Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755821Ab3IMMgT (ORCPT ); Fri, 13 Sep 2013 08:36:19 -0400 Received: from mail-pd0-f178.google.com ([209.85.192.178]:39083 "EHLO mail-pd0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751847Ab3IMMgQ (ORCPT ); Fri, 13 Sep 2013 08:36:16 -0400 MIME-Version: 1.0 In-Reply-To: <20130913121529.GA1437@flint.arm.linux.org.uk> References: <20130912153629.16487.88969@localhost.localdomain> <20130913121529.GA1437@flint.arm.linux.org.uk> Date: Fri, 13 Sep 2013 14:36:15 +0200 X-Google-Sender-Auth: 2SDicuZhSxwFqLVXRjpwHs8OD7Q Message-ID: Subject: Re: [GIT PULL] Btrfs From: Geert Uytterhoeven To: Josh Boyer , Geert Uytterhoeven , Chris Mason , Mark Fasheh , Linus Torvalds , linux-btrfs , "Linux-Kernel@Vger. Kernel. Org" , Linux-Arch Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1759 Lines: 43 On Fri, Sep 13, 2013 at 2:15 PM, Russell King wrote: > On Fri, Sep 13, 2013 at 07:53:21AM -0400, Josh Boyer wrote: >> I'm not an ARM expert, so I don't know if ARM should use the >> asm-generic implementations, or just use __get_user/__put_user in all >> cases. I've CC'd rmk. > > Why do we have uaccess-unaligned.h ? Normally, these kinds of things > are spawned by architectures which have problems with unaligned accesses, > ARM being one of them, but afaik we've never need this. > > With the kernel-side trapping of unaligned accesses on older hardware, > we've always dealt with the normal accessor faulting. > > From what I can tell in the git history, these unaligned put_user and > get_user have existed all the way back to the dawn of git use. > > Can someone enlighten me why we have them? You removed the answer when trimming the quoted part: | "Btrfs is the first user of __put_user_unaligned() outside the compat code, __put_user_unaligned() is used in fs/compat.c, presumably because alignment restrictions may differ between 32- and 64-bit versions of the same CPU family. No one seems to actully use __get_user_unaligned(). Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/