From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f171.google.com (mail-wi0-f171.google.com [209.85.212.171]) by kanga.kvack.org (Postfix) with ESMTP id BC5996B0073 for ; Thu, 11 Dec 2014 09:05:30 -0500 (EST) Received: by mail-wi0-f171.google.com with SMTP id bs8so14670839wib.10 for ; Thu, 11 Dec 2014 06:05:29 -0800 (PST) Received: from e06smtp16.uk.ibm.com (e06smtp16.uk.ibm.com. [195.75.94.112]) by mx.google.com with ESMTPS id 8si2214449wjx.166.2014.12.11.06.05.29 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 11 Dec 2014 06:05:29 -0800 (PST) Received: from /spool/local by e06smtp16.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 11 Dec 2014 14:05:28 -0000 Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by d06dlp01.portsmouth.uk.ibm.com (Postfix) with ESMTP id B9A3D17D8042 for ; Thu, 11 Dec 2014 14:05:48 +0000 (GMT) Received: from d06av12.portsmouth.uk.ibm.com (d06av12.portsmouth.uk.ibm.com [9.149.37.247]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id sBBE5Q8n51118278 for ; Thu, 11 Dec 2014 14:05:26 GMT Received: from d06av12.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av12.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id sBBE5NwM010358 for ; Thu, 11 Dec 2014 07:05:25 -0700 From: Christian Borntraeger Subject: [PATCHv5 0/8] ACCESS_ONCE and non-scalar accesses Date: Thu, 11 Dec 2014 15:05:03 +0100 Message-Id: <1418306712-17245-1-git-send-email-borntraeger@de.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org Cc: linux-arch@vger.kernel.org, paulmck@linux.vnet.ibm.com, torvalds@linux-foundation.org, George Spelvin , Christian Borntraeger , linux-mm@kvack.org As discussed on LKML http://marc.info/?i=54611D86.4040306%40de.ibm.com ACCESS_ONCE might fail with specific compilers for non-scalar accesses. Here is a set of patches to tackle that problem. The first patch introduce READ_ONCE and ASSIGN_ONCE. If the data structure is larger than the machine word size memcpy is used and a warning is emitted. The next patches fix up all in-tree users of ACCESS_ONCE on non-scalar types. Due to all the trouble when dealing with linux-next, I will defer the patch that forces ACCESS_ONCE to work only on scalar types after rc1 to give it a full spin in linux-next. If nobody complains I will ask Linus to pull this for 3.19 next week. The tree can be found at git://git.kernel.org/pub/scm/linux/kernel/git/borntraeger/linux.git linux-next Changelog: v4->v5: 1. READ_ONCE/ASSIGN_ONCE use x instead of p 2. linux/types.h --> uapi/linux/types.h u??-->__u?? to avoid header inclusion fun and compile errors 3. Actually provide data_access_exceeds_word_size. 4. also move handle_pte_fault to a barrier as there is ppc44x which has 64bit ptes and 32bit word size. Some sanity check from a VM person would be good. Cc: linux-mm@kvack.org Christian Borntraeger (8): kernel: Provide READ_ONCE and ASSIGN_ONCE mm: replace ACCESS_ONCE with READ_ONCE or barriers x86/spinlock: Replace ACCESS_ONCE with READ_ONCE x86/gup: Replace ACCESS_ONCE with READ_ONCE mips/gup: Replace ACCESS_ONCE with READ_ONCE arm64/spinlock: Replace ACCESS_ONCE READ_ONCE arm/spinlock: Replace ACCESS_ONCE with READ_ONCE s390/kvm: REPLACE barrier fixup with READ_ONCE arch/arm/include/asm/spinlock.h | 4 +-- arch/arm64/include/asm/spinlock.h | 4 +-- arch/mips/mm/gup.c | 2 +- arch/s390/kvm/gaccess.c | 18 ++++------ arch/x86/include/asm/spinlock.h | 8 ++--- arch/x86/mm/gup.c | 2 +- include/linux/compiler.h | 70 +++++++++++++++++++++++++++++++++++++++ lib/Makefile | 2 +- lib/access.c | 8 +++++ mm/gup.c | 2 +- mm/memory.c | 11 +++++- mm/rmap.c | 3 +- 12 files changed, 108 insertions(+), 26 deletions(-) create mode 100644 lib/access.c -- 1.9.3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org