Commit 88eb7c29 authored by Stefan Hajnoczi's avatar Stefan Hajnoczi
Browse files

iothread: stash thread ID away 



Keep the thread ID around so we can report it via QMP.

There's only one problem: qemu_get_thread_id() (gettid() wrapper on
Linux) must be called from the thread itself.  There is no way to get
the thread ID outside the thread.

This patch uses a condvar to wait for iothread_run() to populate the
thread_id inside the thread.

Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent 48ff2692

iothread.c

+22 −0
Original line number Diff line number Diff line
@@ -26,7 +26,10 @@ struct IOThread { 


    QemuThread thread;

    AioContext *ctx;

    QemuMutex init_done_lock;

    QemuCond init_done_cond;    /* is thread initialization done? */

    bool stopping;

    int thread_id;

};



#define IOTHREAD_GET_CLASS(obj) \
@@ -38,6 +41,11 @@ static void *iothread_run(void *opaque) 
{

    IOThread *iothread = opaque;



    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);

        while (!iothread->stopping && aio_poll(iothread->ctx, true)) {
@@ -55,6 +63,8 @@ static void iothread_instance_finalize(Object *obj) 
    iothread->stopping = true;

    aio_notify(iothread->ctx);

    qemu_thread_join(&iothread->thread);

    qemu_cond_destroy(&iothread->init_done_cond);

    qemu_mutex_destroy(&iothread->init_done_lock);

    aio_context_unref(iothread->ctx);

}
@@ -64,12 +74,24 @@ static void iothread_complete(UserCreatable *obj, Error **errp) 


    iothread->stopping = false;

    iothread->ctx = aio_context_new();

    iothread->thread_id = -1;



    qemu_mutex_init(&iothread->init_done_lock);

    qemu_cond_init(&iothread->init_done_cond);



    /* This assumes we are called from a thread with useful CPU affinity for us

     * to inherit.

     */

    qemu_thread_create(&iothread->thread, "iothread", iothread_run,

                       iothread, QEMU_THREAD_JOINABLE);



    /* 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_mutex_unlock(&iothread->init_done_lock);

}



static void iothread_class_init(ObjectClass *klass, void *class_data)