This is a regression test for a deadlock that could occur in callbacks
called from the aio_poll() in bdrv_drain_poll_top_level(). The
AioContext lock wasn't released and therefore would be taken a second
time in the callback. This would cause a possible AIO_WAIT_WHILE() in
the callback to hang.
Signed-off-by: Kevin Wolf
---
tests/test-bdrv-drain.c | 13 +
1 file changed, 13 insertions(+)
diff --git a/tests/test-bdrv-drain.c b/tests/test-bdrv-drain.c
index 9641a20dd8..07ce5bfddc 100644
--- a/tests/test-bdrv-drain.c
+++ b/tests/test-bdrv-drain.c
@@ -636,6 +636,17 @@ static void test_iothread_aio_cb(void *opaque, int ret)
qemu_event_set(_event);
}
+static void test_iothread_main_thread_bh(void *opaque)
+{
+struct test_iothread_data *data = opaque;
+
+/* Test that the AioContext is not yet locked in a random BH that is
+ * executed during drain, otherwise this would deadlock. */
+aio_context_acquire(bdrv_get_aio_context(data->bs));
+bdrv_flush(data->bs);
+aio_context_release(bdrv_get_aio_context(data->bs));
+}
+
/*
* Starts an AIO request on a BDS that runs in the AioContext of iothread 1.
* The request involves a BH on iothread 2 before it can complete.
@@ -705,6 +716,8 @@ static void test_iothread_common(enum drain_type
drain_type, int drain_thread)
aio_context_acquire(ctx_a);
}
+aio_bh_schedule_oneshot(ctx_a, test_iothread_main_thread_bh, );
+
/* The request is running on the IOThread a. Draining its block device
* will make sure that it has completed as far as the BDS is concerned,
* but the drain in this thread can continue immediately after
--
2.13.6
