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    Subject[PATCH 2/2] net/macvtap: add vhost support
    Date
    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 <arnd@arndb.de>
    ---
    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);
    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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