From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755956AbdJJAXx (ORCPT ); Mon, 9 Oct 2017 20:23:53 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:37038 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755857AbdJJAW6 (ORCPT ); Mon, 9 Oct 2017 20:22:58 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, torvalds@linux-foundation.org, mark.rutland@arm.com, dhowells@redhat.com, linux-arch@vger.kernel.org, peterz@infradead.org, will.deacon@arm.com, "Paul E. McKenney" , Pablo Neira Ayuso , Jozsef Kadlecsik , Florian Westphal , "David S. Miller" , , , Subject: [PATCH RFC tip/core/rcu 14/15] netfilter: Remove now-redundant smp_read_barrier_depends() Date: Mon, 9 Oct 2017 17:22:48 -0700 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20171010001951.GA6476@linux.vnet.ibm.com> References: <20171010001951.GA6476@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17101000-0036-0000-0000-000002792E5B X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007870; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000235; SDB=6.00928858; UDB=6.00467489; IPR=6.00709129; 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 00:22:54 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17101000-0037-0000-0000-00004206C52B Message-Id: <1507594969-8347-14-git-send-email-paulmck@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 READ_ONCE() now implies smp_read_barrier_depends(), which means that the instances in arpt_do_table(), ipt_do_table(), and ip6t_do_table() are now redundant. This commit removes them and adjusts the comments. Signed-off-by: Paul E. McKenney Cc: Pablo Neira Ayuso Cc: Jozsef Kadlecsik Cc: Florian Westphal Cc: "David S. Miller" Cc: Cc: Cc: --- net/ipv4/netfilter/arp_tables.c | 7 +------ net/ipv4/netfilter/ip_tables.c | 7 +------ net/ipv6/netfilter/ip6_tables.c | 7 +------ 3 files changed, 3 insertions(+), 18 deletions(-) diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c index 9e2770fd00be..d555b3b31c49 100644 --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -202,13 +202,8 @@ unsigned int arpt_do_table(struct sk_buff *skb, local_bh_disable(); addend = xt_write_recseq_begin(); - private = table->private; + private = READ_ONCE(table->private); /* Address dependency. */ cpu = smp_processor_id(); - /* - * Ensure we load private-> members after we've fetched the base - * pointer. - */ - smp_read_barrier_depends(); table_base = private->entries; jumpstack = (struct arpt_entry **)private->jumpstack[cpu]; diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c index 39286e543ee6..f63752bec442 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -260,13 +260,8 @@ ipt_do_table(struct sk_buff *skb, WARN_ON(!(table->valid_hooks & (1 << hook))); local_bh_disable(); addend = xt_write_recseq_begin(); - private = table->private; + private = READ_ONCE(table->private); /* Address dependency. */ cpu = smp_processor_id(); - /* - * Ensure we load private-> members after we've fetched the base - * pointer. - */ - smp_read_barrier_depends(); table_base = private->entries; jumpstack = (struct ipt_entry **)private->jumpstack[cpu]; diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c index 01bd3ee5ebc6..52afcab9b0d6 100644 --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -282,12 +282,7 @@ ip6t_do_table(struct sk_buff *skb, local_bh_disable(); addend = xt_write_recseq_begin(); - private = table->private; - /* - * Ensure we load private-> members after we've fetched the base - * pointer. - */ - smp_read_barrier_depends(); + private = READ_ONCE(table->private); /* Address dependency. */ cpu = smp_processor_id(); table_base = private->entries; jumpstack = (struct ip6t_entry **)private->jumpstack[cpu]; -- 2.5.2 From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: [PATCH RFC tip/core/rcu 14/15] netfilter: Remove now-redundant smp_read_barrier_depends() Date: Mon, 9 Oct 2017 17:22:48 -0700 Message-ID: <1507594969-8347-14-git-send-email-paulmck@linux.vnet.ibm.com> References: <20171010001951.GA6476@linux.vnet.ibm.com> Return-path: In-Reply-To: <20171010001951.GA6476@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, torvalds@linux-foundation.org, mark.rutland@arm.com, dhowells@redhat.com, linux-arch@vger.kernel.org, peterz@infradead.org, will.deacon@arm.com, "Paul E. McKenney" , Pablo Neira Ayuso , Jozsef Kadlecsik , Florian Westphal , "David S. Miller" , netfilter-devel@vger.kernel.org, coreteam@netfilter.org, netdev@vger.kernel.org List-Id: linux-arch.vger.kernel.org READ_ONCE() now implies smp_read_barrier_depends(), which means that the instances in arpt_do_table(), ipt_do_table(), and ip6t_do_table() are now redundant. This commit removes them and adjusts the comments. Signed-off-by: Paul E. McKenney Cc: Pablo Neira Ayuso Cc: Jozsef Kadlecsik Cc: Florian Westphal Cc: "David S. Miller" Cc: Cc: Cc: --- net/ipv4/netfilter/arp_tables.c | 7 +------ net/ipv4/netfilter/ip_tables.c | 7 +------ net/ipv6/netfilter/ip6_tables.c | 7 +------ 3 files changed, 3 insertions(+), 18 deletions(-) diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c index 9e2770fd00be..d555b3b31c49 100644 --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -202,13 +202,8 @@ unsigned int arpt_do_table(struct sk_buff *skb, local_bh_disable(); addend = xt_write_recseq_begin(); - private = table->private; + private = READ_ONCE(table->private); /* Address dependency. */ cpu = smp_processor_id(); - /* - * Ensure we load private-> members after we've fetched the base - * pointer. - */ - smp_read_barrier_depends(); table_base = private->entries; jumpstack = (struct arpt_entry **)private->jumpstack[cpu]; diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c index 39286e543ee6..f63752bec442 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -260,13 +260,8 @@ ipt_do_table(struct sk_buff *skb, WARN_ON(!(table->valid_hooks & (1 << hook))); local_bh_disable(); addend = xt_write_recseq_begin(); - private = table->private; + private = READ_ONCE(table->private); /* Address dependency. */ cpu = smp_processor_id(); - /* - * Ensure we load private-> members after we've fetched the base - * pointer. - */ - smp_read_barrier_depends(); table_base = private->entries; jumpstack = (struct ipt_entry **)private->jumpstack[cpu]; diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c index 01bd3ee5ebc6..52afcab9b0d6 100644 --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -282,12 +282,7 @@ ip6t_do_table(struct sk_buff *skb, local_bh_disable(); addend = xt_write_recseq_begin(); - private = table->private; - /* - * Ensure we load private-> members after we've fetched the base - * pointer. - */ - smp_read_barrier_depends(); + private = READ_ONCE(table->private); /* Address dependency. */ cpu = smp_processor_id(); table_base = private->entries; jumpstack = (struct ip6t_entry **)private->jumpstack[cpu]; -- 2.5.2