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[Qemu-devel] [PATCH 11/25] virtio: zero vq->inuse in virtio_reset()
From: |
Michael Roth |
Subject: |
[Qemu-devel] [PATCH 11/25] virtio: zero vq->inuse in virtio_reset() |
Date: |
Tue, 20 Sep 2016 12:05:27 -0500 |
From: Stefan Hajnoczi <address@hidden>
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 <address@hidden>
Cc: qemu-stable <address@hidden>
Reviewed-by: Michael S. Tsirkin <address@hidden>
Signed-off-by: Michael S. Tsirkin <address@hidden>
Reviewed-by: Ladi Prosek <address@hidden>
(cherry picked from commit 4b7f91ed0270a371e1933efa21ba600b6da23ab9)
Signed-off-by: Michael Roth <address@hidden>
---
hw/virtio/virtio.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 5fbaaaa..519bb03 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -816,6 +816,7 @@ void virtio_reset(void *opaque)
vdev->vq[i].signalled_used_valid = false;
vdev->vq[i].notification = true;
vdev->vq[i].vring.num = vdev->vq[i].vring.num_default;
+ vdev->vq[i].inuse = 0;
}
}
--
1.9.1
- [Qemu-devel] [PATCH 00/25] Patch Round-up for stable 2.6.2, freeze on 2016-08-26, Michael Roth, 2016/09/20
- [Qemu-devel] [PATCH 11/25] virtio: zero vq->inuse in virtio_reset(),
Michael Roth <=
- [Qemu-devel] [PATCH 09/25] 9pfs: forbid . and .. in file names, Michael Roth, 2016/09/20
- [Qemu-devel] [PATCH 10/25] 9pfs: handle walk of ".." in the root directory, Michael Roth, 2016/09/20
- [Qemu-devel] [PATCH 12/25] virtio-balloon: discard virtqueue element on reset, Michael Roth, 2016/09/20
- [Qemu-devel] [PATCH 13/25] vnc: fix qemu crash because of SIGSEGV, Michael Roth, 2016/09/20
- [Qemu-devel] [PATCH 14/25] 9pfs: fix potential segfault during walk, Michael Roth, 2016/09/20
- [Qemu-devel] [PATCH 15/25] scsi: mptsas: use g_new0 to allocate MPTSASRequest object, Michael Roth, 2016/09/20
- [Qemu-devel] [PATCH 22/25] crypto: ensure XTS is only used with ciphers with 16 byte blocks, Michael Roth, 2016/09/20
- [Qemu-devel] [PATCH 16/25] scsi: pvscsi: limit process IO loop to ring size, Michael Roth, 2016/09/20
- [Qemu-devel] [PATCH 18/25] scsi-disk: change disk serial length from 20 to 36, Michael Roth, 2016/09/20
- [Qemu-devel] [PATCH 17/25] qemu-char: avoid segfault if user lacks of permisson of a given logfile, Michael Roth, 2016/09/20