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iothread: replace init_done_cond with a semaphore

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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 <peterx@redhat.com>
Message-id: 20190306115532.23025-2-peterx@redhat.com
Message-Id: <20190306115532.23025-2-peterx@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Peter Xu 2019-03-06 19:55:28 +08:00 committed by Stefan Hajnoczi
parent bf4069fbd7
commit 21c4d15b47
2 changed files with 5 additions and 15 deletions
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3
include/sysemu/iothread.h
View File

@ -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;

17
iothread.c
View File

@ -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 {