[NETFILTER]: nf_conntrack: fix smp_processor_id() in preemptible code warning

Since we're using RCU for the conntrack hash now, we need to avoid
getting preempted or interrupted by BHs while changing the stats.

Fixes warning reported by Tilman Schmidt <tilman@imap.cc> when using
preemptible RCU:

[   48.180297] BUG: using smp_processor_id() in preemptible [00000000] code: ntpdate/3562
[   48.180297] caller is __nf_conntrack_find+0x9b/0xeb [nf_conntrack]
[   48.180297] Pid: 3562, comm: ntpdate Not tainted 2.6.25-rc2-mm1-testing #1
[   48.180297]  [<c02015b9>] debug_smp_processor_id+0x99/0xb0
[   48.180297]  [<fac643a7>] __nf_conntrack_find+0x9b/0xeb [nf_conntrack]

Tested-by: Tilman Schmidt <tilman@imap.cc>
Tested-by: Christian Casteyde <casteyde.christian@free.fr> [Bugzilla #10097]
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 327e847d2702d8e647ca656b5e89db6ba2ca74fd..b77eb56a87e33a7ec85bd351e5b6d512922ebbc3 100644 (file)
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -256,13 +256,19 @@ __nf_conntrack_find(const struct nf_conntrack_tuple *tuple)
        struct hlist_node *n;
        unsigned int hash = hash_conntrack(tuple);
 
+       /* Disable BHs the entire time since we normally need to disable them
+        * at least once for the stats anyway.
+        */
+       local_bh_disable();
        hlist_for_each_entry_rcu(h, n, &nf_conntrack_hash[hash], hnode) {
                if (nf_ct_tuple_equal(tuple, &h->tuple)) {
                        NF_CT_STAT_INC(found);
+                       local_bh_enable();
                        return h;
                }
                NF_CT_STAT_INC(searched);
        }
+       local_bh_enable();
 
        return NULL;
 }
@@ -400,17 +406,20 @@ nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple,
        struct hlist_node *n;
        unsigned int hash = hash_conntrack(tuple);
 
-       rcu_read_lock();
+       /* Disable BHs the entire time since we need to disable them at
+        * least once for the stats anyway.
+        */
+       rcu_read_lock_bh();
        hlist_for_each_entry_rcu(h, n, &nf_conntrack_hash[hash], hnode) {
                if (nf_ct_tuplehash_to_ctrack(h) != ignored_conntrack &&
                    nf_ct_tuple_equal(tuple, &h->tuple)) {
                        NF_CT_STAT_INC(found);
-                       rcu_read_unlock();
+                       rcu_read_unlock_bh();
                        return 1;
                }
                NF_CT_STAT_INC(searched);
        }
-       rcu_read_unlock();
+       rcu_read_unlock_bh();
 
        return 0;
 }