \retval -ENOENT    If there's an invalid handle in \a eventqs.
 */
int
LNetEQPoll(lnet_handle_eq_t *eventqs, int neq, int timeout_ms,
	   lnet_event_t *event, int *which)
{
	int wait = 1;
	int rc;
	int i;

	LASSERT(the_lnet.ln_init);
	LASSERT(the_lnet.ln_refcount > 0);

	if (neq < 1)
		return -ENOENT;

	lnet_eq_wait_lock();

	for (;;) {
		for (i = 0; i < neq; i++) {
			lnet_eq_t *eq = lnet_handle2eq(&eventqs[i]);

			if (!eq) {
				lnet_eq_wait_unlock();
				return -ENOENT;
			}

			rc = lnet_eq_dequeue_event(eq, event);
			if (rc != 0) {
				lnet_eq_wait_unlock();
				*which = i;
				return rc;
			}
		}

		if (wait == 0)
			break;

		/*
		 * return value of lnet_eq_wait_locked:
		 * -1 : did nothing and it's sure no new event
		 *  1 : sleep inside and wait until new event
		 *  0 : don't want to wait anymore, but might have new event
		 *      so need to call dequeue again
		 */
		wait = lnet_eq_wait_locked(&timeout_ms);
		if (wait < 0) /* no new event */
			break;
	}

	lnet_eq_wait_unlock();
	return 0;
}
Commit	Line	Data
d7e09d03 PT	1	/*
	2	* GPL HEADER START
	3	*
	4	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License version 2 only,
	8	* as published by the Free Software Foundation.
	9	*
	10	* This program is distributed in the hope that it will be useful, but
	11	* WITHOUT ANY WARRANTY; without even the implied warranty of
	12	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	13	* General Public License version 2 for more details (a copy is included
	14	* in the LICENSE file that accompanied this code).
	15	*
	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.sun.com/software/products/lustre/docs/GPLv2.pdf
	19	*
	20	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
	21	* CA 95054 USA or visit www.sun.com if you need additional information or
	22	* have any questions.
	23	*
	24	* GPL HEADER END
	25	*/
	26	/*
	27	* Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
	28	* Use is subject to license terms.
	29	*
	30	* Copyright (c) 2012, Intel Corporation.
	31	*/
	32	/*
	33	* This file is part of Lustre, http://www.lustre.org/
	34	* Lustre is a trademark of Sun Microsystems, Inc.
	35	*
	36	* lnet/lnet/lib-eq.c
	37	*
	38	* Library level Event queue management routines
	39	*/
	40
	41	#define DEBUG_SUBSYSTEM S_LNET
9fdaf8c0	42	#include "../../include/linux/lnet/lib-lnet.h"
d7e09d03 PT	43
	44	/**
	45	* Create an event queue that has room for \a count number of events.
	46	*
	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
	53	* into the EQ.
	54	*
	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.
	62	*
	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.
	66	*
	67	* \see lnet_eq_handler_t for the discussion on EQ handler semantics.
	68	*/
	69	int
	70	LNetEQAlloc(unsigned int count, lnet_eq_handler_t callback,
	71	lnet_handle_eq_t *handle)
	72	{
7e7ab095	73	lnet_eq_t *eq;
d7e09d03	74
e49d63ea MO	75	LASSERT(the_lnet.ln_init);
e49d63ea MO	76	LASSERT(the_lnet.ln_refcount > 0);
d7e09d03	77
4420cfd3 JS	78	/*
4420cfd3 JS	79	* We need count to be a power of 2 so that when eq_{enq,deq}_seq
d7e09d03	80	* overflow, they don't skip entries, so the queue has the same
4420cfd3 JS	81	* apparent capacity at all times
4420cfd3 JS	82	*/
deaf7e1c OD	83	if (count)
deaf7e1c OD	84	count = roundup_pow_of_two(count);
d7e09d03	85
499217c9	86	if (callback != LNET_EQ_HANDLER_NONE && count != 0)
a446b47d	87	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);
d7e09d03	88
4420cfd3 JS	89	/*
	90	* count can be 0 if only need callback, we can eliminate
	91	* overhead of enqueue event
	92	*/
d7e09d03 PT	93	if (count == 0 && callback == LNET_EQ_HANDLER_NONE)
	94	return -EINVAL;
	95
	96	eq = lnet_eq_alloc();
06ace26e	97	if (!eq)
d7e09d03 PT	98	return -ENOMEM;
	99
	100	if (count != 0) {
	101	LIBCFS_ALLOC(eq->eq_events, count * sizeof(lnet_event_t));
06ace26e	102	if (!eq->eq_events)
d7e09d03	103	goto failed;
4420cfd3 JS	104	/*
	105	* NB allocator has set all event sequence numbers to 0,
	106	* so all them should be earlier than eq_deq_seq
	107	*/
d7e09d03 PT	108	}
	109
	110	eq->eq_deq_seq = 1;
	111	eq->eq_enq_seq = 1;
	112	eq->eq_size = count;
	113	eq->eq_callback = callback;
	114
	115	eq->eq_refs = cfs_percpt_alloc(lnet_cpt_table(),
	116	sizeof(*eq->eq_refs[0]));
06ace26e	117	if (!eq->eq_refs)
d7e09d03 PT	118	goto failed;
	119
	120	/* MUST hold both exclusive lnet_res_lock */
	121	lnet_res_lock(LNET_LOCK_EX);
4420cfd3 JS	122	/*
	123	* NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do
	124	* both EQ lookup and poll event with only lnet_eq_wait_lock
	125	*/
d7e09d03 PT	126	lnet_eq_wait_lock();
	127
	128	lnet_res_lh_initialize(&the_lnet.ln_eq_container, &eq->eq_lh);
	129	list_add(&eq->eq_list, &the_lnet.ln_eq_container.rec_active);
	130
	131	lnet_eq_wait_unlock();
	132	lnet_res_unlock(LNET_LOCK_EX);
	133
	134	lnet_eq2handle(handle, eq);
	135	return 0;
	136
	137	failed:
06ace26e	138	if (eq->eq_events)
d7e09d03 PT	139	LIBCFS_FREE(eq->eq_events, count * sizeof(lnet_event_t));
d7e09d03 PT	140
06ace26e	141	if (eq->eq_refs)
d7e09d03 PT	142	cfs_percpt_free(eq->eq_refs);
	143
	144	lnet_eq_free(eq);
	145	return -ENOMEM;
	146	}
	147	EXPORT_SYMBOL(LNetEQAlloc);
	148
	149	/**
	150	* Release the resources associated with an event queue if it's idle;
	151	* otherwise do nothing and it's up to the user to try again.
	152	*
	153	* \param eqh A handle for the event queue to be released.
	154	*
	155	* \retval 0 If the EQ is not in use and freed.
	156	* \retval -ENOENT If \a eqh does not point to a valid EQ.
	157	* \retval -EBUSY If the EQ is still in use by some MDs.
	158	*/
	159	int
	160	LNetEQFree(lnet_handle_eq_t eqh)
	161	{
7e7ab095 MS	162	struct lnet_eq *eq;
	163	lnet_event_t *events = NULL;
	164	int **refs = NULL;
	165	int *ref;
	166	int rc = 0;
	167	int size = 0;
	168	int i;
d7e09d03 PT	169
	170	LASSERT(the_lnet.ln_init);
	171	LASSERT(the_lnet.ln_refcount > 0);
	172
	173	lnet_res_lock(LNET_LOCK_EX);
4420cfd3 JS	174	/*
	175	* NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do
	176	* both EQ lookup and poll event with only lnet_eq_wait_lock
	177	*/
d7e09d03 PT	178	lnet_eq_wait_lock();
	179
	180	eq = lnet_handle2eq(&eqh);
06ace26e	181	if (!eq) {
d7e09d03 PT	182	rc = -ENOENT;
	183	goto out;
	184	}
	185
	186	cfs_percpt_for_each(ref, i, eq->eq_refs) {
	187	LASSERT(*ref >= 0);
	188	if (*ref == 0)
	189	continue;
	190
	191	CDEBUG(D_NET, "Event equeue (%d: %d) busy on destroy.\n",
	192	i, *ref);
	193	rc = -EBUSY;
	194	goto out;
	195	}
	196
	197	/* stash for free after lock dropped */
7e7ab095 MS	198	events = eq->eq_events;
	199	size = eq->eq_size;
	200	refs = eq->eq_refs;
d7e09d03 PT	201
	202	lnet_res_lh_invalidate(&eq->eq_lh);
	203	list_del(&eq->eq_list);
d9c90615	204	lnet_eq_free(eq);
d7e09d03 PT	205	out:
	206	lnet_eq_wait_unlock();
	207	lnet_res_unlock(LNET_LOCK_EX);
	208
06ace26e	209	if (events)
d7e09d03	210	LIBCFS_FREE(events, size * sizeof(lnet_event_t));
06ace26e	211	if (refs)
d7e09d03 PT	212	cfs_percpt_free(refs);
	213
	214	return rc;
	215	}
	216	EXPORT_SYMBOL(LNetEQFree);
	217
	218	void
	219	lnet_eq_enqueue_event(lnet_eq_t eq, lnet_event_t ev)
	220	{
	221	/* MUST called with resource lock hold but w/o lnet_eq_wait_lock */
	222	int index;
	223
	224	if (eq->eq_size == 0) {
	225	LASSERT(eq->eq_callback != LNET_EQ_HANDLER_NONE);
	226	eq->eq_callback(ev);
	227	return;
	228	}
	229
	230	lnet_eq_wait_lock();
	231	ev->sequence = eq->eq_enq_seq++;
	232
	233	LASSERT(eq->eq_size == LOWEST_BIT_SET(eq->eq_size));
	234	index = ev->sequence & (eq->eq_size - 1);
	235
	236	eq->eq_events[index] = *ev;
	237
	238	if (eq->eq_callback != LNET_EQ_HANDLER_NONE)
	239	eq->eq_callback(ev);
	240
	241	/* Wake anyone waiting in LNetEQPoll() */
	242	if (waitqueue_active(&the_lnet.ln_eq_waitq))
	243	wake_up_all(&the_lnet.ln_eq_waitq);
	244	lnet_eq_wait_unlock();
	245	}
	246
5f5b7384	247	static int
d7e09d03 PT	248	lnet_eq_dequeue_event(lnet_eq_t eq, lnet_event_t ev)
d7e09d03 PT	249	{
7e7ab095 MS	250	int new_index = eq->eq_deq_seq & (eq->eq_size - 1);
	251	lnet_event_t *new_event = &eq->eq_events[new_index];
	252	int rc;
d7e09d03 PT	253
	254	/* must called with lnet_eq_wait_lock hold */
	255	if (LNET_SEQ_GT(eq->eq_deq_seq, new_event->sequence))
0a3bdb00	256	return 0;
d7e09d03 PT	257
	258	/* We've got a new event... */
	259	ev = new_event;
	260
	261	CDEBUG(D_INFO, "event: %p, sequence: %lu, eq->size: %u\n",
	262	new_event, eq->eq_deq_seq, eq->eq_size);
	263
	264	/* ...but did it overwrite an event we've not seen yet? */
	265	if (eq->eq_deq_seq == new_event->sequence) {
	266	rc = 1;
	267	} else {
4420cfd3 JS	268	/*
	269	* don't complain with CERROR: some EQs are sized small
	270	* anyway; if it's important, the caller should complain
	271	*/
d7e09d03 PT	272	CDEBUG(D_NET, "Event Queue Overflow: eq seq %lu ev seq %lu\n",
	273	eq->eq_deq_seq, new_event->sequence);
	274	rc = -EOVERFLOW;
	275	}
	276
	277	eq->eq_deq_seq = new_event->sequence + 1;
0a3bdb00	278	return rc;
d7e09d03 PT	279	}
	280
	281	/**
	282	* A nonblocking function that can be used to get the next event in an EQ.
	283	* If an event handler is associated with the EQ, the handler will run before
	284	* this function returns successfully. The event is removed from the queue.
	285	*
	286	* \param eventq A handle for the event queue.
	287	* \param event On successful return (1 or -EOVERFLOW), this location will
	288	* hold the next event in the EQ.
	289	*
	290	* \retval 0 No pending event in the EQ.
	291	* \retval 1 Indicates success.
	292	* \retval -ENOENT If \a eventq does not point to a valid EQ.
	293	* \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
	294	* at least one event between this event and the last event obtained from the
	295	* EQ has been dropped due to limited space in the EQ.
	296	*/
d7e09d03 PT	297
	298	/**
	299	* Block the calling process until there is an event in the EQ.
	300	* If an event handler is associated with the EQ, the handler will run before
	301	* this function returns successfully. This function returns the next event
	302	* in the EQ and removes it from the EQ.
	303	*
	304	* \param eventq A handle for the event queue.
	305	* \param event On successful return (1 or -EOVERFLOW), this location will
	306	* hold the next event in the EQ.
	307	*
	308	* \retval 1 Indicates success.
	309	* \retval -ENOENT If \a eventq does not point to a valid EQ.
	310	* \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
	311	* at least one event between this event and the last event obtained from the
	312	* EQ has been dropped due to limited space in the EQ.
	313	*/
d7e09d03	314
d7e09d03 PT	315	static int
d7e09d03 PT	316	lnet_eq_wait_locked(int *timeout_ms)
e69ae73b	317	__must_hold(&the_lnet.ln_eq_wait_lock)
d7e09d03	318	{
7e7ab095 MS	319	int tms = *timeout_ms;
	320	int wait;
	321	wait_queue_t wl;
	322	unsigned long now;
d7e09d03 PT	323
	324	if (tms == 0)
	325	return -1; /* don't want to wait and no new event */
	326
9e795d35	327	init_waitqueue_entry(&wl, current);
d7e09d03 PT	328	set_current_state(TASK_INTERRUPTIBLE);
	329	add_wait_queue(&the_lnet.ln_eq_waitq, &wl);
	330
	331	lnet_eq_wait_unlock();
	332
	333	if (tms < 0) {
b3669a7f	334	schedule();
d7e09d03	335	} else {
a11ef8ca AB	336	now = jiffies;
	337	schedule_timeout(msecs_to_jiffies(tms));
	338	tms -= jiffies_to_msecs(jiffies - now);
d7e09d03 PT	339	if (tms < 0) /* no more wait but may have new event */
	340	tms = 0;
	341	}
	342
	343	wait = tms != 0; /* might need to call here again */
	344	*timeout_ms = tms;
	345
	346	lnet_eq_wait_lock();
	347	remove_wait_queue(&the_lnet.ln_eq_waitq, &wl);
	348
	349	return wait;
	350	}
	351
d7e09d03 PT	352	/**
	353	* Block the calling process until there's an event from a set of EQs or
	354	* timeout happens.
	355	*
	356	* If an event handler is associated with the EQ, the handler will run before
	357	* this function returns successfully, in which case the corresponding event
	358	* is consumed.
	359	*
	360	* LNetEQPoll() provides a timeout to allow applications to poll, block for a
	361	* fixed period, or block indefinitely.
	362	*
	363	* \param eventqs,neq An array of EQ handles, and size of the array.
	364	* \param timeout_ms Time in milliseconds to wait for an event to occur on
	365	* one of the EQs. The constant LNET_TIME_FOREVER can be used to indicate an
	366	* infinite timeout.
	367	* \param event,which On successful return (1 or -EOVERFLOW), \a event will
	368	* hold the next event in the EQs, and \a which will contain the index of the
	369	* EQ from which the event was taken.
	370	*
	371	* \retval 0 No pending event in the EQs after timeout.
	372	* \retval 1 Indicates success.
	373	* \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
	374	* at least one event between this event and the last event obtained from the
	375	* EQ indicated by \a which has been dropped due to limited space in the EQ.
	376	* \retval -ENOENT If there's an invalid handle in \a eventqs.
	377	*/
	378	int
	379	LNetEQPoll(lnet_handle_eq_t *eventqs, int neq, int timeout_ms,
	380	lnet_event_t event, int which)
	381	{
7e7ab095 MS	382	int wait = 1;
	383	int rc;
	384	int i;
d7e09d03	385
e49d63ea MO	386	LASSERT(the_lnet.ln_init);
e49d63ea MO	387	LASSERT(the_lnet.ln_refcount > 0);
d7e09d03 PT	388
d7e09d03 PT	389	if (neq < 1)
0a3bdb00	390	return -ENOENT;
d7e09d03 PT	391
	392	lnet_eq_wait_lock();
	393
	394	for (;;) {
	395	for (i = 0; i < neq; i++) {
	396	lnet_eq_t *eq = lnet_handle2eq(&eventqs[i]);
	397
06ace26e	398	if (!eq) {
d7e09d03	399	lnet_eq_wait_unlock();
0a3bdb00	400	return -ENOENT;
d7e09d03 PT	401	}
	402
	403	rc = lnet_eq_dequeue_event(eq, event);
	404	if (rc != 0) {
	405	lnet_eq_wait_unlock();
	406	*which = i;
0a3bdb00	407	return rc;
d7e09d03 PT	408	}
	409	}
	410
	411	if (wait == 0)
	412	break;
	413
	414	/*
	415	* return value of lnet_eq_wait_locked:
	416	* -1 : did nothing and it's sure no new event
	417	* 1 : sleep inside and wait until new event
	418	* 0 : don't want to wait anymore, but might have new event
	419	* so need to call dequeue again
	420	*/
	421	wait = lnet_eq_wait_locked(&timeout_ms);
	422	if (wait < 0) /* no new event */
	423	break;
	424	}
	425
	426	lnet_eq_wait_unlock();
0a3bdb00	427	return 0;
d7e09d03	428	}