path: root/util/osdep.c
diff options
authorStefan Hajnoczi <>2013-10-08 11:58:31 +0200
committerStefan Hajnoczi <>2014-03-25 13:39:31 +0100
commitae2990c259abec198879c362dc13f7047f26c2cf (patch)
treedbf4815eff7df7791a089fffef00d9dc4b71117d /util/osdep.c
parent839a5547574e57cce62f49bfc50fe1f04b00589a (diff)
osdep: initialize glib threads in all QEMU tools
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 <> Signed-off-by: Stefan Hajnoczi <>
Diffstat (limited to 'util/osdep.c')
1 files changed, 18 insertions, 0 deletions
diff --git a/util/osdep.c b/util/osdep.c
index bd4f530..a9029f8 100644
--- a/util/osdep.c
+++ b/util/osdep.c
@@ -436,6 +436,24 @@ int socket_init(void)
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);
+ fprintf(stderr, "glib threading failed to initialize.\n");
+ exit(1);
+ }
/* helper function for iov_send_recv() */
static ssize_t
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