From: Peter Xu <pet...@redhat.com>
Free the AIO context earlier than the GMainContext (if we have) to
workaround a possible Glib bug. No functional change at all.
We encountered a qmp-test hang with oob:
#0 0x00007f35ffe45334 in __lll_lock_wait () from /lib64/libpthread.so.0
#1 0x00007f35ffe405d8 in _L_lock_854 () from /lib64/libpthread.so.0
#2 0x00007f35ffe404a7 in pthread_mutex_lock () from /lib64/libpthread.so.0
#3 0x00007f35fc5b9c9d in g_source_unref_internal (source=0x24f0600,
context=0x7f35f0000960, have_lock=0) at gmain.c:1685
#4 0x0000000000aa6672 in aio_context_unref (ctx=0x24f0600) at
/root/qemu/util/async.c:497
#5 0x000000000065851c in iothread_instance_finalize (obj=0x24f0380) at
/root/qemu/iothread.c:129
#6 0x0000000000962d79 in object_deinit (obj=0x24f0380, type=0x242e960) at
/root/qemu/qom/object.c:462
#7 0x0000000000962e0d in object_finalize (data=0x24f0380) at
/root/qemu/qom/object.c:476
#8 0x0000000000964146 in object_unref (obj=0x24f0380) at
/root/qemu/qom/object.c:924
#9 0x0000000000965880 in object_finalize_child_property (obj=0x24ec640,
name=0x24efca0 "mon_iothread", opaque=0x24f0380) at /root/qemu/qom/object.c:1436
#10 0x0000000000962c33 in object_property_del_child (obj=0x24ec640,
child=0x24f0380, errp=0x0) at /root/qemu/qom/object.c:436
#11 0x0000000000962d26 in object_unparent (obj=0x24f0380) at
/root/qemu/qom/object.c:455
#12 0x0000000000658f00 in iothread_destroy (iothread=0x24f0380) at
/root/qemu/iothread.c:365
#13 0x00000000004c67a8 in monitor_cleanup () at /root/qemu/monitor.c:4663
#14 0x0000000000669e27 in main (argc=16, argv=0x7ffc8b1ae2f8,
envp=0x7ffc8b1ae380) at /root/qemu/vl.c:4749
With glib version 2.28.8-9 (current default version on centos6) we might
encounter above with the old code. It is verified that glib version
2.50.3-3 won't trigger that bug again, but since we are still supporting
glib 2.28.8-9, we may want this workaround.
Signed-off-by: Peter Xu <pet...@redhat.com>
Message-Id: <20180404065346.3252-1-pet...@redhat.com>
Reviewed-by: Fam Zheng <f...@redhat.com>
Signed-off-by: Eric Blake <ebl...@redhat.com>
---
iothread.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/iothread.c b/iothread.c
index e675c384422..d41d661cdf4 100644
--- a/iothread.c
+++ b/iothread.c
@@ -117,16 +117,26 @@ static void iothread_instance_finalize(Object *obj)
IOThread *iothread = IOTHREAD(obj);
iothread_stop(iothread);
+ /*
+ * With glib version 2.28.8-9 (current default version on centos6)
+ * we might encounter problem of qmp-test OOB hang if we unref the
+ * AIO context later than the GMainContext below. Let's free the
+ * AIO context earlier to bypass that possible glib bug.
+ *
+ * It is verified that glib version 2.50.3-3 (or even earlier)
+ * won't trigger that bug again, but since we are still supporting
+ * glib 2.28.8-9, we need this workaround.
+ */
+ if (iothread->ctx) {
+ aio_context_unref(iothread->ctx);
+ iothread->ctx = NULL;
+ }
if (iothread->worker_context) {
g_main_context_unref(iothread->worker_context);
iothread->worker_context = NULL;
}
qemu_cond_destroy(&iothread->init_done_cond);
qemu_mutex_destroy(&iothread->init_done_lock);
- if (!iothread->ctx) {
- return;
- }
- aio_context_unref(iothread->ctx);
}
static void iothread_complete(UserCreatable *obj, Error **errp)
--
2.14.3
