From a0710f7995f914e3044e5899bd8ff6c43c62f916 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Fri, 20 Feb 2015 17:26:52 +0100 Subject: [PATCH] iothread: release iothread around aio_poll This is the first step towards having fine-grained critical sections in dataplane threads, which resolves lock ordering problems between address_space_* functions (which need the BQL when doing MMIO, even after we complete RCU-based dispatch) and the AioContext. Because AioContext does not use contention callbacks anymore, the unit test has to be changed. Signed-off-by: Paolo Bonzini Reviewed-by: Stefan Hajnoczi Message-id: 1424449612-18215-4-git-send-email-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- async.c | 8 +------- iothread.c | 11 ++--------- tests/test-aio.c | 19 +++++++++++-------- 3 files changed, 14 insertions(+), 24 deletions(-) diff --git a/async.c b/async.c index 77d080d..46d9e63 100644 --- a/async.c +++ b/async.c @@ -280,12 +280,6 @@ static void aio_timerlist_notify(void *opaque) aio_notify(opaque); } -static void aio_rfifolock_cb(void *opaque) -{ - /* Kick owner thread in case they are blocked in aio_poll() */ - aio_notify(opaque); -} - AioContext *aio_context_new(Error **errp) { int ret; @@ -303,7 +297,7 @@ AioContext *aio_context_new(Error **errp) event_notifier_test_and_clear); ctx->thread_pool = NULL; qemu_mutex_init(&ctx->bh_lock); - rfifolock_init(&ctx->lock, aio_rfifolock_cb, ctx); + rfifolock_init(&ctx->lock, NULL, NULL); timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx); return ctx; diff --git a/iothread.c b/iothread.c index 342a23f..a1f9109 100644 --- a/iothread.c +++ b/iothread.c @@ -31,21 +31,14 @@ typedef ObjectClass IOThreadClass; static void *iothread_run(void *opaque) { IOThread *iothread = opaque; - bool blocking; qemu_mutex_lock(&iothread->init_done_lock); iothread->thread_id = qemu_get_thread_id(); qemu_cond_signal(&iothread->init_done_cond); qemu_mutex_unlock(&iothread->init_done_lock); - while (!iothread->stopping) { - aio_context_acquire(iothread->ctx); - blocking = true; - while (!iothread->stopping && aio_poll(iothread->ctx, blocking)) { - /* Progress was made, keep going */ - blocking = false; - } - aio_context_release(iothread->ctx); + while (!atomic_read(&iothread->stopping)) { + aio_poll(iothread->ctx, true); } return NULL; } diff --git a/tests/test-aio.c b/tests/test-aio.c index a7cb5c9..4b0cb45 100644 --- a/tests/test-aio.c +++ b/tests/test-aio.c @@ -107,6 +107,7 @@ static void test_notify(void) typedef struct { QemuMutex start_lock; + EventNotifier notifier; bool thread_acquired; } AcquireTestData; @@ -118,6 +119,8 @@ static void *test_acquire_thread(void *opaque) qemu_mutex_lock(&data->start_lock); qemu_mutex_unlock(&data->start_lock); + g_usleep(500000); + event_notifier_set(&data->notifier); aio_context_acquire(ctx); aio_context_release(ctx); @@ -126,20 +129,19 @@ static void *test_acquire_thread(void *opaque) return NULL; } -static void dummy_notifier_read(EventNotifier *unused) +static void dummy_notifier_read(EventNotifier *n) { - g_assert(false); /* should never be invoked */ + event_notifier_test_and_clear(n); } static void test_acquire(void) { QemuThread thread; - EventNotifier notifier; AcquireTestData data; /* Dummy event notifier ensures aio_poll() will block */ - event_notifier_init(¬ifier, false); - aio_set_event_notifier(ctx, ¬ifier, dummy_notifier_read); + event_notifier_init(&data.notifier, false); + aio_set_event_notifier(ctx, &data.notifier, dummy_notifier_read); g_assert(!aio_poll(ctx, false)); /* consume aio_notify() */ qemu_mutex_init(&data.start_lock); @@ -153,12 +155,13 @@ static void test_acquire(void) /* Block in aio_poll(), let other thread kick us and acquire context */ aio_context_acquire(ctx); qemu_mutex_unlock(&data.start_lock); /* let the thread run */ - g_assert(!aio_poll(ctx, true)); + g_assert(aio_poll(ctx, true)); + g_assert(!data.thread_acquired); aio_context_release(ctx); qemu_thread_join(&thread); - aio_set_event_notifier(ctx, ¬ifier, NULL); - event_notifier_cleanup(¬ifier); + aio_set_event_notifier(ctx, &data.notifier, NULL); + event_notifier_cleanup(&data.notifier); g_assert(data.thread_acquired); } -- 2.7.4