netfilter: revised locking for x_tables
[linux-2.6.git] / net / ipv4 / netfilter / arp_tables.c
index 5ba533d..831fe18 100644 (file)
@@ -253,9 +253,9 @@ unsigned int arpt_do_table(struct sk_buff *skb,
        indev = in ? in->name : nulldevname;
        outdev = out ? out->name : nulldevname;
 
-       rcu_read_lock_bh();
-       private = rcu_dereference(table->private);
-       table_base = rcu_dereference(private->entries[smp_processor_id()]);
+       xt_info_rdlock_bh();
+       private = table->private;
+       table_base = private->entries[smp_processor_id()];
 
        e = get_entry(table_base, private->hook_entry[hook]);
        back = get_entry(table_base, private->underflow[hook]);
@@ -273,6 +273,7 @@ unsigned int arpt_do_table(struct sk_buff *skb,
 
                        hdr_len = sizeof(*arp) + (2 * sizeof(struct in_addr)) +
                                (2 * skb->dev->addr_len);
+
                        ADD_COUNTER(e->counters, hdr_len, 1);
 
                        t = arpt_get_target(e);
@@ -328,8 +329,7 @@ unsigned int arpt_do_table(struct sk_buff *skb,
                        e = (void *)e + e->next_offset;
                }
        } while (!hotdrop);
-
-       rcu_read_unlock_bh();
+       xt_info_rdunlock_bh();
 
        if (hotdrop)
                return NF_DROP;
@@ -711,9 +711,12 @@ static void get_counters(const struct xt_table_info *t,
        /* Instead of clearing (by a previous call to memset())
         * the counters and using adds, we set the counters
         * with data used by 'current' CPU
-        * We dont care about preemption here.
+        *
+        * Bottom half has to be disabled to prevent deadlock
+        * if new softirq were to run and call ipt_do_table
         */
-       curcpu = raw_smp_processor_id();
+       local_bh_disable();
+       curcpu = smp_processor_id();
 
        i = 0;
        ARPT_ENTRY_ITERATE(t->entries[curcpu],
@@ -726,73 +729,22 @@ static void get_counters(const struct xt_table_info *t,
                if (cpu == curcpu)
                        continue;
                i = 0;
+               xt_info_wrlock(cpu);
                ARPT_ENTRY_ITERATE(t->entries[cpu],
                                   t->size,
                                   add_entry_to_counter,
                                   counters,
                                   &i);
+               xt_info_wrunlock(cpu);
        }
-}
-
-
-/* We're lazy, and add to the first CPU; overflow works its fey magic
- * and everything is OK. */
-static int
-add_counter_to_entry(struct arpt_entry *e,
-                    const struct xt_counters addme[],
-                    unsigned int *i)
-{
-       ADD_COUNTER(e->counters, addme[*i].bcnt, addme[*i].pcnt);
-
-       (*i)++;
-       return 0;
-}
-
-/* Take values from counters and add them back onto the current cpu */
-static void put_counters(struct xt_table_info *t,
-                        const struct xt_counters counters[])
-{
-       unsigned int i, cpu;
-
-       local_bh_disable();
-       cpu = smp_processor_id();
-       i = 0;
-       ARPT_ENTRY_ITERATE(t->entries[cpu],
-                         t->size,
-                         add_counter_to_entry,
-                         counters,
-                         &i);
        local_bh_enable();
 }
 
-static inline int
-zero_entry_counter(struct arpt_entry *e, void *arg)
-{
-       e->counters.bcnt = 0;
-       e->counters.pcnt = 0;
-       return 0;
-}
-
-static void
-clone_counters(struct xt_table_info *newinfo, const struct xt_table_info *info)
-{
-       unsigned int cpu;
-       const void *loc_cpu_entry = info->entries[raw_smp_processor_id()];
-
-       memcpy(newinfo, info, offsetof(struct xt_table_info, entries));
-       for_each_possible_cpu(cpu) {
-               memcpy(newinfo->entries[cpu], loc_cpu_entry, info->size);
-               ARPT_ENTRY_ITERATE(newinfo->entries[cpu], newinfo->size,
-                                 zero_entry_counter, NULL);
-       }
-}
-
 static struct xt_counters *alloc_counters(struct xt_table *table)
 {
        unsigned int countersize;
        struct xt_counters *counters;
        struct xt_table_info *private = table->private;
-       struct xt_table_info *info;
 
        /* We need atomic snapshot of counters: rest doesn't change
         * (other than comefrom, which userspace doesn't care
@@ -802,30 +754,11 @@ static struct xt_counters *alloc_counters(struct xt_table *table)
        counters = vmalloc_node(countersize, numa_node_id());
 
        if (counters == NULL)
-               goto nomem;
-
-       info = xt_alloc_table_info(private->size);
-       if (!info)
-               goto free_counters;
-
-       clone_counters(info, private);
-
-       mutex_lock(&table->lock);
-       xt_table_entry_swap_rcu(private, info);
-       synchronize_net();      /* Wait until smoke has cleared */
+               return ERR_PTR(-ENOMEM);
 
-       get_counters(info, counters);
-       put_counters(private, counters);
-       mutex_unlock(&table->lock);
-
-       xt_free_table_info(info);
+       get_counters(private, counters);
 
        return counters;
-
- free_counters:
-       vfree(counters);
- nomem:
-       return ERR_PTR(-ENOMEM);
 }
 
 static int copy_entries_to_user(unsigned int total_size,
@@ -1094,8 +1027,9 @@ static int __do_replace(struct net *net, const char *name,
            (newinfo->number <= oldinfo->initial_entries))
                module_put(t->me);
 
-       /* Get the old counters. */
+       /* Get the old counters, and synchronize with replace */
        get_counters(oldinfo, counters);
+
        /* Decrease module usage counts and free resource */
        loc_cpu_old_entry = oldinfo->entries[raw_smp_processor_id()];
        ARPT_ENTRY_ITERATE(loc_cpu_old_entry, oldinfo->size, cleanup_entry,
@@ -1165,10 +1099,23 @@ static int do_replace(struct net *net, void __user *user, unsigned int len)
        return ret;
 }
 
+/* We're lazy, and add to the first CPU; overflow works its fey magic
+ * and everything is OK. */
+static int
+add_counter_to_entry(struct arpt_entry *e,
+                    const struct xt_counters addme[],
+                    unsigned int *i)
+{
+       ADD_COUNTER(e->counters, addme[*i].bcnt, addme[*i].pcnt);
+
+       (*i)++;
+       return 0;
+}
+
 static int do_add_counters(struct net *net, void __user *user, unsigned int len,
                           int compat)
 {
-       unsigned int i;
+       unsigned int i, curcpu;
        struct xt_counters_info tmp;
        struct xt_counters *paddc;
        unsigned int num_counters;
@@ -1224,26 +1171,26 @@ static int do_add_counters(struct net *net, void __user *user, unsigned int len,
                goto free;
        }
 
-       mutex_lock(&t->lock);
+       local_bh_disable();
        private = t->private;
        if (private->number != num_counters) {
                ret = -EINVAL;
                goto unlock_up_free;
        }
 
-       preempt_disable();
        i = 0;
        /* Choose the copy that is on our node */
-       loc_cpu_entry = private->entries[smp_processor_id()];
+       curcpu = smp_processor_id();
+       loc_cpu_entry = private->entries[curcpu];
+       xt_info_wrlock(curcpu);
        ARPT_ENTRY_ITERATE(loc_cpu_entry,
                           private->size,
                           add_counter_to_entry,
                           paddc,
                           &i);
-       preempt_enable();
+       xt_info_wrunlock(curcpu);
  unlock_up_free:
-       mutex_unlock(&t->lock);
-
+       local_bh_enable();
        xt_table_unlock(t);
        module_put(t->me);
  free: