This is a note to let you know that I've just added the patch titled
virtio: Decrement avail idx on buffer detach
to the 2.6.38-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
virtio-decrement-avail-idx-on-buffer-detach.patch
and it can be found in the queue-2.6.38 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From b3258ff1d6086bd2b9eeb556844a868ad7d49bc8 Mon Sep 17 00:00:00 2001
From: Amit Shah <[email protected]>
Date: Wed, 16 Mar 2011 19:12:10 +0530
Subject: virtio: Decrement avail idx on buffer detach
From: Amit Shah <[email protected]>
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 <[email protected]>
Signed-off-by: Amit Shah <[email protected]>
Signed-off-by: Rusty Russell <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
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;
}
Patches currently in stable-queue which might be from [email protected] are
queue-2.6.38/virtio-decrement-avail-idx-on-buffer-detach.patch
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