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Commit f5c5440d authored by Eric Dumazet's avatar Eric Dumazet Committed by Patrick McHardy
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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: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
parent bed1be20

include/linux/netfilter/nfnetlink_log.h

+1 −0
Original line number Diff line number Diff line
@@ -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

net/netfilter/nfnetlink_log.c

+12 −6
Original line number Diff line number Diff line
@@ -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;

	}