From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755809AbdJJAT6 (ORCPT ); Mon, 9 Oct 2017 20:19:58 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:50260 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755564AbdJJAT5 (ORCPT ); Mon, 9 Oct 2017 20:19:57 -0400 Date: Mon, 9 Oct 2017 17:19:51 -0700 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: dhowells@redhat.com, mark.rutland@arm.com, linux-arch@vger.kernel.org, viro@zeniv.linux.org.uk, tj@kernel.org, cl@linux.com, davem@davemloft.net, peterz@infradead.org, mingo@redhat.com, rostedt@goodmis.org, akpm@linux-foundation.org, corbet@lwn.net, james.l.morris@oracle.com, torvalds@linux-foundation.org Subject: [PATCH RFC tip/core/rcu 0/15] Remove to-be-unneeded smp_read_barrier_depends() Reply-To: paulmck@linux.vnet.ibm.com MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 17101000-0052-0000-0000-0000026F2DD6 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007870; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000235; SDB=6.00928857; UDB=6.00467488; IPR=6.00709128; BA=6.00005631; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00017467; XFM=3.00000015; UTC=2017-10-10 00:19:53 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17101000-0053-0000-0000-00005244C7C9 Message-Id: <20171010001951.GA6476@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-10-09_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1707230000 definitions=main-1710100003 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello! Will Deacon has proposed adding smp_read_barrier_depends() to READ_ONCE(), which would mean that quite a few instances of smp_read_barrier_depends() would become redundant. This series depends on Will's change and removes those smp_read_barrier_depends(), while fixing a bug or two along the way. Some of these bugs are subtle, hence posting this sooner rather than later. This patch series depends on an in-progress series from Mark Rutland that changes all calls to ACCESS_ONCE() to either READ_ONCE() or WRITE_ONCE(), depending. This patch series also depends on an upcoming patch from Will Deacon that adds smp_read_barrier_depends() to Alpha's relaxed/release RMW atomic operations. As Will pointed out, once all of these patch series are in place, the core kernel will no longer need any Alpha-specific code, with the sole exception of READ_ONCE() and of course smp_read_barrier_depends() itself. Pretty cool, huh? ;-) Thanx, Paul ------------------------------------------------------------------------ Documentation/memory-barriers.txt | 11 ++++++----- arch/mn10300/kernel/mn10300-serial.c | 7 +++++-- drivers/net/ethernet/qlogic/qed/qed_spq.c | 4 +--- fs/dcache.c | 10 +++------- include/linux/assoc_array_priv.h | 5 +++-- include/linux/percpu-refcount.h | 6 +++--- include/linux/rcupdate.h | 23 +++++++++++------------ include/linux/rtnetlink.h | 3 +-- include/linux/seqlock.h | 3 +-- kernel/events/uprobes.c | 12 ++++++------ kernel/locking/qspinlock.c | 12 +++++------- kernel/tracepoint.c | 9 ++++----- lib/assoc_array.c | 20 ++------------------ lib/percpu-refcount.c | 8 ++++---- mm/ksm.c | 9 +-------- net/ipv4/netfilter/arp_tables.c | 7 +------ net/ipv4/netfilter/ip_tables.c | 7 +------ net/ipv6/netfilter/ip6_tables.c | 7 +------ security/keys/keyring.c | 7 ------- 19 files changed, 59 insertions(+), 111 deletions(-)