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Mon, 10 May 2021 22:34:38 -0700 (PDT) Date: Mon, 10 May 2021 22:34:29 -0700 From: John Fastabend To: Cong Wang , netdev@vger.kernel.org Cc: bpf@vger.kernel.org, jiang.wang@bytedance.com, duanxiongchun@bytedance.com, wangdongdong.6@bytedance.com, Cong Wang , John Fastabend , Daniel Borkmann , Jakub Sitnicki , Lorenz Bauer Message-ID: <609a1765cf6d7_876892080@john-XPS-13-9370.notmuch> In-Reply-To: <20210426025001.7899-3-xiyou.wangcong@gmail.com> References: <20210426025001.7899-1-xiyou.wangcong@gmail.com> <20210426025001.7899-3-xiyou.wangcong@gmail.com> Subject: RE: [Patch bpf-next v3 02/10] af_unix: implement ->read_sock() for sockmap Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Cong Wang wrote: > From: Cong Wang > > Implement ->read_sock() for AF_UNIX datagram socket, it is > pretty much similar to udp_read_sock(). > > Cc: John Fastabend > Cc: Daniel Borkmann > Cc: Jakub Sitnicki > Cc: Lorenz Bauer > Signed-off-by: Cong Wang > --- > 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; Here we should check copied and break if copied is >0. Sure the caller here has desc.count = 1 but its still fairly fragile. > + } > + > + 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); > + > + if (!desc->count) > + break; > + } > + > + return copied; > +} > + > /* > * Sleep until more data has arrived. But check for races.. > */ > -- > 2.25.1 >