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    SubjectRe: [PATCH 2/2] net/macvtap: add vhost support
    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 <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);

    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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