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* 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.gnu.org/licenses/gpl-2.0.html
*
* 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_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)
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 && callback == LNET_EQ_HANDLER_NONE)
return -EINVAL;
eq = lnet_eq_alloc();
if (!eq)
return -ENOMEM;
if (count) {
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_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)
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) {
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)
return -ENXIO; /* 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; /* 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_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) {
lnet_eq_wait_unlock();
*which = i;
return rc;
}
}
if (!wait)
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;
}
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