xref: /openbmc/qemu/tests/unit/iothread.c (revision 9516034d)
1 /*
2  * Event loop thread implementation for unit tests
3  *
4  * Copyright Red Hat Inc., 2013, 2016
5  *
6  * Authors:
7  *  Stefan Hajnoczi   <stefanha@redhat.com>
8  *  Paolo Bonzini     <pbonzini@redhat.com>
9  *
10  * This work is licensed under the terms of the GNU GPL, version 2 or later.
11  * See the COPYING file in the top-level directory.
12  *
13  */
14 
15 #include "qemu/osdep.h"
16 #include "qapi/error.h"
17 #include "block/aio.h"
18 #include "qemu/main-loop.h"
19 #include "qemu/rcu.h"
20 #include "iothread.h"
21 
22 struct IOThread {
23     AioContext *ctx;
24     GMainContext *worker_context;
25     GMainLoop *main_loop;
26 
27     QemuThread thread;
28     QemuMutex init_done_lock;
29     QemuCond init_done_cond;    /* is thread initialization done? */
30     bool stopping;
31 };
32 
iothread_init_gcontext(IOThread * iothread)33 static void iothread_init_gcontext(IOThread *iothread)
34 {
35     GSource *source;
36 
37     iothread->worker_context = g_main_context_new();
38     source = aio_get_g_source(iothread_get_aio_context(iothread));
39     g_source_attach(source, iothread->worker_context);
40     g_source_unref(source);
41     iothread->main_loop = g_main_loop_new(iothread->worker_context, TRUE);
42 }
43 
iothread_run(void * opaque)44 static void *iothread_run(void *opaque)
45 {
46     IOThread *iothread = opaque;
47 
48     rcu_register_thread();
49 
50     qemu_mutex_lock(&iothread->init_done_lock);
51     iothread->ctx = aio_context_new(&error_abort);
52     qemu_set_current_aio_context(iothread->ctx);
53 
54     /*
55      * We must connect the ctx to a GMainContext, because in older versions
56      * of glib the g_source_ref()/unref() functions are not threadsafe
57      * on sources without a context.
58      */
59     iothread_init_gcontext(iothread);
60 
61     /*
62      * g_main_context_push_thread_default() must be called before anything
63      * in this new thread uses glib.
64      */
65     g_main_context_push_thread_default(iothread->worker_context);
66 
67     qemu_cond_signal(&iothread->init_done_cond);
68     qemu_mutex_unlock(&iothread->init_done_lock);
69 
70     while (!qatomic_read(&iothread->stopping)) {
71         aio_poll(iothread->ctx, true);
72     }
73 
74     g_main_context_pop_thread_default(iothread->worker_context);
75     rcu_unregister_thread();
76     return NULL;
77 }
78 
iothread_stop_bh(void * opaque)79 static void iothread_stop_bh(void *opaque)
80 {
81     IOThread *iothread = opaque;
82 
83     iothread->stopping = true;
84 }
85 
iothread_join(IOThread * iothread)86 void iothread_join(IOThread *iothread)
87 {
88     aio_bh_schedule_oneshot(iothread->ctx, iothread_stop_bh, iothread);
89     qemu_thread_join(&iothread->thread);
90     g_main_context_unref(iothread->worker_context);
91     g_main_loop_unref(iothread->main_loop);
92     qemu_cond_destroy(&iothread->init_done_cond);
93     qemu_mutex_destroy(&iothread->init_done_lock);
94     aio_context_unref(iothread->ctx);
95     g_free(iothread);
96 }
97 
iothread_new(void)98 IOThread *iothread_new(void)
99 {
100     IOThread *iothread = g_new0(IOThread, 1);
101 
102     qemu_mutex_init(&iothread->init_done_lock);
103     qemu_cond_init(&iothread->init_done_cond);
104     qemu_thread_create(&iothread->thread, NULL, iothread_run,
105                        iothread, QEMU_THREAD_JOINABLE);
106 
107     /* Wait for initialization to complete */
108     qemu_mutex_lock(&iothread->init_done_lock);
109     while (iothread->ctx == NULL) {
110         qemu_cond_wait(&iothread->init_done_cond,
111                        &iothread->init_done_lock);
112     }
113     qemu_mutex_unlock(&iothread->init_done_lock);
114     return iothread;
115 }
116 
iothread_get_aio_context(IOThread * iothread)117 AioContext *iothread_get_aio_context(IOThread *iothread)
118 {
119     return iothread->ctx;
120 }
121