On Thu, Feb 21, 2013 at 05:29:55PM +0100, Paolo Bonzini wrote:
> During the review of the dataplane code, the EventPoll API morphed itself
> (not concidentially) into something very very similar to an AioContext.
> Thus, it is trivial to convert virtio-blk-dataplane to use AioContext,
> and a first baby step towards letting dataplane talk directly to the
> QEMU block layer.
>
> The only interesting note is the value-copy of EventNotifiers. At least
> in my opinion this is part of the EventNotifier API and is even portable
> to Windows. Of course, in this case you should not close the notifier's
> underlying file descriptors or handle with event_notifier_cleanup.
>
> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
> ---
> hw/dataplane/Makefile.objs | 2 +-
> hw/dataplane/event-poll.c | 100
> ---------------------------------------------
> hw/dataplane/event-poll.h | 40 ------------------
> hw/dataplane/virtio-blk.c | 41 ++++++++++---------
> 4 files changed, 22 insertions(+), 161 deletions(-)
> delete mode 100644 hw/dataplane/event-poll.c
> delete mode 100644 hw/dataplane/event-poll.h
>
> diff --git a/hw/dataplane/Makefile.objs b/hw/dataplane/Makefile.objs
> index 3e47d05..701111c 100644
> --- a/hw/dataplane/Makefile.objs
> +++ b/hw/dataplane/Makefile.objs
> @@ -1 +1 @@
> -obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += hostmem.o vring.o event-poll.o ioq.o
> virtio-blk.o
> +obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += hostmem.o vring.o ioq.o virtio-blk.o
> diff --git a/hw/dataplane/event-poll.c b/hw/dataplane/event-poll.c
> deleted file mode 100644
> index 2b55c6e..0000000
> --- a/hw/dataplane/event-poll.c
> +++ /dev/null
> @@ -1,100 +0,0 @@
> -/*
> - * Event loop with file descriptor polling
> - *
> - * Copyright 2012 IBM, Corp.
> - * Copyright 2012 Red Hat, Inc. and/or its affiliates
> - *
> - * Authors:
> - * Stefan Hajnoczi <stefa...@redhat.com>
> - *
> - * This work is licensed under the terms of the GNU GPL, version 2 or later.
> - * See the COPYING file in the top-level directory.
> - *
> - */
> -
> -#include <sys/epoll.h>
> -#include "hw/dataplane/event-poll.h"
> -
> -/* Add an event notifier and its callback for polling */
> -void event_poll_add(EventPoll *poll, EventHandler *handler,
> - EventNotifier *notifier, EventCallback *callback)
> -{
> - struct epoll_event event = {
> - .events = EPOLLIN,
> - .data.ptr = handler,
> - };
> - handler->notifier = notifier;
> - handler->callback = callback;
> - if (epoll_ctl(poll->epoll_fd, EPOLL_CTL_ADD,
> - event_notifier_get_fd(notifier), &event) != 0) {
> - fprintf(stderr, "failed to add event handler to epoll: %m\n");
> - exit(1);
> - }
> -}
> -
> -/* Event callback for stopping event_poll() */
> -static void handle_stop(EventHandler *handler)
> -{
> - /* Do nothing */
> -}
> -
> -void event_poll_init(EventPoll *poll)
> -{
> - /* Create epoll file descriptor */
> - poll->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
> - if (poll->epoll_fd < 0) {
> - fprintf(stderr, "epoll_create1 failed: %m\n");
> - exit(1);
> - }
> -
> - /* Set up stop notifier */
> - if (event_notifier_init(&poll->stop_notifier, 0) < 0) {
> - fprintf(stderr, "failed to init stop notifier\n");
> - exit(1);
> - }
> - event_poll_add(poll, &poll->stop_handler,
> - &poll->stop_notifier, handle_stop);
> -}
> -
> -void event_poll_cleanup(EventPoll *poll)
> -{
> - event_notifier_cleanup(&poll->stop_notifier);
> - close(poll->epoll_fd);
> - poll->epoll_fd = -1;
> -}
> -
> -/* Block until the next event and invoke its callback */
> -void event_poll(EventPoll *poll)
> -{
> - EventHandler *handler;
> - struct epoll_event event;
> - int nevents;
> -
> - /* Wait for the next event. Only do one event per call to keep the
> - * function simple, this could be changed later. */
> - do {
> - nevents = epoll_wait(poll->epoll_fd, &event, 1, -1);
> - } while (nevents < 0 && errno == EINTR);
> - if (unlikely(nevents != 1)) {
> - fprintf(stderr, "epoll_wait failed: %m\n");
> - exit(1); /* should never happen */
> - }
> -
> - /* Find out which event handler has become active */
> - handler = event.data.ptr;
> -
> - /* Clear the eventfd */
> - event_notifier_test_and_clear(handler->notifier);
Wouldn't we need to move this into the handle_io/handle_notify to maintain the
old behavior?
