Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752104AbdLATvB (ORCPT ); Fri, 1 Dec 2017 14:51:01 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:39674 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751456AbdLATvA (ORCPT ); Fri, 1 Dec 2017 14:51:00 -0500 Date: Fri, 1 Dec 2017 11:50:53 -0800 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com Subject: [PATCH tip/core/rcu 0/21] De-emphasize {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: 17120119-0048-0000-0000-0000020E3A3C X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008137; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000243; SDB=6.00953999; UDB=6.00482085; IPR=6.00734075; BA=6.00005726; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00018295; XFM=3.00000015; UTC=2017-12-01 19:50:57 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17120119-0049-0000-0000-0000435627FD Message-Id: <20171201195053.GA23494@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-12-01_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1712010232 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3619 Lines: 61 Hello! Now that READ_ONCE() includes smp_read_barrier_depends(), almost nothing else needs to, the exceptions being DEC Alpha architecture-specific code and of course READ_ONCE() itself. This series therefore removes smp_read_barrier_depends() and read_barrier_depends() from elsewhere, as they no longer have any effect. Note that this patch series also prohibits use of InfiniBand on DEC Alpha: (1) A poll of DEC Alpha users revealed no use of InfiniBand and (2) It is not clear that InfiniBand's memory ordering correctly handles DEC Alpha, even with the smp_read_barrier_depends() invocations. Note also that patch 4 moves to release-acquire ordering to ensure that the name length is properly synchronized. An alternative approach would be to place the length in with the name, so that dependency ordering would cover both the length and the name, but doing so seemed a bit intrusive for this series. Thanx, Paul ------------------------------------------------------------------------ Documentation/RCU/Design/Requirements/Requirements.html | 3 - Documentation/RCU/rcu_dereference.txt | 6 -- Documentation/RCU/whatisRCU.txt | 3 - Documentation/circular-buffers.txt | 3 - Documentation/memory-barriers.txt | 18 ++++--- arch/mn10300/kernel/mn10300-serial.c | 7 ++- drivers/dma/ioat/dma.c | 2 drivers/infiniband/Kconfig | 1 drivers/infiniband/hw/hfi1/rc.c | 4 - drivers/infiniband/hw/hfi1/ruc.c | 1 drivers/infiniband/hw/hfi1/sdma.c | 1 drivers/infiniband/hw/hfi1/uc.c | 2 drivers/infiniband/hw/hfi1/ud.c | 2 drivers/infiniband/hw/qib/qib_rc.c | 3 - drivers/infiniband/hw/qib/qib_ruc.c | 1 drivers/infiniband/hw/qib/qib_uc.c | 2 drivers/infiniband/hw/qib/qib_ud.c | 2 drivers/infiniband/sw/rdmavt/qp.c | 1 drivers/net/ethernet/qlogic/qed/qed_spq.c | 4 - drivers/vhost/vhost.c | 7 --- fs/dcache.c | 10 +--- include/linux/genetlink.h | 3 - include/linux/netfilter/nfnetlink.h | 3 - 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 | 37 +++++----------- 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 --- scripts/checkpatch.pl | 6 ++ security/keys/keyring.c | 7 --- 38 files changed, 85 insertions(+), 160 deletions(-)