netdev - Re: [PATCH v3 net-next 10/19] tls: Fix zerocopy_from

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Date:   Thu, 12 Jul 2018 15:28:39 -0400
From:   Boris Pismenny <borisp@...lanox.com>
To:     Dave Watson <davejwatson@...com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org, aviadye@...lanox.com,
        saeedm@...lanox.com
Subject: Re: [PATCH v3 net-next 10/19] tls: Fix zerocopy_from_iter iov
 handling



On 7/12/2018 12:46 PM, Dave Watson wrote:
> On 07/11/18 10:54 PM, Boris Pismenny wrote:
>> zerocopy_from_iter iterates over the message, but it doesn't revert the
>> updates made by the iov iteration. This patch fixes it. Now, the iov can
>> be used after calling zerocopy_from_iter.
> 
> This breaks tests (which I will send up as selftests shortly).  I
> believe we are depending on zerocopy_from_iter to advance the iter,
> and if zerocopy_from_iter returns a failure, then we revert it.  So
> you can revert it here if you want, but you'd have to advance it if we
> actually used it instead.
> 

Only in the send side do we depend on this semantic. On the receive 
side, we need to revert it in case we go to the fallback flow.