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![Paolo Bonzini](/assets/img/avatar_default.png)
If ret is WAIT_TIMEOUT and there was an event returned by select(), we can write to a location after the end of the array. But in that case we can retry the WaitForMultipleObjects call with the same set of events, so just move the event[ret - WAIT_OBJECT_0] assignment inside the existin conditional. Reported-by: TeLeMan <geleman@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: TeLeMan <geleman@gmail.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
354 lines
9.6 KiB
C
354 lines
9.6 KiB
C
/*
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* QEMU aio implementation
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*
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* Copyright IBM Corp., 2008
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* Copyright Red Hat Inc., 2012
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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* Paolo Bonzini <pbonzini@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*
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* Contributions after 2012-01-13 are licensed under the terms of the
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* GNU GPL, version 2 or (at your option) any later version.
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*/
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#include "qemu-common.h"
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#include "block/block.h"
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#include "qemu/queue.h"
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#include "qemu/sockets.h"
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struct AioHandler {
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EventNotifier *e;
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IOHandler *io_read;
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IOHandler *io_write;
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EventNotifierHandler *io_notify;
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GPollFD pfd;
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int deleted;
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void *opaque;
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QLIST_ENTRY(AioHandler) node;
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};
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void aio_set_fd_handler(AioContext *ctx,
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int fd,
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IOHandler *io_read,
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IOHandler *io_write,
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void *opaque)
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{
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/* fd is a SOCKET in our case */
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AioHandler *node;
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QLIST_FOREACH(node, &ctx->aio_handlers, node) {
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if (node->pfd.fd == fd && !node->deleted) {
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break;
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}
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}
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/* Are we deleting the fd handler? */
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if (!io_read && !io_write) {
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if (node) {
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/* If the lock is held, just mark the node as deleted */
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if (ctx->walking_handlers) {
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node->deleted = 1;
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node->pfd.revents = 0;
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} else {
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/* Otherwise, delete it for real. We can't just mark it as
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* deleted because deleted nodes are only cleaned up after
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* releasing the walking_handlers lock.
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*/
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QLIST_REMOVE(node, node);
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g_free(node);
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}
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}
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} else {
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HANDLE event;
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if (node == NULL) {
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/* Alloc and insert if it's not already there */
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node = g_malloc0(sizeof(AioHandler));
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node->pfd.fd = fd;
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QLIST_INSERT_HEAD(&ctx->aio_handlers, node, node);
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}
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node->pfd.events = 0;
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if (node->io_read) {
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node->pfd.events |= G_IO_IN;
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}
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if (node->io_write) {
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node->pfd.events |= G_IO_OUT;
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}
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node->e = &ctx->notifier;
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/* Update handler with latest information */
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node->opaque = opaque;
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node->io_read = io_read;
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node->io_write = io_write;
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event = event_notifier_get_handle(&ctx->notifier);
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WSAEventSelect(node->pfd.fd, event,
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FD_READ | FD_ACCEPT | FD_CLOSE |
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FD_CONNECT | FD_WRITE | FD_OOB);
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}
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aio_notify(ctx);
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}
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void aio_set_event_notifier(AioContext *ctx,
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EventNotifier *e,
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EventNotifierHandler *io_notify)
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{
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AioHandler *node;
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QLIST_FOREACH(node, &ctx->aio_handlers, node) {
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if (node->e == e && !node->deleted) {
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break;
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}
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}
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/* Are we deleting the fd handler? */
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if (!io_notify) {
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if (node) {
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g_source_remove_poll(&ctx->source, &node->pfd);
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/* If the lock is held, just mark the node as deleted */
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if (ctx->walking_handlers) {
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node->deleted = 1;
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node->pfd.revents = 0;
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} else {
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/* Otherwise, delete it for real. We can't just mark it as
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* deleted because deleted nodes are only cleaned up after
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* releasing the walking_handlers lock.
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*/
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QLIST_REMOVE(node, node);
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g_free(node);
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}
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}
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} else {
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if (node == NULL) {
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/* Alloc and insert if it's not already there */
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node = g_malloc0(sizeof(AioHandler));
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node->e = e;
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node->pfd.fd = (uintptr_t)event_notifier_get_handle(e);
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node->pfd.events = G_IO_IN;
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QLIST_INSERT_HEAD(&ctx->aio_handlers, node, node);
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g_source_add_poll(&ctx->source, &node->pfd);
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}
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/* Update handler with latest information */
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node->io_notify = io_notify;
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}
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aio_notify(ctx);
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}
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bool aio_prepare(AioContext *ctx)
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{
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static struct timeval tv0;
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AioHandler *node;
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bool have_select_revents = false;
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fd_set rfds, wfds;
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/* fill fd sets */
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FD_ZERO(&rfds);
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FD_ZERO(&wfds);
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QLIST_FOREACH(node, &ctx->aio_handlers, node) {
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if (node->io_read) {
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FD_SET ((SOCKET)node->pfd.fd, &rfds);
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}
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if (node->io_write) {
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FD_SET ((SOCKET)node->pfd.fd, &wfds);
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}
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}
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if (select(0, &rfds, &wfds, NULL, &tv0) > 0) {
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QLIST_FOREACH(node, &ctx->aio_handlers, node) {
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node->pfd.revents = 0;
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if (FD_ISSET(node->pfd.fd, &rfds)) {
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node->pfd.revents |= G_IO_IN;
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have_select_revents = true;
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}
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if (FD_ISSET(node->pfd.fd, &wfds)) {
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node->pfd.revents |= G_IO_OUT;
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have_select_revents = true;
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}
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}
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}
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return have_select_revents;
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}
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bool aio_pending(AioContext *ctx)
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{
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AioHandler *node;
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QLIST_FOREACH(node, &ctx->aio_handlers, node) {
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if (node->pfd.revents && node->io_notify) {
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return true;
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}
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if ((node->pfd.revents & G_IO_IN) && node->io_read) {
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return true;
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}
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if ((node->pfd.revents & G_IO_OUT) && node->io_write) {
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return true;
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}
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}
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return false;
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}
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static bool aio_dispatch_handlers(AioContext *ctx, HANDLE event)
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{
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AioHandler *node;
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bool progress = false;
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/*
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* We have to walk very carefully in case aio_set_fd_handler is
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* called while we're walking.
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*/
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node = QLIST_FIRST(&ctx->aio_handlers);
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while (node) {
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AioHandler *tmp;
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int revents = node->pfd.revents;
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ctx->walking_handlers++;
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if (!node->deleted &&
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(revents || event_notifier_get_handle(node->e) == event) &&
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node->io_notify) {
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node->pfd.revents = 0;
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node->io_notify(node->e);
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/* aio_notify() does not count as progress */
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if (node->e != &ctx->notifier) {
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progress = true;
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}
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}
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if (!node->deleted &&
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(node->io_read || node->io_write)) {
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node->pfd.revents = 0;
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if ((revents & G_IO_IN) && node->io_read) {
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node->io_read(node->opaque);
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progress = true;
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}
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if ((revents & G_IO_OUT) && node->io_write) {
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node->io_write(node->opaque);
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progress = true;
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}
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/* if the next select() will return an event, we have progressed */
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if (event == event_notifier_get_handle(&ctx->notifier)) {
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WSANETWORKEVENTS ev;
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WSAEnumNetworkEvents(node->pfd.fd, event, &ev);
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if (ev.lNetworkEvents) {
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progress = true;
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}
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}
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}
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tmp = node;
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node = QLIST_NEXT(node, node);
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ctx->walking_handlers--;
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if (!ctx->walking_handlers && tmp->deleted) {
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QLIST_REMOVE(tmp, node);
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g_free(tmp);
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}
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}
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return progress;
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}
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bool aio_dispatch(AioContext *ctx)
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{
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bool progress;
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progress = aio_bh_poll(ctx);
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progress |= aio_dispatch_handlers(ctx, INVALID_HANDLE_VALUE);
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progress |= timerlistgroup_run_timers(&ctx->tlg);
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return progress;
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}
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bool aio_poll(AioContext *ctx, bool blocking)
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{
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AioHandler *node;
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HANDLE events[MAXIMUM_WAIT_OBJECTS + 1];
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bool was_dispatching, progress, have_select_revents, first;
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int count;
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int timeout;
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have_select_revents = aio_prepare(ctx);
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if (have_select_revents) {
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blocking = false;
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}
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was_dispatching = ctx->dispatching;
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progress = false;
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/* aio_notify can avoid the expensive event_notifier_set if
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* everything (file descriptors, bottom halves, timers) will
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* be re-evaluated before the next blocking poll(). This is
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* already true when aio_poll is called with blocking == false;
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* if blocking == true, it is only true after poll() returns.
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*
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* If we're in a nested event loop, ctx->dispatching might be true.
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* In that case we can restore it just before returning, but we
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* have to clear it now.
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*/
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aio_set_dispatching(ctx, !blocking);
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ctx->walking_handlers++;
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/* fill fd sets */
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count = 0;
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QLIST_FOREACH(node, &ctx->aio_handlers, node) {
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if (!node->deleted && node->io_notify) {
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events[count++] = event_notifier_get_handle(node->e);
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}
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}
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ctx->walking_handlers--;
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first = true;
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/* wait until next event */
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while (count > 0) {
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HANDLE event;
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int ret;
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timeout = blocking
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? qemu_timeout_ns_to_ms(aio_compute_timeout(ctx)) : 0;
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ret = WaitForMultipleObjects(count, events, FALSE, timeout);
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aio_set_dispatching(ctx, true);
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if (first && aio_bh_poll(ctx)) {
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progress = true;
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}
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first = false;
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/* if we have any signaled events, dispatch event */
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event = NULL;
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if ((DWORD) (ret - WAIT_OBJECT_0) < count) {
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event = events[ret - WAIT_OBJECT_0];
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events[ret - WAIT_OBJECT_0] = events[--count];
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} else if (!have_select_revents) {
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break;
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}
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have_select_revents = false;
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blocking = false;
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progress |= aio_dispatch_handlers(ctx, event);
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}
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progress |= timerlistgroup_run_timers(&ctx->tlg);
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aio_set_dispatching(ctx, was_dispatching);
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return progress;
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}
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