linux-kernel - Re: [RFC][PATCH 5/7] x86: convert arch_futex_atomic_op_inuser() to user_access_begin/user_access

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Message-ID: <CAHk-=wgMmmnQTFT7U9+q2BsyV6Ge+LAnnhPmv0SUtFBV1D4tVw@mail.gmail.com>
Date:   Mon, 23 Mar 2020 12:06:39 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [RFC][PATCH 5/7] x86: convert arch_futex_atomic_op_inuser() to user_access_begin/user_access_end()

On Mon, Mar 23, 2020 at 11:53 AM Al Viro <viro@...iv.linux.org.uk> wrote:
>
> From: Al Viro <viro@...iv.linux.org.uk>
>
> Lift stac/clac pairs from __futex_atomic_op{1,2} into arch_futex_atomic_op_inuser(),
> fold them with access_ok() in there.

So this is a deep internal macro and already has the double
underscore, but I'm inclined to say "add the unsafe here too" for
those __futex_atomic_opX() macros that are now called inside that
user_access_begin/end region.

And wouldn't it be lovely to get rid of the error return thing, and
pass in a label instead, the way "usafe_get/put_user()" works too?
That might be a separate patch from the "reorg" thing, though.

             Linus