glib versions prior to 2.31.0 require an explicit g_thread_init() call
to enable multi-threading.
Failure to initialize threading causes glib to take single-threaded code
paths without synchronization. For example, the g_slice allocator will
crash due to race conditions.
Fix this for all QEMU tool programs (qemu-nbd, qemu-io, qemu-img) by
moving the g_thread_init() call from vl.c:main() into a new
osdep.c:thread_init() constructor function.
thread_init() has __attribute__((constructor)) and is automatically
invoked by the runtime during startup.
We can now drop the "simple" trace backend's g_thread_init() call since
thread_init() already called it.
Note that we must keep coroutine-gthread.c's g_thread_init() call which
is located in a constructor function. There is no guarantee for
constructor function ordering so thread_init() may only be called later.
Reported-by: Mario de Chenno <mario.dechenno@unina2.it>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
{
GThread *thread;
- if (!g_thread_supported()) {
-#if !GLIB_CHECK_VERSION(2, 31, 0)
- g_thread_init(NULL);
-#else
- fprintf(stderr, "glib threading failed to initialize.\n");
- exit(1);
-#endif
- }
-
#if !GLIB_CHECK_VERSION(2, 31, 0)
trace_available_cond = g_cond_new();
trace_empty_cond = g_cond_new();
return 0;
}
+/* Ensure that glib is running in multi-threaded mode */
+static void __attribute__((constructor)) thread_init(void)
+{
+ if (!g_thread_supported()) {
+#if !GLIB_CHECK_VERSION(2, 31, 0)
+ /* Old versions of glib require explicit initialization. Failure to do
+ * this results in the single-threaded code paths being taken inside
+ * glib. For example, the g_slice allocator will not be thread-safe
+ * and cause crashes.
+ */
+ g_thread_init(NULL);
+#else
+ fprintf(stderr, "glib threading failed to initialize.\n");
+ exit(1);
+#endif
+ }
+}
+
#ifndef CONFIG_IOVEC
/* helper function for iov_send_recv() */
static ssize_t
qemu_init_exec_dir(argv[0]);
g_mem_set_vtable(&mem_trace);
- if (!g_thread_supported()) {
-#if !GLIB_CHECK_VERSION(2, 31, 0)
- g_thread_init(NULL);
-#else
- fprintf(stderr, "glib threading failed to initialize.\n");
- exit(1);
-#endif
- }
module_call_init(MODULE_INIT_QOM);