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netfilter: nfnetlink_log: RCU conversion, part 2 

- must use atomic_inc_not_zero() in instance_lookup_get()

- must use hlist_add_head_rcu() instead of hlist_add_head()

- must use hlist_del_rcu() instead of hlist_del()

- Introduce NFULNL_COPY_DISABLED to stop lockless reader from using an
instance, before we do final instance_put() on it.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
Eric Dumazet 2010-06-14 16:15:23 +02:00 committed by Patrick McHardy
parent bed1be2086
commit f5c5440d40
2 changed files with 13 additions and 6 deletions
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1
include/linux/netfilter/nfnetlink_log.h
View File

@ -89,6 +89,7 @@ enum nfulnl_attr_config {
#define NFULNL_COPY_NONE 0x00
#define NFULNL_COPY_META 0x01
#define NFULNL_COPY_PACKET 0x02
#define NFULNL_COPY_DISABLED 0x03
#define NFULNL_CFG_F_SEQ 0x0001
#define NFULNL_CFG_F_SEQ_GLOBAL 0x0002

18
net/netfilter/nfnetlink_log.c
View File

@ -109,8 +109,8 @@ instance_lookup_get(u_int16_t group_num)
rcu_read_lock_bh();
inst = __instance_lookup(group_num);
if (inst)
instance_get(inst);
if (inst && !atomic_inc_not_zero(&inst->use))
inst = NULL;
rcu_read_unlock_bh();
return inst;
@ -171,7 +171,7 @@ instance_create(u_int16_t group_num, int pid)
inst->copy_mode = NFULNL_COPY_PACKET;
inst->copy_range = NFULNL_COPY_RANGE_MAX;
hlist_add_head(&inst->hlist,
hlist_add_head_rcu(&inst->hlist,
&instance_table[instance_hashfn(group_num)]);
spin_unlock_bh(&instances_lock);
@ -185,18 +185,23 @@ out_unlock:
static void __nfulnl_flush(struct nfulnl_instance *inst);
/* called with BH disabled */
static void
__instance_destroy(struct nfulnl_instance *inst)
{
/* first pull it out of the global list */
hlist_del(&inst->hlist);
hlist_del_rcu(&inst->hlist);
/* then flush all pending packets from skb */
spin_lock_bh(&inst->lock);
spin_lock(&inst->lock);
/* lockless readers wont be able to use us */
inst->copy_mode = NFULNL_COPY_DISABLED;
if (inst->skb)
__nfulnl_flush(inst);
spin_unlock_bh(&inst->lock);
spin_unlock(&inst->lock);
/* and finally put the refcount */
instance_put(inst);
@ -624,6 +629,7 @@ nfulnl_log_packet(u_int8_t pf,
size += nla_total_size(data_len);
break;
case NFULNL_COPY_DISABLED:
default:
goto unlock_and_release;
}