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Commit fe8dd45b authored by Jason Wang's avatar Jason Wang Committed by David S. Miller
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tun: switch to new type of msg_control 



This patch introduces to a new tun/tap specific msg_control:

#define TUN_MSG_UBUF 1
#define TUN_MSG_PTR  2
struct tun_msg_ctl {
       int type;
       void *ptr;
};

This allows us to pass different kinds of msg_control through
sendmsg(). The first supported type is ubuf (TUN_MSG_UBUF) which will
be used by the existed vhost_net zerocopy code. The second is XDP
buff, which allows vhost_net to pass XDP buff to TUN. This could be
used to implement accepting an array of XDP buffs from vhost_net in
the following patches.

Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1a097910

drivers/net/tap.c

+12 −6
Original line number Diff line number Diff line
@@ -619,7 +619,7 @@ static inline struct sk_buff *tap_alloc_skb(struct sock *sk, size_t prepad, 
#define TAP_RESERVE HH_DATA_OFF(ETH_HLEN)



/* Get packet from user space buffer */

static ssize_t tap_get_user(struct tap_queue *q, struct msghdr *m,

static ssize_t tap_get_user(struct tap_queue *q, void *msg_control,

			    struct iov_iter *from, int noblock)

{

	int good_linear = SKB_MAX_HEAD(TAP_RESERVE);
@@ -663,7 +663,7 @@ static ssize_t tap_get_user(struct tap_queue *q, struct msghdr *m, 
	if (unlikely(len < ETH_HLEN))

		goto err;



	if (m && m->msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) {

	if (msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) {

		struct iov_iter i;



		copylen = vnet_hdr.hdr_len ?
@@ -724,11 +724,11 @@ static ssize_t tap_get_user(struct tap_queue *q, struct msghdr *m, 
	tap = rcu_dereference(q->tap);

	/* copy skb_ubuf_info for callback when skb has no error */

	if (zerocopy) {

		skb_shinfo(skb)->destructor_arg = m->msg_control;

		skb_shinfo(skb)->destructor_arg = msg_control;

		skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;

		skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;

	} else if (m && m->msg_control) {

		struct ubuf_info *uarg = m->msg_control;

	} else if (msg_control) {

		struct ubuf_info *uarg = msg_control;

		uarg->callback(uarg, false);

	}
@@ -1150,7 +1150,13 @@ static int tap_sendmsg(struct socket *sock, struct msghdr *m, 
		       size_t total_len)

{

	struct tap_queue *q = container_of(sock, struct tap_queue, sock);

	return tap_get_user(q, m, &m->msg_iter, m->msg_flags & MSG_DONTWAIT);

	struct tun_msg_ctl *ctl = m->msg_control;



	if (ctl && ctl->type != TUN_MSG_UBUF)

		return -EINVAL;



	return tap_get_user(q, ctl ? ctl->ptr : NULL, &m->msg_iter,

			    m->msg_flags & MSG_DONTWAIT);

}



static int tap_recvmsg(struct socket *sock, struct msghdr *m,

drivers/net/tun.c

+5 −1
Original line number Diff line number Diff line
@@ -2431,11 +2431,15 @@ static int tun_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len) 
	int ret;

	struct tun_file *tfile = container_of(sock, struct tun_file, socket);

	struct tun_struct *tun = tun_get(tfile);

	struct tun_msg_ctl *ctl = m->msg_control;



	if (!tun)

		return -EBADFD;



	ret = tun_get_user(tun, tfile, m->msg_control, &m->msg_iter,

	if (ctl && ctl->type != TUN_MSG_UBUF)

		return -EINVAL;



	ret = tun_get_user(tun, tfile, ctl ? ctl->ptr : NULL, &m->msg_iter,

			   m->msg_flags & MSG_DONTWAIT,

			   m->msg_flags & MSG_MORE);

	tun_put(tun);

drivers/vhost/net.c

+5 −2
Original line number Diff line number Diff line
@@ -620,6 +620,7 @@ static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock) 
		.msg_controllen = 0,

		.msg_flags = MSG_DONTWAIT,

	};

	struct tun_msg_ctl ctl;

	size_t len, total_len = 0;

	int err;

	struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
@@ -664,8 +665,10 @@ static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock) 
			ubuf->ctx = nvq->ubufs;

			ubuf->desc = nvq->upend_idx;

			refcount_set(&ubuf->refcnt, 1);

			msg.msg_control = ubuf;

			msg.msg_controllen = sizeof(ubuf);

			msg.msg_control = &ctl;

			ctl.type = TUN_MSG_UBUF;

			ctl.ptr = ubuf;

			msg.msg_controllen = sizeof(ctl);

			ubufs = nvq->ubufs;

			atomic_inc(&ubufs->refcount);

			nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;

include/linux/if_tun.h

+14 −0
Original line number Diff line number Diff line
@@ -16,9 +16,23 @@ 
#define __IF_TUN_H



#include <uapi/linux/if_tun.h>

#include <uapi/linux/virtio_net.h>



#define TUN_XDP_FLAG 0x1UL



#define TUN_MSG_UBUF 1

#define TUN_MSG_PTR  2

struct tun_msg_ctl {

	unsigned short type;

	unsigned short num;

	void *ptr;

};



struct tun_xdp_hdr {

	int buflen;

	struct virtio_net_hdr gso;

};



#if defined(CONFIG_TUN) || defined(CONFIG_TUN_MODULE)

struct socket *tun_get_socket(struct file *);

struct ptr_ring *tun_get_tx_ring(struct file *file);