4e8c7465ad
it can be easily distinguished from other non-vCPU threads in forthcoming changes. Obtained from: NetApp
433 lines
8.2 KiB
C
433 lines
8.2 KiB
C
/*-
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* Copyright (c) 2011 NetApp, Inc.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY NETAPP, INC ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL NETAPP, INC OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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/*
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* Micro event library for FreeBSD, designed for a single i/o thread
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* using kqueue, and having events be persistent by default.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <assert.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/event.h>
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#include <sys/time.h>
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#include <pthread.h>
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#include <pthread_np.h>
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#include "mevent.h"
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#define MEVENT_MAX 64
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#define MEV_ENABLE 1
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#define MEV_DISABLE 2
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#define MEV_DEL_PENDING 3
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extern char *vmname;
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static pthread_t mevent_tid;
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static int mevent_pipefd[2];
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static pthread_mutex_t mevent_lmutex = PTHREAD_MUTEX_INITIALIZER;
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struct mevent {
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void (*me_func)(int, enum ev_type, void *);
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int me_fd;
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enum ev_type me_type;
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void *me_param;
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int me_cq;
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int me_state;
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int me_closefd;
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LIST_ENTRY(mevent) me_list;
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};
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static LIST_HEAD(listhead, mevent) global_head, change_head;
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static void
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mevent_qlock(void)
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{
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pthread_mutex_lock(&mevent_lmutex);
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}
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static void
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mevent_qunlock(void)
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{
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pthread_mutex_unlock(&mevent_lmutex);
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}
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static void
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mevent_pipe_read(int fd, enum ev_type type, void *param)
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{
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char buf[MEVENT_MAX];
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int status;
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/*
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* Drain the pipe read side. The fd is non-blocking so this is
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* safe to do.
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*/
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do {
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status = read(fd, buf, sizeof(buf));
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} while (status == MEVENT_MAX);
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}
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static void
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mevent_notify(void)
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{
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char c;
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/*
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* If calling from outside the i/o thread, write a byte on the
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* pipe to force the i/o thread to exit the blocking kevent call.
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*/
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if (mevent_pipefd[1] != 0 && pthread_self() != mevent_tid) {
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write(mevent_pipefd[1], &c, 1);
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}
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}
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static int
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mevent_kq_filter(struct mevent *mevp)
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{
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int retval;
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retval = 0;
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if (mevp->me_type == EVF_READ)
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retval = EVFILT_READ;
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if (mevp->me_type == EVF_WRITE)
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retval = EVFILT_WRITE;
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return (retval);
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}
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static int
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mevent_kq_flags(struct mevent *mevp)
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{
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int ret;
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switch (mevp->me_state) {
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case MEV_ENABLE:
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ret = EV_ADD;
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break;
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case MEV_DISABLE:
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ret = EV_DISABLE;
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break;
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case MEV_DEL_PENDING:
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ret = EV_DELETE;
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break;
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}
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return (ret);
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}
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static int
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mevent_kq_fflags(struct mevent *mevp)
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{
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/* XXX nothing yet, perhaps EV_EOF for reads ? */
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return (0);
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}
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static int
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mevent_build(int mfd, struct kevent *kev)
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{
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struct mevent *mevp, *tmpp;
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int i;
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i = 0;
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mevent_qlock();
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LIST_FOREACH_SAFE(mevp, &change_head, me_list, tmpp) {
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if (mevp->me_closefd) {
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/*
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* A close of the file descriptor will remove the
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* event
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*/
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close(mevp->me_fd);
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} else {
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kev[i].ident = mevp->me_fd;
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kev[i].filter = mevent_kq_filter(mevp);
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kev[i].flags = mevent_kq_flags(mevp);
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kev[i].fflags = mevent_kq_fflags(mevp);
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kev[i].data = 0;
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kev[i].udata = mevp;
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i++;
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}
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mevp->me_cq = 0;
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LIST_REMOVE(mevp, me_list);
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if (mevp->me_state == MEV_DEL_PENDING) {
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free(mevp);
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} else {
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LIST_INSERT_HEAD(&global_head, mevp, me_list);
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}
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assert(i < MEVENT_MAX);
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}
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mevent_qunlock();
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return (i);
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}
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static void
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mevent_handle(struct kevent *kev, int numev)
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{
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struct mevent *mevp;
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int i;
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for (i = 0; i < numev; i++) {
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mevp = kev[i].udata;
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/* XXX check for EV_ERROR ? */
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(*mevp->me_func)(mevp->me_fd, mevp->me_type, mevp->me_param);
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}
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}
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struct mevent *
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mevent_add(int fd, enum ev_type type,
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void (*func)(int, enum ev_type, void *), void *param)
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{
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struct mevent *lp, *mevp;
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if (fd < 0 || func == NULL) {
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return (NULL);
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}
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mevp = NULL;
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mevent_qlock();
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/*
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* Verify that the fd/type tuple is not present in any list
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*/
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LIST_FOREACH(lp, &global_head, me_list) {
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if (lp->me_fd == fd && lp->me_type == type) {
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goto exit;
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}
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}
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LIST_FOREACH(lp, &change_head, me_list) {
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if (lp->me_fd == fd && lp->me_type == type) {
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goto exit;
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}
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}
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/*
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* Allocate an entry, populate it, and add it to the change list.
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*/
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mevp = malloc(sizeof(struct mevent));
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if (mevp == NULL) {
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goto exit;
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}
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memset(mevp, 0, sizeof(struct mevent));
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mevp->me_fd = fd;
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mevp->me_type = type;
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mevp->me_func = func;
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mevp->me_param = param;
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LIST_INSERT_HEAD(&change_head, mevp, me_list);
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mevp->me_cq = 1;
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mevp->me_state = MEV_ENABLE;
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mevent_notify();
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exit:
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mevent_qunlock();
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return (mevp);
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}
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static int
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mevent_update(struct mevent *evp, int newstate)
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{
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/*
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* It's not possible to enable/disable a deleted event
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*/
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if (evp->me_state == MEV_DEL_PENDING)
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return (EINVAL);
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/*
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* No update needed if state isn't changing
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*/
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if (evp->me_state == newstate)
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return (0);
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mevent_qlock();
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evp->me_state = newstate;
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/*
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* Place the entry onto the changed list if not already there.
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*/
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if (evp->me_cq == 0) {
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evp->me_cq = 1;
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LIST_REMOVE(evp, me_list);
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LIST_INSERT_HEAD(&change_head, evp, me_list);
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mevent_notify();
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}
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mevent_qunlock();
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return (0);
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}
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int
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mevent_enable(struct mevent *evp)
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{
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return (mevent_update(evp, MEV_ENABLE));
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}
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int
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mevent_disable(struct mevent *evp)
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{
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return (mevent_update(evp, MEV_DISABLE));
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}
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static int
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mevent_delete_event(struct mevent *evp, int closefd)
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{
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mevent_qlock();
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/*
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* Place the entry onto the changed list if not already there, and
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* mark as to be deleted.
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*/
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if (evp->me_cq == 0) {
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evp->me_cq = 1;
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LIST_REMOVE(evp, me_list);
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LIST_INSERT_HEAD(&change_head, evp, me_list);
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mevent_notify();
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}
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evp->me_state = MEV_DEL_PENDING;
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if (closefd)
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evp->me_closefd = 1;
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mevent_qunlock();
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return (0);
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}
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int
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mevent_delete(struct mevent *evp)
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{
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return (mevent_delete_event(evp, 0));
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}
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int
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mevent_delete_close(struct mevent *evp)
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{
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return (mevent_delete_event(evp, 1));
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}
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static void
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mevent_set_name(void)
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{
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char tname[MAXCOMLEN + 1];
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snprintf(tname, sizeof(tname), "%s mevent", vmname);
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pthread_set_name_np(mevent_tid, tname);
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}
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void
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mevent_dispatch(void)
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{
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struct kevent changelist[MEVENT_MAX];
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struct kevent eventlist[MEVENT_MAX];
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struct mevent *pipev;
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int mfd;
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int numev;
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int ret;
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mevent_tid = pthread_self();
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mevent_set_name();
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mfd = kqueue();
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assert(mfd > 0);
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/*
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* Open the pipe that will be used for other threads to force
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* the blocking kqueue call to exit by writing to it. Set the
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* descriptor to non-blocking.
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*/
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ret = pipe(mevent_pipefd);
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if (ret < 0) {
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perror("pipe");
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exit(0);
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}
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/*
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* Add internal event handler for the pipe write fd
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*/
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pipev = mevent_add(mevent_pipefd[0], EVF_READ, mevent_pipe_read, NULL);
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assert(pipev != NULL);
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for (;;) {
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/*
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* Build changelist if required.
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* XXX the changelist can be put into the blocking call
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* to eliminate the extra syscall. Currently better for
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* debug.
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*/
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numev = mevent_build(mfd, changelist);
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if (numev) {
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ret = kevent(mfd, changelist, numev, NULL, 0, NULL);
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if (ret == -1) {
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perror("Error return from kevent change");
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}
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}
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/*
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* Block awaiting events
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*/
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ret = kevent(mfd, NULL, 0, eventlist, MEVENT_MAX, NULL);
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if (ret == -1) {
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perror("Error return from kevent monitor");
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}
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/*
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* Handle reported events
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*/
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mevent_handle(eventlist, ret);
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}
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}
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