From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH] tcp: really ignore MSG_ZEROCOPY if no SO_ZEROCOPY
Date: Fri, 07 Sep 2018 23:11:42 -0700 (PDT)
Message-ID: <20180907.231142.274109264940766007.davem@davemloft.net>
References: <20180906135459.15529-1-vincent.whitchurch@axis.com>
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Cc: netdev@vger.kernel.org, willemb@google.com, rabinv@axis.com
To: vincent.whitchurch@axis.com
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From: Vincent Whitchurch <vincent.whitchurch@axis.com>
Date: Thu,  6 Sep 2018 15:54:59 +0200

> According to the documentation in msg_zerocopy.rst, the SO_ZEROCOPY
> flag was introduced because send(2) ignores unknown message flags and
> any legacy application which was accidentally passing the equivalent of
> MSG_ZEROCOPY earlier should not see any new behaviour.
> 
> Before commit f214f915e7db ("tcp: enable MSG_ZEROCOPY"), a send(2) call
> which passed the equivalent of MSG_ZEROCOPY without setting SO_ZEROCOPY
> would succeed.  However, after that commit, it fails with -ENOBUFS.  So
> it appears that the SO_ZEROCOPY flag fails to fulfill its intended
> purpose.  Fix it.
> 
> Fixes: f214f915e7db ("tcp: enable MSG_ZEROCOPY")
> Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>

Applied and queued up for -stable, thanks.