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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: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2014-02-27 11:48:41 +01:00
parent 48ff269272
commit 88eb7c29e4
1 changed files with 22 additions and 0 deletions
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22
iothread.c
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@ -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)