Revert "netfilter: x_tables: Update remaining dereference to RCU"

[ Upstream commit abe7034b9a ]

This reverts commit 443d6e86f8.

This (and the following) patch basically re-implemented the RCU
mechanisms of patch 784544739a. That patch was replaced because of the
performance problems that it created when replacing tables. Now, we have
the same issue: the call to synchronize_rcu() makes replacing tables
slower by as much as an order of magnitude.

Revert these patches and fix the issue in a different way.

Signed-off-by: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Mark Tomlinson 2021-03-08 14:24:11 +13:00 committed by Greg Kroah-Hartman
parent 81bc258370
commit 74bc0e5132
3 changed files with 3 additions and 3 deletions

View file

@ -1405,7 +1405,7 @@ static int compat_get_entries(struct net *net,
xt_compat_lock(NFPROTO_ARP);
t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
if (!IS_ERR(t)) {
const struct xt_table_info *private = xt_table_get_private_protected(t);
const struct xt_table_info *private = t->private;
struct xt_table_info info;
ret = compat_table_info(private, &info);

View file

@ -1619,7 +1619,7 @@ compat_get_entries(struct net *net, struct compat_ipt_get_entries __user *uptr,
xt_compat_lock(AF_INET);
t = xt_find_table_lock(net, AF_INET, get.name);
if (!IS_ERR(t)) {
const struct xt_table_info *private = xt_table_get_private_protected(t);
const struct xt_table_info *private = t->private;
struct xt_table_info info;
ret = compat_table_info(private, &info);
if (!ret && get.size == info.size)

View file

@ -1628,7 +1628,7 @@ compat_get_entries(struct net *net, struct compat_ip6t_get_entries __user *uptr,
xt_compat_lock(AF_INET6);
t = xt_find_table_lock(net, AF_INET6, get.name);
if (!IS_ERR(t)) {
const struct xt_table_info *private = xt_table_get_private_protected(t);
const struct xt_table_info *private = t->private;
struct xt_table_info info;
ret = compat_table_info(private, &info);
if (!ret && get.size == info.size)