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yaml
---
r: 340566
b: refs/heads/master
c: 6e914fc
h: refs/heads/master
v: v3
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Jason Wang authored and David S. Miller committed Nov 1, 2012
1 parent f2a4be5 commit cdb02ab
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Showing 2 changed files with 48 additions and 49 deletions.
2 changes: 1 addition & 1 deletion [refs]
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Original file line number Diff line number Diff line change
@@ -1,2 +1,2 @@
---
refs/heads/master: 54f968d6efdbf7dec36faa44fc11f01b0e4d1990
refs/heads/master: 6e914fc70793f540015bd99744cd456b8d7fdfbd
95 changes: 47 additions & 48 deletions trunk/drivers/net/tun.c
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Original file line number Diff line number Diff line change
Expand Up @@ -115,13 +115,16 @@ struct tap_filter {
* tap_filter were kept in tun_struct since they were used for filtering for the
* netdevice not for a specific queue (at least I didn't see the reqirement for
* this).
*
* RCU usage:
* The tun_file and tun_struct are loosely coupled, the pointer from on to the
* other can only be read while rcu_read_lock or rtnl_lock is held.
*/
struct tun_file {
struct sock sk;
struct socket socket;
struct socket_wq wq;
atomic_t count;
struct tun_struct *tun;
struct tun_struct __rcu *tun;
struct net *net;
struct fasync_struct *fasync;
/* only used for fasnyc */
Expand All @@ -133,7 +136,7 @@ struct tun_file {
* file were attached to a persist device.
*/
struct tun_struct {
struct tun_file *tfile;
struct tun_file __rcu *tfile;
unsigned int flags;
kuid_t owner;
kgid_t group;
Expand Down Expand Up @@ -179,13 +182,11 @@ static int tun_attach(struct tun_struct *tun, struct file *file)
if (!err)
goto out;
}
tfile->tun = tun;
rcu_assign_pointer(tfile->tun, tun);
tfile->socket.sk->sk_sndbuf = tun->sndbuf;
tun->tfile = tfile;
rcu_assign_pointer(tun->tfile, tfile);
netif_carrier_on(tun->dev);
dev_hold(tun->dev);
sock_hold(&tfile->sk);
atomic_inc(&tfile->count);

out:
netif_tx_unlock_bh(tun->dev);
Expand All @@ -194,34 +195,29 @@ static int tun_attach(struct tun_struct *tun, struct file *file)

static void __tun_detach(struct tun_struct *tun)
{
struct tun_file *tfile = tun->tfile;
struct tun_file *tfile = rcu_dereference_protected(tun->tfile,
lockdep_rtnl_is_held());
/* Detach from net device */
netif_tx_lock_bh(tun->dev);
netif_carrier_off(tun->dev);
tun->tfile = NULL;
tfile->tun = NULL;
netif_tx_unlock_bh(tun->dev);

/* Drop read queue */
skb_queue_purge(&tfile->socket.sk->sk_receive_queue);

/* Drop the extra count on the net device */
dev_put(tun->dev);
}
rcu_assign_pointer(tun->tfile, NULL);
if (tfile) {
rcu_assign_pointer(tfile->tun, NULL);

static void tun_detach(struct tun_struct *tun)
{
rtnl_lock();
__tun_detach(tun);
rtnl_unlock();
synchronize_net();
/* Drop read queue */
skb_queue_purge(&tfile->socket.sk->sk_receive_queue);
}
}

static struct tun_struct *__tun_get(struct tun_file *tfile)
{
struct tun_struct *tun = NULL;
struct tun_struct *tun;

if (atomic_inc_not_zero(&tfile->count))
tun = tfile->tun;
rcu_read_lock();
tun = rcu_dereference(tfile->tun);
if (tun)
dev_hold(tun->dev);
rcu_read_unlock();

return tun;
}
Expand All @@ -233,10 +229,7 @@ static struct tun_struct *tun_get(struct file *file)

static void tun_put(struct tun_struct *tun)
{
struct tun_file *tfile = tun->tfile;

if (atomic_dec_and_test(&tfile->count))
tun_detach(tfile->tun);
dev_put(tun->dev);
}

/* TAP filtering */
Expand Down Expand Up @@ -357,14 +350,15 @@ static const struct ethtool_ops tun_ethtool_ops;
static void tun_net_uninit(struct net_device *dev)
{
struct tun_struct *tun = netdev_priv(dev);
struct tun_file *tfile = tun->tfile;
struct tun_file *tfile = rcu_dereference_protected(tun->tfile,
lockdep_rtnl_is_held());

/* Inform the methods they need to stop using the dev.
*/
if (tfile) {
wake_up_all(&tfile->wq.wait);
if (atomic_dec_and_test(&tfile->count))
__tun_detach(tun);
__tun_detach(tun);
synchronize_net();
}
}

Expand All @@ -386,14 +380,16 @@ static int tun_net_close(struct net_device *dev)
static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct tun_struct *tun = netdev_priv(dev);
struct tun_file *tfile = tun->tfile;

tun_debug(KERN_INFO, tun, "tun_net_xmit %d\n", skb->len);
struct tun_file *tfile;

rcu_read_lock();
tfile = rcu_dereference(tun->tfile);
/* Drop packet if interface is not attached */
if (!tfile)
goto drop;

tun_debug(KERN_INFO, tun, "tun_net_xmit %d\n", skb->len);

/* Drop if the filter does not like it.
* This is a noop if the filter is disabled.
* Filter can be enabled only for the TAP devices. */
Expand Down Expand Up @@ -435,11 +431,14 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
kill_fasync(&tfile->fasync, SIGIO, POLL_IN);
wake_up_interruptible_poll(&tfile->wq.wait, POLLIN |
POLLRDNORM | POLLRDBAND);

rcu_read_unlock();
return NETDEV_TX_OK;

drop:
dev->stats.tx_dropped++;
kfree_skb(skb);
rcu_read_unlock();
return NETDEV_TX_OK;
}

Expand Down Expand Up @@ -1089,7 +1088,6 @@ static int tun_sendmsg(struct kiocb *iocb, struct socket *sock,

if (!tun)
return -EBADFD;

ret = tun_get_user(tun, tfile, m->msg_control, m->msg_iov, total_len,
m->msg_iovlen, m->msg_flags & MSG_DONTWAIT);
tun_put(tun);
Expand Down Expand Up @@ -1662,8 +1660,7 @@ static int tun_chr_open(struct inode *inode, struct file * file)
&tun_proto);
if (!tfile)
return -ENOMEM;
atomic_set(&tfile->count, 0);
tfile->tun = NULL;
rcu_assign_pointer(tfile->tun, NULL);
tfile->net = get_net(current->nsproxy->net_ns);
tfile->flags = 0;

Expand Down Expand Up @@ -1691,26 +1688,30 @@ static int tun_chr_close(struct inode *inode, struct file *file)
struct tun_struct *tun;
struct net *net = tfile->net;

tun = __tun_get(tfile);
rtnl_lock();

tun = rcu_dereference_protected(tfile->tun, lockdep_rtnl_is_held());
if (tun) {
struct net_device *dev = tun->dev;

tun_debug(KERN_INFO, tun, "tun_chr_close\n");

__tun_detach(tun);

synchronize_net();

/* If desirable, unregister the netdevice. */
if (!(tun->flags & TUN_PERSIST)) {
rtnl_lock();
if (dev->reg_state == NETREG_REGISTERED)
unregister_netdevice(dev);
rtnl_unlock();
}

/* drop the reference that netdevice holds */
sock_put(&tfile->sk);
}

rtnl_unlock();

/* drop the reference that file holds */
BUG_ON(!test_bit(SOCK_EXTERNALLY_ALLOCATED,
&tfile->socket.flags));
Expand Down Expand Up @@ -1842,14 +1843,12 @@ static void tun_cleanup(void)
* holding a reference to the file for as long as the socket is in use. */
struct socket *tun_get_socket(struct file *file)
{
struct tun_struct *tun;
struct tun_file *tfile = file->private_data;
struct tun_file *tfile;
if (file->f_op != &tun_fops)
return ERR_PTR(-EINVAL);
tun = tun_get(file);
if (!tun)
tfile = file->private_data;
if (!tfile)
return ERR_PTR(-EBADFD);
tun_put(tun);
return &tfile->socket;
}
EXPORT_SYMBOL_GPL(tun_get_socket);
Expand Down

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