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Message-ID: <20100219142359.467b9440@nehalam>
Date: Fri, 19 Feb 2010 14:23:59 -0800
From: Stephen Hemminger <shemminger@...tta.com>
To: Stephen Hemminger <shemminger@...tta.com>
Cc: Alexander Viro <viro@...iv.linux.org.uk>,
Andrew Morton <akpm@...ux-foundation.org>,
Rusty Russell <rusty@...tcorp.com.au>,
Peter Oberparleiter <oberpar@...ux.vnet.ibm.com>,
Miklos Szeredi <mszeredi@...e.cz>,
Eric Dumazet <eric.dumazet@...il.com>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
"David S. Miller" <davem@...emloft.net>,
Jiri Pirko <jpirko@...hat.com>, Jiri Olsa <jolsa@...hat.com>,
Ingo Molnar <mingo@...e.hu>,
Alexey Dobriyan <adobriyan@...il.com>,
Jamal Hadi Salim <hadi@...erus.ca>,
Neil Horman <nhorman@...driver.com>, netdev@...r.kernel.org
Subject: [PATCH] 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: Stephen Hemminger <shemminger@...tta.com>
---
v2 - > v3: Need to not call remove_packet with lock held.
include/net/netns/packet.h | 4 ++--
include/net/sock.h | 10 ++++++++++
net/packet/af_packet.c | 42 ++++++++++++++++++++----------------------
3 files changed, 32 insertions(+), 24 deletions(-)
--- a/include/net/netns/packet.h 2010-02-19 13:57:59.990116946 -0800
+++ b/include/net/netns/packet.h 2010-02-19 13:58:48.026119562 -0800
@@ -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;
};
--- a/net/packet/af_packet.c 2010-02-19 13:57:59.978117421 -0800
+++ b/net/packet/af_packet.c 2010-02-19 14:14:56.893492702 -0800
@@ -1262,24 +1262,22 @@ static int packet_release(struct socket
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
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
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 notifi
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 notifi
}
break;
case NETDEV_UP:
- spin_lock(&po->bind_lock);
- if (dev->ifindex == po->ifindex && po->num &&
- !po->running) {
- dev_add_pack(&po->prot_hook);
- sock_hold(sk);
- po->running = 1;
+ if (dev->ifindex == po->ifindex) {
+ spin_lock(&po->bind_lock);
+ if (po->num && !po->running) {
+ dev_add_pack(&po->prot_hook);
+ sock_hold(sk);
+ po->running = 1;
+ }
+ spin_unlock(&po->bind_lock);
}
- 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_netd
#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 pack
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))
--- a/include/net/sock.h 2010-02-19 13:58:00.006118906 -0800
+++ b/include/net/sock.h 2010-02-19 13:58:48.030119401 -0800
@@ -381,6 +381,7 @@ static __inline__ void __sk_del_node(str
__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(s
}
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(struc
__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(
#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) \
--
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