| /* |
| * 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_socket.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; |
| } |