This is a note to let you know that I've just added the patch titled
vhost_net: poll vhost queue after marking DMA is done
to the 3.10-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:
vhost_net-poll-vhost-queue-after-marking-dma-is-done.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From d0fc38475bf219aebcd5cbbc4d6b58df1ac866bb Mon Sep 17 00:00:00 2001
From: Jason Wang <[email protected]>
Date: Mon, 2 Sep 2013 16:41:00 +0800
Subject: vhost_net: poll vhost queue after marking DMA is done
From: Jason Wang <[email protected]>
[ Upstream commit 19c73b3e08d16ee923f3962df4abf6205127896a ]
We used to poll vhost queue before making DMA is done, this is racy if vhost
thread were waked up before marking DMA is done which can result the signal to
be missed. Fix this by always polling the vhost thread before DMA is done.
Signed-off-by: Jason Wang <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/vhost/net.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -307,6 +307,11 @@ static void vhost_zerocopy_callback(stru
struct vhost_virtqueue *vq = ubufs->vq;
int cnt = atomic_read(&ubufs->kref.refcount);
+ /* set len to mark this desc buffers done DMA */
+ vq->heads[ubuf->desc].len = success ?
+ VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
+ vhost_net_ubuf_put(ubufs);
+
/*
* Trigger polling thread if guest stopped submitting new buffers:
* in this case, the refcount after decrement will eventually reach 1
@@ -317,10 +322,6 @@ static void vhost_zerocopy_callback(stru
*/
if (cnt <= 2 || !(cnt % 16))
vhost_poll_queue(&vq->poll);
- /* set len to mark this desc buffers done DMA */
- vq->heads[ubuf->desc].len = success ?
- VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
- vhost_net_ubuf_put(ubufs);
}
/* Expects to be always run from workqueue - which acts as
Patches currently in stable-queue which might be from [email protected] are
queue-3.10/vhost_net-poll-vhost-queue-after-marking-dma-is-done.patch
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