linux-kernel - Re: [RFC] vfs: don't bother clearing close_on

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Message-ID: <CA+55aFxGD0aftAb49X1G-f79WCD8znkeQX0bSfDVDjBiUCQ2fQ@mail.gmail.com>
Date:	Tue, 3 Nov 2015 14:45:01 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [RFC] vfs: don't bother clearing close_on_exec bit for unused fds

On Tue, Nov 3, 2015 at 1:41 AM, Rasmus Villemoes
<linux@...musvillemoes.dk> wrote:
>
> I'm sure I've missed something, hence the RFC. But if not, there's
> probably also a few memsets which become redundant. And the
> __set_close_on_exec part should probably be its own patch...

The patch looks fine to me. I'm not sure the __set_close_on_exec part
even makes sense, because if you set that bit, it usually really *is*
clear before, so testing it beforehand is just pointless.  And if
somebody really keeps setting the bit, they are doing something stupid
anyway..

So I have nothing against the patch, but I do wonder how much it
matters. If there isn't a noticeable performance win, I'd almost
rather just keep the close-on-exec bitmap up-to-date. Hmm?

               Linus
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