422 lines
12 KiB
C
422 lines
12 KiB
C
/*
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* GPL HEADER START
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*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 only,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License version 2 for more details (a copy is included
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* in the LICENSE file that accompanied this code).
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*
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* You should have received a copy of the GNU General Public License
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* version 2 along with this program; If not, see
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* http://www.gnu.org/licenses/gpl-2.0.html
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*
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* GPL HEADER END
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*/
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/*
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* Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
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* Use is subject to license terms.
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*
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* Copyright (c) 2012, Intel Corporation.
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*/
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/*
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* This file is part of Lustre, http://www.lustre.org/
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* Lustre is a trademark of Sun Microsystems, Inc.
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*
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* lnet/lnet/lib-eq.c
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*
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* Library level Event queue management routines
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*/
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#define DEBUG_SUBSYSTEM S_LNET
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#include "../../include/linux/lnet/lib-lnet.h"
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/**
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* Create an event queue that has room for \a count number of events.
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*
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* The event queue is circular and older events will be overwritten by new
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* ones if they are not removed in time by the user using the functions
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* LNetEQGet(), LNetEQWait(), or LNetEQPoll(). It is up to the user to
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* determine the appropriate size of the event queue to prevent this loss
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* of events. Note that when EQ handler is specified in \a callback, no
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* event loss can happen, since the handler is run for each event deposited
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* into the EQ.
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*
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* \param count The number of events to be stored in the event queue. It
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* will be rounded up to the next power of two.
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* \param callback A handler function that runs when an event is deposited
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* into the EQ. The constant value LNET_EQ_HANDLER_NONE can be used to
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* indicate that no event handler is desired.
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* \param handle On successful return, this location will hold a handle for
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* the newly created EQ.
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*
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* \retval 0 On success.
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* \retval -EINVAL If an parameter is not valid.
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* \retval -ENOMEM If memory for the EQ can't be allocated.
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*
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* \see lnet_eq_handler_t for the discussion on EQ handler semantics.
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*/
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int
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LNetEQAlloc(unsigned int count, lnet_eq_handler_t callback,
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struct lnet_handle_eq *handle)
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{
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struct lnet_eq *eq;
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LASSERT(the_lnet.ln_refcount > 0);
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/*
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* We need count to be a power of 2 so that when eq_{enq,deq}_seq
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* overflow, they don't skip entries, so the queue has the same
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* apparent capacity at all times
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*/
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if (count)
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count = roundup_pow_of_two(count);
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if (callback != LNET_EQ_HANDLER_NONE && count)
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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);
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/*
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* count can be 0 if only need callback, we can eliminate
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* overhead of enqueue event
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*/
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if (!count && callback == LNET_EQ_HANDLER_NONE)
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return -EINVAL;
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eq = lnet_eq_alloc();
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if (!eq)
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return -ENOMEM;
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if (count) {
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LIBCFS_ALLOC(eq->eq_events, count * sizeof(struct lnet_event));
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if (!eq->eq_events)
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goto failed;
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/*
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* NB allocator has set all event sequence numbers to 0,
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* so all them should be earlier than eq_deq_seq
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*/
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}
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eq->eq_deq_seq = 1;
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eq->eq_enq_seq = 1;
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eq->eq_size = count;
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eq->eq_callback = callback;
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eq->eq_refs = cfs_percpt_alloc(lnet_cpt_table(),
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sizeof(*eq->eq_refs[0]));
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if (!eq->eq_refs)
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goto failed;
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/* MUST hold both exclusive lnet_res_lock */
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lnet_res_lock(LNET_LOCK_EX);
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/*
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* NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do
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* both EQ lookup and poll event with only lnet_eq_wait_lock
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*/
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lnet_eq_wait_lock();
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lnet_res_lh_initialize(&the_lnet.ln_eq_container, &eq->eq_lh);
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list_add(&eq->eq_list, &the_lnet.ln_eq_container.rec_active);
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lnet_eq_wait_unlock();
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lnet_res_unlock(LNET_LOCK_EX);
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lnet_eq2handle(handle, eq);
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return 0;
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failed:
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if (eq->eq_events)
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LIBCFS_FREE(eq->eq_events, count * sizeof(struct lnet_event));
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if (eq->eq_refs)
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cfs_percpt_free(eq->eq_refs);
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lnet_eq_free(eq);
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return -ENOMEM;
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}
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EXPORT_SYMBOL(LNetEQAlloc);
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/**
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* Release the resources associated with an event queue if it's idle;
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* otherwise do nothing and it's up to the user to try again.
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*
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* \param eqh A handle for the event queue to be released.
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*
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* \retval 0 If the EQ is not in use and freed.
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* \retval -ENOENT If \a eqh does not point to a valid EQ.
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* \retval -EBUSY If the EQ is still in use by some MDs.
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*/
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int
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LNetEQFree(struct lnet_handle_eq eqh)
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{
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struct lnet_eq *eq;
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struct lnet_event *events = NULL;
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int **refs = NULL;
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int *ref;
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int rc = 0;
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int size = 0;
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int i;
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LASSERT(the_lnet.ln_refcount > 0);
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lnet_res_lock(LNET_LOCK_EX);
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/*
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* NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do
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* both EQ lookup and poll event with only lnet_eq_wait_lock
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*/
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lnet_eq_wait_lock();
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eq = lnet_handle2eq(&eqh);
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if (!eq) {
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rc = -ENOENT;
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goto out;
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}
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cfs_percpt_for_each(ref, i, eq->eq_refs) {
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LASSERT(*ref >= 0);
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if (!*ref)
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continue;
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CDEBUG(D_NET, "Event equeue (%d: %d) busy on destroy.\n",
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i, *ref);
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rc = -EBUSY;
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goto out;
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}
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/* stash for free after lock dropped */
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events = eq->eq_events;
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size = eq->eq_size;
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refs = eq->eq_refs;
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lnet_res_lh_invalidate(&eq->eq_lh);
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list_del(&eq->eq_list);
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lnet_eq_free(eq);
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out:
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lnet_eq_wait_unlock();
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lnet_res_unlock(LNET_LOCK_EX);
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if (events)
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LIBCFS_FREE(events, size * sizeof(struct lnet_event));
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if (refs)
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cfs_percpt_free(refs);
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return rc;
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}
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EXPORT_SYMBOL(LNetEQFree);
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void
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lnet_eq_enqueue_event(struct lnet_eq *eq, struct lnet_event *ev)
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{
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/* MUST called with resource lock hold but w/o lnet_eq_wait_lock */
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int index;
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if (!eq->eq_size) {
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LASSERT(eq->eq_callback != LNET_EQ_HANDLER_NONE);
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eq->eq_callback(ev);
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return;
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}
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lnet_eq_wait_lock();
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ev->sequence = eq->eq_enq_seq++;
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LASSERT(eq->eq_size == LOWEST_BIT_SET(eq->eq_size));
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index = ev->sequence & (eq->eq_size - 1);
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eq->eq_events[index] = *ev;
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if (eq->eq_callback != LNET_EQ_HANDLER_NONE)
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eq->eq_callback(ev);
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/* Wake anyone waiting in LNetEQPoll() */
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if (waitqueue_active(&the_lnet.ln_eq_waitq))
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wake_up_all(&the_lnet.ln_eq_waitq);
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lnet_eq_wait_unlock();
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}
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static int
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lnet_eq_dequeue_event(struct lnet_eq *eq, struct lnet_event *ev)
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{
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int new_index = eq->eq_deq_seq & (eq->eq_size - 1);
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struct lnet_event *new_event = &eq->eq_events[new_index];
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int rc;
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/* must called with lnet_eq_wait_lock hold */
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if (LNET_SEQ_GT(eq->eq_deq_seq, new_event->sequence))
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return 0;
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/* We've got a new event... */
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*ev = *new_event;
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CDEBUG(D_INFO, "event: %p, sequence: %lu, eq->size: %u\n",
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new_event, eq->eq_deq_seq, eq->eq_size);
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/* ...but did it overwrite an event we've not seen yet? */
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if (eq->eq_deq_seq == new_event->sequence) {
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rc = 1;
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} else {
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/*
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* don't complain with CERROR: some EQs are sized small
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* anyway; if it's important, the caller should complain
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*/
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CDEBUG(D_NET, "Event Queue Overflow: eq seq %lu ev seq %lu\n",
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eq->eq_deq_seq, new_event->sequence);
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rc = -EOVERFLOW;
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}
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eq->eq_deq_seq = new_event->sequence + 1;
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return rc;
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}
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/**
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* A nonblocking function that can be used to get the next event in an EQ.
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* If an event handler is associated with the EQ, the handler will run before
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* this function returns successfully. The event is removed from the queue.
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*
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* \param eventq A handle for the event queue.
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* \param event On successful return (1 or -EOVERFLOW), this location will
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* hold the next event in the EQ.
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*
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* \retval 0 No pending event in the EQ.
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* \retval 1 Indicates success.
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* \retval -ENOENT If \a eventq does not point to a valid EQ.
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* \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
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* at least one event between this event and the last event obtained from the
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* EQ has been dropped due to limited space in the EQ.
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*/
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/**
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* Block the calling process until there is an event in the EQ.
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* If an event handler is associated with the EQ, the handler will run before
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* this function returns successfully. This function returns the next event
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* in the EQ and removes it from the EQ.
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*
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* \param eventq A handle for the event queue.
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* \param event On successful return (1 or -EOVERFLOW), this location will
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* hold the next event in the EQ.
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*
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* \retval 1 Indicates success.
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* \retval -ENOENT If \a eventq does not point to a valid EQ.
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* \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
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* at least one event between this event and the last event obtained from the
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* EQ has been dropped due to limited space in the EQ.
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*/
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static int
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lnet_eq_wait_locked(int *timeout_ms)
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__must_hold(&the_lnet.ln_eq_wait_lock)
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{
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int tms = *timeout_ms;
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int wait;
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wait_queue_entry_t wl;
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unsigned long now;
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if (!tms)
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return -ENXIO; /* don't want to wait and no new event */
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init_waitqueue_entry(&wl, current);
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set_current_state(TASK_INTERRUPTIBLE);
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add_wait_queue(&the_lnet.ln_eq_waitq, &wl);
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lnet_eq_wait_unlock();
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if (tms < 0) {
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schedule();
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} else {
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now = jiffies;
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schedule_timeout(msecs_to_jiffies(tms));
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tms -= jiffies_to_msecs(jiffies - now);
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if (tms < 0) /* no more wait but may have new event */
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tms = 0;
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}
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wait = tms; /* might need to call here again */
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*timeout_ms = tms;
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lnet_eq_wait_lock();
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remove_wait_queue(&the_lnet.ln_eq_waitq, &wl);
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return wait;
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}
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/**
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* Block the calling process until there's an event from a set of EQs or
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* timeout happens.
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*
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* If an event handler is associated with the EQ, the handler will run before
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* this function returns successfully, in which case the corresponding event
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* is consumed.
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*
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* LNetEQPoll() provides a timeout to allow applications to poll, block for a
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* fixed period, or block indefinitely.
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*
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* \param eventqs,neq An array of EQ handles, and size of the array.
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* \param timeout_ms Time in milliseconds to wait for an event to occur on
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* one of the EQs. The constant LNET_TIME_FOREVER can be used to indicate an
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* infinite timeout.
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* \param event,which On successful return (1 or -EOVERFLOW), \a event will
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* hold the next event in the EQs, and \a which will contain the index of the
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* EQ from which the event was taken.
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*
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* \retval 0 No pending event in the EQs after timeout.
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* \retval 1 Indicates success.
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* \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
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* at least one event between this event and the last event obtained from the
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* EQ indicated by \a which has been dropped due to limited space in the EQ.
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* \retval -ENOENT If there's an invalid handle in \a eventqs.
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*/
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int
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LNetEQPoll(struct lnet_handle_eq *eventqs, int neq, int timeout_ms,
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struct lnet_event *event, int *which)
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{
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int wait = 1;
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int rc;
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int i;
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LASSERT(the_lnet.ln_refcount > 0);
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if (neq < 1)
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return -ENOENT;
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lnet_eq_wait_lock();
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for (;;) {
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for (i = 0; i < neq; i++) {
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struct lnet_eq *eq = lnet_handle2eq(&eventqs[i]);
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if (!eq) {
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lnet_eq_wait_unlock();
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return -ENOENT;
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}
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rc = lnet_eq_dequeue_event(eq, event);
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if (rc) {
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lnet_eq_wait_unlock();
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*which = i;
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return rc;
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}
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}
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if (!wait)
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break;
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/*
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* return value of lnet_eq_wait_locked:
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* -1 : did nothing and it's sure no new event
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* 1 : sleep inside and wait until new event
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* 0 : don't want to wait anymore, but might have new event
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* so need to call dequeue again
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*/
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wait = lnet_eq_wait_locked(&timeout_ms);
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if (wait < 0) /* no new event */
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break;
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}
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lnet_eq_wait_unlock();
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return 0;
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}
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