netdev - Re: [PATCH v2] Implement close-on-fork

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Date:   Fri, 15 May 2020 17:03:42 +0100
From:   Al Viro <viro@...iv.linux.org.uk>
To:     Nate Karstens <nate.karstens@...min.com>
Cc:     Jeff Layton <jlayton@...nel.org>,
        "J. Bruce Fields" <bfields@...ldses.org>,
        Arnd Bergmann <arnd@...db.de>,
        Richard Henderson <rth@...ddle.net>,
        Ivan Kokshaysky <ink@...assic.park.msu.ru>,
        Matt Turner <mattst88@...il.com>,
        "James E.J. Bottomley" <James.Bottomley@...senpartnership.com>,
        Helge Deller <deller@....de>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        David Laight <David.Laight@...lab.com>,
        linux-fsdevel@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-alpha@...r.kernel.org, linux-parisc@...r.kernel.org,
        sparclinux@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Changli Gao <xiaosuo@...il.com>
Subject: Re: [PATCH v2] Implement close-on-fork

On Fri, May 15, 2020 at 10:23:17AM -0500, Nate Karstens wrote:

> This functionality was approved by the Austin Common Standards
> Revision Group for inclusion in the next revision of the POSIX
> standard (see issue 1318 in the Austin Group Defect Tracker).

It penalizes every call of fork() in the system (as well as adds
an extra dirtied cacheline on each socket()/open()/etc.), adds
memory footprint and complicates the API.  All of that - to deal
with rather uncommon problem that already has a portable solution.

As for the Austin Group, the only authority it has ever had derives
from consensus between existing Unices.  "Solaris does it, Linux and
*BSD do not" translates into "Austin Group is welcome to take a hike".
BTW, contrary to the lovely bit of misrepresentation in that
thread of theirs ("<LWN URL> suggests that" != "someone's comment
under LWN article says it _appears_ that"), none of *BSD do it.

IMO it's a bad idea.

NAKed-by: Al Viro <viro@...iv.linux.org.uk>