From 9db6f24509ee8a28818693d6a15257b873d9422a Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Thu, 15 Aug 2019 13:23:11 +0100 Subject: [PATCH 09/10] iothread: replace init_done_cond with a semaphore RH-Author: Stefan Hajnoczi Message-id: <20190815132311.22027-3-stefanha@redhat.com> Patchwork-id: 89996 O-Subject: [RHEL-8.1.0 qemu-kvm PATCH v2 2/2] iothread: replace init_done_cond with a semaphore Bugzilla: 1687541 RH-Acked-by: Peter Xu RH-Acked-by: John Snow RH-Acked-by: Markus Armbruster From: Peter Xu Only sending an init-done message using lock+cond seems an overkill to me. Replacing it with a simpler semaphore. Meanwhile, init the semaphore unconditionally, then we can destroy it unconditionally too in finalize which seems cleaner. Signed-off-by: Peter Xu Message-id: 20190306115532.23025-2-peterx@redhat.com Message-Id: <20190306115532.23025-2-peterx@redhat.com> Signed-off-by: Stefan Hajnoczi (cherry picked from commit 21c4d15b4708b7d30c450041a560df670f36cac8) Signed-off-by: Stefan Hajnoczi Signed-off-by: Danilo C. L. de Paula --- include/sysemu/iothread.h | 3 +-- iothread.c | 17 ++++------------- 2 files changed, 5 insertions(+), 15 deletions(-) diff --git a/include/sysemu/iothread.h b/include/sysemu/iothread.h index 8a7ac2c..50411ba 100644 --- a/include/sysemu/iothread.h +++ b/include/sysemu/iothread.h @@ -27,8 +27,7 @@ typedef struct { GMainContext *worker_context; GMainLoop *main_loop; GOnce once; - QemuMutex init_done_lock; - QemuCond init_done_cond; /* is thread initialization done? */ + QemuSemaphore init_done_sem; /* is thread init done? */ bool stopping; /* has iothread_stop() been called? */ bool running; /* should iothread_run() continue? */ int thread_id; diff --git a/iothread.c b/iothread.c index 2fb1cdf..b92232f 100644 --- a/iothread.c +++ b/iothread.c @@ -55,10 +55,8 @@ static void *iothread_run(void *opaque) rcu_register_thread(); my_iothread = iothread; - 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); + qemu_sem_post(&iothread->init_done_sem); while (iothread->running) { aio_poll(iothread->ctx, true); @@ -111,6 +109,7 @@ static void iothread_instance_init(Object *obj) iothread->poll_max_ns = IOTHREAD_POLL_MAX_NS_DEFAULT; iothread->thread_id = -1; + qemu_sem_init(&iothread->init_done_sem, 0); } static void iothread_instance_finalize(Object *obj) @@ -119,10 +118,6 @@ static void iothread_instance_finalize(Object *obj) iothread_stop(iothread); - if (iothread->thread_id != -1) { - qemu_cond_destroy(&iothread->init_done_cond); - qemu_mutex_destroy(&iothread->init_done_lock); - } /* * Before glib2 2.33.10, there is a glib2 bug that GSource context * pointer may not be cleared even if the context has already been @@ -141,6 +136,7 @@ static void iothread_instance_finalize(Object *obj) g_main_context_unref(iothread->worker_context); iothread->worker_context = NULL; } + qemu_sem_destroy(&iothread->init_done_sem); } static void iothread_complete(UserCreatable *obj, Error **errp) @@ -169,8 +165,6 @@ static void iothread_complete(UserCreatable *obj, Error **errp) return; } - qemu_mutex_init(&iothread->init_done_lock); - qemu_cond_init(&iothread->init_done_cond); iothread->once = (GOnce) G_ONCE_INIT; /* This assumes we are called from a thread with useful CPU affinity for us @@ -184,12 +178,9 @@ static void iothread_complete(UserCreatable *obj, Error **errp) g_free(name); /* Wait for initialization to complete */ - qemu_mutex_lock(&iothread->init_done_lock); while (iothread->thread_id == -1) { - qemu_cond_wait(&iothread->init_done_cond, - &iothread->init_done_lock); + qemu_sem_wait(&iothread->init_done_sem); } - qemu_mutex_unlock(&iothread->init_done_lock); } typedef struct { -- 1.8.3.1