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Date: Tue, 26 Jun 2012 11:42:17 +0800
From: Jason Wang <jasowang@...hat.com>
To: "Michael S. Tsirkin" <mst@...hat.com>
CC: habanero@...ux.vnet.ibm.com, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, krkumar2@...ibm.com,
tahm@...ux.vnet.ibm.com, akong@...hat.com, davem@...emloft.net,
shemminger@...tta.com, mashirle@...ibm.com
Subject: Re: [net-next RFC V3 PATCH 4/6] tuntap: multiqueue support
On 06/25/2012 04:25 PM, Michael S. Tsirkin wrote:
> On Mon, Jun 25, 2012 at 02:10:18PM +0800, Jason Wang wrote:
>> This patch adds multiqueue support for tap device. This is done by abstracting
>> each queue as a file/socket and allowing multiple sockets to be attached to the
>> tuntap device (an array of tun_file were stored in the tun_struct). Userspace
>> could write and read from those files to do the parallel packet
>> sending/receiving.
>>
>> Unlike the previous single queue implementation, the socket and device were
>> loosely coupled, each of them were allowed to go away first. In order to let the
>> tx path lockless, netif_tx_loch_bh() is replaced by RCU/NETIF_F_LLTX to
>> synchronize between data path and system call.
> Don't use LLTX/RCU. It's not worth it.
> Use something like netif_set_real_num_tx_queues.
>
>> The tx queue selecting is first based on the recorded rxq index of an skb, it
>> there's no such one, then choosing based on rx hashing (skb_get_rxhash()).
>>
>> Signed-off-by: Jason Wang<jasowang@...hat.com>
> Interestingly macvtap switched to hashing first:
> ef0002b577b52941fb147128f30bd1ecfdd3ff6d
> (the commit log is corrupted but see what it
> does in the patch).
> Any idea why?
Yes, so tap should be changed to behave same as macvtap. I remember the
reason we do that is to make sure the packet of a single flow to be
queued to a fixed socket/virtqueues. As 10g cards like ixgbe choose the
rx queue for a flow based on the last tx queue where the packets of that
flow comes. So if we are using recored rx queue in macvtap, the queue
index of a flow would change as vhost thread moves amongs processors.
But during test tun/tap, one interesting thing I find is that even ixgbe
has recorded the queue index during rx, it seems be lost when tap tries
to transmit skbs to userspace.
>> ---
>> drivers/net/tun.c | 371 +++++++++++++++++++++++++++++++++--------------------
>> 1 files changed, 232 insertions(+), 139 deletions(-)
>>
>> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
>> index 8233b0a..5c26757 100644
>> --- a/drivers/net/tun.c
>> +++ b/drivers/net/tun.c
>> @@ -107,6 +107,8 @@ struct tap_filter {
>> unsigned char addr[FLT_EXACT_COUNT][ETH_ALEN];
>> };
>>
>> +#define MAX_TAP_QUEUES (NR_CPUS< 16 ? NR_CPUS : 16)
> Why the limit? I am guessing you copied this from macvtap?
> This is problematic for a number of reasons:
> - will not play well with migration
> - will not work well for a large guest
>
> Yes, macvtap needs to be fixed too.
>
> I am guessing what it is trying to prevent is queueing
> up a huge number of packets?
> So just divide the default tx queue limit by the # of queues.
>
> And by the way, for MQ applications maybe we can finally
> ignore tx queue altogether and limit the total number
> of bytes queued?
> To avoid regressions we can make it large like 64M/# queues.
> Could be a separate patch I think, and for a single queue
> might need a compatible mode though I am not sure.
>
>> +
>> struct tun_file {
>> struct sock sk;
>> struct socket socket;
>> @@ -114,16 +116,18 @@ struct tun_file {
>> int vnet_hdr_sz;
>> struct tap_filter txflt;
>> atomic_t count;
>> - struct tun_struct *tun;
>> + struct tun_struct __rcu *tun;
>> struct net *net;
>> struct fasync_struct *fasync;
>> unsigned int flags;
>> + u16 queue_index;
>> };
>>
>> struct tun_sock;
>>
>> struct tun_struct {
>> - struct tun_file *tfile;
>> + struct tun_file *tfiles[MAX_TAP_QUEUES];
>> + unsigned int numqueues;
>> unsigned int flags;
>> uid_t owner;
>> gid_t group;
>> @@ -138,80 +142,159 @@ struct tun_struct {
>> #endif
>> };
>>
>> -static int tun_attach(struct tun_struct *tun, struct file *file)
>> +static DEFINE_SPINLOCK(tun_lock);
>> +
>> +/*
>> + * tun_get_queue(): calculate the queue index
>> + * - if skbs comes from mq nics, we can just borrow
>> + * - if not, calculate from the hash
>> + */
>> +static struct tun_file *tun_get_queue(struct net_device *dev,
>> + struct sk_buff *skb)
>> {
>> - struct tun_file *tfile = file->private_data;
>> - int err;
>> + struct tun_struct *tun = netdev_priv(dev);
>> + struct tun_file *tfile = NULL;
>> + int numqueues = tun->numqueues;
>> + __u32 rxq;
>>
>> - ASSERT_RTNL();
>> + BUG_ON(!rcu_read_lock_held());
>>
>> - netif_tx_lock_bh(tun->dev);
>> + if (!numqueues)
>> + goto out;
>>
>> - err = -EINVAL;
>> - if (tfile->tun)
>> + if (numqueues == 1) {
>> + tfile = rcu_dereference(tun->tfiles[0]);
> Instead of hacks like this, you can ask for an MQ
> flag to be set in SETIFF. Then you won't need to
> handle attach/detach at random times.
> And most of the scary num_queues checks can go away.
> You can then also ask userspace about the max # of queues
> to expect if you want to save some memory.
>
>
>> goto out;
>> + }
>>
>> - err = -EBUSY;
>> - if (tun->tfile)
>> + if (likely(skb_rx_queue_recorded(skb))) {
>> + rxq = skb_get_rx_queue(skb);
>> +
>> + while (unlikely(rxq>= numqueues))
>> + rxq -= numqueues;
>> +
>> + tfile = rcu_dereference(tun->tfiles[rxq]);
>> goto out;
>> + }
>>
>> - err = 0;
>> - tfile->tun = tun;
>> - tun->tfile = tfile;
>> - netif_carrier_on(tun->dev);
>> - dev_hold(tun->dev);
>> - sock_hold(&tfile->sk);
>> - atomic_inc(&tfile->count);
>> + /* Check if we can use flow to select a queue */
>> + rxq = skb_get_rxhash(skb);
>> + if (rxq) {
>> + u32 idx = ((u64)rxq * numqueues)>> 32;
> This completely confuses me. What's the logic here?
> How do we even know it's in range?
>
>> + tfile = rcu_dereference(tun->tfiles[idx]);
>> + goto out;
>> + }
>>
>> + tfile = rcu_dereference(tun->tfiles[0]);
>> out:
>> - netif_tx_unlock_bh(tun->dev);
>> - return err;
>> + return tfile;
>> }
>>
>> -static void __tun_detach(struct tun_struct *tun)
>> +static int tun_detach(struct tun_file *tfile, bool clean)
>> {
>> - struct tun_file *tfile = tun->tfile;
>> - /* Detach from net device */
>> - netif_tx_lock_bh(tun->dev);
>> - netif_carrier_off(tun->dev);
>> - tun->tfile = 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);
>> -}
>> + struct tun_struct *tun;
>> + struct net_device *dev = NULL;
>> + bool destroy = false;
>>
>> -static void tun_detach(struct tun_struct *tun)
>> -{
>> - rtnl_lock();
>> - __tun_detach(tun);
>> - rtnl_unlock();
>> -}
>> + spin_lock(&tun_lock);
>>
>> -static struct tun_struct *__tun_get(struct tun_file *tfile)
>> -{
>> - struct tun_struct *tun = NULL;
>> + tun = rcu_dereference_protected(tfile->tun,
>> + lockdep_is_held(&tun_lock));
>> + if (tun) {
>> + u16 index = tfile->queue_index;
>> + BUG_ON(index>= tun->numqueues);
>> + dev = tun->dev;
>> +
>> + rcu_assign_pointer(tun->tfiles[index],
>> + tun->tfiles[tun->numqueues - 1]);
>> + tun->tfiles[index]->queue_index = index;
>> + rcu_assign_pointer(tfile->tun, NULL);
>> + --tun->numqueues;
>> + sock_put(&tfile->sk);
>>
>> - if (atomic_inc_not_zero(&tfile->count))
>> - tun = tfile->tun;
>> + if (tun->numqueues == 0&& !(tun->flags& TUN_PERSIST))
>> + destroy = true;
> Please don't use flags like that. Use dedicated labels and goto there on error.
>
>
>> + }
>>
>> - return tun;
>> + spin_unlock(&tun_lock);
>> +
>> + synchronize_rcu();
>> + if (clean)
>> + sock_put(&tfile->sk);
>> +
>> + if (destroy) {
>> + rtnl_lock();
>> + if (dev->reg_state == NETREG_REGISTERED)
>> + unregister_netdevice(dev);
>> + rtnl_unlock();
>> + }
>> +
>> + return 0;
>> }
>>
>> -static struct tun_struct *tun_get(struct file *file)
>> +static void tun_detach_all(struct net_device *dev)
>> {
>> - return __tun_get(file->private_data);
>> + struct tun_struct *tun = netdev_priv(dev);
>> + struct tun_file *tfile, *tfile_list[MAX_TAP_QUEUES];
>> + int i, j = 0;
>> +
>> + spin_lock(&tun_lock);
>> +
>> + for (i = 0; i< MAX_TAP_QUEUES&& tun->numqueues; i++) {
>> + tfile = rcu_dereference_protected(tun->tfiles[i],
>> + lockdep_is_held(&tun_lock));
>> + BUG_ON(!tfile);
>> + wake_up_all(&tfile->wq.wait);
>> + tfile_list[j++] = tfile;
>> + rcu_assign_pointer(tfile->tun, NULL);
>> + --tun->numqueues;
>> + }
>> + BUG_ON(tun->numqueues != 0);
>> + /* guarantee that any future tun_attach will fail */
>> + tun->numqueues = MAX_TAP_QUEUES;
>> + spin_unlock(&tun_lock);
>> +
>> + synchronize_rcu();
>> + for (--j; j>= 0; j--)
>> + sock_put(&tfile_list[j]->sk);
>> }
>>
>> -static void tun_put(struct tun_struct *tun)
>> +static int tun_attach(struct tun_struct *tun, struct file *file)
>> {
>> - struct tun_file *tfile = tun->tfile;
>> + struct tun_file *tfile = file->private_data;
>> + int err;
>> +
>> + ASSERT_RTNL();
>> +
>> + spin_lock(&tun_lock);
>>
>> - if (atomic_dec_and_test(&tfile->count))
>> - tun_detach(tfile->tun);
>> + err = -EINVAL;
>> + if (rcu_dereference_protected(tfile->tun, lockdep_is_held(&tun_lock)))
>> + goto out;
>> +
>> + err = -EBUSY;
>> + if (!(tun->flags& TUN_TAP_MQ)&& tun->numqueues == 1)
>> + goto out;
>> +
>> + if (tun->numqueues == MAX_TAP_QUEUES)
>> + goto out;
>> +
>> + err = 0;
>> + tfile->queue_index = tun->numqueues;
>> + rcu_assign_pointer(tfile->tun, tun);
>> + rcu_assign_pointer(tun->tfiles[tun->numqueues], tfile);
>> + sock_hold(&tfile->sk);
>> + tun->numqueues++;
>> +
>> + if (tun->numqueues == 1)
>> + netif_carrier_on(tun->dev);
>> +
>> + /* device is allowed to go away first, so no need to hold extra
>> + * refcnt. */
>> +
>> +out:
>> + spin_unlock(&tun_lock);
>> + return err;
>> }
>>
>> /* TAP filtering */
>> @@ -331,16 +414,7 @@ static const struct ethtool_ops tun_ethtool_ops;
>> /* Net device detach from fd. */
>> static void tun_net_uninit(struct net_device *dev)
>> {
>> - struct tun_struct *tun = netdev_priv(dev);
>> - struct tun_file *tfile = tun->tfile;
>> -
>> - /* 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_all(dev);
>> }
>>
>> /* Net device open. */
>> @@ -360,10 +434,10 @@ static int tun_net_close(struct net_device *dev)
>> /* Net device start xmit */
>> 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;
>> + struct tun_file *tfile = NULL;
>>
>> - tun_debug(KERN_INFO, tun, "tun_net_xmit %d\n", skb->len);
>> + rcu_read_lock();
>> + tfile = tun_get_queue(dev, skb);
>>
>> /* Drop packet if interface is not attached */
>> if (!tfile)
>> @@ -381,7 +455,8 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
>>
>> if (skb_queue_len(&tfile->socket.sk->sk_receive_queue)
>> >= dev->tx_queue_len) {
>> - if (!(tun->flags& TUN_ONE_QUEUE)) {
>> + if (!(tfile->flags& TUN_ONE_QUEUE)&&
> Which patch moved flags from tun to tfile?
>
>> + !(tfile->flags& TUN_TAP_MQ)) {
>> /* Normal queueing mode. */
>> /* Packet scheduler handles dropping of further packets. */
>> netif_stop_queue(dev);
>> @@ -390,7 +465,7 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
>> * error is more appropriate. */
>> dev->stats.tx_fifo_errors++;
>> } else {
>> - /* Single queue mode.
>> + /* Single queue mode or multi queue mode.
>> * Driver handles dropping of all packets itself. */
> Please don't do this. Stop the queue on overrun as appropriate.
> ONE_QUEUE is a legacy hack.
>
> BTW we really should stop queue before we start dropping packets,
> but that can be a separate patch.
>
>> goto drop;
>> }
>> @@ -408,9 +483,11 @@ 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:
>> + rcu_read_unlock();
>> dev->stats.tx_dropped++;
>> kfree_skb(skb);
>> return NETDEV_TX_OK;
>> @@ -527,16 +604,22 @@ static void tun_net_init(struct net_device *dev)
>> static unsigned int tun_chr_poll(struct file *file, poll_table * wait)
>> {
>> struct tun_file *tfile = file->private_data;
>> - struct tun_struct *tun = __tun_get(tfile);
>> + struct tun_struct *tun = NULL;
>> struct sock *sk;
>> unsigned int mask = 0;
>>
>> - if (!tun)
>> + if (!tfile)
>> return POLLERR;
>>
>> - sk = tfile->socket.sk;
>> + rcu_read_lock();
>> + tun = rcu_dereference(tfile->tun);
>> + if (!tun) {
>> + rcu_read_unlock();
>> + return POLLERR;
>> + }
>> + rcu_read_unlock();
>>
>> - tun_debug(KERN_INFO, tun, "tun_chr_poll\n");
>> + sk =&tfile->sk;
>>
>> poll_wait(file,&tfile->wq.wait, wait);
>>
>> @@ -548,10 +631,12 @@ static unsigned int tun_chr_poll(struct file *file, poll_table * wait)
>> sock_writeable(sk)))
>> mask |= POLLOUT | POLLWRNORM;
>>
>> - if (tun->dev->reg_state != NETREG_REGISTERED)
>> + rcu_read_lock();
>> + tun = rcu_dereference(tfile->tun);
>> + if (!tun || tun->dev->reg_state != NETREG_REGISTERED)
>> mask = POLLERR;
>> + rcu_read_unlock();
>>
>> - tun_put(tun);
>> return mask;
>> }
>>
>> @@ -708,9 +793,12 @@ static ssize_t tun_get_user(struct tun_file *tfile,
>> skb_shinfo(skb)->gso_segs = 0;
>> }
>>
>> - tun = __tun_get(tfile);
>> - if (!tun)
>> + rcu_read_lock();
>> + tun = rcu_dereference(tfile->tun);
>> + if (!tun) {
>> + rcu_read_unlock();
>> return -EBADFD;
>> + }
>>
>> switch (tfile->flags& TUN_TYPE_MASK) {
>> case TUN_TUN_DEV:
>> @@ -720,26 +808,30 @@ static ssize_t tun_get_user(struct tun_file *tfile,
>> skb->protocol = eth_type_trans(skb, tun->dev);
>> break;
>> }
>> -
>> - netif_rx_ni(skb);
>> tun->dev->stats.rx_packets++;
>> tun->dev->stats.rx_bytes += len;
>> - tun_put(tun);
>> + rcu_read_unlock();
>> +
>> + netif_rx_ni(skb);
>> +
>> return count;
>>
>> err_free:
>> count = -EINVAL;
>> kfree_skb(skb);
>> err:
>> - tun = __tun_get(tfile);
>> - if (!tun)
>> + rcu_read_lock();
>> + tun = rcu_dereference(tfile->tun);
>> + if (!tun) {
>> + rcu_read_unlock();
>> return -EBADFD;
>> + }
>>
>> if (drop)
>> tun->dev->stats.rx_dropped++;
>> if (error)
>> tun->dev->stats.rx_frame_errors++;
>> - tun_put(tun);
>> + rcu_read_unlock();
>> return count;
>> }
>>
>> @@ -833,12 +925,13 @@ static ssize_t tun_put_user(struct tun_file *tfile,
>> skb_copy_datagram_const_iovec(skb, 0, iv, total, len);
>> total += skb->len;
>>
>> - tun = __tun_get(tfile);
>> + rcu_read_lock();
>> + tun = rcu_dereference(tfile->tun);
>> if (tun) {
>> tun->dev->stats.tx_packets++;
>> tun->dev->stats.tx_bytes += len;
>> - tun_put(tun);
>> }
>> + rcu_read_unlock();
>>
>> return total;
>> }
>> @@ -869,28 +962,31 @@ static ssize_t tun_do_read(struct tun_file *tfile,
>> break;
>> }
>>
>> - tun = __tun_get(tfile);
>> + rcu_read_lock();
>> + tun = rcu_dereference(tfile->tun);
>> if (!tun) {
>> - ret = -EIO;
>> + ret = -EBADFD;
> BADFD is for when you get passed something like -1 fd.
> Here fd is OK, it's just in a bad state so you can not do IO.
>
>
>> + rcu_read_unlock();
>> break;
>> }
>> if (tun->dev->reg_state != NETREG_REGISTERED) {
>> ret = -EIO;
>> - tun_put(tun);
>> + rcu_read_unlock();
>> break;
>> }
>> - tun_put(tun);
>> + rcu_read_unlock();
>>
>> /* Nothing to read, let's sleep */
>> schedule();
>> continue;
>> }
>>
>> - tun = __tun_get(tfile);
>> + rcu_read_lock();
>> + tun = rcu_dereference(tfile->tun);
>> if (tun) {
>> netif_wake_queue(tun->dev);
>> - tun_put(tun);
>> }
>> + rcu_read_unlock();
>>
>> ret = tun_put_user(tfile, skb, iv, len);
>> kfree_skb(skb);
>> @@ -1038,6 +1134,9 @@ static int tun_flags(struct tun_struct *tun)
>> if (tun->flags& TUN_VNET_HDR)
>> flags |= IFF_VNET_HDR;
>>
>> + if (tun->flags& TUN_TAP_MQ)
>> + flags |= IFF_MULTI_QUEUE;
>> +
>> return flags;
>> }
>>
>> @@ -1097,8 +1196,7 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
>> err = tun_attach(tun, file);
>> if (err< 0)
>> return err;
>> - }
>> - else {
>> + } else {
>> char *name;
>> unsigned long flags = 0;
>>
>> @@ -1142,6 +1240,8 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
>> dev->hw_features = NETIF_F_SG | NETIF_F_FRAGLIST |
>> TUN_USER_FEATURES;
>> dev->features = dev->hw_features;
>> + if (ifr->ifr_flags& IFF_MULTI_QUEUE)
>> + dev->features |= NETIF_F_LLTX;
>>
>> err = register_netdevice(tun->dev);
>> if (err< 0)
>> @@ -1154,7 +1254,7 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
>>
>> err = tun_attach(tun, file);
>> if (err< 0)
>> - goto failed;
>> + goto err_free_dev;
>> }
>>
>> tun_debug(KERN_INFO, tun, "tun_set_iff\n");
>> @@ -1174,6 +1274,11 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
>> else
>> tun->flags&= ~TUN_VNET_HDR;
>>
>> + if (ifr->ifr_flags& IFF_MULTI_QUEUE)
>> + tun->flags |= TUN_TAP_MQ;
>> + else
>> + tun->flags&= ~TUN_TAP_MQ;
>> +
>> /* Cache flags from tun device */
>> tfile->flags = tun->flags;
>> /* Make sure persistent devices do not get stuck in
>> @@ -1187,7 +1292,6 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
>>
>> err_free_dev:
>> free_netdev(dev);
>> -failed:
>> return err;
>> }
>>
>> @@ -1264,38 +1368,40 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
>> (unsigned int __user*)argp);
>> }
>>
>> - rtnl_lock();
>> -
>> - tun = __tun_get(tfile);
>> - if (cmd == TUNSETIFF&& !tun) {
>> + ret = 0;
>> + if (cmd == TUNSETIFF) {
>> + rtnl_lock();
>> ifr.ifr_name[IFNAMSIZ-1] = '\0';
>> -
>> ret = tun_set_iff(tfile->net, file,&ifr);
>> -
>> + rtnl_unlock();
>> if (ret)
>> - goto unlock;
>> -
>> + return ret;
>> if (copy_to_user(argp,&ifr, ifreq_len))
>> - ret = -EFAULT;
>> - goto unlock;
>> + return -EFAULT;
>> + return ret;
>> }
>>
>> + rtnl_lock();
>> +
>> + rcu_read_lock();
>> +
>> ret = -EBADFD;
>> + tun = rcu_dereference(tfile->tun);
>> if (!tun)
>> goto unlock;
>> + else
>> + ret = 0;
>>
>> - tun_debug(KERN_INFO, tun, "tun_chr_ioctl cmd %d\n", cmd);
>> -
>> - ret = 0;
>> switch (cmd) {
>> case TUNGETIFF:
>> ret = tun_get_iff(current->nsproxy->net_ns, tun,&ifr);
>> + rcu_read_unlock();
>> if (ret)
>> - break;
>> + goto out;
>>
>> if (copy_to_user(argp,&ifr, ifreq_len))
>> ret = -EFAULT;
>> - break;
>> + goto out;
>>
>> case TUNSETNOCSUM:
>> /* Disable/Enable checksum */
>> @@ -1357,9 +1463,10 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
>> /* Get hw address */
>> memcpy(ifr.ifr_hwaddr.sa_data, tun->dev->dev_addr, ETH_ALEN);
>> ifr.ifr_hwaddr.sa_family = tun->dev->type;
>> + rcu_read_unlock();
>> if (copy_to_user(argp,&ifr, ifreq_len))
>> ret = -EFAULT;
>> - break;
>> + goto out;
>>
>> case SIOCSIFHWADDR:
>> /* Set hw address */
>> @@ -1375,9 +1482,9 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
>> }
>>
>> unlock:
>> + rcu_read_unlock();
>> +out:
>> rtnl_unlock();
>> - if (tun)
>> - tun_put(tun);
>> return ret;
>> }
>>
>> @@ -1517,6 +1624,11 @@ out:
>> return ret;
>> }
>>
>> +static void tun_sock_destruct(struct sock *sk)
>> +{
>> + skb_queue_purge(&sk->sk_receive_queue);
>> +}
>> +
>> static int tun_chr_open(struct inode *inode, struct file * file)
>> {
>> struct net *net = current->nsproxy->net_ns;
>> @@ -1540,6 +1652,7 @@ static int tun_chr_open(struct inode *inode, struct file * file)
>> sock_init_data(&tfile->socket,&tfile->sk);
>>
>> tfile->sk.sk_write_space = tun_sock_write_space;
>> + tfile->sk.sk_destruct = tun_sock_destruct;
>> tfile->sk.sk_sndbuf = INT_MAX;
>> file->private_data = tfile;
>>
>> @@ -1549,31 +1662,8 @@ static int tun_chr_open(struct inode *inode, struct file * file)
>> static int tun_chr_close(struct inode *inode, struct file *file)
>> {
>> struct tun_file *tfile = file->private_data;
>> - struct tun_struct *tun;
>> -
>> - tun = __tun_get(tfile);
>> - if (tun) {
>> - struct net_device *dev = tun->dev;
>> -
>> - tun_debug(KERN_INFO, tun, "tun_chr_close\n");
>> -
>> - __tun_detach(tun);
>> -
>> - /* 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);
>> -
>> - }
>> -
>> - /* drop the reference that file holds */
>> - sock_put(&tfile->sk);
>> + tun_detach(tfile, true);
>>
>> return 0;
>> }
>> @@ -1700,14 +1790,17 @@ 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_struct *tun = NULL;
>> struct tun_file *tfile = file->private_data;
>> if (file->f_op !=&tun_fops)
>> return ERR_PTR(-EINVAL);
>> - tun = tun_get(file);
>> - if (!tun)
>> + rcu_read_lock();
>> + tun = rcu_dereference(tfile->tun);
>> + if (!tun) {
>> + rcu_read_unlock();
>> return ERR_PTR(-EBADFD);
>> - tun_put(tun);
>> + }
>> + rcu_read_unlock();
>> return&tfile->socket;
>> }
>> EXPORT_SYMBOL_GPL(tun_get_socket);
--
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