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netfilter: ipset: add resched points during set listing

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When sets are extremely large we can get softlockup during ipset -L.
We could fix this by adding cond_resched_rcu() at the right location
during iteration, but this only works if RCU nesting depth is 1.

At this time entire variant->list() is called under under rcu_read_lock_bh.
This used to be a read_lock_bh() but as rcu doesn't really lock anything,
it does not appear to be needed, so remove it (ipset increments set
reference count before this, so a set deletion should not be possible).

Reported-by: Li Shuang <shuali@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2017-11-30 21:08:05 +01:00 committed by Pablo Neira Ayuso
parent 49971b8853
commit a778a15fa5
3 changed files with 2 additions and 2 deletions
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1
net/netfilter/ipset/ip_set_bitmap_gen.h
View File

@ -227,6 +227,7 @@ mtype_list(const struct ip_set *set,
rcu_read_lock();
for (; cb->args[IPSET_CB_ARG0] < map->elements;
cb->args[IPSET_CB_ARG0]++) {
cond_resched_rcu();
id = cb->args[IPSET_CB_ARG0];
x = get_ext(set, map, id);
if (!test_bit(id, map->members) ||

2
net/netfilter/ipset/ip_set_core.c
View File

@ -1388,9 +1388,7 @@ dump_last:
set->variant->uref(set, cb, true);
/* fall through */
default:
rcu_read_lock_bh();
ret = set->variant->list(set, skb, cb);
rcu_read_unlock_bh();
if (!cb->args[IPSET_CB_ARG0])
/* Set is done, proceed with next one */
goto next_set;

1
net/netfilter/ipset/ip_set_hash_gen.h
View File

@ -1143,6 +1143,7 @@ mtype_list(const struct ip_set *set,
rcu_read_lock();
for (; cb->args[IPSET_CB_ARG0] < jhash_size(t->htable_bits);
cb->args[IPSET_CB_ARG0]++) {
cond_resched_rcu();
incomplete = skb_tail_pointer(skb);
n = rcu_dereference(hbucket(t, cb->args[IPSET_CB_ARG0]));
pr_debug("cb->arg bucket: %lu, t %p n %p\n",