netfilter: ipset: add resched points during set listing

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>

diff --git a/net/netfilter/ipset/ip_set_bitmap_gen.h b/net/netfilter/ipset/ip_set_bitmap_gen.h
index 5ca18f0..8afe882 100644 (file)
--- a/net/netfilter/ipset/ip_set_bitmap_gen.h
+++ b/net/netfilter/ipset/ip_set_bitmap_gen.h
@@ -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) ||

diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c
index 1f3c03b..89b4445 100644 (file)
--- a/net/netfilter/ipset/ip_set_core.c
+++ b/net/netfilter/ipset/ip_set_core.c
@@ -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;

diff --git a/net/netfilter/ipset/ip_set_hash_gen.h b/net/netfilter/ipset/ip_set_hash_gen.h
index efffc8e..8ef079d 100644 (file)
--- a/net/netfilter/ipset/ip_set_hash_gen.h
+++ b/net/netfilter/ipset/ip_set_hash_gen.h
@@ -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",