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netfilter: Remove now-redundant smp_read_barrier_depends()

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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 <paulmck@linux.vnet.ibm.com>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Cc: Florian Westphal <fw@strlen.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: <netfilter-devel@vger.kernel.org>
Cc: <coreteam@netfilter.org>
Cc: <netdev@vger.kernel.org>
This commit is contained in:
Paul E. McKenney 2017-10-09 12:09:04 -07:00
parent 08df477434
commit 4be2b04e43
3 changed files with 3 additions and 18 deletions
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7
net/ipv4/netfilter/arp_tables.c
View File

@ -202,13 +202,8 @@ unsigned int arpt_do_table(struct sk_buff *skb,
local_bh_disable(); local_bh_disable();
addend = xt_write_recseq_begin(); addend = xt_write_recseq_begin();
private = table->private; private = READ_ONCE(table->private); /* Address dependency. */
cpu = smp_processor_id(); cpu = smp_processor_id();
/*
* Ensure we load private-> members after we've fetched the base
* pointer.
*/
smp_read_barrier_depends();
table_base = private->entries; table_base = private->entries;
jumpstack = (struct arpt_entry **)private->jumpstack[cpu]; jumpstack = (struct arpt_entry **)private->jumpstack[cpu];

7
net/ipv4/netfilter/ip_tables.c
View File

@ -260,13 +260,8 @@ ipt_do_table(struct sk_buff *skb,
WARN_ON(!(table->valid_hooks & (1 << hook))); WARN_ON(!(table->valid_hooks & (1 << hook)));
local_bh_disable(); local_bh_disable();
addend = xt_write_recseq_begin(); addend = xt_write_recseq_begin();
private = table->private; private = READ_ONCE(table->private); /* Address dependency. */
cpu = smp_processor_id(); cpu = smp_processor_id();
/*
* Ensure we load private-> members after we've fetched the base
* pointer.
*/
smp_read_barrier_depends();
table_base = private->entries; table_base = private->entries;
jumpstack = (struct ipt_entry **)private->jumpstack[cpu]; jumpstack = (struct ipt_entry **)private->jumpstack[cpu];

7
net/ipv6/netfilter/ip6_tables.c
View File

@ -282,12 +282,7 @@ ip6t_do_table(struct sk_buff *skb,
local_bh_disable(); local_bh_disable();
addend = xt_write_recseq_begin(); addend = xt_write_recseq_begin();
private = table->private; private = READ_ONCE(table->private); /* Address dependency. */
/*
* Ensure we load private-> members after we've fetched the base
* pointer.
*/
smp_read_barrier_depends();
cpu = smp_processor_id(); cpu = smp_processor_id();
table_base = private->entries; table_base = private->entries;
jumpstack = (struct ip6t_entry **)private->jumpstack[cpu]; jumpstack = (struct ip6t_entry **)private->jumpstack[cpu];