On 2021/3/23 8:38, Cong Wang wrote:
> From: Cong Wang <cong.w...@bytedance.com>
>
> 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.fastab...@gmail.com>
> Cc: Daniel Borkmann <dan...@iogearbox.net>
> Cc: Jakub Sitnicki <ja...@cloudflare.com>
> Cc: Lorenz Bauer <l...@cloudflare.com>
> Signed-off-by: Cong Wang <cong.w...@bytedance.com>
> ---
> 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?
if (!skb) {
if (!copied)
copied = err;
break;
}
> + if (offset < skb->len) {
> + int used;
> + size_t len;
> +
> + len = skb->len - offset;
> + used = recv_actor(desc, skb, offset, len);
> + if (used <= 0) {
> + if (!copied)
> + copied = used;
> + break;
As here it seems handling the "copied == 0" error case.
> + } else if (used <= len) {
> + copied += used;
> + offset += used;
> + }
> + }
> + if (!desc->count)
> + break;
> + }
> +
> + return copied;
> +}
> +EXPORT_SYMBOL(udp_read_sock);
> +
> /*
> * This should be easy, if there is something there we
> * return it, otherwise we block.
> diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
> index 802f5111805a..71de739b4a9e 100644
> --- a/net/ipv6/af_inet6.c
> +++ b/net/ipv6/af_inet6.c
> @@ -714,6 +714,7 @@ const struct proto_ops inet6_dgram_ops = {
> .getsockopt = sock_common_getsockopt, /* ok */
> .sendmsg = inet6_sendmsg, /* retpoline's sake */
> .recvmsg = inet6_recvmsg, /* retpoline's sake */
> + .read_sock = udp_read_sock,
> .mmap = sock_no_mmap,
> .sendpage = sock_no_sendpage,
> .set_peek_off = sk_set_peek_off,
>
