/* * 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.h" #include "qemu-queue.h" #include "qemu_socket.h" struct AioHandler { EventNotifier *e; EventNotifierHandler *io_notify; AioFlushEventNotifierHandler *io_flush; GPollFD pfd; int deleted; QLIST_ENTRY(AioHandler) node; }; void aio_set_event_notifier(AioContext *ctx, EventNotifier *e, EventNotifierHandler *io_notify, AioFlushEventNotifierHandler *io_flush) { 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; node->io_flush = io_flush; } 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; } bool aio_poll(AioContext *ctx, bool blocking) { AioHandler *node; HANDLE events[MAXIMUM_WAIT_OBJECTS + 1]; bool busy, progress; int count; 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; ctx->walking_handlers++; if (node->pfd.revents && node->io_notify) { node->pfd.revents = 0; node->io_notify(node->e); 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++; /* fill fd sets */ busy = false; count = 0; 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->e) == 0) { continue; } busy = true; } if (!node->deleted && node->io_notify) { events[count++] = event_notifier_get_handle(node->e); } } ctx->walking_handlers--; /* No AIO operations? Get us out of here */ if (!busy) { return progress; } /* wait until next event */ for (;;) { int timeout = blocking ? INFINITE : 0; int ret = WaitForMultipleObjects(count, events, FALSE, timeout); /* if we have any signaled events, dispatch event */ if ((DWORD) (ret - WAIT_OBJECT_0) >= count) { break; } blocking = false; /* 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 && event_notifier_get_handle(node->e) == events[ret - WAIT_OBJECT_0] && node->io_notify) { node->io_notify(node->e); 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; }