On Mon, Mar 22, 2021 at 11:31 PM Yunsheng Lin <linyunsheng@xxxxxxxxxx> wrote:
>
> On 2021/3/23 8:38, Cong Wang wrote:
> > From: Cong Wang <cong.wang@xxxxxxxxxxxxx>
> >
> > This is similar to tcp_read_sock(), except we do not need
> > to worry about connections, we just need to retrieve skb
> > from UDP receive queue.
> >
> > Cc: John Fastabend <john.fastabend@xxxxxxxxx>
> > Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
> > Cc: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
> > Cc: Lorenz Bauer <lmb@xxxxxxxxxxxxxx>
> > Signed-off-by: Cong Wang <cong.wang@xxxxxxxxxxxxx>
> > ---
> > include/net/udp.h | 2 ++
> > net/ipv4/af_inet.c | 1 +
> > net/ipv4/udp.c | 35 +++++++++++++++++++++++++++++++++++
> > net/ipv6/af_inet6.c | 1 +
> > 4 files changed, 39 insertions(+)
> >
> > diff --git a/include/net/udp.h b/include/net/udp.h
> > index df7cc1edc200..347b62a753c3 100644
> > --- a/include/net/udp.h
> > +++ b/include/net/udp.h
> > @@ -329,6 +329,8 @@ struct sock *__udp6_lib_lookup(struct net *net,
> > struct sk_buff *skb);
> > struct sock *udp6_lib_lookup_skb(const struct sk_buff *skb,
> > __be16 sport, __be16 dport);
> > +int udp_read_sock(struct sock *sk, read_descriptor_t *desc,
> > + sk_read_actor_t recv_actor);
> >
> > /* UDP uses skb->dev_scratch to cache as much information as possible and avoid
> > * possibly multiple cache miss on dequeue()
> > diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
> > index 1355e6c0d567..f17870ee558b 100644
> > --- a/net/ipv4/af_inet.c
> > +++ b/net/ipv4/af_inet.c
> > @@ -1070,6 +1070,7 @@ const struct proto_ops inet_dgram_ops = {
> > .setsockopt = sock_common_setsockopt,
> > .getsockopt = sock_common_getsockopt,
> > .sendmsg = inet_sendmsg,
> > + .read_sock = udp_read_sock,
> > .recvmsg = inet_recvmsg,
> > .mmap = sock_no_mmap,
> > .sendpage = inet_sendpage,
> > diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> > index 38952aaee3a1..a0adee3b1af4 100644
> > --- a/net/ipv4/udp.c
> > +++ b/net/ipv4/udp.c
> > @@ -1782,6 +1782,41 @@ struct sk_buff *__skb_recv_udp(struct sock *sk, unsigned int flags,
> > }
> > EXPORT_SYMBOL(__skb_recv_udp);
> >
> > +int udp_read_sock(struct sock *sk, read_descriptor_t *desc,
> > + sk_read_actor_t recv_actor)
> > +{
> > + int copied = 0;
> > +
> > + while (1) {
> > + int offset = 0, err;
> > + struct sk_buff *skb;
> > +
> > + skb = __skb_recv_udp(sk, 0, 1, &offset, &err);
> > + if (!skb)
> > + break;
>
> Does above error handling need the below additional handling?
> It seems __skb_recv_udp() will return the error by parameter "err",
> if "copied == 0", does it need to return the error?
Not for skmsg case, because the return value is just unused:
static void sk_psock_verdict_data_ready(struct sock *sk)
{
struct socket *sock = sk->sk_socket;
read_descriptor_t desc;
if (unlikely(!sock || !sock->ops || !sock->ops->read_sock))
return;
desc.arg.data = sk;
desc.error = 0;
desc.count = 1;
sock->ops->read_sock(sk, &desc, sk_psock_verdict_recv);
}
Thanks.
