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qemu/main-loop.c
Stefan Weil 3239ad0469 main-loop: Calculate poll timeout using timeout argument 
The timeout argument was unused up to now,
but it can be used to reduce the poll_timeout when it is infinite
(negative value) or larger than timeout.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2012-05-01 10:46:25 +00:00

510 lines
13 KiB
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/*
* QEMU System Emulator
*
* Copyright (c) 2003-2008 Fabrice Bellard
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu-common.h"
#include "qemu-timer.h"
#include "slirp/slirp.h"
#include "main-loop.h"
#ifndef _WIN32
#include "compatfd.h"
static int io_thread_fd = -1;
void qemu_notify_event(void)
{
/* Write 8 bytes to be compatible with eventfd. */
static const uint64_t val = 1;
ssize_t ret;
if (io_thread_fd == -1) {
return;
}
do {
ret = write(io_thread_fd, &val, sizeof(val));
} while (ret < 0 && errno == EINTR);
/* EAGAIN is fine, a read must be pending. */
if (ret < 0 && errno != EAGAIN) {
fprintf(stderr, "qemu_notify_event: write() failed: %s\n",
strerror(errno));
exit(1);
}
}
static void qemu_event_read(void *opaque)
{
int fd = (intptr_t)opaque;
ssize_t len;
char buffer[512];
/* Drain the notify pipe. For eventfd, only 8 bytes will be read. */
do {
len = read(fd, buffer, sizeof(buffer));
} while ((len == -1 && errno == EINTR) || len == sizeof(buffer));
}
static int qemu_event_init(void)
{
int err;
int fds[2];
err = qemu_eventfd(fds);
if (err == -1) {
return -errno;
}
err = fcntl_setfl(fds[0], O_NONBLOCK);
if (err < 0) {
goto fail;
}
err = fcntl_setfl(fds[1], O_NONBLOCK);
if (err < 0) {
goto fail;
}
qemu_set_fd_handler2(fds[0], NULL, qemu_event_read, NULL,
(void *)(intptr_t)fds[0]);
io_thread_fd = fds[1];
return 0;
fail:
close(fds[0]);
close(fds[1]);
return err;
}
/* If we have signalfd, we mask out the signals we want to handle and then
* use signalfd to listen for them. We rely on whatever the current signal
* handler is to dispatch the signals when we receive them.
*/
static void sigfd_handler(void *opaque)
{
int fd = (intptr_t)opaque;
struct qemu_signalfd_siginfo info;
struct sigaction action;
ssize_t len;
while (1) {
do {
len = read(fd, &info, sizeof(info));
} while (len == -1 && errno == EINTR);
if (len == -1 && errno == EAGAIN) {
break;
}
if (len != sizeof(info)) {
printf("read from sigfd returned %zd: %m\n", len);
return;
}
sigaction(info.ssi_signo, NULL, &action);
if ((action.sa_flags & SA_SIGINFO) && action.sa_sigaction) {
action.sa_sigaction(info.ssi_signo,
(siginfo_t *)&info, NULL);
} else if (action.sa_handler) {
action.sa_handler(info.ssi_signo);
}
}
}
static int qemu_signal_init(void)
{
int sigfd;
sigset_t set;
/*
* SIG_IPI must be blocked in the main thread and must not be caught
* by sigwait() in the signal thread. Otherwise, the cpu thread will
* not catch it reliably.
*/
sigemptyset(&set);
sigaddset(&set, SIG_IPI);
sigaddset(&set, SIGIO);
sigaddset(&set, SIGALRM);
sigaddset(&set, SIGBUS);
pthread_sigmask(SIG_BLOCK, &set, NULL);
sigdelset(&set, SIG_IPI);
sigfd = qemu_signalfd(&set);
if (sigfd == -1) {
fprintf(stderr, "failed to create signalfd\n");
return -errno;
}
fcntl_setfl(sigfd, O_NONBLOCK);
qemu_set_fd_handler2(sigfd, NULL, sigfd_handler, NULL,
(void *)(intptr_t)sigfd);
return 0;
}
#else /* _WIN32 */
static HANDLE qemu_event_handle = NULL;
static void dummy_event_handler(void *opaque)
{
}
static int qemu_event_init(void)
{
qemu_event_handle = CreateEvent(NULL, FALSE, FALSE, NULL);
if (!qemu_event_handle) {
fprintf(stderr, "Failed CreateEvent: %ld\n", GetLastError());
return -1;
}
qemu_add_wait_object(qemu_event_handle, dummy_event_handler, NULL);
return 0;
}
void qemu_notify_event(void)
{
if (!qemu_event_handle) {
return;
}
if (!SetEvent(qemu_event_handle)) {
fprintf(stderr, "qemu_notify_event: SetEvent failed: %ld\n",
GetLastError());
exit(1);
}
}
static int qemu_signal_init(void)
{
return 0;
}
#endif
int main_loop_init(void)
{
int ret;
qemu_mutex_lock_iothread();
ret = qemu_signal_init();
if (ret) {
return ret;
}
/* Note eventfd must be drained before signalfd handlers run */
ret = qemu_event_init();
if (ret) {
return ret;
}
return 0;
}
static fd_set rfds, wfds, xfds;
static int nfds;
static GPollFD poll_fds[1024 * 2]; /* this is probably overkill */
static int n_poll_fds;
static int max_priority;
#ifndef _WIN32
static void glib_select_fill(int *max_fd, fd_set *rfds, fd_set *wfds,
fd_set *xfds, uint32_t *cur_timeout)
{
GMainContext *context = g_main_context_default();
int i;
int timeout = 0;
g_main_context_prepare(context, &max_priority);
n_poll_fds = g_main_context_query(context, max_priority, &timeout,
poll_fds, ARRAY_SIZE(poll_fds));
g_assert(n_poll_fds <= ARRAY_SIZE(poll_fds));
for (i = 0; i < n_poll_fds; i++) {
GPollFD *p = &poll_fds[i];
if ((p->events & G_IO_IN)) {
FD_SET(p->fd, rfds);
*max_fd = MAX(*max_fd, p->fd);
}
if ((p->events & G_IO_OUT)) {
FD_SET(p->fd, wfds);
*max_fd = MAX(*max_fd, p->fd);
}
if ((p->events & G_IO_ERR)) {
FD_SET(p->fd, xfds);
*max_fd = MAX(*max_fd, p->fd);
}
}
if (timeout >= 0 && timeout < *cur_timeout) {
*cur_timeout = timeout;
}
}
static void glib_select_poll(fd_set *rfds, fd_set *wfds, fd_set *xfds,
bool err)
{
GMainContext *context = g_main_context_default();
if (!err) {
int i;
for (i = 0; i < n_poll_fds; i++) {
GPollFD *p = &poll_fds[i];
if ((p->events & G_IO_IN) && FD_ISSET(p->fd, rfds)) {
p->revents |= G_IO_IN;
}
if ((p->events & G_IO_OUT) && FD_ISSET(p->fd, wfds)) {
p->revents |= G_IO_OUT;
}
if ((p->events & G_IO_ERR) && FD_ISSET(p->fd, xfds)) {
p->revents |= G_IO_ERR;
}
}
}
if (g_main_context_check(context, max_priority, poll_fds, n_poll_fds)) {
g_main_context_dispatch(context);
}
}
static int os_host_main_loop_wait(uint32_t timeout)
{
struct timeval tv, *tvarg = NULL;
int ret;
glib_select_fill(&nfds, &rfds, &wfds, &xfds, &timeout);
if (timeout < UINT32_MAX) {
tvarg = &tv;
tv.tv_sec = timeout / 1000;
tv.tv_usec = (timeout % 1000) * 1000;
}
if (timeout > 0) {
qemu_mutex_unlock_iothread();
}
ret = select(nfds + 1, &rfds, &wfds, &xfds, tvarg);
if (timeout > 0) {
qemu_mutex_lock_iothread();
}
glib_select_poll(&rfds, &wfds, &xfds, (ret < 0));
return ret;
}
#else
/***********************************************************/
/* Polling handling */
typedef struct PollingEntry {
PollingFunc *func;
void *opaque;
struct PollingEntry *next;
} PollingEntry;
static PollingEntry *first_polling_entry;
int qemu_add_polling_cb(PollingFunc *func, void *opaque)
{
PollingEntry **ppe, *pe;
pe = g_malloc0(sizeof(PollingEntry));
pe->func = func;
pe->opaque = opaque;
for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next);
*ppe = pe;
return 0;
}
void qemu_del_polling_cb(PollingFunc *func, void *opaque)
{
PollingEntry **ppe, *pe;
for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next) {
pe = *ppe;
if (pe->func == func && pe->opaque == opaque) {
*ppe = pe->next;
g_free(pe);
break;
}
}
}
/***********************************************************/
/* Wait objects support */
typedef struct WaitObjects {
int num;
int revents[MAXIMUM_WAIT_OBJECTS + 1];
HANDLE events[MAXIMUM_WAIT_OBJECTS + 1];
WaitObjectFunc *func[MAXIMUM_WAIT_OBJECTS + 1];
void *opaque[MAXIMUM_WAIT_OBJECTS + 1];
} WaitObjects;
static WaitObjects wait_objects = {0};
int qemu_add_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
{
WaitObjects *w = &wait_objects;
if (w->num >= MAXIMUM_WAIT_OBJECTS) {
return -1;
}
w->events[w->num] = handle;
w->func[w->num] = func;
w->opaque[w->num] = opaque;
w->revents[w->num] = 0;
w->num++;
return 0;
}
void qemu_del_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
{
int i, found;
WaitObjects *w = &wait_objects;
found = 0;
for (i = 0; i < w->num; i++) {
if (w->events[i] == handle) {
found = 1;
}
if (found) {
w->events[i] = w->events[i + 1];
w->func[i] = w->func[i + 1];
w->opaque[i] = w->opaque[i + 1];
w->revents[i] = w->revents[i + 1];
}
}
if (found) {
w->num--;
}
}
void qemu_fd_register(int fd)
{
WSAEventSelect(fd, qemu_event_handle, FD_READ | FD_ACCEPT | FD_CLOSE |
FD_CONNECT | FD_WRITE | FD_OOB);
}
static int os_host_main_loop_wait(uint32_t timeout)
{
GMainContext *context = g_main_context_default();
int ret, i;
PollingEntry *pe;
WaitObjects *w = &wait_objects;
gint poll_timeout;
static struct timeval tv0;
/* XXX: need to suppress polling by better using win32 events */
ret = 0;
for (pe = first_polling_entry; pe != NULL; pe = pe->next) {
ret |= pe->func(pe->opaque);
}
if (ret != 0) {
return ret;
}
if (nfds >= 0) {
ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv0);
if (ret != 0) {
timeout = 0;
}
}
g_main_context_prepare(context, &max_priority);
n_poll_fds = g_main_context_query(context, max_priority, &poll_timeout,
poll_fds, ARRAY_SIZE(poll_fds));
g_assert(n_poll_fds <= ARRAY_SIZE(poll_fds));
for (i = 0; i < w->num; i++) {
poll_fds[n_poll_fds + i].fd = (DWORD_PTR)w->events[i];
poll_fds[n_poll_fds + i].events = G_IO_IN;
}
if (poll_timeout < 0 || timeout < poll_timeout) {
poll_timeout = timeout;
}
qemu_mutex_unlock_iothread();
ret = g_poll(poll_fds, n_poll_fds + w->num, poll_timeout);
qemu_mutex_lock_iothread();
if (ret > 0) {
for (i = 0; i < w->num; i++) {
w->revents[i] = poll_fds[n_poll_fds + i].revents;
}
for (i = 0; i < w->num; i++) {
if (w->revents[i] && w->func[i]) {
w->func[i](w->opaque[i]);
}
}
}
if (g_main_context_check(context, max_priority, poll_fds, n_poll_fds)) {
g_main_context_dispatch(context);
}
/* If an edge-triggered socket event occurred, select will return a
* positive result on the next iteration. We do not need to do anything
* here.
*/
return ret;
}
#endif
int main_loop_wait(int nonblocking)
{
int ret;
uint32_t timeout = UINT32_MAX;
if (nonblocking) {
timeout = 0;
} else {
qemu_bh_update_timeout(&timeout);
}
/* poll any events */
/* XXX: separate device handlers from system ones */
nfds = -1;
FD_ZERO(&rfds);
FD_ZERO(&wfds);
FD_ZERO(&xfds);
#ifdef CONFIG_SLIRP
slirp_update_timeout(&timeout);
slirp_select_fill(&nfds, &rfds, &wfds, &xfds);
#endif
qemu_iohandler_fill(&nfds, &rfds, &wfds, &xfds);
ret = os_host_main_loop_wait(timeout);
qemu_iohandler_poll(&rfds, &wfds, &xfds, ret);
#ifdef CONFIG_SLIRP
slirp_select_poll(&rfds, &wfds, &xfds, (ret < 0));
#endif
qemu_run_all_timers();
/* Check bottom-halves last in case any of the earlier events triggered
them. */
qemu_bh_poll();
return ret;
}
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