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[Qemu-devel] [PATCH v3 3/7] poll: Add epoll implementation for qemu_poll
From: |
Fam Zheng |
Subject: |
[Qemu-devel] [PATCH v3 3/7] poll: Add epoll implementation for qemu_poll |
Date: |
Thu, 16 Apr 2015 12:57:32 +0800 |
This implements qemu_poll with ppoll + epoll. The only complex part is
qemu_poll_set_fds, which will sync up epollfd with epoll_ctl by
computing the symmetric difference of previous and new fds.
The ppoll is used to retain ns precision of timeout.
Signed-off-by: Fam Zheng <address@hidden>
---
Makefile.objs | 4 +-
poll-linux.c | 232 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 235 insertions(+), 1 deletion(-)
create mode 100644 poll-linux.c
diff --git a/Makefile.objs b/Makefile.objs
index 77a56d0..d3f6f51 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -9,7 +9,9 @@ util-obj-y = util/ qobject/ qapi/ qapi-types.o qapi-visit.o
qapi-event.o
block-obj-y = async.o thread-pool.o
block-obj-y += nbd.o block.o blockjob.o
block-obj-y += main-loop.o iohandler.o qemu-timer.o
-block-obj-$(CONFIG_POSIX) += aio-posix.o poll-glib.o
+block-obj-$(CONFIG_POSIX) += aio-posix.o
+block-obj-$(CONFIG_EPOLL) += poll-linux.o
+block-obj-$(if $(CONFIG_EPOLL),n,$(CONFIG_POSIX)) += poll-glib.o
block-obj-$(CONFIG_WIN32) += aio-win32.o
block-obj-y += block/
block-obj-y += qemu-io-cmds.o
diff --git a/poll-linux.c b/poll-linux.c
new file mode 100644
index 0000000..7605004
--- /dev/null
+++ b/poll-linux.c
@@ -0,0 +1,232 @@
+/*
+ * epoll implementation for QEMU Poll API
+ *
+ * Copyright Red Hat, Inc. 2014
+ *
+ * Authors:
+ * Fam Zheng <address@hidden>
+ *
+ * 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 <glib.h>
+#include <poll.h>
+#include "qemu-common.h"
+#include "qemu/timer.h"
+#include "qemu/poll.h"
+
+struct QEMUPoll {
+ int epollfd;
+ struct epoll_event *events;
+ int max_events;
+ int nevents;
+ GHashTable *fds;
+};
+
+QEMUPoll *qemu_poll_new(void)
+{
+ int epollfd;
+ QEMUPoll *qpoll = g_new0(QEMUPoll, 1);
+ epollfd = epoll_create1(EPOLL_CLOEXEC);
+ if (epollfd < 0) {
+ perror("epoll_create1:");
+ abort();
+ }
+ qpoll->epollfd = epollfd;
+ qpoll->max_events = 1;
+ qpoll->events = g_new(struct epoll_event, 1);
+ qpoll->fds = g_hash_table_new_full(g_int_hash, g_int_equal,
+ NULL, g_free);
+ return qpoll;
+}
+
+void qemu_poll_free(QEMUPoll *qpoll)
+{
+ g_free(qpoll->events);
+ g_hash_table_destroy(qpoll->fds);
+ close(qpoll->epollfd);
+ g_free(qpoll);
+}
+
+int qemu_poll(QEMUPoll *qpoll, int64_t timeout_ns)
+{
+ int r;
+ struct pollfd fd = {
+ .fd = qpoll->epollfd,
+ .events = POLLIN | POLLOUT | POLLERR | POLLHUP,
+ };
+
+ if (timeout_ns >= 0) {
+ struct timespec ts;
+ ts.tv_sec = timeout_ns / 1000000000LL;
+ ts.tv_nsec = timeout_ns % 1000000000LL;
+ r = ppoll(&fd, 1, &ts, NULL);
+ } else {
+ r = ppoll(&fd, 1, NULL, NULL);
+ }
+
+ if (r > 0) {
+ r = epoll_wait(qpoll->epollfd,
+ qpoll->events,
+ qpoll->max_events,
+ 0);
+ qpoll->nevents = r;
+ }
+ return r;
+}
+
+static inline uint32_t epoll_event_from_gio_events(int gio_events)
+{
+
+ return (gio_events & G_IO_IN ? EPOLLIN : 0) |
+ (gio_events & G_IO_OUT ? EPOLLOUT : 0) |
+ (gio_events & G_IO_ERR ? EPOLLERR : 0) |
+ (gio_events & G_IO_HUP ? EPOLLHUP : 0);
+}
+
+
+/* Add an fd to poll. Return -EEXIST if fd already registered. */
+int qemu_poll_add(QEMUPoll *qpoll, int fd, int gio_events, void *opaque)
+{
+ int ret;
+ struct epoll_event ev;
+ QEMUPollEvent *e;
+
+ ev.events = epoll_event_from_gio_events(gio_events);
+ ev.data.fd = fd;
+ ret = epoll_ctl(qpoll->epollfd, EPOLL_CTL_ADD, fd, &ev);
+ if (ret) {
+ ret = -errno;
+ return ret;
+ }
+ qpoll->max_events++;
+ qpoll->events = g_renew(struct epoll_event,
+ qpoll->events,
+ qpoll->max_events);
+ /* Shouldn't get here if the fd is already added since epoll_ctl would
+ * return -EEXIST, assert to be sure */
+ assert(g_hash_table_lookup(qpoll->fds, &fd) == NULL);
+ e = g_new0(QEMUPollEvent, 1);
+ e->fd = fd;
+ e->events = gio_events;
+ e->opaque = opaque;
+ g_hash_table_insert(qpoll->fds, &e->fd, e);
+ return ret;
+}
+
+/* Delete a previously added fd. Return -ENOENT if fd not registered. */
+int qemu_poll_del(QEMUPoll *qpoll, int fd)
+{
+ int ret;
+
+ if (!g_hash_table_lookup(qpoll->fds, &fd)) {
+ ret = -ENOENT;
+ goto out;
+ }
+ ret = epoll_ctl(qpoll->epollfd, EPOLL_CTL_DEL, fd, NULL);
+ if (ret) {
+ ret = -errno;
+ goto out;
+ }
+ qpoll->max_events--;
+ qpoll->events = g_renew(struct epoll_event,
+ qpoll->events,
+ qpoll->max_events);
+out:
+ g_hash_table_remove(qpoll->fds, &fd);
+ return ret;
+}
+
+static void qemu_poll_copy_fd(gpointer key, gpointer value, gpointer user_data)
+{
+ GHashTable *dst = user_data;
+ QEMUPollEvent *event, *copy;
+
+ event = value;
+ copy = g_new(QEMUPollEvent, 1);
+ *copy = *event;
+ g_hash_table_insert(dst, ©->fd, copy);
+}
+
+static void qemu_poll_del_fd(gpointer key, gpointer value, gpointer user_data)
+{
+ QEMUPoll *qpoll = user_data;
+ QEMUPollEvent *event = value;
+
+ qemu_poll_del(qpoll, event->fd);
+}
+
+int qemu_poll_set_fds(QEMUPoll *qpoll, GPollFD *fds, int nfds)
+{
+ int i;
+ int updated = 0;
+ int ret = nfds;
+ int old_size = g_hash_table_size(qpoll->fds);
+
+ for (i = 0; i < nfds; i++) {
+ int r;
+ GPollFD *fd = &fds[i];
+ QEMUPollEvent *e = g_hash_table_lookup(qpoll->fds, &fd->fd);
+ if (e) {
+ updated++;
+ assert(e->fd == fd->fd);
+ if (e->events == fd->events) {
+ e->opaque = fd;
+ continue;
+ }
+ r = qemu_poll_del(qpoll, fd->fd);
+ if (r < 0) {
+ ret = r;
+ break;
+ }
+ }
+ r = qemu_poll_add(qpoll, fd->fd, fd->events, fd);
+ if (r < 0) {
+ ret = r;
+ break;
+ }
+ }
+
+ if (updated < old_size) {
+ GHashTable *fds_copy;
+
+ fds_copy = g_hash_table_new_full(g_int_hash, g_int_equal, NULL,
g_free);
+ g_hash_table_foreach(qpoll->fds, qemu_poll_copy_fd, fds_copy);
+
+ /* Some fds need to be removed, as they are not seen in new fds */
+ for (i = 0; i < nfds; i++) {
+ GPollFD *fd = &fds[i];
+ g_hash_table_remove(fds_copy, &fd->fd);
+ }
+
+ g_hash_table_foreach(fds_copy, qemu_poll_del_fd, qpoll);
+ g_hash_table_destroy(fds_copy);
+ }
+ return ret;
+}
+
+int qemu_poll_get_events(QEMUPoll *qpoll,
+ QEMUPollEvent *events,
+ int max_events)
+{
+ int i;
+ QEMUPollEvent *p;
+ struct epoll_event *ev;
+ int fd;
+
+ for (i = 0; i < MIN(qpoll->nevents, max_events); i++) {
+ ev = &qpoll->events[i];
+ fd = ev->data.fd;
+ p = g_hash_table_lookup(qpoll->fds, &fd);
+ assert(p);
+
+ events[i].revents = ev->events;
+ events[i].opaque = p->opaque;
+ events[i].fd = fd;
+ events[i].events = p->events;
+ }
+ return i;
+}
--
1.9.3
- [Qemu-devel] [PATCH v3 0/7] aio: Support epoll by introducing qemu_poll abstraction, Fam Zheng, 2015/04/16
- [Qemu-devel] [PATCH v3 1/7] poll: Introduce QEMU Poll API, Fam Zheng, 2015/04/16
- [Qemu-devel] [PATCH v3 3/7] poll: Add epoll implementation for qemu_poll,
Fam Zheng <=
- [Qemu-devel] [PATCH v3 2/7] posix-aio: Use QEMU poll interface, Fam Zheng, 2015/04/16
- [Qemu-devel] [PATCH v3 4/7] main-loop: Replace qemu_poll_ns with qemu_poll, Fam Zheng, 2015/04/16
- [Qemu-devel] [PATCH v3 5/7] tests: Add test case for qemu_poll, Fam Zheng, 2015/04/16
- [Qemu-devel] [PATCH v3 6/7] poll-glib: Support ppoll, Fam Zheng, 2015/04/16
- [Qemu-devel] [PATCH v3 7/7] poll-linux: Add timerfd support, Fam Zheng, 2015/04/16
- Re: [Qemu-devel] [PATCH v3 0/7] aio: Support epoll by introducing qemu_poll abstraction, Stefan Hajnoczi, 2015/04/16