Date: Wed, 29 Mar 2017 21:29:39 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Cc: "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Richard Henderson <rth@twiddle.net>,
        Russell King <linux@armlinux.org.uk>,
        Will Deacon <will.deacon@arm.com>,
        Haavard Skinnemoen <hskinnemoen@gmail.com>,
        Steven Miao <realmz6@gmail.com>,
        Jesper Nilsson <jesper.nilsson@axis.com>,
        Mark Salter <msalter@redhat.com>,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Richard Kuo <rkuo@codeaurora.org>, Tony Luck <tony.luck@intel.com>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        James Hogan <james.hogan@imgtec.com>, Michal Simek <monstr@monstr.eu>,
        David Howells <dhowells@redhat.com>, Ley Foon Tan <lftan@altera.com>,
        Jonas Bonn <jonas@southpole.se>, Helge Deller <deller@gmx.de>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>,
        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>,
        Richard Weinberger <richard@nod.at>, Guan Xuetao <gxt@mprc.pku.edu.cn>,
        Thomas Gleixner <tglx@linutronix.de>, Chris Zankel <chris@zankel.net>
Subject: Re: [RFC][CFT][PATCHSET v1] uaccess unification
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On Wed, Mar 29, 2017 at 01:08:12PM -0700, Vineet Gupta wrote:

> Hi Al,
> 
> Thx for taking this up. It seems ARC was missing INLINE_COPY* switch likely due to
> existing 2 variants (inline/out-of-line) we already have.
> I've added a patch for that (attached too) - boot tested the series on ARC.

BTW, I wonder if inlining all of the copy_{to,from}_user() is actually a win.
It's probably arch-dependent and it would be nice if somebody compared
performance with and without inlining those...  ARC, in particular, has
__arc_copy_{to,from}_user() inlining a whole lot, even in case of non-constant
size and your patch, AFAICS, will inline all of it in *all* cases.  It might
end up being a win, but that's not apriori obvious...  Do you have any
profiling results in that area?