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freebsd/usr.sbin/bhyve/mevent.c

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/*-
* Copyright (c) 2011 NetApp, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY NETAPP, INC ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL NETAPP, INC OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
/*
* Micro event library for FreeBSD, designed for a single i/o thread
* using kqueue, and having events be persistent by default.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/event.h>
#include <sys/time.h>
#include <pthread.h>
#include <pthread_np.h>
#include "mevent.h"
#define MEVENT_MAX 64
#define MEV_ADD 1
#define MEV_ENABLE 2
#define MEV_DISABLE 3
#define MEV_DEL_PENDING 4
extern char *vmname;
static pthread_t mevent_tid;
static int mevent_timid = 43;
static int mevent_pipefd[2];
static pthread_mutex_t mevent_lmutex = PTHREAD_MUTEX_INITIALIZER;
struct mevent {
void (*me_func)(int, enum ev_type, void *);
#define me_msecs me_fd
int me_fd;
int me_timid;
enum ev_type me_type;
void *me_param;
int me_cq;
int me_state;
int me_closefd;
LIST_ENTRY(mevent) me_list;
};
static LIST_HEAD(listhead, mevent) global_head, change_head;
static void
mevent_qlock(void)
{
pthread_mutex_lock(&mevent_lmutex);
}
static void
mevent_qunlock(void)
{
pthread_mutex_unlock(&mevent_lmutex);
}
static void
mevent_pipe_read(int fd, enum ev_type type, void *param)
{
char buf[MEVENT_MAX];
int status;
/*
* Drain the pipe read side. The fd is non-blocking so this is
* safe to do.
*/
do {
status = read(fd, buf, sizeof(buf));
} while (status == MEVENT_MAX);
}
static void
mevent_notify(void)
{
char c;
/*
* If calling from outside the i/o thread, write a byte on the
* pipe to force the i/o thread to exit the blocking kevent call.
*/
if (mevent_pipefd[1] != 0 && pthread_self() != mevent_tid) {
write(mevent_pipefd[1], &c, 1);
}
}
static int
mevent_kq_filter(struct mevent *mevp)
{
int retval;
retval = 0;
if (mevp->me_type == EVF_READ)
retval = EVFILT_READ;
if (mevp->me_type == EVF_WRITE)
retval = EVFILT_WRITE;
if (mevp->me_type == EVF_TIMER)
retval = EVFILT_TIMER;
if (mevp->me_type == EVF_SIGNAL)
retval = EVFILT_SIGNAL;
return (retval);
}
static int
mevent_kq_flags(struct mevent *mevp)
{
int ret;
switch (mevp->me_state) {
case MEV_ADD:
ret = EV_ADD; /* implicitly enabled */
break;
case MEV_ENABLE:
ret = EV_ENABLE;
break;
case MEV_DISABLE:
ret = EV_DISABLE;
break;
case MEV_DEL_PENDING:
ret = EV_DELETE;
break;
default:
assert(0);
break;
}
return (ret);
}
static int
mevent_kq_fflags(struct mevent *mevp)
{
/* XXX nothing yet, perhaps EV_EOF for reads ? */
return (0);
}
static int
mevent_build(int mfd, struct kevent *kev)
{
struct mevent *mevp, *tmpp;
int i;
i = 0;
mevent_qlock();
LIST_FOREACH_SAFE(mevp, &change_head, me_list, tmpp) {
if (mevp->me_closefd) {
/*
* A close of the file descriptor will remove the
* event
*/
close(mevp->me_fd);
} else {
if (mevp->me_type == EVF_TIMER) {
kev[i].ident = mevp->me_timid;
kev[i].data = mevp->me_msecs;
} else {
kev[i].ident = mevp->me_fd;
kev[i].data = 0;
}
kev[i].filter = mevent_kq_filter(mevp);
kev[i].flags = mevent_kq_flags(mevp);
kev[i].fflags = mevent_kq_fflags(mevp);
kev[i].udata = mevp;
i++;
}
mevp->me_cq = 0;
LIST_REMOVE(mevp, me_list);
if (mevp->me_state == MEV_DEL_PENDING) {
free(mevp);
} else {
LIST_INSERT_HEAD(&global_head, mevp, me_list);
}
assert(i < MEVENT_MAX);
}
mevent_qunlock();
return (i);
}
static void
mevent_handle(struct kevent *kev, int numev)
{
struct mevent *mevp;
int i;
for (i = 0; i < numev; i++) {
mevp = kev[i].udata;
/* XXX check for EV_ERROR ? */
(*mevp->me_func)(mevp->me_fd, mevp->me_type, mevp->me_param);
}
}
struct mevent *
mevent_add(int tfd, enum ev_type type,
void (*func)(int, enum ev_type, void *), void *param)
{
struct mevent *lp, *mevp;
if (tfd < 0 || func == NULL) {
return (NULL);
}
mevp = NULL;
mevent_qlock();
/*
* Verify that the fd/type tuple is not present in any list
*/
LIST_FOREACH(lp, &global_head, me_list) {
if (type != EVF_TIMER && lp->me_fd == tfd &&
lp->me_type == type) {
goto exit;
}
}
LIST_FOREACH(lp, &change_head, me_list) {
if (type != EVF_TIMER && lp->me_fd == tfd &&
lp->me_type == type) {
goto exit;
}
}
/*
* Allocate an entry, populate it, and add it to the change list.
*/
mevp = calloc(1, sizeof(struct mevent));
if (mevp == NULL) {
goto exit;
}
if (type == EVF_TIMER) {
mevp->me_msecs = tfd;
mevp->me_timid = mevent_timid++;
} else
mevp->me_fd = tfd;
mevp->me_type = type;
mevp->me_func = func;
mevp->me_param = param;
LIST_INSERT_HEAD(&change_head, mevp, me_list);
mevp->me_cq = 1;
mevp->me_state = MEV_ADD;
mevent_notify();
exit:
mevent_qunlock();
return (mevp);
}
static int
mevent_update(struct mevent *evp, int newstate)
{
/*
* It's not possible to enable/disable a deleted event
*/
if (evp->me_state == MEV_DEL_PENDING)
return (EINVAL);
/*
* No update needed if state isn't changing
*/
if (evp->me_state == newstate)
return (0);
mevent_qlock();
evp->me_state = newstate;
/*
* Place the entry onto the changed list if not already there.
*/
if (evp->me_cq == 0) {
evp->me_cq = 1;
LIST_REMOVE(evp, me_list);
LIST_INSERT_HEAD(&change_head, evp, me_list);
mevent_notify();
}
mevent_qunlock();
return (0);
}
int
mevent_enable(struct mevent *evp)
{
return (mevent_update(evp, MEV_ENABLE));
}
int
mevent_disable(struct mevent *evp)
{
return (mevent_update(evp, MEV_DISABLE));
}
static int
mevent_delete_event(struct mevent *evp, int closefd)
{
mevent_qlock();
/*
* Place the entry onto the changed list if not already there, and
* mark as to be deleted.
*/
if (evp->me_cq == 0) {
evp->me_cq = 1;
LIST_REMOVE(evp, me_list);
LIST_INSERT_HEAD(&change_head, evp, me_list);
mevent_notify();
}
evp->me_state = MEV_DEL_PENDING;
if (closefd)
evp->me_closefd = 1;
mevent_qunlock();
return (0);
}
int
mevent_delete(struct mevent *evp)
{
return (mevent_delete_event(evp, 0));
}
int
mevent_delete_close(struct mevent *evp)
{
return (mevent_delete_event(evp, 1));
}
static void
mevent_set_name(void)
{
pthread_set_name_np(mevent_tid, "mevent");
}
void
mevent_dispatch(void)
{
struct kevent changelist[MEVENT_MAX];
struct kevent eventlist[MEVENT_MAX];
struct mevent *pipev;
int mfd;
int numev;
int ret;
mevent_tid = pthread_self();
mevent_set_name();
mfd = kqueue();
assert(mfd > 0);
/*
* Open the pipe that will be used for other threads to force
* the blocking kqueue call to exit by writing to it. Set the
* descriptor to non-blocking.
*/
ret = pipe(mevent_pipefd);
if (ret < 0) {
perror("pipe");
exit(0);
}
/*
* Add internal event handler for the pipe write fd
*/
pipev = mevent_add(mevent_pipefd[0], EVF_READ, mevent_pipe_read, NULL);
assert(pipev != NULL);
for (;;) {
/*
* Build changelist if required.
* XXX the changelist can be put into the blocking call
* to eliminate the extra syscall. Currently better for
* debug.
*/
numev = mevent_build(mfd, changelist);
if (numev) {
ret = kevent(mfd, changelist, numev, NULL, 0, NULL);
if (ret == -1) {
perror("Error return from kevent change");
}
}
/*
* Block awaiting events
*/
ret = kevent(mfd, NULL, 0, eventlist, MEVENT_MAX, NULL);
if (ret == -1 && errno != EINTR) {
perror("Error return from kevent monitor");
}
/*
* Handle reported events
*/
mevent_handle(eventlist, ret);
}
}