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tun: switch to new type of msg_control

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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: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jason Wang
2018-09-12 11:17:06 +08:00
committed by David S. Miller
parent 1a097910ad
commit fe8dd45bb7
4 changed files with 36 additions and 9 deletions
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18
drivers/net/tap.c
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@@ -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,