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/*
* QEMU aio implementation
*
* Copyright IBM Corp., 2008
* Copyright Red Hat Inc., 2012
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
* Paolo Bonzini <pbonzini@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
* Contributions after 2012-01-13 are licensed under the terms of the
* GNU GPL, version 2 or (at your option) any later version.
*/
#include "qemu-common.h"
#include "block/block.h"
#include "qemu/queue.h"
#include "qemu/sockets.h"
struct AioHandler {
EventNotifier *e;
EventNotifierHandler *io_notify;
GPollFD pfd;
int deleted;
QLIST_ENTRY(AioHandler) node;
};
void aio_set_event_notifier(AioContext *ctx,
EventNotifier *e,
EventNotifierHandler *io_notify)
{
AioHandler *node;
QLIST_FOREACH(node, &ctx->aio_handlers, node) {
if (node->e == e && !node->deleted) {
break;
}
}
/* Are we deleting the fd handler? */
if (!io_notify) {
if (node) {
g_source_remove_poll(&ctx->source, &node->pfd);
/* If the lock is held, just mark the node as deleted */
if (ctx->walking_handlers) {
node->deleted = 1;
node->pfd.revents = 0;
} else {
/* Otherwise, delete it for real. We can't just mark it as
* deleted because deleted nodes are only cleaned up after
* releasing the walking_handlers lock.
*/
QLIST_REMOVE(node, node);
g_free(node);
}
}
} else {
if (node == NULL) {
/* Alloc and insert if it's not already there */
node = g_malloc0(sizeof(AioHandler));
node->e = e;
node->pfd.fd = (uintptr_t)event_notifier_get_handle(e);
node->pfd.events = G_IO_IN;
QLIST_INSERT_HEAD(&ctx->aio_handlers, node, node);
g_source_add_poll(&ctx->source, &node->pfd);
}
/* Update handler with latest information */
node->io_notify = io_notify;
}
aio_notify(ctx);
}
bool aio_pending(AioContext *ctx)
{
AioHandler *node;
QLIST_FOREACH(node, &ctx->aio_handlers, node) {
if (node->pfd.revents && node->io_notify) {
return true;
}
}
return false;
}
static bool aio_dispatch_handlers(AioContext *ctx, HANDLE event)
{
AioHandler *node;
bool progress = false;
/*
* We have to walk very carefully in case aio_set_fd_handler is
* called while we're walking.
*/
node = QLIST_FIRST(&ctx->aio_handlers);
while (node) {
AioHandler *tmp;
ctx->walking_handlers++;
if (!node->deleted &&
(node->pfd.revents || event_notifier_get_handle(node->e) == event) &&
node->io_notify) {
node->pfd.revents = 0;
node->io_notify(node->e);
/* aio_notify() does not count as progress */
if (node->e != &ctx->notifier) {
progress = true;
}
}
tmp = node;
node = QLIST_NEXT(node, node);
ctx->walking_handlers--;
if (!ctx->walking_handlers && tmp->deleted) {
QLIST_REMOVE(tmp, node);
g_free(tmp);
}
}
return progress;
}
bool aio_dispatch(AioContext *ctx)
{
bool progress;
progress = aio_bh_poll(ctx);
progress |= aio_dispatch_handlers(ctx, INVALID_HANDLE_VALUE);
progress |= timerlistgroup_run_timers(&ctx->tlg);
return progress;
}
bool aio_poll(AioContext *ctx, bool blocking)
{
AioHandler *node;
HANDLE events[MAXIMUM_WAIT_OBJECTS + 1];
bool was_dispatching, progress, first;
int count;
int timeout;
was_dispatching = ctx->dispatching;
progress = false;
/* aio_notify can avoid the expensive event_notifier_set if
* everything (file descriptors, bottom halves, timers) will
* be re-evaluated before the next blocking poll(). This is
* already true when aio_poll is called with blocking == false;
* if blocking == true, it is only true after poll() returns.
*
* If we're in a nested event loop, ctx->dispatching might be true.
* In that case we can restore it just before returning, but we
* have to clear it now.
*/
aio_set_dispatching(ctx, !blocking);
ctx->walking_handlers++;
/* fill fd sets */
count = 0;
QLIST_FOREACH(node, &ctx->aio_handlers, node) {
if (!node->deleted && node->io_notify) {
events[count++] = event_notifier_get_handle(node->e);
}
}
ctx->walking_handlers--;
first = true;
/* wait until next event */
while (count > 0) {
int ret;
timeout = blocking
? qemu_timeout_ns_to_ms(aio_compute_timeout(ctx)) : 0;
ret = WaitForMultipleObjects(count, events, FALSE, timeout);
aio_set_dispatching(ctx, true);
if (first && aio_bh_poll(ctx)) {
progress = true;
}
first = false;
/* if we have any signaled events, dispatch event */
if ((DWORD) (ret - WAIT_OBJECT_0) >= count) {
break;
}
blocking = false;
progress |= aio_dispatch_handlers(ctx, events[ret - WAIT_OBJECT_0]);
/* Try again, but only call each handler once. */
events[ret - WAIT_OBJECT_0] = events[--count];
}
progress |= timerlistgroup_run_timers(&ctx->tlg);
aio_set_dispatching(ctx, was_dispatching);
return progress;
}
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