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[Qemu-devel] [PATCH v2 14/39] event_notifier: enable it to use pipes
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH v2 14/39] event_notifier: enable it to use pipes |
Date: |
Wed, 31 Oct 2012 16:30:31 +0100 |
This takes the eventfd emulation code from the main loop. When the
EventNotifier is used for the main loop too, we need this compatibility
code.
Without CONFIG_EVENTFD, event_notifier_get_fd is only usable for the
"read" side of the notifier, for example to set a select() handler.
The return value of event_notifier_set changes to the cleaner 0/-errno.
No caller is actually checking the return value.
Reviewed-by: Anthony Liguori <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
event_notifier-posix.c | 85 ++++++++++++++++++++++++++++++++++++++++----------
event_notifier.h | 3 +-
2 file modificati, 71 inserzioni(+), 17 rimozioni(-)
diff --git a/event_notifier-posix.c b/event_notifier-posix.c
index 2c207e1..6f3239a 100644
--- a/event_notifier-posix.c
+++ b/event_notifier-posix.c
@@ -20,48 +20,101 @@
void event_notifier_init_fd(EventNotifier *e, int fd)
{
- e->fd = fd;
+ e->rfd = fd;
+ e->wfd = fd;
}
int event_notifier_init(EventNotifier *e, int active)
{
+ int fds[2];
+ int ret;
+
#ifdef CONFIG_EVENTFD
- int fd = eventfd(!!active, EFD_NONBLOCK | EFD_CLOEXEC);
- if (fd < 0)
- return -errno;
- e->fd = fd;
- return 0;
+ ret = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
#else
- return -ENOSYS;
+ ret = -1;
+ errno = ENOSYS;
#endif
+ if (ret >= 0) {
+ e->rfd = e->wfd = ret;
+ } else {
+ if (errno != ENOSYS) {
+ return -errno;
+ }
+ if (qemu_pipe(fds) < 0) {
+ return -errno;
+ }
+ ret = fcntl_setfl(fds[0], O_NONBLOCK);
+ if (ret < 0) {
+ ret = -errno;
+ goto fail;
+ }
+ ret = fcntl_setfl(fds[1], O_NONBLOCK);
+ if (ret < 0) {
+ ret = -errno;
+ goto fail;
+ }
+ e->rfd = fds[0];
+ e->wfd = fds[1];
+ }
+ if (active) {
+ event_notifier_set(e);
+ }
+ return 0;
+
+fail:
+ close(fds[0]);
+ close(fds[1]);
+ return ret;
}
void event_notifier_cleanup(EventNotifier *e)
{
- close(e->fd);
+ if (e->rfd != e->wfd) {
+ close(e->rfd);
+ }
+ close(e->wfd);
}
int event_notifier_get_fd(EventNotifier *e)
{
- return e->fd;
+ return e->rfd;
}
int event_notifier_set_handler(EventNotifier *e,
EventNotifierHandler *handler)
{
- return qemu_set_fd_handler(e->fd, (IOHandler *)handler, NULL, e);
+ return qemu_set_fd_handler(e->rfd, (IOHandler *)handler, NULL, e);
}
int event_notifier_set(EventNotifier *e)
{
- uint64_t value = 1;
- int r = write(e->fd, &value, sizeof(value));
- return r == sizeof(value);
+ static const uint64_t value = 1;
+ ssize_t ret;
+
+ do {
+ ret = write(e->wfd, &value, sizeof(value));
+ } while (ret < 0 && errno == EINTR);
+
+ /* EAGAIN is fine, a read must be pending. */
+ if (ret < 0 && errno != EAGAIN) {
+ return -errno;
+ }
+ return 0;
}
int event_notifier_test_and_clear(EventNotifier *e)
{
- uint64_t value;
- int r = read(e->fd, &value, sizeof(value));
- return r == sizeof(value);
+ int value;
+ ssize_t len;
+ char buffer[512];
+
+ /* Drain the notify pipe. For eventfd, only 8 bytes will be read. */
+ value = 0;
+ do {
+ len = read(e->rfd, buffer, sizeof(buffer));
+ value |= (len > 0);
+ } while ((len == -1 && errno == EINTR) || len == sizeof(buffer));
+
+ return value;
}
diff --git a/event_notifier.h b/event_notifier.h
index b283a49..88b57af 100644
--- a/event_notifier.h
+++ b/event_notifier.h
@@ -23,7 +23,8 @@ struct EventNotifier {
#ifdef _WIN32
HANDLE event;
#else
- int fd;
+ int rfd;
+ int wfd;
#endif
};
--
1.7.12.1
- [Qemu-devel] [PATCH v2 24/39] aio: make AioContexts GSources, (continued)
- [Qemu-devel] [PATCH v2 24/39] aio: make AioContexts GSources, Paolo Bonzini, 2012/10/31
- [Qemu-devel] [PATCH v2 27/39] main-loop: use GSource to poll AIO file descriptors, Paolo Bonzini, 2012/10/31
- [Qemu-devel] [PATCH v2 29/39] aio: clean up now-unused functions, Paolo Bonzini, 2012/10/31
- [Qemu-devel] [PATCH v2 33/39] threadpool: do not take lock in event_notifier_ready, Paolo Bonzini, 2012/10/31
- [Qemu-devel] [PATCH v2 32/39] aio: add generic thread-pool facility, Paolo Bonzini, 2012/10/31
- [Qemu-devel] [PATCH v2 34/39] block: switch posix-aio-compat to threadpool, Paolo Bonzini, 2012/10/31
- [Qemu-devel] [PATCH v2 35/39] raw: merge posix-aio-compat.c into block/raw-posix.c, Paolo Bonzini, 2012/10/31
- [Qemu-devel] [PATCH v2 36/39] raw-posix: rename raw-posix-aio.h, hide unavailable prototypes, Paolo Bonzini, 2012/10/31
- [Qemu-devel] [PATCH v2 37/39] raw-win32: add emulated AIO support, Paolo Bonzini, 2012/10/31
- [Qemu-devel] [PATCH v2 30/39] linux-aio: use event notifiers, Paolo Bonzini, 2012/10/31
- [Qemu-devel] [PATCH v2 14/39] event_notifier: enable it to use pipes,
Paolo Bonzini <=
- [Qemu-devel] [PATCH v2 15/39] vl: init main loop earlier, Paolo Bonzini, 2012/10/31
- [Qemu-devel] [PATCH v2 31/39] qemu-thread: add QemuSemaphore, Paolo Bonzini, 2012/10/31
- [Qemu-devel] [PATCH v2 13/39] event_notifier: add Win32 implementation, Paolo Bonzini, 2012/10/31
- [Qemu-devel] [PATCH v2 28/39] main-loop: use aio_notify for qemu_notify_event, Paolo Bonzini, 2012/10/31
- [Qemu-devel] [PATCH v2 16/39] aio: change qemu_aio_set_fd_handler to return void, Paolo Bonzini, 2012/10/31
- [Qemu-devel] [PATCH v2 26/39] aio: call aio_notify after setting I/O handlers, Paolo Bonzini, 2012/10/31
- [Qemu-devel] [PATCH v2 19/39] aio: add I/O handlers to the AioContext interface, Paolo Bonzini, 2012/10/31
- [Qemu-devel] [PATCH v2 39/39] raw-win32: implement native asynchronous I/O, Paolo Bonzini, 2012/10/31
- [Qemu-devel] [PATCH v2 38/39] raw-posix: move linux-aio.c to block/, Paolo Bonzini, 2012/10/31
- [Qemu-devel] [PATCH v2 18/39] aio: introduce AioContext, move bottom halves there, Paolo Bonzini, 2012/10/31