4.9-stable review patch. If anyone has any objections, please let me know.
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From: Greg Kurz groug@kaod.org
commit 26d99834f89e76514076d9cd06f61e56e6a509b8 upstream.
When a 9p request is successfully flushed, the server is expected to just mark it as used without sending a 9p reply (ie, without writing data into the buffer). In this case, virtqueue_get_buf() will return len == 0 and we must not report a REQ_STATUS_RCVD status to the client, otherwise the client will erroneously assume the request has not been flushed.
Cc: stable@vger.kernel.org Signed-off-by: Greg Kurz groug@kaod.org Signed-off-by: Michael S. Tsirkin mst@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/9p/trans_virtio.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/net/9p/trans_virtio.c +++ b/net/9p/trans_virtio.c @@ -160,7 +160,8 @@ static void req_done(struct virtqueue *v spin_unlock_irqrestore(&chan->lock, flags); /* Wakeup if anyone waiting for VirtIO ring space. */ wake_up(chan->vc_wq); - p9_client_cb(chan->client, req, REQ_STATUS_RCVD); + if (len) + p9_client_cb(chan->client, req, REQ_STATUS_RCVD); } }