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From: Julian Assange <proff@iq.org>
Message-Id: <199701012224.JAA06593@profane.iq.org>
Subject: struct file locking
To: hackers@freebsd.org
Date: Thu, 2 Jan 1997 09:24:38 +1100 (EST)
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I am expanding the inet/socket code to permit firewall entries
based on uid/gid. I have an aesthetic issue and one locking
issue.

I need to pass socket credential information into ip_output.  There
are two ways of doing this. I can add a back-pointer to the socket
structure from the struct ipoption mbuf, or I can add an extra
parameter to ip_output. I am inclinded towards the first option,
for source-level compatability reasons.

In the socket structure I intend to create a back-pointer to
originating struct file's->u_cred. What do I need to do to insure
these last two structures are reliably locked and in memory?

Cheers,
Julian.