From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Vrabel <david.vrabel@citrix.com>
Subject: Re: [PATCH net-next] xen-netback: improve
 guest-receive-side flow control
Date: Mon, 2 Dec 2013 11:52:18 +0000
Message-ID: <529C7472.60303@citrix.com>
References: <1385644272-29728-1-git-send-email-paul.durrant@citrix.com>
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To: Paul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>, Ian Campbell <ian.campbell@citrix.com>, xen-devel@lists.xen.org
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On 28/11/13 13:11, Paul Durrant wrote:
> The flow control code relies on a double pass of tke skb, firstly to count
> the number of ring slots needed to supply sufficient grant references, and
> another to actually consume those references and build the grant copy
> operations. It transpires that, in some scenarios, the initial count and the
> number of references consumed differs and, after this happens a number of
> times, flow control is completely broken.

Can you describe in more detail the cases where it gets it wrong?

> -unsigned int xenvif_count_skb_slots(struct xenvif *vif, struct sk_buff *skb)

Any patch that gets rid of this gets my vote (provided it works!).

Can you list all the guest frontends that you've tested this with?

David