[Patch bpf-next 11/19] af_unix: implement ->read_sock() for sockmap

[Cong Wang]

From: Cong Wang <cong.w...@bytedance.com>

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>
---
 net/unix/af_unix.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 4e1fa4ecbcfb..9315c4f4c27a 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -662,6 +662,7 @@ static ssize_t unix_stream_splice_read(struct socket *,  
loff_t *ppos,
 static int __unix_dgram_sendmsg(struct sock*, struct msghdr *, size_t);
 static int unix_dgram_sendmsg(struct socket *, struct msghdr *, size_t);
 static int unix_dgram_recvmsg(struct socket *, struct msghdr *, size_t, int);
+int unix_read_sock(struct sock *sk, read_descriptor_t *desc, sk_read_actor_t 
recv_actor);
 static int unix_dgram_connect(struct socket *, struct sockaddr *,
                              int, int);
 static int unix_seqpacket_sendmsg(struct socket *, struct msghdr *, size_t);
@@ -739,6 +740,7 @@ static const struct proto_ops unix_dgram_ops = {
        .listen =       sock_no_listen,
        .shutdown =     unix_shutdown,
        .sendmsg =      unix_dgram_sendmsg,
+       .read_sock =    unix_read_sock,
        .sendmsg_locked = __unix_dgram_sendmsg,
        .recvmsg =      unix_dgram_recvmsg,
        .mmap =         sock_no_mmap,
@@ -2190,6 +2192,50 @@ static int unix_dgram_recvmsg(struct socket *sock, 
struct msghdr *msg,
        return err;
 }
 
+int unix_read_sock(struct sock *sk, read_descriptor_t *desc,
+                  sk_read_actor_t recv_actor)
+{
+       unsigned int flags = MSG_DONTWAIT;
+       struct unix_sock *u = unix_sk(sk);
+       struct sk_buff *skb;
+       int copied = 0;
+
+       while (1) {
+               int offset, err;
+
+               mutex_lock(&u->iolock);
+               skb = __skb_recv_datagram(sk, &sk->sk_receive_queue, flags,
+                                         &offset, &err);
+               if (!skb) {
+                       mutex_unlock(&u->iolock);
+                       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;
+                               mutex_unlock(&u->iolock);
+                               break;
+                       } else if (used <= len) {
+                               copied += used;
+                               offset += used;
+                       }
+               }
+               mutex_unlock(&u->iolock);
+
+               if (!desc->count)
+                       break;
+       }
+
+       return copied;
+}
+
 /*
  *     Sleep until more data has arrived. But check for races..
  */
-- 
2.25.1