qemu/main-loop.c
Paolo Bonzini 49cf57281b vl: delay thread initialization after daemonization
Commit ac4119c (chardev: Use timer instead of bottom-half to postpone
open event, 2012-10-12) moved the alarm timer initialization to an earlier
point but failed to consider that it depends on qemu_init_main_loop.

Later, commit 1c53786 (vl: init main loop earlier, 2012-10-30) fixed
this, but left -daemonize in two different ways.  First, timers need to
be reinitialized after forking.  Second, the global mutex was being held
by the parent, and thus dropped after forking.

The first is now fixed using pthread_atfork.  For the second part,
make sure that the global mutex is not taken before daemonization,
and similarly delay qemu_thread_self.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2012-11-02 13:07:55 -05:00

463 lines
12 KiB
C

/*
* 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"
#include "qemu-aio.h"
#ifndef _WIN32
#include "compatfd.h"
/* 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 int qemu_signal_init(void)
{
return 0;
}
#endif
static AioContext *qemu_aio_context;
void qemu_notify_event(void)
{
if (!qemu_aio_context) {
return;
}
aio_notify(qemu_aio_context);
}
int qemu_init_main_loop(void)
{
int ret;
GSource *src;
init_clocks();
if (init_timer_alarm() < 0) {
fprintf(stderr, "could not initialize alarm timer\n");
exit(1);
}
ret = qemu_signal_init();
if (ret) {
return ret;
}
qemu_aio_context = aio_context_new();
src = aio_get_g_source(qemu_aio_context);
g_source_attach(src, NULL);
g_source_unref(src);
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, event_notifier_get_handle(&qemu_aio_context->notifier),
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;
}
/* 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();
return ret;
}
/* Functions to operate on the main QEMU AioContext. */
QEMUBH *qemu_bh_new(QEMUBHFunc *cb, void *opaque)
{
return aio_bh_new(qemu_aio_context, cb, opaque);
}
void qemu_aio_flush(void)
{
aio_flush(qemu_aio_context);
}
bool qemu_aio_wait(void)
{
return aio_poll(qemu_aio_context, true);
}
#ifdef CONFIG_POSIX
void qemu_aio_set_fd_handler(int fd,
IOHandler *io_read,
IOHandler *io_write,
AioFlushHandler *io_flush,
void *opaque)
{
aio_set_fd_handler(qemu_aio_context, fd, io_read, io_write, io_flush,
opaque);
}
#endif
void qemu_aio_set_event_notifier(EventNotifier *notifier,
EventNotifierHandler *io_read,
AioFlushEventNotifierHandler *io_flush)
{
aio_set_event_notifier(qemu_aio_context, notifier, io_read, io_flush);
}