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Commit 808f5114 authored by stephen hemminger's avatar stephen hemminger Committed by David S. Miller
Browse files

packet: convert socket list to RCU (v3) 



Convert AF_PACKET to use RCU, eliminating one more reader/writer lock.

There is no need for a real sk_del_node_init_rcu(), because sk_del_node_init
is doing the equivalent thing to hlst_del_init_rcu already; but added
some comments to try and make that obvious.

Signed-off-by: default avatarStephen Hemminger <shemminger@vyatta.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1cc52327

include/net/netns/packet.h

+2 −2
Original line number Diff line number Diff line
@@ -4,11 +4,11 @@ 
#ifndef __NETNS_PACKET_H__

#define __NETNS_PACKET_H__



#include <linux/list.h>

#include <linux/rculist.h>

#include <linux/spinlock.h>



struct netns_packet {

	rwlock_t		sklist_lock;

	spinlock_t		sklist_lock;

	struct hlist_head	sklist;

};

include/net/sock.h

+10 −0
Original line number Diff line number Diff line
@@ -381,6 +381,7 @@ static __inline__ void __sk_del_node(struct sock *sk) 
	__hlist_del(&sk->sk_node);

}



/* NB: equivalent to hlist_del_init_rcu */

static __inline__ int __sk_del_node_init(struct sock *sk)

{

	if (sk_hashed(sk)) {
@@ -421,6 +422,7 @@ static __inline__ int sk_del_node_init(struct sock *sk) 
	}

	return rc;

}

#define sk_del_node_init_rcu(sk)	sk_del_node_init(sk)



static __inline__ int __sk_nulls_del_node_init_rcu(struct sock *sk)

{
@@ -454,6 +456,12 @@ static __inline__ void sk_add_node(struct sock *sk, struct hlist_head *list) 
	__sk_add_node(sk, list);

}



static __inline__ void sk_add_node_rcu(struct sock *sk, struct hlist_head *list)

{

	sock_hold(sk);

	hlist_add_head_rcu(&sk->sk_node, list);

}



static __inline__ void __sk_nulls_add_node_rcu(struct sock *sk, struct hlist_nulls_head *list)

{

	hlist_nulls_add_head_rcu(&sk->sk_nulls_node, list);
@@ -478,6 +486,8 @@ static __inline__ void sk_add_bind_node(struct sock *sk, 


#define sk_for_each(__sk, node, list) \

	hlist_for_each_entry(__sk, node, list, sk_node)

#define sk_for_each_rcu(__sk, node, list) \

	hlist_for_each_entry_rcu(__sk, node, list, sk_node)

#define sk_nulls_for_each(__sk, node, list) \

	hlist_nulls_for_each_entry(__sk, node, list, sk_nulls_node)

#define sk_nulls_for_each_rcu(__sk, node, list) \

net/packet/af_packet.c

+31 −31
Original line number Diff line number Diff line
@@ -1262,24 +1262,22 @@ static int packet_release(struct socket *sock) 
	net = sock_net(sk);

	po = pkt_sk(sk);



	write_lock_bh(&net->packet.sklist_lock);

	sk_del_node_init(sk);

	spin_lock_bh(&net->packet.sklist_lock);

	sk_del_node_init_rcu(sk);

	sock_prot_inuse_add(net, sk->sk_prot, -1);

	write_unlock_bh(&net->packet.sklist_lock);



	/*

	 *	Unhook packet receive handler.

	 */

	spin_unlock_bh(&net->packet.sklist_lock);



	spin_lock(&po->bind_lock);

	if (po->running) {

		/*

		 *	Remove the protocol hook

		 * Remove from protocol table

		 */

		dev_remove_pack(&po->prot_hook);

		po->running = 0;

		po->num = 0;

		__dev_remove_pack(&po->prot_hook);

		__sock_put(sk);

	}

	spin_unlock(&po->bind_lock);



	packet_flush_mclist(sk);
@@ -1291,10 +1289,10 @@ static int packet_release(struct socket *sock) 
	if (po->tx_ring.pg_vec)

		packet_set_ring(sk, &req, 1, 1);



	synchronize_net();

	/*

	 *	Now the socket is dead. No more input will appear.

	 */



	sock_orphan(sk);

	sock->sk = NULL;
@@ -1478,10 +1476,11 @@ static int packet_create(struct net *net, struct socket *sock, int protocol, 
		po->running = 1;

	}



	write_lock_bh(&net->packet.sklist_lock);

	sk_add_node(sk, &net->packet.sklist);

	spin_lock_bh(&net->packet.sklist_lock);

	sk_add_node_rcu(sk, &net->packet.sklist);

	sock_prot_inuse_add(net, &packet_proto, 1);

	write_unlock_bh(&net->packet.sklist_lock);

	spin_unlock_bh(&net->packet.sklist_lock);



	return 0;

out:

	return err;
@@ -2075,8 +2074,8 @@ static int packet_notifier(struct notifier_block *this, unsigned long msg, void 
	struct net_device *dev = data;

	struct net *net = dev_net(dev);



	read_lock(&net->packet.sklist_lock);

	sk_for_each(sk, node, &net->packet.sklist) {

	rcu_read_lock();

	sk_for_each_rcu(sk, node, &net->packet.sklist) {

		struct packet_sock *po = pkt_sk(sk);



		switch (msg) {
@@ -2104,18 +2103,19 @@ static int packet_notifier(struct notifier_block *this, unsigned long msg, void 
			}

			break;

		case NETDEV_UP:

			if (dev->ifindex == po->ifindex) {

				spin_lock(&po->bind_lock);

			if (dev->ifindex == po->ifindex && po->num &&

			    !po->running) {

				if (po->num && !po->running) {

					dev_add_pack(&po->prot_hook);

					sock_hold(sk);

					po->running = 1;

				}

				spin_unlock(&po->bind_lock);

			}

			break;

		}

	}

	read_unlock(&net->packet.sklist_lock);

	rcu_read_unlock();

	return NOTIFY_DONE;

}
@@ -2512,24 +2512,24 @@ static struct notifier_block packet_netdev_notifier = { 
#ifdef CONFIG_PROC_FS



static void *packet_seq_start(struct seq_file *seq, loff_t *pos)

	__acquires(seq_file_net(seq)->packet.sklist_lock)

	__acquires(RCU)

{

	struct net *net = seq_file_net(seq);

	read_lock(&net->packet.sklist_lock);

	return seq_hlist_start_head(&net->packet.sklist, *pos);



	rcu_read_lock();

	return seq_hlist_start_head_rcu(&net->packet.sklist, *pos);

}



static void *packet_seq_next(struct seq_file *seq, void *v, loff_t *pos)

{

	struct net *net = seq_file_net(seq);

	return seq_hlist_next(v, &net->packet.sklist, pos);

	return seq_hlist_next_rcu(v, &net->packet.sklist, pos);

}



static void packet_seq_stop(struct seq_file *seq, void *v)

	__releases(seq_file_net(seq)->packet.sklist_lock)

	__releases(RCU)

{

	struct net *net = seq_file_net(seq);

	read_unlock(&net->packet.sklist_lock);

	rcu_read_unlock();

}



static int packet_seq_show(struct seq_file *seq, void *v)
@@ -2581,7 +2581,7 @@ static const struct file_operations packet_seq_fops = { 


static int __net_init packet_net_init(struct net *net)

{

	rwlock_init(&net->packet.sklist_lock);

	spin_lock_init(&net->packet.sklist_lock);

	INIT_HLIST_HEAD(&net->packet.sklist);



	if (!proc_net_fops_create(net, "packet", 0, &packet_seq_fops))