| /* |
| * 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 "block/block.h" |
| #include "qemu/main-loop.h" |
| #include "qemu/queue.h" |
| #include "qemu/sockets.h" |
| #include "qapi/error.h" |
| #include "qemu/rcu_queue.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; |
| }; |
| |
| static void aio_remove_fd_handler(AioContext *ctx, AioHandler *node) |
| { |
| /* |
| * If the GSource is in the process of being destroyed then |
| * g_source_remove_poll() causes an assertion failure. Skip |
| * removal in that case, because glib cleans up its state during |
| * destruction anyway. |
| */ |
| if (!g_source_is_destroyed(&ctx->source)) { |
| g_source_remove_poll(&ctx->source, &node->pfd); |
| } |
| |
| /* If aio_poll is in progress, just mark the node as deleted */ |
| if (qemu_lockcnt_count(&ctx->list_lock)) { |
| 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 list_lock. |
| */ |
| QLIST_REMOVE(node, node); |
| g_free(node); |
| } |
| } |
| |
| void aio_set_fd_handler(AioContext *ctx, |
| int fd, |
| bool is_external, |
| IOHandler *io_read, |
| IOHandler *io_write, |
| AioPollFn *io_poll, |
| IOHandler *io_poll_ready, |
| void *opaque) |
| { |
| /* fd is a SOCKET in our case */ |
| AioHandler *old_node; |
| AioHandler *node = NULL; |
| |
| qemu_lockcnt_lock(&ctx->list_lock); |
| QLIST_FOREACH(old_node, &ctx->aio_handlers, node) { |
| if (old_node->pfd.fd == fd && !old_node->deleted) { |
| break; |
| } |
| } |
| |
| if (io_read || io_write) { |
| HANDLE event; |
| long bitmask = 0; |
| |
| /* Alloc and insert if it's not already there */ |
| node = g_new0(AioHandler, 1); |
| node->pfd.fd = fd; |
| |
| 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; |
| |
| if (io_read) { |
| bitmask |= FD_READ | FD_ACCEPT | FD_CLOSE; |
| } |
| |
| if (io_write) { |
| bitmask |= FD_WRITE | FD_CONNECT; |
| } |
| |
| QLIST_INSERT_HEAD_RCU(&ctx->aio_handlers, node, node); |
| event = event_notifier_get_handle(&ctx->notifier); |
| WSAEventSelect(node->pfd.fd, event, bitmask); |
| } |
| if (old_node) { |
| aio_remove_fd_handler(ctx, old_node); |
| } |
| |
| qemu_lockcnt_unlock(&ctx->list_lock); |
| aio_notify(ctx); |
| } |
| |
| void aio_set_fd_poll(AioContext *ctx, int fd, |
| IOHandler *io_poll_begin, |
| IOHandler *io_poll_end) |
| { |
| /* Not implemented */ |
| } |
| |
| void aio_set_event_notifier(AioContext *ctx, |
| EventNotifier *e, |
| bool is_external, |
| EventNotifierHandler *io_notify, |
| AioPollFn *io_poll, |
| EventNotifierHandler *io_poll_ready) |
| { |
| AioHandler *node; |
| |
| qemu_lockcnt_lock(&ctx->list_lock); |
| 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) { |
| aio_remove_fd_handler(ctx, 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_RCU(&ctx->aio_handlers, node, node); |
| |
| g_source_add_poll(&ctx->source, &node->pfd); |
| } |
| /* Update handler with latest information */ |
| node->io_notify = io_notify; |
| } |
| |
| qemu_lockcnt_unlock(&ctx->list_lock); |
| aio_notify(ctx); |
| } |
| |
| void aio_set_event_notifier_poll(AioContext *ctx, |
| EventNotifier *notifier, |
| EventNotifierHandler *io_poll_begin, |
| EventNotifierHandler *io_poll_end) |
| { |
| /* Not implemented */ |
| } |
| |
| bool aio_prepare(AioContext *ctx) |
| { |
| static struct timeval tv0; |
| AioHandler *node; |
| bool have_select_revents = false; |
| fd_set rfds, wfds; |
| |
| /* |
| * We have to walk very carefully in case aio_set_fd_handler is |
| * called while we're walking. |
| */ |
| qemu_lockcnt_inc(&ctx->list_lock); |
| |
| /* fill fd sets */ |
| FD_ZERO(&rfds); |
| FD_ZERO(&wfds); |
| QLIST_FOREACH_RCU(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_RCU(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; |
| } |
| } |
| } |
| |
| qemu_lockcnt_dec(&ctx->list_lock); |
| return have_select_revents; |
| } |
| |
| bool aio_pending(AioContext *ctx) |
| { |
| AioHandler *node; |
| bool result = false; |
| |
| /* |
| * We have to walk very carefully in case aio_set_fd_handler is |
| * called while we're walking. |
| */ |
| qemu_lockcnt_inc(&ctx->list_lock); |
| QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) { |
| if (node->pfd.revents && node->io_notify) { |
| result = true; |
| break; |
| } |
| |
| if ((node->pfd.revents & G_IO_IN) && node->io_read) { |
| result = true; |
| break; |
| } |
| if ((node->pfd.revents & G_IO_OUT) && node->io_write) { |
| result = true; |
| break; |
| } |
| } |
| |
| qemu_lockcnt_dec(&ctx->list_lock); |
| return result; |
| } |
| |
| static bool aio_dispatch_handlers(AioContext *ctx, HANDLE event) |
| { |
| AioHandler *node; |
| bool progress = false; |
| AioHandler *tmp; |
| |
| /* |
| * We have to walk very carefully in case aio_set_fd_handler is |
| * called while we're walking. |
| */ |
| QLIST_FOREACH_SAFE_RCU(node, &ctx->aio_handlers, node, tmp) { |
| int revents = node->pfd.revents; |
| |
| 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; |
| } |
| } |
| } |
| |
| if (node->deleted) { |
| if (qemu_lockcnt_dec_if_lock(&ctx->list_lock)) { |
| QLIST_REMOVE(node, node); |
| g_free(node); |
| qemu_lockcnt_inc_and_unlock(&ctx->list_lock); |
| } |
| } |
| } |
| |
| return progress; |
| } |
| |
| void aio_dispatch(AioContext *ctx) |
| { |
| qemu_lockcnt_inc(&ctx->list_lock); |
| aio_bh_poll(ctx); |
| aio_dispatch_handlers(ctx, INVALID_HANDLE_VALUE); |
| qemu_lockcnt_dec(&ctx->list_lock); |
| timerlistgroup_run_timers(&ctx->tlg); |
| } |
| |
| bool aio_poll(AioContext *ctx, bool blocking) |
| { |
| AioHandler *node; |
| HANDLE events[MAXIMUM_WAIT_OBJECTS]; |
| bool progress, have_select_revents, first; |
| unsigned count; |
| int timeout; |
| |
| /* |
| * There cannot be two concurrent aio_poll calls for the same AioContext (or |
| * an aio_poll concurrent with a GSource prepare/check/dispatch callback). |
| * We rely on this below to avoid slow locked accesses to ctx->notify_me. |
| * |
| * aio_poll() may only be called in the AioContext's thread. iohandler_ctx |
| * is special in that it runs in the main thread, but that thread's context |
| * is qemu_aio_context. |
| */ |
| assert(in_aio_context_home_thread(ctx == iohandler_get_aio_context() ? |
| qemu_get_aio_context() : 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) { |
| qatomic_set(&ctx->notify_me, qatomic_read(&ctx->notify_me) + 2); |
| /* |
| * Write ctx->notify_me before computing the timeout |
| * (reading bottom half flags, etc.). Pairs with |
| * smp_mb in aio_notify(). |
| */ |
| smp_mb(); |
| } |
| |
| qemu_lockcnt_inc(&ctx->list_lock); |
| have_select_revents = aio_prepare(ctx); |
| |
| /* fill fd sets */ |
| count = 0; |
| QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) { |
| if (!node->deleted && node->io_notify |
| && aio_node_check(ctx, node->is_external)) { |
| assert(count < MAXIMUM_WAIT_OBJECTS); |
| events[count++] = event_notifier_get_handle(node->e); |
| } |
| } |
| |
| 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; |
| ret = WaitForMultipleObjects(count, events, FALSE, timeout); |
| if (blocking) { |
| assert(first); |
| qatomic_store_release(&ctx->notify_me, |
| qatomic_read(&ctx->notify_me) - 2); |
| aio_notify_accept(ctx); |
| } |
| |
| if (first) { |
| 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); |
| |
| qemu_lockcnt_dec(&ctx->list_lock); |
| |
| progress |= timerlistgroup_run_timers(&ctx->tlg); |
| return progress; |
| } |
| |
| void aio_context_setup(AioContext *ctx) |
| { |
| } |
| |
| void aio_context_destroy(AioContext *ctx) |
| { |
| } |
| |
| void aio_context_use_g_source(AioContext *ctx) |
| { |
| } |
| |
| void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns, |
| int64_t grow, int64_t shrink, Error **errp) |
| { |
| if (max_ns) { |
| error_setg(errp, "AioContext polling is not implemented on Windows"); |
| } |
| } |
| |
| void aio_context_set_aio_params(AioContext *ctx, int64_t max_batch, |
| Error **errp) |
| { |
| } |
