| /* |
| * 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/sockets.h" |
| |
| struct AioHandler |
| { |
| GPollFD pfd; |
| IOHandler *io_read; |
| IOHandler *io_write; |
| int deleted; |
| int pollfds_idx; |
| 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, |
| 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->opaque = opaque; |
| node->pollfds_idx = -1; |
| |
| node->pfd.events = (io_read ? G_IO_IN | G_IO_HUP | G_IO_ERR : 0); |
| node->pfd.events |= (io_write ? G_IO_OUT | G_IO_ERR : 0); |
| } |
| |
| aio_notify(ctx); |
| } |
| |
| void aio_set_event_notifier(AioContext *ctx, |
| EventNotifier *notifier, |
| EventNotifierHandler *io_read) |
| { |
| aio_set_fd_handler(ctx, event_notifier_get_fd(notifier), |
| (IOHandler *)io_read, NULL, notifier); |
| } |
| |
| bool aio_prepare(AioContext *ctx) |
| { |
| return false; |
| } |
| |
| bool aio_pending(AioContext *ctx) |
| { |
| AioHandler *node; |
| |
| QLIST_FOREACH(node, &ctx->aio_handlers, node) { |
| int revents; |
| |
| 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_dispatch(AioContext *ctx) |
| { |
| AioHandler *node; |
| bool progress = false; |
| |
| /* |
| * If there are callbacks left that have been queued, we need to call them. |
| * 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 aio_poll loops). |
| */ |
| if (aio_bh_poll(ctx)) { |
| progress = true; |
| } |
| |
| /* |
| * 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; |
| |
| ctx->walking_handlers++; |
| |
| revents = node->pfd.revents & node->pfd.events; |
| node->pfd.revents = 0; |
| |
| if (!node->deleted && |
| (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR)) && |
| node->io_read) { |
| node->io_read(node->opaque); |
| |
| /* aio_notify() does not count as progress */ |
| if (node->opaque != &ctx->notifier) { |
| progress = true; |
| } |
| } |
| if (!node->deleted && |
| (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); |
| } |
| } |
| |
| /* Run our timers */ |
| progress |= timerlistgroup_run_timers(&ctx->tlg); |
| |
| return progress; |
| } |
| |
| bool aio_poll(AioContext *ctx, bool blocking) |
| { |
| AioHandler *node; |
| bool was_dispatching; |
| int ret; |
| bool progress; |
| |
| was_dispatching = ctx->dispatching; |
| 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. |
| * |
| * If we're in a nested event loop, ctx->dispatching might be true. |
| * In that case we can restore it just before returning, but we |
| * have to clear it now. |
| */ |
| aio_set_dispatching(ctx, !blocking); |
| |
| ctx->walking_handlers++; |
| |
| g_array_set_size(ctx->pollfds, 0); |
| |
| /* fill pollfds */ |
| QLIST_FOREACH(node, &ctx->aio_handlers, node) { |
| node->pollfds_idx = -1; |
| if (!node->deleted && node->pfd.events) { |
| GPollFD pfd = { |
| .fd = node->pfd.fd, |
| .events = node->pfd.events, |
| }; |
| node->pollfds_idx = ctx->pollfds->len; |
| g_array_append_val(ctx->pollfds, pfd); |
| } |
| } |
| |
| ctx->walking_handlers--; |
| |
| /* wait until next event */ |
| ret = qemu_poll_ns((GPollFD *)ctx->pollfds->data, |
| ctx->pollfds->len, |
| blocking ? aio_compute_timeout(ctx) : 0); |
| |
| /* if we have any readable fds, dispatch event */ |
| if (ret > 0) { |
| QLIST_FOREACH(node, &ctx->aio_handlers, node) { |
| if (node->pollfds_idx != -1) { |
| GPollFD *pfd = &g_array_index(ctx->pollfds, GPollFD, |
| node->pollfds_idx); |
| node->pfd.revents = pfd->revents; |
| } |
| } |
| } |
| |
| /* Run dispatch even if there were no readable fds to run timers */ |
| aio_set_dispatching(ctx, true); |
| if (aio_dispatch(ctx)) { |
| progress = true; |
| } |
| |
| aio_set_dispatching(ctx, was_dispatching); |
| return progress; |
| } |