Messages in this thread | | | Subject | Re: [PATCH net-next 08/11] tun: switch to new type of msg_control | From | Jason Wang <> | Date | Fri, 7 Sep 2018 11:35:13 +0800 |
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On 2018年09月07日 00:54, Michael S. Tsirkin wrote: > On Thu, Sep 06, 2018 at 12:05:23PM +0800, Jason Wang wrote: >> 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> > At this point, do we want to just add a new sock opt for tap's > benefit? Seems cleaner than (ab)using sendmsg.
I think it won't be much difference, we still need a void pointer.
>> --- >> drivers/net/tap.c | 18 ++++++++++++------ >> drivers/net/tun.c | 6 +++++- >> drivers/vhost/net.c | 7 +++++-- >> include/linux/if_tun.h | 7 +++++++ >> 4 files changed, 29 insertions(+), 9 deletions(-) >> >> diff --git a/drivers/net/tap.c b/drivers/net/tap.c >> index f0f7cd977667..7996ed7cbf18 100644 >> --- a/drivers/net/tap.c >> +++ b/drivers/net/tap.c >> @@ -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, >> diff --git a/drivers/net/tun.c b/drivers/net/tun.c >> index ff1cbf3ebd50..c839a4bdcbd9 100644 >> --- a/drivers/net/tun.c >> +++ b/drivers/net/tun.c >> @@ -2429,11 +2429,15 @@ 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); >> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c >> index 4e656f89cb22..fb01ce6d981c 100644 >> --- a/drivers/vhost/net.c >> +++ b/drivers/vhost/net.c >> @@ -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; >> diff --git a/include/linux/if_tun.h b/include/linux/if_tun.h >> index 3d2996dc7d85..ba46dced1f38 100644 >> --- a/include/linux/if_tun.h >> +++ b/include/linux/if_tun.h >> @@ -19,6 +19,13 @@ >> >> #define TUN_XDP_FLAG 0x1UL >> >> +#define TUN_MSG_UBUF 1 >> +#define TUN_MSG_PTR 2 > Looks like TUN_MSG_PTR should be pushed out to a follow-up patch?
Ok.
> >> +struct tun_msg_ctl { >> + int type; >> + void *ptr; >> +}; >> + > type actually includes a size. Why not two short fields then?
Yes, this sounds better.
Thanks
> >> #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); >> -- >> 2.17.1
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