/* * QEMU aio implementation * * Copyright IBM, Corp. 2008 * * Authors: * Anthony Liguori * * 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); } } } assert(progress || busy); return true; }