/* * 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/osdep.h" #include "qemu-common.h" #include "block/block.h" #include "qemu/queue.h" #include "qemu/sockets.h" struct AioHandler { EventNotifier *e; IOHandler *io_read; IOHandler *io_write; EventNotifierHandler *io_notify; GPollFD pfd; int deleted; void *opaque; bool is_external; QLIST_ENTRY(AioHandler) node; }; void aio_set_fd_handler(AioContext *ctx, int fd, bool is_external, IOHandler *io_read, IOHandler *io_write, void *opaque) { /* fd is a SOCKET in our case */ AioHandler *node; QLIST_FOREACH(node, &ctx->aio_handlers, node) { if (node->pfd.fd == fd && !node->deleted) { break; } } /* Are we deleting the fd handler? */ if (!io_read && !io_write) { if (node) { /* 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 { HANDLE event; if (node == NULL) { /* Alloc and insert if it's not already there */ node = g_new0(AioHandler, 1); node->pfd.fd = fd; QLIST_INSERT_HEAD(&ctx->aio_handlers, node, node); } node->pfd.events = 0; if (node->io_read) { node->pfd.events |= G_IO_IN; } if (node->io_write) { node->pfd.events |= G_IO_OUT; } node->e = &ctx->notifier; /* Update handler with latest information */ node->opaque = opaque; node->io_read = io_read; node->io_write = io_write; node->is_external = is_external; event = event_notifier_get_handle(&ctx->notifier); WSAEventSelect(node->pfd.fd, event, FD_READ | FD_ACCEPT | FD_CLOSE | FD_CONNECT | FD_WRITE | FD_OOB); } aio_notify(ctx); } void aio_set_event_notifier(AioContext *ctx, EventNotifier *e, bool is_external, 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_new0(AioHandler, 1); node->e = e; node->pfd.fd = (uintptr_t)event_notifier_get_handle(e); node->pfd.events = G_IO_IN; node->is_external = is_external; 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_prepare(AioContext *ctx) { static struct timeval tv0; AioHandler *node; bool have_select_revents = false; fd_set rfds, wfds; /* fill fd sets */ FD_ZERO(&rfds); FD_ZERO(&wfds); QLIST_FOREACH(node, &ctx->aio_handlers, node) { if (node->io_read) { FD_SET ((SOCKET)node->pfd.fd, &rfds); } if (node->io_write) { FD_SET ((SOCKET)node->pfd.fd, &wfds); } } if (select(0, &rfds, &wfds, NULL, &tv0) > 0) { QLIST_FOREACH(node, &ctx->aio_handlers, node) { node->pfd.revents = 0; if (FD_ISSET(node->pfd.fd, &rfds)) { node->pfd.revents |= G_IO_IN; have_select_revents = true; } if (FD_ISSET(node->pfd.fd, &wfds)) { node->pfd.revents |= G_IO_OUT; have_select_revents = true; } } } return have_select_revents; } bool aio_pending(AioContext *ctx) { AioHandler *node; QLIST_FOREACH(node, &ctx->aio_handlers, node) { if (node->pfd.revents && node->io_notify) { return true; } if ((node->pfd.revents & G_IO_IN) && node->io_read) { return true; } if ((node->pfd.revents & G_IO_OUT) && node->io_write) { 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; int revents = node->pfd.revents; ctx->walking_handlers++; if (!node->deleted && (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; } } if (!node->deleted && (node->io_read || node->io_write)) { node->pfd.revents = 0; if ((revents & G_IO_IN) && node->io_read) { node->io_read(node->opaque); progress = true; } if ((revents & G_IO_OUT) && node->io_write) { node->io_write(node->opaque); progress = true; } /* if the next select() will return an event, we have progressed */ if (event == event_notifier_get_handle(&ctx->notifier)) { WSANETWORKEVENTS ev; WSAEnumNetworkEvents(node->pfd.fd, event, &ev); if (ev.lNetworkEvents) { 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 progress, have_select_revents, first; int count; int timeout; aio_context_acquire(ctx); 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, * so disable the optimization now. */ if (blocking) { atomic_add(&ctx->notify_me, 2); } have_select_revents = aio_prepare(ctx); ctx->walking_handlers++; /* fill fd sets */ count = 0; QLIST_FOREACH(node, &ctx->aio_handlers, node) { if (!node->deleted && node->io_notify && aio_node_check(ctx, node->is_external)) { events[count++] = event_notifier_get_handle(node->e); } } ctx->walking_handlers--; first = true; /* ctx->notifier is always registered. */ assert(count > 0); /* Multiple iterations, all of them non-blocking except the first, * may be necessary to process all pending events. After the first * WaitForMultipleObjects call ctx->notify_me will be decremented. */ do { HANDLE event; int ret; timeout = blocking && !have_select_revents ? qemu_timeout_ns_to_ms(aio_compute_timeout(ctx)) : 0; if (timeout) { aio_context_release(ctx); } ret = WaitForMultipleObjects(count, events, FALSE, timeout); if (blocking) { assert(first); atomic_sub(&ctx->notify_me, 2); } if (timeout) { aio_context_acquire(ctx); } if (first) { aio_notify_accept(ctx); progress |= aio_bh_poll(ctx); first = false; } /* if we have any signaled events, dispatch event */ event = NULL; if ((DWORD) (ret - WAIT_OBJECT_0) < count) { event = events[ret - WAIT_OBJECT_0]; events[ret - WAIT_OBJECT_0] = events[--count]; } else if (!have_select_revents) { break; } have_select_revents = false; blocking = false; progress |= aio_dispatch_handlers(ctx, event); } while (count > 0); progress |= timerlistgroup_run_timers(&ctx->tlg); aio_context_release(ctx); return progress; } void aio_context_setup(AioContext *ctx, Error **errp) { }