[Qemu-devel] Re: [PATCH 2/2] net/macvtap: add vhost support

[Michael S. Tsirkin]

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 <address@hidden>
> ---
>  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
> 
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