From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: [PATCH RFC tip/core/rcu 0/15] Remove to-be-unneeded smp_read_barrier_depends() Date: Mon, 9 Oct 2017 17:19:51 -0700 Message-ID: <20171010001951.GA6476@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:41027 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755560AbdJJAT4 (ORCPT ); Mon, 9 Oct 2017 20:19:56 -0400 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v9A0JQPL118126 for ; Mon, 9 Oct 2017 20:19:56 -0400 Received: from e14.ny.us.ibm.com (e14.ny.us.ibm.com [129.33.205.204]) by mx0b-001b2d01.pphosted.com with ESMTP id 2dgcabvnd1-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 09 Oct 2017 20:19:56 -0400 Received: from localhost by e14.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 9 Oct 2017 20:19:55 -0400 Content-Disposition: inline Sender: linux-arch-owner@vger.kernel.org List-ID: 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 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(-)