From mboxrd@z Thu Jan  1 00:00:00 1970
From: Willem de Bruijn <willemb@google.com>
Subject: Re: LTP recv/recvmsg tests failing on 3.17
Date: Tue, 23 Sep 2014 12:24:57 -0400
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To: Chuck Ebbert <cebbert.lkml@gmail.com>
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> But I was also wondering why we return EAGAIN here for no data waiting,
> when we return EINVAL for the same case with a different type of data.
> There's no spec and it's not documented, so I guess the answer is "it's
> always been that way."

EAGAIN is the common response. I don't know why TCP urgent
data returns EINVAL. It is unusual enough that the relevant line
in tcp_recv_urg explicitly comments on it:

                return -EINVAL; /* Yes this is right ! */