netdev - Re: [V9fs-developer] [PATCH] 9p/trans_virtio: discard zero-length reply

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Message-ID: <20180208185232.46fca063@bahia.lan>
Date:   Thu, 8 Feb 2018 18:52:32 +0100
From:   Greg Kurz <groug@...d.org>
To:     v9fs-developer@...ts.sourceforge.net,
        "Michael S. Tsirkin" <mst@...hat.com>
Cc:     Latchesar Ionkov <lucho@...kov.net>,
        Eric Van Hensbergen <ericvh@...il.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Ron Minnich <rminnich@...dia.gov>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [V9fs-developer] [PATCH] 9p/trans_virtio: discard zero-length
 reply

Ping ?

Michael,

Since this is virtio code and you have acked the QEMU part of the fix already,
would you be kind enough to take this through your tree ?

Cheers,

--
Greg

On Mon, 22 Jan 2018 22:02:05 +0100
Greg Kurz <groug@...d.org> wrote:

> 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.
> 
> Signed-off-by: Greg Kurz <groug@...d.org>
> ---
>  net/9p/trans_virtio.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
> index 0845aad4ba51..ca08c72ef4de 100644
> --- a/net/9p/trans_virtio.c
> +++ b/net/9p/trans_virtio.c
> @@ -171,7 +171,8 @@ static void req_done(struct virtqueue *vq)
>  		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);
>  	}
>  }
>  
> 
> 
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