linux-kernel - Re: [git pull] vfs.git get_user_pages

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Message-ID: <20171121183529.GA6349@redhat.com>
Date:   Tue, 21 Nov 2017 19:35:29 +0100
From:   Andrea Arcangeli <aarcange@...hat.com>
To:     Al Viro <viro@...IV.linux.org.uk>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [git pull] vfs.git get_user_pages_fast() conversion

On Sat, Nov 18, 2017 at 09:45:31PM +0000, Al Viro wrote:
> in __get_user_pages_locked(), or am I missing something subtle there?  Andrea?

You're not missing anything as far as the logic is concerned.

However see the __always_inline, I added "notify_drop" purely to
optimize away such branch at build time so that gcc doesn't need to
include in every different copy it does of it. "notify_drop" is known
at build time and constant true/false, the other variables are not.

Either you drop the __always_inline or "notify_drop" makes sense to me
to keep to reduce the size of the inline and run faster at runtime.

Thanks,
Andrea