Messages in this thread Patch in this message | | | Date | Fri, 29 Apr 2011 11:55:32 -0700 | From | Greg KH <> | Subject | [09/55] virtio: Decrement avail idx on buffer detach |
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2.6.38-stable review patch. If anyone has any objections, please let us know.
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From: Amit Shah <amit.shah@redhat.com>
commit b3258ff1d6086bd2b9eeb556844a868ad7d49bc8 upstream.
When detaching a buffer from a vq, the avail.idx value should be decremented as well.
This was noticed by hot-unplugging a virtio console port and then plugging in a new one on the same number (re-using the vqs which were just 'disowned'). qemu reported
'Guest moved used index from 0 to 256'
when any IO was attempted on the new port.
Reported-by: juzhang <juzhang@redhat.com> Signed-off-by: Amit Shah <amit.shah@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- drivers/virtio/virtio_ring.c | 1 + 1 file changed, 1 insertion(+)
--- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -371,6 +371,7 @@ void *virtqueue_detach_unused_buf(struct /* detach_buf clears data, so grab it now. */ buf = vq->data[i]; detach_buf(vq, i); + vq->vring.avail->idx--; END_USE(vq); return buf; }
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