Commit 21c4d15b authored by Peter Xu's avatar Peter Xu Committed by Stefan Hajnoczi
Browse files

iothread: replace init_done_cond with a semaphore 



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: default avatarPeter Xu <peterx@redhat.com>
Message-id: 20190306115532.23025-2-peterx@redhat.com
Message-Id: <20190306115532.23025-2-peterx@redhat.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent bf4069fb

include/sysemu/iothread.h

+1 −2
Original line number Diff line number Diff line
@@ -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;

iothread.c

+4 −13
Original line number Diff line number Diff line
@@ -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 {