On Wed, Mar 06, 2019 at 07:55:28PM +0800, Peter Xu wrote:
> 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 <[email protected]>
Sorry I've definitely lost Stefan's r-b for this patch. It's the same
patch as the one I posted in v1.
> ---
> 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 8a7ac2c528..50411ba54a 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 e615b7ae52..6e297e9ef1 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);
> @@ -115,6 +113,7 @@ 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)
> @@ -123,10 +122,6 @@ 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
> @@ -145,6 +140,7 @@ 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)
> @@ -173,8 +169,6 @@ 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
> @@ -188,12 +182,9 @@ 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 {
> --
> 2.17.1
>
Regards,
--
Peter Xu
