libqos: improve event_index test with timeout

The virtio event_index feature lets the device driver tell the device
how many requests to process before raising the next interrupt.
virtio-blk-test.c tries to verify that the device does not raise an
interrupt unnecessarily.

Unfortunately the test has a race condition.  It spins checking for an
interrupt up to 100 times and then assumes the request has finished.  On
a slow host the I/O request could still be in flight and the test would
fail.

This patch waits for the request to complete, or until a 30-second
timeout is reached.  If an interrupt is raised while waiting the test
fails since the device was not supposed to raise interrupts.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/tests/virtio-blk-test.c b/tests/virtio-blk-test.c
index 588666cff1..0e3bfa7eb2 100644
--- a/tests/virtio-blk-test.c
+++ b/tests/virtio-blk-test.c
@@ -42,6 +42,7 @@
 
 #define TEST_IMAGE_SIZE         (64 * 1024 * 1024)
 #define QVIRTIO_BLK_TIMEOUT     100
+#define QVIRTIO_BLK_TIMEOUT_US  (30 * 1000 * 1000)
 #define PCI_SLOT                0x04
 #define PCI_FN                  0x00
 
@@ -595,10 +596,9 @@ static void pci_idx(void)
     qvirtqueue_kick(&qvirtio_pci, &dev->vdev, &vqpci->vq, free_head);
 
     /* No notification expected */
-    g_assert(!qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
-                                                        QVIRTIO_BLK_TIMEOUT));
-
-    status = readb(req_addr + 528);
+    status = qvirtio_wait_status_byte_no_isr(&qvirtio_pci, &dev->vdev,
+                                             &vqpci->vq, req_addr + 528,
+                                             QVIRTIO_BLK_TIMEOUT_US);
     g_assert_cmpint(status, ==, 0);
 
     guest_free(alloc, req_addr);