Re: [Qemu-devel] [PATCH 03/12] main-loop: use event notifiers

[Anthony Liguori <anthony@codemonkey.ws>]

Paolo Bonzini <pbonzini@redhat.com> writes:

Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>

Regards,

Anthony Liguori

> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  Makefile.objs |    4 +--
>  main-loop.c   |  106 ++++++++-------------------------------------------------
>  oslib-posix.c |   31 -----------------
>  qemu-common.h |    1 -
>  4 files changed, 17 insertions(+), 125 deletions(-)
>
> diff --git a/Makefile.objs b/Makefile.objs
> index ecdfaf9..6ed1981 100644
> --- a/Makefile.objs
> +++ b/Makefile.objs
> @@ -20,8 +20,8 @@ universal-obj-y += $(qom-obj-y)
>  #######################################################################
>  # oslib-obj-y is code depending on the OS (win32 vs posix)
>  oslib-obj-y = osdep.o
> -oslib-obj-$(CONFIG_WIN32) += oslib-win32.o qemu-thread-win32.o
> -oslib-obj-$(CONFIG_POSIX) += oslib-posix.o qemu-thread-posix.o
> +oslib-obj-$(CONFIG_WIN32) += oslib-win32.o qemu-thread-win32.o event_notifier-win32.o
> +oslib-obj-$(CONFIG_POSIX) += oslib-posix.o qemu-thread-posix.o event_notifier-posix.o
>  
>  #######################################################################
>  # coroutines
> diff --git a/main-loop.c b/main-loop.c
> index eb3b6e6..81f49b3 100644
> --- a/main-loop.c
> +++ b/main-loop.c
> @@ -26,75 +26,12 @@
>  #include "qemu-timer.h"
>  #include "slirp/slirp.h"
>  #include "main-loop.h"
> +#include "event_notifier.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.
> @@ -164,40 +101,22 @@ static int qemu_signal_init(void)
>  
>  #else /* _WIN32 */
>  
> -static HANDLE qemu_event_handle = NULL;
> -
> -static void dummy_event_handler(void *opaque)
> -{
> -}
> -
> -static int qemu_event_init(void)
> +static int qemu_signal_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;
>  }
> +#endif
> +
> +static EventNotifier io_thread_notifier;
> +static int io_thread_initialized;
>  
>  void qemu_notify_event(void)
>  {
> -    if (!qemu_event_handle) {
> +    if (!io_thread_initialized) {
>          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;
> +    event_notifier_set(&io_thread_notifier);
>  }
> -#endif
>  
>  int main_loop_init(void)
>  {
> @@ -210,11 +129,15 @@ int main_loop_init(void)
>      }
>  
>      /* Note eventfd must be drained before signalfd handlers run */
> -    ret = qemu_event_init();
> +    ret = event_notifier_init(&io_thread_notifier, 0);
>      if (ret) {
>          return ret;
>      }
>  
> +    io_thread_initialized = true;
> +    event_notifier_set_handler(&io_thread_notifier,
> +                               (EventNotifierHandler *)
> +                               event_notifier_test_and_clear);
>      return 0;
>  }
>  
> @@ -400,7 +323,8 @@ void qemu_del_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
>  
>  void qemu_fd_register(int fd)
>  {
> -    WSAEventSelect(fd, qemu_event_handle, FD_READ | FD_ACCEPT | FD_CLOSE |
> +    WSAEventSelect(fd, event_notifier_get_handle(&io_thread_notifier),
> +                   FD_READ | FD_ACCEPT | FD_CLOSE |
>                     FD_CONNECT | FD_WRITE | FD_OOB);
>  }
>  
> diff --git a/oslib-posix.c b/oslib-posix.c
> index 6b7ba64..2c6b044 100644
> --- a/oslib-posix.c
> +++ b/oslib-posix.c
> @@ -58,9 +58,6 @@ static int running_on_valgrind = -1;
>  #ifdef CONFIG_LINUX
>  #include <sys/syscall.h>
>  #endif
> -#ifdef CONFIG_EVENTFD
> -#include <sys/eventfd.h>
> -#endif
>  
>  int qemu_get_thread_id(void)
>  {
> @@ -180,34 +177,6 @@ int qemu_pipe(int pipefd[2])
>      return ret;
>  }
>  
> -/*
> - * Creates an eventfd that looks like a pipe and has EFD_CLOEXEC set.
> - */
> -int qemu_eventfd(int fds[2])
> -{
> -#ifdef CONFIG_EVENTFD
> -    int ret;
> -
> -    ret = eventfd(0, 0);
> -    if (ret >= 0) {
> -        fds[0] = ret;
> -        fds[1] = dup(ret);
> -        if (fds[1] == -1) {
> -            close(ret);
> -            return -1;
> -        }
> -        qemu_set_cloexec(ret);
> -        qemu_set_cloexec(fds[1]);
> -        return 0;
> -    }
> -    if (errno != ENOSYS) {
> -        return -1;
> -    }
> -#endif
> -
> -    return qemu_pipe(fds);
> -}
> -
>  int qemu_utimens(const char *path, const struct timespec *times)
>  {
>      struct timeval tv[2], tv_now;
> diff --git a/qemu-common.h b/qemu-common.h
> index 9d9e603..036d254 100644
> --- a/qemu-common.h
> +++ b/qemu-common.h
> @@ -195,7 +195,6 @@ ssize_t qemu_recv_full(int fd, void *buf, size_t count, int flags)
>      QEMU_WARN_UNUSED_RESULT;
>  
>  #ifndef _WIN32
> -int qemu_eventfd(int pipefd[2]);
>  int qemu_pipe(int pipefd[2]);
>  #endif
>  
> -- 
> 1.7.10.4