block: move AioContext, QEMUTimer, main-loop to libqemuutil

AioContext is fairly self contained, the only dependency is QEMUTimer but
that in turn doesn't need anything else.  So move them out of block-obj-y
to avoid introducing a dependency from io/ to block-obj-y.

main-loop and its dependency iohandler also need to be moved, because
later in this series io/ will call iohandler_get_aio_context.

[Changed copyright "the QEMU team" to "other QEMU contributors" as
suggested by Daniel Berrange and agreed by Paolo.
--Stefan]

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 20170213135235.12274-2-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 0 insertions, 758 deletions

diff --git a/aio-posix.c b/aio-posix.c
deleted file mode 100644
index 577527fda5..0000000000
--- a/aio-posix.c
+++ /dev/null
@@ -1,758 +0,0 @@
-/*
- * 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/osdep.h"
-#include "qemu-common.h"
-#include "block/block.h"
-#include "qemu/rcu_queue.h"
-#include "qemu/sockets.h"
-#include "qemu/cutils.h"
-#include "trace-root.h"
-#ifdef CONFIG_EPOLL_CREATE1
-#include <sys/epoll.h>
-#endif
-
-struct AioHandler
-{
-    GPollFD pfd;
-    IOHandler *io_read;
-    IOHandler *io_write;
-    AioPollFn *io_poll;
-    IOHandler *io_poll_begin;
-    IOHandler *io_poll_end;
-    int deleted;
-    void *opaque;
-    bool is_external;
-    QLIST_ENTRY(AioHandler) node;
-};
-
-#ifdef CONFIG_EPOLL_CREATE1
-
-/* The fd number threashold to switch to epoll */
-#define EPOLL_ENABLE_THRESHOLD 64
-
-static void aio_epoll_disable(AioContext *ctx)
-{
-    ctx->epoll_available = false;
-    if (!ctx->epoll_enabled) {
-        return;
-    }
-    ctx->epoll_enabled = false;
-    close(ctx->epollfd);
-}
-
-static inline int epoll_events_from_pfd(int pfd_events)
-{
-    return (pfd_events & G_IO_IN ? EPOLLIN : 0) |
-           (pfd_events & G_IO_OUT ? EPOLLOUT : 0) |
-           (pfd_events & G_IO_HUP ? EPOLLHUP : 0) |
-           (pfd_events & G_IO_ERR ? EPOLLERR : 0);
-}
-
-static bool aio_epoll_try_enable(AioContext *ctx)
-{
-    AioHandler *node;
-    struct epoll_event event;
-
-    QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) {
-        int r;
-        if (node->deleted || !node->pfd.events) {
-            continue;
-        }
-        event.events = epoll_events_from_pfd(node->pfd.events);
-        event.data.ptr = node;
-        r = epoll_ctl(ctx->epollfd, EPOLL_CTL_ADD, node->pfd.fd, &event);
-        if (r) {
-            return false;
-        }
-    }
-    ctx->epoll_enabled = true;
-    return true;
-}
-
-static void aio_epoll_update(AioContext *ctx, AioHandler *node, bool is_new)
-{
-    struct epoll_event event;
-    int r;
-    int ctl;
-
-    if (!ctx->epoll_enabled) {
-        return;
-    }
-    if (!node->pfd.events) {
-        ctl = EPOLL_CTL_DEL;
-    } else {
-        event.data.ptr = node;
-        event.events = epoll_events_from_pfd(node->pfd.events);
-        ctl = is_new ? EPOLL_CTL_ADD : EPOLL_CTL_MOD;
-    }
-
-    r = epoll_ctl(ctx->epollfd, ctl, node->pfd.fd, &event);
-    if (r) {
-        aio_epoll_disable(ctx);
-    }
-}
-
-static int aio_epoll(AioContext *ctx, GPollFD *pfds,
-                     unsigned npfd, int64_t timeout)
-{
-    AioHandler *node;
-    int i, ret = 0;
-    struct epoll_event events[128];
-
-    assert(npfd == 1);
-    assert(pfds[0].fd == ctx->epollfd);
-    if (timeout > 0) {
-        ret = qemu_poll_ns(pfds, npfd, timeout);
-    }
-    if (timeout <= 0 || ret > 0) {
-        ret = epoll_wait(ctx->epollfd, events,
-                         sizeof(events) / sizeof(events[0]),
-                         timeout);
-        if (ret <= 0) {
-            goto out;
-        }
-        for (i = 0; i < ret; i++) {
-            int ev = events[i].events;
-            node = events[i].data.ptr;
-            node->pfd.revents = (ev & EPOLLIN ? G_IO_IN : 0) |
-                (ev & EPOLLOUT ? G_IO_OUT : 0) |
-                (ev & EPOLLHUP ? G_IO_HUP : 0) |
-                (ev & EPOLLERR ? G_IO_ERR : 0);
-        }
-    }
-out:
-    return ret;
-}
-
-static bool aio_epoll_enabled(AioContext *ctx)
-{
-    /* Fall back to ppoll when external clients are disabled. */
-    return !aio_external_disabled(ctx) && ctx->epoll_enabled;
-}
-
-static bool aio_epoll_check_poll(AioContext *ctx, GPollFD *pfds,
-                                 unsigned npfd, int64_t timeout)
-{
-    if (!ctx->epoll_available) {
-        return false;
-    }
-    if (aio_epoll_enabled(ctx)) {
-        return true;
-    }
-    if (npfd >= EPOLL_ENABLE_THRESHOLD) {
-        if (aio_epoll_try_enable(ctx)) {
-            return true;
-        } else {
-            aio_epoll_disable(ctx);
-        }
-    }
-    return false;
-}
-
-#else
-
-static void aio_epoll_update(AioContext *ctx, AioHandler *node, bool is_new)
-{
-}
-
-static int aio_epoll(AioContext *ctx, GPollFD *pfds,
-                     unsigned npfd, int64_t timeout)
-{
-    assert(false);
-}
-
-static bool aio_epoll_enabled(AioContext *ctx)
-{
-    return false;
-}
-
-static bool aio_epoll_check_poll(AioContext *ctx, GPollFD *pfds,
-                          unsigned npfd, int64_t timeout)
-{
-    return false;
-}
-
-#endif
-
-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,
-                        bool is_external,
-                        IOHandler *io_read,
-                        IOHandler *io_write,
-                        AioPollFn *io_poll,
-                        void *opaque)
-{
-    AioHandler *node;
-    bool is_new = false;
-    bool deleted = false;
-
-    qemu_lockcnt_lock(&ctx->list_lock);
-
-    node = find_aio_handler(ctx, fd);
-
-    /* Are we deleting the fd handler? */
-    if (!io_read && !io_write && !io_poll) {
-        if (node == NULL) {
-            qemu_lockcnt_unlock(&ctx->list_lock);
-            return;
-        }
-
-        g_source_remove_poll(&ctx->source, &node->pfd);
-
-        /* If the lock is held, 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 while
-             * no one is walking the handlers list.
-             */
-            QLIST_REMOVE(node, node);
-            deleted = true;
-        }
-
-        if (!node->io_poll) {
-            ctx->poll_disable_cnt--;
-        }
-    } else {
-        if (node == NULL) {
-            /* Alloc and insert if it's not already there */
-            node = g_new0(AioHandler, 1);
-            node->pfd.fd = fd;
-            QLIST_INSERT_HEAD_RCU(&ctx->aio_handlers, node, node);
-
-            g_source_add_poll(&ctx->source, &node->pfd);
-            is_new = true;
-
-            ctx->poll_disable_cnt += !io_poll;
-        } else {
-            ctx->poll_disable_cnt += !io_poll - !node->io_poll;
-        }
-
-        /* Update handler with latest information */
-        node->io_read = io_read;
-        node->io_write = io_write;
-        node->io_poll = io_poll;
-        node->opaque = opaque;
-        node->is_external = is_external;
-
-        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_epoll_update(ctx, node, is_new);
-    qemu_lockcnt_unlock(&ctx->list_lock);
-    aio_notify(ctx);
-
-    if (deleted) {
-        g_free(node);
-    }
-}
-
-void aio_set_fd_poll(AioContext *ctx, int fd,
-                     IOHandler *io_poll_begin,
-                     IOHandler *io_poll_end)
-{
-    AioHandler *node = find_aio_handler(ctx, fd);
-
-    if (!node) {
-        return;
-    }
-
-    node->io_poll_begin = io_poll_begin;
-    node->io_poll_end = io_poll_end;
-}
-
-void aio_set_event_notifier(AioContext *ctx,
-                            EventNotifier *notifier,
-                            bool is_external,
-                            EventNotifierHandler *io_read,
-                            AioPollFn *io_poll)
-{
-    aio_set_fd_handler(ctx, event_notifier_get_fd(notifier), is_external,
-                       (IOHandler *)io_read, NULL, io_poll, notifier);
-}
-
-void aio_set_event_notifier_poll(AioContext *ctx,
-                                 EventNotifier *notifier,
-                                 EventNotifierHandler *io_poll_begin,
-                                 EventNotifierHandler *io_poll_end)
-{
-    aio_set_fd_poll(ctx, event_notifier_get_fd(notifier),
-                    (IOHandler *)io_poll_begin,
-                    (IOHandler *)io_poll_end);
-}
-
-static void poll_set_started(AioContext *ctx, bool started)
-{
-    AioHandler *node;
-
-    if (started == ctx->poll_started) {
-        return;
-    }
-
-    ctx->poll_started = started;
-
-    qemu_lockcnt_inc(&ctx->list_lock);
-    QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) {
-        IOHandler *fn;
-
-        if (node->deleted) {
-            continue;
-        }
-
-        if (started) {
-            fn = node->io_poll_begin;
-        } else {
-            fn = node->io_poll_end;
-        }
-
-        if (fn) {
-            fn(node->opaque);
-        }
-    }
-    qemu_lockcnt_dec(&ctx->list_lock);
-}
-
-
-bool aio_prepare(AioContext *ctx)
-{
-    /* Poll mode cannot be used with glib's event loop, disable it. */
-    poll_set_started(ctx, false);
-
-    return false;
-}
-
-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) {
-        int revents;
-
-        revents = node->pfd.revents & node->pfd.events;
-        if (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR) && node->io_read &&
-            aio_node_check(ctx, node->is_external)) {
-            result = true;
-            break;
-        }
-        if (revents & (G_IO_OUT | G_IO_ERR) && node->io_write &&
-            aio_node_check(ctx, node->is_external)) {
-            result = true;
-            break;
-        }
-    }
-    qemu_lockcnt_dec(&ctx->list_lock);
-
-    return result;
-}
-
-static bool aio_dispatch_handlers(AioContext *ctx)
-{
-    AioHandler *node, *tmp;
-    bool progress = 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_SAFE_RCU(node, &ctx->aio_handlers, node, tmp) {
-        int revents;
-
-        revents = node->pfd.revents & node->pfd.events;
-        node->pfd.revents = 0;
-
-        if (!node->deleted &&
-            (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR)) &&
-            aio_node_check(ctx, node->is_external) &&
-            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)) &&
-            aio_node_check(ctx, node->is_external) &&
-            node->io_write) {
-            node->io_write(node->opaque);
-            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);
-            }
-        }
-    }
-
-    qemu_lockcnt_dec(&ctx->list_lock);
-    return progress;
-}
-
-/*
- * Note that dispatch_fds == false has the side-effect of post-poning the
- * freeing of deleted handlers.
- */
-bool aio_dispatch(AioContext *ctx, bool dispatch_fds)
-{
-    bool progress;
-
-    /*
-     * 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).
-     */
-    progress = aio_bh_poll(ctx);
-
-    if (dispatch_fds) {
-        progress |= aio_dispatch_handlers(ctx);
-    }
-
-    /* Run our timers */
-    progress |= timerlistgroup_run_timers(&ctx->tlg);
-
-    return progress;
-}
-
-/* These thread-local variables are used only in a small part of aio_poll
- * around the call to the poll() system call.  In particular they are not
- * used while aio_poll is performing callbacks, which makes it much easier
- * to think about reentrancy!
- *
- * Stack-allocated arrays would be perfect but they have size limitations;
- * heap allocation is expensive enough that we want to reuse arrays across
- * calls to aio_poll().  And because poll() has to be called without holding
- * any lock, the arrays cannot be stored in AioContext.  Thread-local data
- * has none of the disadvantages of these three options.
- */
-static __thread GPollFD *pollfds;
-static __thread AioHandler **nodes;
-static __thread unsigned npfd, nalloc;
-static __thread Notifier pollfds_cleanup_notifier;
-
-static void pollfds_cleanup(Notifier *n, void *unused)
-{
-    g_assert(npfd == 0);
-    g_free(pollfds);
-    g_free(nodes);
-    nalloc = 0;
-}
-
-static void add_pollfd(AioHandler *node)
-{
-    if (npfd == nalloc) {
-        if (nalloc == 0) {
-            pollfds_cleanup_notifier.notify = pollfds_cleanup;
-            qemu_thread_atexit_add(&pollfds_cleanup_notifier);
-            nalloc = 8;
-        } else {
-            g_assert(nalloc <= INT_MAX);
-            nalloc *= 2;
-        }
-        pollfds = g_renew(GPollFD, pollfds, nalloc);
-        nodes = g_renew(AioHandler *, nodes, nalloc);
-    }
-    nodes[npfd] = node;
-    pollfds[npfd] = (GPollFD) {
-        .fd = node->pfd.fd,
-        .events = node->pfd.events,
-    };
-    npfd++;
-}
-
-static bool run_poll_handlers_once(AioContext *ctx)
-{
-    bool progress = false;
-    AioHandler *node;
-
-    QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) {
-        if (!node->deleted && node->io_poll &&
-            aio_node_check(ctx, node->is_external) &&
-            node->io_poll(node->opaque)) {
-            progress = true;
-        }
-
-        /* Caller handles freeing deleted nodes.  Don't do it here. */
-    }
-
-    return progress;
-}
-
-/* run_poll_handlers:
- * @ctx: the AioContext
- * @max_ns: maximum time to poll for, in nanoseconds
- *
- * Polls for a given time.
- *
- * Note that ctx->notify_me must be non-zero so this function can detect
- * aio_notify().
- *
- * Note that the caller must have incremented ctx->list_lock.
- *
- * Returns: true if progress was made, false otherwise
- */
-static bool run_poll_handlers(AioContext *ctx, int64_t max_ns)
-{
-    bool progress;
-    int64_t end_time;
-
-    assert(ctx->notify_me);
-    assert(qemu_lockcnt_count(&ctx->list_lock) > 0);
-    assert(ctx->poll_disable_cnt == 0);
-
-    trace_run_poll_handlers_begin(ctx, max_ns);
-
-    end_time = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + max_ns;
-
-    do {
-        progress = run_poll_handlers_once(ctx);
-    } while (!progress && qemu_clock_get_ns(QEMU_CLOCK_REALTIME) < end_time);
-
-    trace_run_poll_handlers_end(ctx, progress);
-
-    return progress;
-}
-
-/* try_poll_mode:
- * @ctx: the AioContext
- * @blocking: busy polling is only attempted when blocking is true
- *
- * ctx->notify_me must be non-zero so this function can detect aio_notify().
- *
- * Note that the caller must have incremented ctx->list_lock.
- *
- * Returns: true if progress was made, false otherwise
- */
-static bool try_poll_mode(AioContext *ctx, bool blocking)
-{
-    if (blocking && ctx->poll_max_ns && ctx->poll_disable_cnt == 0) {
-        /* See qemu_soonest_timeout() uint64_t hack */
-        int64_t max_ns = MIN((uint64_t)aio_compute_timeout(ctx),
-                             (uint64_t)ctx->poll_ns);
-
-        if (max_ns) {
-            poll_set_started(ctx, true);
-
-            if (run_poll_handlers(ctx, max_ns)) {
-                return true;
-            }
-        }
-    }
-
-    poll_set_started(ctx, false);
-
-    /* Even if we don't run busy polling, try polling once in case it can make
-     * progress and the caller will be able to avoid ppoll(2)/epoll_wait(2).
-     */
-    return run_poll_handlers_once(ctx);
-}
-
-bool aio_poll(AioContext *ctx, bool blocking)
-{
-    AioHandler *node;
-    int i;
-    int ret = 0;
-    bool progress;
-    int64_t timeout;
-    int64_t start = 0;
-
-    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);
-    }
-
-    qemu_lockcnt_inc(&ctx->list_lock);
-
-    if (ctx->poll_max_ns) {
-        start = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
-    }
-
-    if (try_poll_mode(ctx, blocking)) {
-        progress = true;
-    } else {
-        assert(npfd == 0);
-
-        /* fill pollfds */
-
-        if (!aio_epoll_enabled(ctx)) {
-            QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) {
-                if (!node->deleted && node->pfd.events
-                    && aio_node_check(ctx, node->is_external)) {
-                    add_pollfd(node);
-                }
-            }
-        }
-
-        timeout = blocking ? aio_compute_timeout(ctx) : 0;
-
-        /* wait until next event */
-        if (timeout) {
-            aio_context_release(ctx);
-        }
-        if (aio_epoll_check_poll(ctx, pollfds, npfd, timeout)) {
-            AioHandler epoll_handler;
-
-            epoll_handler.pfd.fd = ctx->epollfd;
-            epoll_handler.pfd.events = G_IO_IN | G_IO_OUT | G_IO_HUP | G_IO_ERR;
-            npfd = 0;
-            add_pollfd(&epoll_handler);
-            ret = aio_epoll(ctx, pollfds, npfd, timeout);
-        } else  {
-            ret = qemu_poll_ns(pollfds, npfd, timeout);
-        }
-        if (timeout) {
-            aio_context_acquire(ctx);
-        }
-    }
-
-    if (blocking) {
-        atomic_sub(&ctx->notify_me, 2);
-    }
-
-    /* Adjust polling time */
-    if (ctx->poll_max_ns) {
-        int64_t block_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start;
-
-        if (block_ns <= ctx->poll_ns) {
-            /* This is the sweet spot, no adjustment needed */
-        } else if (block_ns > ctx->poll_max_ns) {
-            /* We'd have to poll for too long, poll less */
-            int64_t old = ctx->poll_ns;
-
-            if (ctx->poll_shrink) {
-                ctx->poll_ns /= ctx->poll_shrink;
-            } else {
-                ctx->poll_ns = 0;
-            }
-
-            trace_poll_shrink(ctx, old, ctx->poll_ns);
-        } else if (ctx->poll_ns < ctx->poll_max_ns &&
-                   block_ns < ctx->poll_max_ns) {
-            /* There is room to grow, poll longer */
-            int64_t old = ctx->poll_ns;
-            int64_t grow = ctx->poll_grow;
-
-            if (grow == 0) {
-                grow = 2;
-            }
-
-            if (ctx->poll_ns) {
-                ctx->poll_ns *= grow;
-            } else {
-                ctx->poll_ns = 4000; /* start polling at 4 microseconds */
-            }
-
-            if (ctx->poll_ns > ctx->poll_max_ns) {
-                ctx->poll_ns = ctx->poll_max_ns;
-            }
-
-            trace_poll_grow(ctx, old, ctx->poll_ns);
-        }
-    }
-
-    aio_notify_accept(ctx);
-
-    /* if we have any readable fds, dispatch event */
-    if (ret > 0) {
-        for (i = 0; i < npfd; i++) {
-            nodes[i]->pfd.revents = pollfds[i].revents;
-        }
-    }
-
-    npfd = 0;
-    qemu_lockcnt_dec(&ctx->list_lock);
-
-    /* Run dispatch even if there were no readable fds to run timers */
-    if (aio_dispatch(ctx, ret > 0)) {
-        progress = true;
-    }
-
-    aio_context_release(ctx);
-
-    return progress;
-}
-
-void aio_context_setup(AioContext *ctx)
-{
-    /* TODO remove this in final patch submission */
-    if (getenv("QEMU_AIO_POLL_MAX_NS")) {
-        fprintf(stderr, "The QEMU_AIO_POLL_MAX_NS environment variable has "
-                "been replaced with -object iothread,poll-max-ns=NUM\n");
-        exit(1);
-    }
-
-#ifdef CONFIG_EPOLL_CREATE1
-    assert(!ctx->epollfd);
-    ctx->epollfd = epoll_create1(EPOLL_CLOEXEC);
-    if (ctx->epollfd == -1) {
-        fprintf(stderr, "Failed to create epoll instance: %s", strerror(errno));
-        ctx->epoll_available = false;
-    } else {
-        ctx->epoll_available = true;
-    }
-#endif
-}
-
-void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns,
-                                 int64_t grow, int64_t shrink, Error **errp)
-{
-    /* No thread synchronization here, it doesn't matter if an incorrect value
-     * is used once.
-     */
-    ctx->poll_max_ns = max_ns;
-    ctx->poll_ns = 0;
-    ctx->poll_grow = grow;
-    ctx->poll_shrink = shrink;
-
-    aio_notify(ctx);
-}