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From: Alfred Perlstein <bright@mu.org>
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To: Richard Sharpe <realrichardsharpe@gmail.com>
Subject: Re: Seeing EINVAL from writev on 8.0 to a non-blocking socket even
 though the data seems to hit the wire
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On 5/1/13 8:03 PM, Richard Sharpe wrote:
> Hi folks,
>
> I am checking to see if there are any known bugs with respect to this
> in FreeBSD 8.0.
>
> Situation is that Samba 3.6.6 uses writev to a non-blocking socket to
> get the SMB2 requests on the wire.
>
> Intermittently, we see the writev return EINVAL even though the data
> has gotten on the wire. This I have verified by grabbing a capture and
> comparing the SMB Sequence number in the last outgoing packet on the
> wire vs the in-memory contents when we get EINVAL.
>
> Sometimes it occurs on a four-element IOVEC, sometimes we get EAGAIN
> on the four-element IOVEC and then we get EINVAL when retrying on a
> smaller IOVEC.
>
> Where should I look to check if there is some path where this might be
> happening? Is this even the correct mailing list?
>
What does the iovec look like when you get EINVAL? Can you sanity check
it? Is there anything special about it? (zero length vecs?)

I think there are a few "maxvals" that if overrun cause EINVAL to be
returned. example is if your iovec is somehow huge or has many, many
elements.

-Alfred