File 0300-virtio-zero-vq-inuse-in-virtio_rese.patch of Package qemu-linux-user.7445

Overview Repositories Revisions Requests Users Attributes Meta

File 0300-virtio-zero-vq-inuse-in-virtio_rese.patch of Package qemu-linux-user.7445

From b7e9c54f8299e89ca1375167667c4b701610b542 Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Wed, 7 Sep 2016 11:51:25 -0400
Subject: [PATCH] virtio: zero vq->inuse in virtio_reset()

vq->inuse must be zeroed upon device reset like most other virtqueue
fields.

In theory, virtio_reset() just needs assert(vq->inuse == 0) since
devices must clean up in-flight requests during reset (requests cannot
not be leaked!).

In practice, it is difficult to achieve vq->inuse == 0 across reset
because balloon, blk, 9p, etc implement various different strategies for
cleaning up requests.  Most devices call g_free(elem) directly without
telling virtio.c that the VirtQueueElement is cleaned up.  Therefore
vq->inuse is not decremented during reset.

This patch zeroes vq->inuse and trusts that devices are not leaking
VirtQueueElements across reset.

I will send a follow-up series that refactors request life-cycle across
all devices and converts vq->inuse = 0 into assert(vq->inuse == 0) but
this more invasive approach is not appropriate for stable trees.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Cc: qemu-stable <qemu-stable@nongnu.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Ladi Prosek <lprosek@redhat.com>
(cherry picked from commit 4b7f91ed0270a371e1933efa21ba600b6da23ab9)
[BR: BSC#1015048]
Signed-off-by: Bruce Rogers <brogers@suse.com>
---
 hw/virtio/virtio.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 9f1e86b2b7..43d7db13e8 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -638,6 +638,7 @@ void virtio_reset(void *opaque)
         vdev->vq[i].signalled_used = 0;
         vdev->vq[i].signalled_used_valid = false;
         vdev->vq[i].notification = true;
+        vdev->vq[i].inuse = 0;
     }
 }

Places

File 0300-virtio-zero-vq-inuse-in-virtio_rese.patch of Package qemu-linux-user.7445

Places