Subject: Re: [PATCH 2/2] net/macvtap: add vhost support

From: "Michael S. Tsirkin" <[email-masked]>
Date: Sun, 14 Feb 2010 15:27:32 +0200

On Sat, Feb 13, 2010 at 11:35:08AM +0100, Arnd Bergmann wrote:
> This adds support for passing a macvtap file descriptor into
> vhost-net, much like we already do for tun/tap.
> 
> Most of the new code is taken from the respective patch
> in the tun driver and may get consolidated in the future.
> 
> Signed-off-by: Arnd Bergmann <[email-masked]>
> ---
>  drivers/net/macvtap.c      |   98 ++++++++++++++++++++++++++++++++++---------
>  drivers/vhost/net.c        |    8 +++-
>  include/linux/if_macvlan.h |   13 ++++++
>  3 files changed, 96 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
> index 7050997..e354501 100644
> --- a/drivers/net/macvtap.c
> +++ b/drivers/net/macvtap.c
> @@ -58,6 +58,8 @@ static unsigned int macvtap_major;
>  static struct class *macvtap_class;
>  static struct cdev macvtap_cdev;
>  
> +static const struct proto_ops macvtap_socket_ops;
> +
>  /*
>   * RCU usage:
>   * The macvtap_queue and the macvlan_dev are loosely coupled, the
> @@ -176,7 +178,7 @@ static int macvtap_forward(struct net_device *dev, struct sk_buff *skb)
>  		return -ENOLINK;
>  
>  	skb_queue_tail(&q->sk.sk_receive_queue, skb);
> -	wake_up(q->sk.sk_sleep);
> +	wake_up_interruptible_poll(q->sk.sk_sleep, POLLIN | POLLRDNORM | POLLRDBAND);
>  	return 0;
>  }
>  
> @@ -242,7 +244,7 @@ static void macvtap_sock_write_space(struct sock *sk)
>  		return;
>  
>  	if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
> -		wake_up_interruptible_sync(sk->sk_sleep);
> +		wake_up_interruptible_poll(sk->sk_sleep, POLLOUT | POLLWRNORM | POLLWRBAND);
>  }
>  
>  static int macvtap_open(struct inode *inode, struct file *file)
> @@ -270,6 +272,8 @@ static int macvtap_open(struct inode *inode, struct file *file)
>  	init_waitqueue_head(&q->sock.wait);
>  	q->sock.type = SOCK_RAW;
>  	q->sock.state = SS_CONNECTED;
> +	q->sock.file = file;
> +	q->sock.ops = &macvtap_socket_ops;
>  	sock_init_data(&q->sock, &q->sk);
>  	q->sk.sk_write_space = macvtap_sock_write_space;
>  
> @@ -387,32 +391,20 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q,
>  
>  	rcu_read_lock_bh();
>  	vlan = rcu_dereference(q->vlan);
> -	macvlan_count_rx(vlan, len, ret == 0, 0);
> +	if (vlan)
> +		macvlan_count_rx(vlan, len, ret == 0, 0);
>  	rcu_read_unlock_bh();
>  
>  	return ret ? ret : len;
>  }
>  
> -static ssize_t macvtap_aio_read(struct kiocb *iocb, const struct iovec *iv,
> -				unsigned long count, loff_t pos)
> +static ssize_t macvtap_do_read(struct macvtap_queue *q, struct kiocb *iocb,
> +			       const struct iovec *iv, unsigned long len,
> +			       int noblock)
>  {
> -	struct file *file = iocb->ki_filp;
> -	struct macvtap_queue *q = file->private_data;
> -
>  	DECLARE_WAITQUEUE(wait, current);
>  	struct sk_buff *skb;
> -	ssize_t len, ret = 0;
> -
> -	if (!q) {
> -		ret = -ENOLINK;
> -		goto out;
> -	}
> -
> -	len = iov_length(iv, count);
> -	if (len < 0) {
> -		ret = -EINVAL;
> -		goto out;
> -	}
> +	ssize_t ret = 0;
>  
>  	add_wait_queue(q->sk.sk_sleep, &wait);
>  	while (len) {
> @@ -421,7 +413,7 @@ static ssize_t macvtap_aio_read(struct kiocb *iocb, const struct iovec *iv,
>  		/* Read frames from the queue */
>  		skb = skb_dequeue(&q->sk.sk_receive_queue);
>  		if (!skb) {
> -			if (file->f_flags & O_NONBLOCK) {
> +			if (noblock) {
>  				ret = -EAGAIN;
>  				break;
>  			}
> @@ -440,7 +432,24 @@ static ssize_t macvtap_aio_read(struct kiocb *iocb, const struct iovec *iv,
>  
>  	current->state = TASK_RUNNING;
>  	remove_wait_queue(q->sk.sk_sleep, &wait);
> +	return ret;
> +}
> +
> +static ssize_t macvtap_aio_read(struct kiocb *iocb, const struct iovec *iv,
> +				unsigned long count, loff_t pos)
> +{
> +	struct file *file = iocb->ki_filp;
> +	struct macvtap_queue *q = file->private_data;
> +	ssize_t len, ret = 0;
>  
> +	len = iov_length(iv, count);
> +	if (len < 0) {
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
> +	ret = macvtap_do_read(q, iocb, iv, len, file->f_flags & O_NONBLOCK);
> +	ret = min_t(ssize_t, ret, len); /* XXX copied from tun.c. Why? */
>  out:
>  	return ret;
>  }
> @@ -538,6 +547,53 @@ static const struct file_operations macvtap_fops = {
>  #endif
>  };
>  
> +static int macvtap_sendmsg(struct kiocb *iocb, struct socket *sock,
> +			   struct msghdr *m, size_t total_len)
> +{
> +	struct macvtap_queue *q = container_of(sock, struct macvtap_queue, sock);
> +	return macvtap_get_user(q, m->msg_iov, total_len,
> +			    m->msg_flags & MSG_DONTWAIT);
> +}
> +
> +static int macvtap_recvmsg(struct kiocb *iocb, struct socket *sock,
> +			   struct msghdr *m, size_t total_len,
> +			   int flags)
> +{
> +	struct macvtap_queue *q = container_of(sock, struct macvtap_queue, sock);
> +	int ret;
> +	if (flags & ~(MSG_DONTWAIT|MSG_TRUNC))
> +		return -EINVAL;
> +	ret = macvtap_do_read(q, iocb, m->msg_iov, total_len,
> +			  flags & MSG_DONTWAIT);
> +	if (ret > total_len) {
> +		m->msg_flags |= MSG_TRUNC;
> +		ret = flags & MSG_TRUNC ? ret : total_len;
> +	}
> +	return ret;
> +}
> +
> +/* Ops structure to mimic raw sockets with tun */
> +static const struct proto_ops macvtap_socket_ops = {
> +	.sendmsg = macvtap_sendmsg,
> +	.recvmsg = macvtap_recvmsg,
> +};
> +
> +/* Get an underlying socket object from tun file.  Returns error unless file is
> + * attached to a device.  The returned object works like a packet socket, it
> + * can be used for sock_sendmsg/sock_recvmsg.  The caller is responsible for
> + * holding a reference to the file for as long as the socket is in use. */
> +struct socket *macvtap_get_socket(struct file *file)
> +{
> +	struct macvtap_queue *q;
> +	if (file->f_op != &macvtap_fops)
> +		return ERR_PTR(-EINVAL);
> +	q = file->private_data;
> +	if (!q)
> +		return ERR_PTR(-EBADFD);
> +	return &q->sock;
> +}
> +EXPORT_SYMBOL_GPL(macvtap_get_socket);
> +
>  static int macvtap_init(void)
>  {
>  	int err;
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index 4c89283..91a324c 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -22,6 +22,7 @@
>  #include <linux/if_packet.h>
>  #include <linux/if_arp.h>
>  #include <linux/if_tun.h>
> +#include <linux/if_macvlan.h>
>  
>  #include <net/sock.h>
>  
> @@ -452,13 +453,16 @@ err:
>  	return ERR_PTR(r);
>  }
>  
> -static struct socket *get_tun_socket(int fd)
> +static struct socket *get_tap_socket(int fd)
>  {
>  	struct file *file = fget(fd);
>  	struct socket *sock;
>  	if (!file)
>  		return ERR_PTR(-EBADF);
>  	sock = tun_get_socket(file);
> +	if (!IS_ERR(sock))
> +		return sock;
> +	sock = macvtap_get_socket(file);
>  	if (IS_ERR(sock))
>  		fput(file);
>  	return sock;
> @@ -473,7 +477,7 @@ static struct socket *get_socket(int fd)
>  	sock = get_raw_socket(fd);
>  	if (!IS_ERR(sock))
>  		return sock;
> -	sock = get_tun_socket(fd);
> +	sock = get_tap_socket(fd);
>  	if (!IS_ERR(sock))
>  		return sock;
>  	return ERR_PTR(-ENOTSOCK);

This will also need a dependency on macvtap in Kconfig.
See how it's done for tun.

> diff --git a/include/linux/if_macvlan.h b/include/linux/if_macvlan.h
> index 51f1512..7d7f1e3 100644
> --- a/include/linux/if_macvlan.h
> +++ b/include/linux/if_macvlan.h
> @@ -7,6 +7,19 @@
>  #include <linux/netlink.h>
>  #include <net/netlink.h>
>  
> +#if defined(CONFIG_MACVTAP) || defined(CONFIG_MACVTAP_MODULE)
> +struct socket *macvtap_get_socket(struct file *);
> +#else
> +#include <linux/err.h>
> +#include <linux/errno.h>
> +struct file;
> +struct socket;
> +static inline struct socket *macvtap_get_socket(struct file *f)
> +{
> +	return ERR_PTR(-EINVAL);
> +}
> +#endif /* CONFIG_MACVTAP */
> +
>  struct macvlan_port;
>  struct macvtap_queue;
>  
> -- 
> 1.6.3.3
> 
> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
> the body of a message to [email-masked]
> More majordomo info at  http://vger.kernel.org/majordomo-info.html