On Wed, May 5, 2021 at 10:14 AM Jakub Sitnicki <jakub@xxxxxxxxxxxxxx> wrote:
>
> On Mon, Apr 26, 2021 at 04:49 AM CEST, Cong Wang wrote:
> > From: Cong Wang <cong.wang@xxxxxxxxxxxxx>
> >
> > Implement ->read_sock() for AF_UNIX datagram socket, it is
> > pretty much similar to udp_read_sock().
> >
> > 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>
> > ---
> > net/unix/af_unix.c | 38 ++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 38 insertions(+)
> >
> > diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
> > index 5a31307ceb76..f4dc22db371d 100644
> > --- a/net/unix/af_unix.c
> > +++ b/net/unix/af_unix.c
> > @@ -661,6 +661,8 @@ static ssize_t unix_stream_splice_read(struct socket *, loff_t *ppos,
> > unsigned int flags);
> > static int unix_dgram_sendmsg(struct socket *, struct msghdr *, size_t);
> > static int unix_dgram_recvmsg(struct socket *, struct msghdr *, size_t, int);
> > +static 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);
> > @@ -738,6 +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,
> > .recvmsg = unix_dgram_recvmsg,
> > .mmap = sock_no_mmap,
> > .sendpage = sock_no_sendpage,
> > @@ -2183,6 +2186,41 @@ static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
> > return err;
> > }
> >
> > +static int unix_read_sock(struct sock *sk, read_descriptor_t *desc,
> > + sk_read_actor_t recv_actor)
> > +{
> > + int copied = 0;
> > +
> > + while (1) {
> > + struct unix_sock *u = unix_sk(sk);
> > + struct sk_buff *skb;
> > + int used, err;
> > +
> > + mutex_lock(&u->iolock);
> > + skb = skb_recv_datagram(sk, 0, 1, &err);
> > + if (!skb) {
> > + mutex_unlock(&u->iolock);
> > + return err;
> > + }
> > +
> > + used = recv_actor(desc, skb, 0, skb->len);
> > + if (used <= 0) {
> > + if (!copied)
> > + copied = used;
> > + mutex_unlock(&u->iolock);
> > + break;
> > + } else if (used <= skb->len) {
> > + copied += used;
> > + }
> > + mutex_unlock(&u->iolock);
>
> Do we need hold the mutex for recv_actor to process the skb?
Hm, it does look like we can just release it after dequeuing the
skb. Let me double check.
Thanks.
