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From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Wed, 29 Mar 2017 16:43:05 -0700
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Subject: Re: [RFC][CFT][PATCHSET v1] uaccess unification
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Vineet Gupta <Vineet.Gupta1@synopsys.com>,
        "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
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        Haavard Skinnemoen <hskinnemoen@gmail.com>,
        Steven Miao <realmz6@gmail.com>,
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        Mark Salter <msalter@redhat.com>,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Richard Kuo <rkuo@codeaurora.org>, Tony Luck <tony.luck@intel.com>,
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        Ralf Baechle <ralf@linux-mips.org>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Chen Liqin <liqin.linux@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Chris Metcalf <cmetcalf@mellanox.com>,
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On Wed, Mar 29, 2017 at 4:09 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> IMO that's a separate series.  For now I would be bloody happy if we got
>         * arch-dependent asm fixes out of the way
>         * everything consolidated outside of arch/*
>         * arch/*/include/uaccess*.h simplified.

Sure, I agree.

At the same time, I just think that we really *should* aim for a
simpler uaccess.h in the long term, so I would prefer we not encourage
architectures to do things that simply won't matter.

> As for __copy_in_user()... I'm not sure we want to keep it in the long run -

I agree, it's probably not worth it at all.

In fact, I suspect none of the "__copy_.*_user()" versions are worth
it, and we should strive to remove them.

There aren't even that many users, and they _have_ caused security
issues when people have had some path that hasn't checked the range.

                Linus