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linux-v4l2: Add eventfd to signal udev on shutdown 

Currently we use signals based on os_event's but the udev code blocks in
a 1s select (now poll) that cannot be signalled without an FD. This adds
an extra eventfd which will be signalled along with the os_event to
trigger the poll.

Also switches from select to poll to avoid issues with large fd values.
master
Kurt Kartaltepe 2022-07-16 17:06:44 -07:00 committed by Georges Basile Stavracas Neto
parent bad54448ce
commit f788e9f6b7
1 changed files with 22 additions and 10 deletions
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32
plugins/linux-v4l2/v4l2-udev.c
View File

@ -15,6 +15,9 @@ You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <sys/eventfd.h>
#include <poll.h>
#include <unistd.h>
#include <libudev.h>
#include <util/threading.h>
@ -40,6 +43,7 @@ static pthread_mutex_t udev_mutex = PTHREAD_MUTEX_INITIALIZER;
static pthread_t udev_thread;
static os_event_t *udev_event;
static int udev_event_fd;
static signal_handler_t *udev_signalhandler = NULL;
@ -108,8 +112,6 @@ static void *udev_event_thread(void *vptr)
UNUSED_PARAMETER(vptr);
int fd;
fd_set fds;
struct timeval tv;
struct udev *udev;
struct udev_monitor *mon;
struct udev_device *dev;
@ -127,12 +129,14 @@ static void *udev_event_thread(void *vptr)
fd = udev_monitor_get_fd(mon);
while (os_event_try(udev_event) == EAGAIN) {
FD_ZERO(&fds);
FD_SET(fd, &fds);
tv.tv_sec = 1;
tv.tv_usec = 0;
struct pollfd fds[2];
if (select(fd + 1, &fds, NULL, NULL, &tv) <= 0)
fds[0].fd = fd;
fds[0].events = POLLIN;
fds[1].fd = udev_event_fd;
fds[1].events = POLLIN;
if (poll(fds, 2, 1000) <= 0)
continue;
dev = udev_monitor_receive_device(mon);
@ -158,13 +162,19 @@ void v4l2_init_udev(void)
if (udev_refs == 0) {
if (os_event_init(&udev_event, OS_EVENT_TYPE_MANUAL) != 0)
goto fail;
if (pthread_create(&udev_thread, NULL, udev_event_thread,
NULL) != 0)
if ((udev_event_fd = eventfd(0, EFD_CLOEXEC)) < 0)
goto fail;
if (pthread_create(&udev_thread, NULL, udev_event_thread,
NULL) != 0) {
close(udev_event_fd);
goto fail;
}
udev_signalhandler = signal_handler_create();
if (!udev_signalhandler)
if (!udev_signalhandler) {
close(udev_event_fd);
goto fail;
}
signal_handler_add_array(udev_signalhandler, udev_signals);
}
udev_refs++;
@ -180,8 +190,10 @@ void v4l2_unref_udev(void)
/* unref udev monitor */
if (udev_refs && --udev_refs == 0) {
os_event_signal(udev_event);
eventfd_write(udev_event_fd, 1);
pthread_join(udev_thread, NULL);
os_event_destroy(udev_event);
close(udev_event_fd);
if (udev_signalhandler)
signal_handler_destroy(udev_signalhandler);