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[Qemu-devel] [PATCH] virtio-crypto: fix virtio_queue_set_notification()
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH] virtio-crypto: fix virtio_queue_set_notification() race |
Date: |
Wed, 16 Nov 2016 20:17:32 +0000 |
We must check for new virtqueue buffers after re-enabling notifications.
This prevents the race condition where the guest added buffers just
after we stopped popping the virtqueue but before we re-enabled
notifications.
I think the virtio-crypto code was based on virtio-net but this crucial
detail was missed. virtio-net does not have the race condition because
it processes the virtqueue one more time after re-enabling
notifications.
Cc: Gonglei <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
hw/virtio/virtio-crypto.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/hw/virtio/virtio-crypto.c b/hw/virtio/virtio-crypto.c
index 3293843..847dc9d 100644
--- a/hw/virtio/virtio-crypto.c
+++ b/hw/virtio/virtio-crypto.c
@@ -692,8 +692,17 @@ static void virtio_crypto_dataq_bh(void *opaque)
return;
}
- virtio_crypto_handle_dataq(vdev, q->dataq);
- virtio_queue_set_notification(q->dataq, 1);
+ for (;;) {
+ virtio_crypto_handle_dataq(vdev, q->dataq);
+ virtio_queue_set_notification(q->dataq, 1);
+
+ /* Are we done or did the guest add more buffers? */
+ if (virtio_queue_empty(q->dataq)) {
+ break;
+ }
+
+ virtio_queue_set_notification(q->dataq, 0);
+ }
}
static void
--
2.7.4
- [Qemu-devel] [PATCH] virtio-crypto: fix virtio_queue_set_notification() race,
Stefan Hajnoczi <=