qemu/aio-posix.c

269 lines
7.3 KiB
C

/*
* QEMU aio implementation
*
* Copyright IBM, Corp. 2008
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.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
{
GPollFD pfd;
IOHandler *io_read;
IOHandler *io_write;
AioFlushHandler *io_flush;
int deleted;
void *opaque;
QLIST_ENTRY(AioHandler) node;
};
static AioHandler *find_aio_handler(AioContext *ctx, int fd)
{
AioHandler *node;
QLIST_FOREACH(node, &ctx->aio_handlers, node) {
if (node->pfd.fd == fd)
if (!node->deleted)
return node;
}
return NULL;
}
void aio_set_fd_handler(AioContext *ctx,
int fd,
IOHandler *io_read,
IOHandler *io_write,
AioFlushHandler *io_flush,
void *opaque)
{
AioHandler *node;
node = find_aio_handler(ctx, fd);
/* Are we deleting the fd handler? */
if (!io_read && !io_write) {
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->pfd.fd = fd;
QLIST_INSERT_HEAD(&ctx->aio_handlers, node, node);
g_source_add_poll(&ctx->source, &node->pfd);
}
/* Update handler with latest information */
node->io_read = io_read;
node->io_write = io_write;
node->io_flush = io_flush;
node->opaque = opaque;
node->pfd.events = (io_read ? G_IO_IN | G_IO_HUP : 0);
node->pfd.events |= (io_write ? G_IO_OUT : 0);
}
aio_notify(ctx);
}
void aio_set_event_notifier(AioContext *ctx,
EventNotifier *notifier,
EventNotifierHandler *io_read,
AioFlushEventNotifierHandler *io_flush)
{
aio_set_fd_handler(ctx, event_notifier_get_fd(notifier),
(IOHandler *)io_read, NULL,
(AioFlushHandler *)io_flush, notifier);
}
bool aio_pending(AioContext *ctx)
{
AioHandler *node;
QLIST_FOREACH(node, &ctx->aio_handlers, node) {
int revents;
/*
* FIXME: right now we cannot get G_IO_HUP and G_IO_ERR because
* main-loop.c is still select based (due to the slirp legacy).
* If main-loop.c ever switches to poll, G_IO_ERR should be
* tested too. Dispatching G_IO_ERR to both handlers should be
* okay, since handlers need to be ready for spurious wakeups.
*/
revents = node->pfd.revents & node->pfd.events;
if (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR) && node->io_read) {
return true;
}
if (revents & (G_IO_OUT | G_IO_ERR) && node->io_write) {
return true;
}
}
return false;
}
bool aio_poll(AioContext *ctx, bool blocking)
{
static struct timeval tv0;
AioHandler *node;
fd_set rdfds, wrfds;
int max_fd = -1;
int ret;
bool busy, progress;
progress = false;
/*
* If there are callbacks left that have been queued, we need to call then.
* Do not call select in this case, because it is possible that the caller
* does not need a complete flush (as is the case for qemu_aio_wait loops).
*/
if (aio_bh_poll(ctx)) {
blocking = false;
progress = true;
}
/*
* Then dispatch any pending callbacks from the GSource.
*
* We have to walk very carefully in case qemu_aio_set_fd_handler is
* called while we're walking.
*/
node = QLIST_FIRST(&ctx->aio_handlers);
while (node) {
AioHandler *tmp;
int revents;
ctx->walking_handlers++;
revents = node->pfd.revents & node->pfd.events;
node->pfd.revents = 0;
/* See comment in aio_pending. */
if (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR) && node->io_read) {
node->io_read(node->opaque);
progress = true;
}
if (revents & (G_IO_OUT | G_IO_ERR) && node->io_write) {
node->io_write(node->opaque);
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);
}
}
if (progress && !blocking) {
return true;
}
ctx->walking_handlers++;
FD_ZERO(&rdfds);
FD_ZERO(&wrfds);
/* fill fd sets */
busy = false;
QLIST_FOREACH(node, &ctx->aio_handlers, node) {
/* If there aren't pending AIO operations, don't invoke callbacks.
* Otherwise, if there are no AIO requests, qemu_aio_wait() would
* wait indefinitely.
*/
if (!node->deleted && node->io_flush) {
if (node->io_flush(node->opaque) == 0) {
continue;
}
busy = true;
}
if (!node->deleted && node->io_read) {
FD_SET(node->pfd.fd, &rdfds);
max_fd = MAX(max_fd, node->pfd.fd + 1);
}
if (!node->deleted && node->io_write) {
FD_SET(node->pfd.fd, &wrfds);
max_fd = MAX(max_fd, node->pfd.fd + 1);
}
}
ctx->walking_handlers--;
/* No AIO operations? Get us out of here */
if (!busy) {
return progress;
}
/* wait until next event */
ret = select(max_fd, &rdfds, &wrfds, NULL, blocking ? NULL : &tv0);
/* if we have any readable fds, dispatch event */
if (ret > 0) {
/* we have to walk very carefully in case
* qemu_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 &&
FD_ISSET(node->pfd.fd, &rdfds) &&
node->io_read) {
node->io_read(node->opaque);
progress = true;
}
if (!node->deleted &&
FD_ISSET(node->pfd.fd, &wrfds) &&
node->io_write) {
node->io_write(node->opaque);
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;
}