Series comparison

From: Geliang Tang <tanggeliang@kylinos.cn>

v9:
 - merge the squash-to patches.
 - a new patch "drop release and lock again in splice_read".

v8:
 - export struct tcp_splice_state and tcp_splice_data_recv() in net/tcp.h.
 - add a new helper mptcp_recv_should_stop.
 - add mptcp_connect_splice.sh.
 - update commit logs.

v7:
 - only patch 1 and patch 2 changed.
 - add a new helper mptcp_eat_recv_skb.
 - invoke skb_peek in mptcp_recv_skb().
 - use while ((skb = mptcp_recv_skb(sk)) != NULL) instead of
 skb_queue_walk_safe(&sk->sk_receive_queue, skb, tmp).

v6:
 - address Paolo's comments for v4, v5 (thanks)

v5:
 - extract the common code of __mptcp_recvmsg_mskq() and mptcp_read_sock()
 into a new helper __mptcp_recvmsg_desc() to reduce duplication code.

v4:
 - v3 doesn't work for MPTCP fallback tests in mptcp_connect.sh, this
   set fix it.
 - invoke __mptcp_move_skbs in mptcp_read_sock.
 - use INDIRECT_CALL_INET_1 in __tcp_splice_read.

v3:
 - merge the two squash-to patches.
 - use sk->sk_rcvbuf instead of INT_MAX as the max len in
 mptcp_read_sock().
 - add splice io mode for mptcp_connect and drop mptcp_splice.c test.
 - the splice test for packetdrill is also added here:
https://github.com/multipath-tcp/packetdrill/pull/162

v2:
 - set splice_read of mptcp
 - add a splice selftest.

I have good news! I recently added MPTCP support to "NVME over TCP".
And my RFC patches are under review by NVME maintainer Hannes.

Replacing "NVME over TCP" with MPTCP is very simple. I used IPPROTO_MPTCP
instead of IPPROTO_TCP to create MPTCP sockets on both target and host
sides, these sockets are created in Kernel space.

nvmet_tcp_add_port:

ret = sock_create(port->addr.ss_family, SOCK_STREAM,
				IPPROTO_MPTCP, &port->sock);

nvme_tcp_alloc_queue:

ret = sock_create_kern(current->nsproxy->net_ns,
			ctrl->addr.ss_family, SOCK_STREAM,
			IPPROTO_MPTCP, &queue->sock);

nvme_tcp_try_recv() needs to call .read_sock interface of struct
proto_ops, but it is not implemented in MPTCP. So I implemented it
with reference to __mptcp_recvmsg_mskq().

Since the NVME part patches are still under reviewing, I only send the
MPTCP part patches in this set to MPTCP ML for your opinions.

Geliang Tang (9):
  mptcp: add eat_recv_skb helper
  mptcp: implement .read_sock
  tcp: drop release and lock again in splice_read
  tcp: export splice_state and splice_data_recv
  tcp: add recv_should_stop helper
  mptcp: use recv_should_stop helper
  mptcp: implement .splice_read
  selftests: mptcp: add splice io mode
  selftests: mptcp: connect: cover splice mode

include/net/tcp.h                             |  35 +++
 net/ipv4/tcp.c                                |  90 ++------
 net/mptcp/protocol.c                          | 204 +++++++++++++++---
 tools/testing/selftests/net/mptcp/Makefile    |   2 +-
 .../selftests/net/mptcp/mptcp_connect.c       |  63 +++++-
 .../net/mptcp/mptcp_connect_splice.sh         |   4 +
 6 files changed, 288 insertions(+), 110 deletions(-)
 create mode 100755 tools/testing/selftests/net/mptcp/mptcp_connect_splice.sh

-- 
2.48.1

From: Geliang Tang <tanggeliang@kylinos.cn>

This patch extracts the free skb related code in __mptcp_recvmsg_mskq()
into a new helper mptcp_eat_recv_skb().

Use sk_eat_skb() in this helper instead of open-coding it.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 net/mptcp/protocol.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index XXXXXXX..XXXXXXX 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -XXX,XX +XXX,XX @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 
 static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied);
 
+static void mptcp_eat_recv_skb(struct sock *sk, struct sk_buff *skb)
+{
+	/* avoid the indirect call, we know the destructor is sock_wfree */
+	skb->destructor = NULL;
+	atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
+	sk_mem_uncharge(sk, skb->truesize);
+	sk_eat_skb(sk, skb);
+}
+
 static int __mptcp_recvmsg_mskq(struct sock *sk,
 				struct msghdr *msg,
 				size_t len, int flags,
@@ -XXX,XX +XXX,XX @@ static int __mptcp_recvmsg_mskq(struct sock *sk,
 		}
 
 		if (!(flags & MSG_PEEK)) {
-			/* avoid the indirect call, we know the destructor is sock_wfree */
-			skb->destructor = NULL;
-			atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
-			sk_mem_uncharge(sk, skb->truesize);
-			__skb_unlink(skb, &sk->sk_receive_queue);
-			__kfree_skb(skb);
+			mptcp_eat_recv_skb(sk, skb);
 			msk->bytes_consumed += count;
 		}
 
-- 
2.48.1

From: Geliang Tang <tanggeliang@kylinos.cn>

nvme_tcp_try_recv() needs to call .read_sock interface of struct
proto_ops, but it's not implemented in MPTCP.

This patch implements it with reference to __tcp_read_sock() and
__mptcp_recvmsg_mskq().

Corresponding to tcp_recv_skb(), a new helper for MPTCP named
mptcp_recv_skb() is added to peek a skb from sk->sk_receive_queue.

Compared with __mptcp_recvmsg_mskq(), mptcp_read_sock() uses
sk->sk_rcvbuf as the max read length. The LISTEN status is checked
before the while loop, and mptcp_recv_skb() and mptcp_cleanup_rbuf()
are invoked after the loop. In the loop, all flags checks for
__mptcp_recvmsg_mskq() are removed.

Reviewed-by: Hannes Reinecke <hare@kernel.org>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 net/mptcp/protocol.c | 62 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index XXXXXXX..XXXXXXX 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -XXX,XX +XXX,XX @@ static __poll_t mptcp_poll(struct file *file, struct socket *sock,
 	return mask;
 }
 
+static struct sk_buff *mptcp_recv_skb(struct sock *sk)
+{
+	if (skb_queue_empty(&sk->sk_receive_queue))
+		__mptcp_move_skbs(sk);
+	return skb_peek(&sk->sk_receive_queue);
+}
+
+/*
+ * Note:
+ *	- It is assumed that the socket was locked by the caller.
+ */
+static int mptcp_read_sock(struct sock *sk, read_descriptor_t *desc,
+			   sk_read_actor_t recv_actor)
+{
+	struct mptcp_sock *msk = mptcp_sk(sk);
+	size_t len = sk->sk_rcvbuf;
+	struct sk_buff *skb;
+	int copied = 0;
+
+	if (sk->sk_state == TCP_LISTEN)
+		return -ENOTCONN;
+	while ((skb = mptcp_recv_skb(sk)) != NULL) {
+		u32 offset = MPTCP_SKB_CB(skb)->offset;
+		u32 data_len = skb->len - offset;
+		u32 size = min_t(size_t, len - copied, data_len);
+		int count;
+
+		count = recv_actor(desc, skb, offset, size);
+		if (count <= 0) {
+			if (!copied)
+				copied = count;
+			break;
+		}
+
+		copied += count;
+
+		if (count < data_len) {
+			MPTCP_SKB_CB(skb)->offset += count;
+			MPTCP_SKB_CB(skb)->map_seq += count;
+			msk->bytes_consumed += count;
+			break;
+		}
+
+		mptcp_eat_recv_skb(sk, skb);
+		msk->bytes_consumed += count;
+
+		if (copied >= len)
+			break;
+	}
+
+	mptcp_rcv_space_adjust(msk, copied);
+
+	if (copied > 0) {
+		mptcp_recv_skb(sk);
+		mptcp_cleanup_rbuf(msk, copied);
+	}
+
+	return copied;
+}
+
 static const struct proto_ops mptcp_stream_ops = {
 	.family		   = PF_INET,
 	.owner		   = THIS_MODULE,
@@ -XXX,XX +XXX,XX @@ static const struct proto_ops mptcp_stream_ops = {
 	.recvmsg	   = inet_recvmsg,
 	.mmap		   = sock_no_mmap,
 	.set_rcvlowat	   = mptcp_set_rcvlowat,
+	.read_sock	   = mptcp_read_sock,
 };
 
 static struct inet_protosw mptcp_protosw = {
@@ -XXX,XX +XXX,XX @@ static const struct proto_ops mptcp_v6_stream_ops = {
 	.compat_ioctl	   = inet6_compat_ioctl,
 #endif
 	.set_rcvlowat	   = mptcp_set_rcvlowat,
+	.read_sock	   = mptcp_read_sock,
 };
 
 static struct proto mptcp_v6_prot;
-- 
2.48.1

From: Geliang Tang <tanggeliang@kylinos.cn>

Export struct tcp_splice_state and tcp_splice_data_recv() in net/tcp.h so
that they can be used by MPTCP.

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 include/net/tcp.h | 12 ++++++++++++
 net/ipv4/tcp.c    | 13 ++-----------
 2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index XXXXXXX..XXXXXXX 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -XXX,XX +XXX,XX @@ static_assert((1 << ATO_BITS) > TCP_DELACK_MAX);
  */
 #define	TFO_SERVER_WO_SOCKOPT1	0x400
 
+/*
+ * TCP splice context
+ */
+struct tcp_splice_state {
+	struct pipe_inode_info *pipe;
+	size_t len;
+	unsigned int flags;
+};
+
+int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
+			 unsigned int offset, size_t len);
+
 
 /* sysctl variables for tcp */
 extern int sysctl_tcp_max_orphans;
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index XXXXXXX..XXXXXXX 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -XXX,XX +XXX,XX @@ EXPORT_SYMBOL(tcp_have_smc);
 struct percpu_counter tcp_sockets_allocated ____cacheline_aligned_in_smp;
 EXPORT_IPV6_MOD(tcp_sockets_allocated);
 
-/*
- * TCP splice context
- */
-struct tcp_splice_state {
-	struct pipe_inode_info *pipe;
-	size_t len;
-	unsigned int flags;
-};
-
 /*
  * Pressure flag: try to collapse.
  * Technical note: it is used by multiple contexts non atomically.
@@ -XXX,XX +XXX,XX @@ void tcp_push(struct sock *sk, int flags, int mss_now,
 	__tcp_push_pending_frames(sk, mss_now, nonagle);
 }
 
-static int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
-				unsigned int offset, size_t len)
+int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
+			 unsigned int offset, size_t len)
 {
 	struct tcp_splice_state *tss = rd_desc->arg.data;
 	int ret;
-- 
2.48.1

From: Geliang Tang <tanggeliang@kylinos.cn>

Factor out a new helper tcp_recv_should_stop() from tcp_recvmsg_locked()
and tcp_splice_read() to check whether to stop receiving. It will be used
for MPTCP too.

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 include/net/tcp.h | 23 +++++++++++++++
 net/ipv4/tcp.c    | 75 ++++++++---------------------------------------
 2 files changed, 35 insertions(+), 63 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index XXXXXXX..XXXXXXX 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -XXX,XX +XXX,XX @@ struct tcp_splice_state {
 int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
 			 unsigned int offset, size_t len);
 
+static inline int tcp_recv_should_stop(struct sock *sk, long timeo)
+{
+	if (sock_flag(sk, SOCK_DONE))
+		return -ENETDOWN;
+
+	if (sk->sk_err)
+		return sock_error(sk);
+
+	if (sk->sk_shutdown & RCV_SHUTDOWN)
+		return -ESHUTDOWN;
+
+	if (sk->sk_state == TCP_CLOSE)
+		return -ENOTCONN;
+
+	if (!timeo)
+		return -EAGAIN;
+
+	if (signal_pending(current))
+		return sock_intr_errno(timeo);
+
+	return 0;
+}
+
 
 /* sysctl variables for tcp */
 extern int sysctl_tcp_max_orphans;
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index XXXXXXX..XXXXXXX 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -XXX,XX +XXX,XX @@ ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
 	};
 	long timeo;
 	ssize_t spliced;
-	int ret;
+	int ret, err;
 
 	sock_rps_record_flow(sk);
 	/*
@@ -XXX,XX +XXX,XX @@ ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
 		else if (!ret) {
 			if (spliced)
 				break;
-			if (sock_flag(sk, SOCK_DONE))
-				break;
-			if (sk->sk_err) {
-				ret = sock_error(sk);
-				break;
-			}
-			if (sk->sk_shutdown & RCV_SHUTDOWN)
-				break;
-			if (sk->sk_state == TCP_CLOSE) {
-				/*
-				 * This occurs when user tries to read
-				 * from never connected socket.
-				 */
-				ret = -ENOTCONN;
-				break;
-			}
-			if (!timeo) {
-				ret = -EAGAIN;
+			err = tcp_recv_should_stop(sk, timeo);
+			if (err < 0) {
+				if (err != -ESHUTDOWN && err != -ENETDOWN)
+					ret = err;
 				break;
 			}
 			/* if __tcp_splice_read() got nothing while we have
@@ -XXX,XX +XXX,XX @@ ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
 			ret = sk_wait_data(sk, &timeo, NULL);
 			if (ret < 0)
 				break;
-			if (signal_pending(current)) {
-				ret = sock_intr_errno(timeo);
-				break;
-			}
 			continue;
 		}
 		tss.len -= ret;
 		spliced += ret;
 
-		if (!tss.len || !timeo)
+		if (!tss.len)
 			break;
 
-		if (sk->sk_err || sk->sk_state == TCP_CLOSE ||
-		    (sk->sk_shutdown & RCV_SHUTDOWN) ||
-		    signal_pending(current))
+		if (tcp_recv_should_stop(sk, timeo))
 			break;
 	}
 
@@ -XXX,XX +XXX,XX @@ static int tcp_recvmsg_locked(struct sock *sk, struct msghdr *msg, size_t len,
 		if (copied >= target && !READ_ONCE(sk->sk_backlog.tail))
 			break;
 
-		if (copied) {
-			if (!timeo ||
-			    sk->sk_err ||
-			    sk->sk_state == TCP_CLOSE ||
-			    (sk->sk_shutdown & RCV_SHUTDOWN) ||
-			    signal_pending(current))
-				break;
-		} else {
-			if (sock_flag(sk, SOCK_DONE))
-				break;
-
-			if (sk->sk_err) {
-				copied = sock_error(sk);
-				break;
-			}
-
-			if (sk->sk_shutdown & RCV_SHUTDOWN)
-				break;
-
-			if (sk->sk_state == TCP_CLOSE) {
-				/* This occurs when user tries to read
-				 * from never connected socket.
-				 */
-				copied = -ENOTCONN;
-				break;
-			}
-
-			if (!timeo) {
-				copied = -EAGAIN;
-				break;
-			}
-
-			if (signal_pending(current)) {
-				copied = sock_intr_errno(timeo);
-				break;
-			}
+		err = tcp_recv_should_stop(sk, timeo);
+		if (err < 0) {
+			if (!copied && err != -ESHUTDOWN && err != -ENETDOWN)
+				copied = err;
+			break;
 		}
 
 		if (copied >= target) {
-- 
2.48.1

From: Geliang Tang <tanggeliang@kylinos.cn>

Use the newly added tcp_recv_should_stop() helper in mptcp_recvmsg() to
check whether to stop receiving.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 net/mptcp/protocol.c | 32 ++++++--------------------------
 1 file changed, 6 insertions(+), 26 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index XXXXXXX..XXXXXXX 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -XXX,XX +XXX,XX @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 		if (copied >= target)
 			break;
 
-		if (copied) {
-			if (sk->sk_err ||
-			    sk->sk_state == TCP_CLOSE ||
-			    (sk->sk_shutdown & RCV_SHUTDOWN) ||
-			    !timeo ||
-			    signal_pending(current))
-				break;
-		} else {
-			if (sk->sk_err) {
-				copied = sock_error(sk);
+		err = tcp_recv_should_stop(sk, timeo);
+		if (err < 0) {
+			if (copied)
 				break;
-			}
 
-			if (sk->sk_shutdown & RCV_SHUTDOWN) {
+			if (err == -ESHUTDOWN) {
 				/* race breaker: the shutdown could be after the
 				 * previous receive queue check
 				 */
@@ -XXX,XX +XXX,XX @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 				break;
 			}
 
-			if (sk->sk_state == TCP_CLOSE) {
-				copied = -ENOTCONN;
-				break;
-			}
-
-			if (!timeo) {
-				copied = -EAGAIN;
-				break;
-			}
-
-			if (signal_pending(current)) {
-				copied = sock_intr_errno(timeo);
-				break;
-			}
+			copied = err;
+			break;
 		}
 
 		pr_debug("block timeout %ld\n", timeo);
-- 
2.48.1

From: Geliang Tang <tanggeliang@kylinos.cn>

This patch implements .splice_read interface of mptcp struct proto_ops
as mptcp_splice_read() with reference to tcp_splice_read().

Corresponding to __tcp_splice_read(), __mptcp_splice_read() is defined,
invoking mptcp_read_sock() instead of tcp_read_sock().

mptcp_splice_read() is almost the same as tcp_splice_read(), except for
sock_rps_record_flow() and __mptcp_move_skbs().

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 net/mptcp/protocol.c | 94 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 94 insertions(+)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index XXXXXXX..XXXXXXX 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -XXX,XX +XXX,XX @@ static int mptcp_read_sock(struct sock *sk, read_descriptor_t *desc,
 	return copied;
 }
 
+static int __mptcp_splice_read(struct sock *sk, struct tcp_splice_state *tss)
+{
+	/* Store TCP splice context information in read_descriptor_t. */
+	read_descriptor_t rd_desc = {
+		.arg.data = tss,
+		.count	  = tss->len,
+	};
+
+	return mptcp_read_sock(sk, &rd_desc, tcp_splice_data_recv);
+}
+
+/**
+ *  mptcp_splice_read - splice data from MPTCP socket to a pipe
+ * @sock:	socket to splice from
+ * @ppos:	position (not valid)
+ * @pipe:	pipe to splice to
+ * @len:	number of bytes to splice
+ * @flags:	splice modifier flags
+ *
+ * Description:
+ *    Will read pages from given socket and fill them into a pipe.
+ *
+ **/
+static ssize_t mptcp_splice_read(struct socket *sock, loff_t *ppos,
+				 struct pipe_inode_info *pipe, size_t len,
+				 unsigned int flags)
+{
+	struct tcp_splice_state tss = {
+		.pipe	= pipe,
+		.len	= len,
+		.flags	= flags,
+	};
+	struct sock *sk = sock->sk;
+	ssize_t spliced = 0;
+	int ret = 0, err;
+	long timeo;
+
+	/*
+	 * We can't seek on a socket input
+	 */
+	if (unlikely(*ppos))
+		return -ESPIPE;
+
+	lock_sock(sk);
+
+	timeo = sock_rcvtimeo(sk, sock->file->f_flags & O_NONBLOCK);
+	while (tss.len) {
+		ret = __mptcp_splice_read(sk, &tss);
+		if (ret < 0) {
+			break;
+		} else if (!ret) {
+			if (spliced)
+				break;
+			err = tcp_recv_should_stop(sk, timeo);
+			if (err < 0) {
+				if (err == -ESHUTDOWN) {
+					if (__mptcp_move_skbs(sk))
+						continue;
+					break;
+				}
+				ret = err;
+				break;
+			}
+			/* if __mptcp_splice_read() got nothing while we have
+			 * an skb in receive queue, we do not want to loop.
+			 * This might happen with URG data.
+			 */
+			if (!skb_queue_empty(&sk->sk_receive_queue))
+				break;
+			ret = sk_wait_data(sk, &timeo, NULL);
+			if (ret < 0)
+				break;
+			continue;
+		}
+		tss.len -= ret;
+		spliced += ret;
+
+		if (!tss.len)
+			break;
+
+		if (tcp_recv_should_stop(sk, timeo))
+			break;
+	}
+
+	release_sock(sk);
+
+	if (spliced)
+		return spliced;
+
+	return ret;
+}
+
 static const struct proto_ops mptcp_stream_ops = {
 	.family		   = PF_INET,
 	.owner		   = THIS_MODULE,
@@ -XXX,XX +XXX,XX @@ static const struct proto_ops mptcp_stream_ops = {
 	.mmap		   = sock_no_mmap,
 	.set_rcvlowat	   = mptcp_set_rcvlowat,
 	.read_sock	   = mptcp_read_sock,
+	.splice_read	   = mptcp_splice_read,
 };
 
 static struct inet_protosw mptcp_protosw = {
@@ -XXX,XX +XXX,XX @@ static const struct proto_ops mptcp_v6_stream_ops = {
 #endif
 	.set_rcvlowat	   = mptcp_set_rcvlowat,
 	.read_sock	   = mptcp_read_sock,
+	.splice_read	   = mptcp_splice_read,
 };
 
 static struct proto mptcp_v6_prot;
-- 
2.48.1

From: Geliang Tang <tanggeliang@kylinos.cn>

This patch adds a new 'splice' io mode for mptcp_connect to test
the newly added read_sock() and splice_read() functions of MPTCP.

do_splice() efficiently transfers data directly between two file
descriptors (infd and outfd) without copying to userspace, using
Linux's splice() system call.

Usage:
	./mptcp_connect.sh -m splice

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 .../selftests/net/mptcp/mptcp_connect.c       | 63 ++++++++++++++++++-
 1 file changed, 62 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.c b/tools/testing/selftests/net/mptcp/mptcp_connect.c
index XXXXXXX..XXXXXXX 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_connect.c
+++ b/tools/testing/selftests/net/mptcp/mptcp_connect.c
@@ -XXX,XX +XXX,XX @@ enum cfg_mode {
 	CFG_MODE_POLL,
 	CFG_MODE_MMAP,
 	CFG_MODE_SENDFILE,
+	CFG_MODE_SPLICE,
 };
 
 enum cfg_peek {
@@ -XXX,XX +XXX,XX @@ static void die_usage(void)
 	fprintf(stderr, "\t-j     -- add additional sleep at connection start and tear down "
 		"-- for MPJ tests\n");
 	fprintf(stderr, "\t-l     -- listens mode, accepts incoming connection\n");
-	fprintf(stderr, "\t-m [poll|mmap|sendfile] -- use poll(default)/mmap+write/sendfile\n");
+	fprintf(stderr, "\t-m [poll|mmap|sendfile|splice] -- use poll(default)/mmap+write/sendfile/splice\n");
 	fprintf(stderr, "\t-M mark -- set socket packet mark\n");
 	fprintf(stderr, "\t-o option -- test sockopt <option>\n");
 	fprintf(stderr, "\t-p num -- use port num\n");
@@ -XXX,XX +XXX,XX @@ static int copyfd_io_sendfile(int infd, int peerfd, int outfd,
 	return err;
 }
 
+static int do_splice(const int infd, const int outfd, const size_t len,
+		     struct wstate *winfo)
+{
+	int pipefd[2];
+	ssize_t bytes;
+	int err;
+
+	err = pipe(pipefd);
+	if (err)
+		return err;
+
+	while ((bytes = splice(infd, NULL, pipefd[1], NULL,
+			       len - winfo->total_len,
+			       SPLICE_F_MOVE | SPLICE_F_MORE)) > 0) {
+		splice(pipefd[0], NULL, outfd, NULL, bytes,
+		       SPLICE_F_MOVE | SPLICE_F_MORE);
+	}
+
+	close(pipefd[0]);
+	close(pipefd[1]);
+
+	return 0;
+}
+
+static int copyfd_io_splice(int infd, int peerfd, int outfd, unsigned int size,
+			    bool *in_closed_after_out, struct wstate *winfo)
+{
+	int err;
+
+	if (listen_mode) {
+		err = do_splice(peerfd, outfd, size, winfo);
+		if (err)
+			return err;
+
+		err = do_splice(infd, peerfd, size, winfo);
+	} else {
+		err = do_splice(infd, peerfd, size, winfo);
+		if (err)
+			return err;
+
+		shut_wr(peerfd);
+
+		err = do_splice(peerfd, outfd, size, winfo);
+		*in_closed_after_out = true;
+	}
+
+	return err;
+}
+
 static int copyfd_io(int infd, int peerfd, int outfd, bool close_peerfd, struct wstate *winfo)
 {
 	bool in_closed_after_out = false;
@@ -XXX,XX +XXX,XX @@ static int copyfd_io(int infd, int peerfd, int outfd, bool close_peerfd, struct
 					 &in_closed_after_out, winfo);
 		break;
 
+	case CFG_MODE_SPLICE:
+		file_size = get_infd_size(infd);
+		if (file_size < 0)
+			return file_size;
+		ret = copyfd_io_splice(infd, peerfd, outfd, file_size,
+				       &in_closed_after_out, winfo);
+		break;
+
 	default:
 		fprintf(stderr, "Invalid mode %d\n", cfg_mode);
 
@@ -XXX,XX +XXX,XX @@ int parse_mode(const char *mode)
 		return CFG_MODE_MMAP;
 	if (!strcasecmp(mode, "sendfile"))
 		return CFG_MODE_SENDFILE;
+	if (!strcasecmp(mode, "splice"))
+		return CFG_MODE_SPLICE;
 
 	fprintf(stderr, "Unknown test mode: %s\n", mode);
 	fprintf(stderr, "Supported modes are:\n");
 	fprintf(stderr, "\t\t\"poll\" - interleaved read/write using poll()\n");
 	fprintf(stderr, "\t\t\"mmap\" - send entire input file (mmap+write), then read response (-l will read input first)\n");
 	fprintf(stderr, "\t\t\"sendfile\" - send entire input file (sendfile), then read response (-l will read input first)\n");
+	fprintf(stderr, "\t\t\"splice\" - send entire input file (splice), then read response (-l will read input first)\n");
 
 	die_usage();
 
-- 
2.48.1

From: Geliang Tang <tanggeliang@kylinos.cn>

The "splice" alternate mode for mptcp_connect.sh/.c is available now,
this patch adds mptcp_connect_splice.sh to test it in the MPTCP CI by
default.

Suggested-by: Matthieu Baerts <matttbe@kernel.org>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 tools/testing/selftests/net/mptcp/Makefile                | 2 +-
 tools/testing/selftests/net/mptcp/mptcp_connect_splice.sh | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)
 create mode 100755 tools/testing/selftests/net/mptcp/mptcp_connect_splice.sh

diff --git a/tools/testing/selftests/net/mptcp/Makefile b/tools/testing/selftests/net/mptcp/Makefile
index XXXXXXX..XXXXXXX 100644
--- a/tools/testing/selftests/net/mptcp/Makefile
+++ b/tools/testing/selftests/net/mptcp/Makefile
@@ -XXX,XX +XXX,XX @@ top_srcdir = ../../../../..
 CFLAGS += -Wall -Wl,--no-as-needed -O2 -g -I$(top_srcdir)/usr/include $(KHDR_INCLUDES)
 
 TEST_PROGS := mptcp_connect.sh mptcp_connect_mmap.sh mptcp_connect_sendfile.sh \
-	      mptcp_connect_checksum.sh pm_netlink.sh mptcp_join.sh diag.sh \
+	      mptcp_connect_splice.sh mptcp_connect_checksum.sh pm_netlink.sh mptcp_join.sh diag.sh \
 	      simult_flows.sh mptcp_sockopt.sh userspace_pm.sh
 
 TEST_GEN_FILES = mptcp_connect pm_nl_ctl mptcp_sockopt mptcp_inq mptcp_diag
diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect_splice.sh b/tools/testing/selftests/net/mptcp/mptcp_connect_splice.sh
new file mode 100755
index XXXXXXX..XXXXXXX
--- /dev/null
+++ b/tools/testing/selftests/net/mptcp/mptcp_connect_splice.sh
@@ -XXX,XX +XXX,XX @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+"$(dirname "${0}")/mptcp_connect.sh" -m splice "${@}"
-- 
2.48.1

From: Geliang Tang <tanggeliang@kylinos.cn>

v12:
 - rebase on "mptcp: receive path improvement" 1-7.
 - some cleanups.

v11:
 - drop "tcp: drop release and lock again in splice_read", and add this
   release and lock again in mptcp_splice_read too. (Thanks Mat, I didn't
   understand the intent of this code before.)
 - call mptcp_rps_record_subflows() in mptcp_splice_read as Mat
   suggested.

v10:
 - add an offset parameter for mptcp_recv_skb and make it more like
tcp_recv_skb.
 - Link: https://patchwork.kernel.org/project/mptcp/cover/cover.1756780274.git.tanggeliang@kylinos.cn/

v9:
 - merge the squash-to patches.
 - a new patch "drop release and lock again in splice_read".
 - Link: https://patchwork.kernel.org/project/mptcp/cover/cover.1752399660.git.tanggeliang@kylinos.cn/

v8:
 - export struct tcp_splice_state and tcp_splice_data_recv() in net/tcp.h.
 - add a new helper mptcp_recv_should_stop.
 - add mptcp_connect_splice.sh.
 - update commit logs.

v6:
 - address Paolo's comments for v4, v5 (thanks)

v5:
 - extract the common code of __mptcp_recvmsg_mskq() and mptcp_read_sock()
 into a new helper __mptcp_recvmsg_desc() to reduce duplication code.

v4:
 - v3 doesn't work for MPTCP fallback tests in mptcp_connect.sh, this
   set fix it.
 - invoke __mptcp_move_skbs in mptcp_read_sock.
 - use INDIRECT_CALL_INET_1 in __tcp_splice_read.

v2:
 - set splice_read of mptcp
 - add a splice selftest.

I have good news! I recently added MPTCP support to "NVME over TCP".
And my RFC patches are under review by NVME maintainer Hannes.

Replacing "NVME over TCP" with MPTCP is very simple. I used IPPROTO_MPTCP
instead of IPPROTO_TCP to create MPTCP sockets on both target and host
sides, these sockets are created in Kernel space.

nvmet_tcp_add_port:

ret = sock_create(port->addr.ss_family, SOCK_STREAM,
				IPPROTO_MPTCP, &port->sock);

nvme_tcp_alloc_queue:

ret = sock_create_kern(current->nsproxy->net_ns,
			ctrl->addr.ss_family, SOCK_STREAM,
			IPPROTO_MPTCP, &queue->sock);

nvme_tcp_try_recv() needs to call .read_sock interface of struct
proto_ops, but it is not implemented in MPTCP. So I implemented it
with reference to __mptcp_recvmsg_mskq().

Since the NVME part patches are still under reviewing, I only send the
MPTCP part patches in this set to MPTCP ML for your opinions.

Geliang Tang (8):
  mptcp: add eat_recv_skb helper
  mptcp: implement .read_sock
  tcp: export splice_state and splice_data_recv
  tcp: add recv_should_stop helper
  mptcp: use recv_should_stop helper
  mptcp: implement .splice_read
  selftests: mptcp: add splice io mode
  selftests: mptcp: connect: cover splice mode

include/net/tcp.h                             |  35 +++
 net/ipv4/tcp.c                                |  86 ++-----
 net/mptcp/protocol.c                          | 224 +++++++++++++++---
 tools/testing/selftests/net/mptcp/Makefile    |   1 +
 .../selftests/net/mptcp/mptcp_connect.c       |  63 ++++-
 .../net/mptcp/mptcp_connect_splice.sh         |   5 +
 6 files changed, 304 insertions(+), 110 deletions(-)
 create mode 100755 tools/testing/selftests/net/mptcp/mptcp_connect_splice.sh

-- 
2.43.0

From: Geliang Tang <tanggeliang@kylinos.cn>

This patch extracts the free skb related code in __mptcp_recvmsg_mskq()
into a new helper mptcp_eat_recv_skb().

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 net/mptcp/protocol.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index XXXXXXX..XXXXXXX 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -XXX,XX +XXX,XX @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 
 static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied);
 
+static void mptcp_eat_recv_skb(struct sock *sk, struct sk_buff *skb)
+{
+	/* avoid the indirect call, we know the destructor is sock_rfree */
+	skb->destructor = NULL;
+	skb->sk = NULL;
+	atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
+	sk_mem_uncharge(sk, skb->truesize);
+	__skb_unlink(skb, &sk->sk_receive_queue);
+	skb_attempt_defer_free(skb);
+}
+
 static int __mptcp_recvmsg_mskq(struct sock *sk,
 				struct msghdr *msg,
 				size_t len, int flags,
@@ -XXX,XX +XXX,XX @@ static int __mptcp_recvmsg_mskq(struct sock *sk,
 		}
 
 		if (!(flags & MSG_PEEK)) {
-			/* avoid the indirect call, we know the destructor is sock_rfree */
-			skb->destructor = NULL;
-			skb->sk = NULL;
-			atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
-			sk_mem_uncharge(sk, skb->truesize);
-			__skb_unlink(skb, &sk->sk_receive_queue);
-			skb_attempt_defer_free(skb);
+			mptcp_eat_recv_skb(sk, skb);
 			msk->bytes_consumed += count;
 		}
 
-- 
2.43.0

From: Geliang Tang <tanggeliang@kylinos.cn>

nvme_tcp_try_recv() needs to call .read_sock interface of struct
proto_ops, but it's not implemented in MPTCP.

This patch implements it with reference to __tcp_read_sock() and
__mptcp_recvmsg_mskq().

Corresponding to tcp_recv_skb(), a new helper for MPTCP named
mptcp_recv_skb() is added to peek a skb from sk->sk_receive_queue.

Reviewed-by: Hannes Reinecke <hare@kernel.org>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 net/mptcp/protocol.c | 74 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index XXXXXXX..XXXXXXX 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -XXX,XX +XXX,XX @@ static __poll_t mptcp_poll(struct file *file, struct socket *sock,
 	return mask;
 }
 
+static struct sk_buff *mptcp_recv_skb(struct sock *sk, u32 *off)
+{
+	struct sk_buff *skb;
+	u32 offset;
+
+	if (skb_queue_empty(&sk->sk_receive_queue))
+		__mptcp_move_skbs(sk);
+
+	while ((skb = skb_peek(&sk->sk_receive_queue)) != NULL) {
+		offset = MPTCP_SKB_CB(skb)->offset;
+		if (offset < skb->len) {
+			*off = offset;
+			return skb;
+		}
+		mptcp_eat_recv_skb(sk, skb);
+	}
+	return NULL;
+}
+
+/*
+ * Note:
+ *	- It is assumed that the socket was locked by the caller.
+ */
+static int mptcp_read_sock(struct sock *sk, read_descriptor_t *desc,
+			   sk_read_actor_t recv_actor)
+{
+	struct mptcp_sock *msk = mptcp_sk(sk);
+	size_t len = sk->sk_rcvbuf;
+	struct sk_buff *skb;
+	int copied = 0;
+	u32 offset;
+
+	if (sk->sk_state == TCP_LISTEN)
+		return -ENOTCONN;
+	while ((skb = mptcp_recv_skb(sk, &offset)) != NULL) {
+		u32 data_len = skb->len - offset;
+		u32 size = min_t(size_t, len - copied, data_len);
+		int count;
+
+		count = recv_actor(desc, skb, offset, size);
+		if (count <= 0) {
+			if (!copied)
+				copied = count;
+			break;
+		}
+
+		copied += count;
+
+		if (count < data_len) {
+			MPTCP_SKB_CB(skb)->offset += count;
+			MPTCP_SKB_CB(skb)->map_seq += count;
+			msk->bytes_consumed += count;
+			break;
+		}
+
+		mptcp_eat_recv_skb(sk, skb);
+		msk->bytes_consumed += count;
+
+		if (copied >= len)
+			break;
+	}
+
+	mptcp_rcv_space_adjust(msk, copied);
+
+	if (copied > 0) {
+		mptcp_recv_skb(sk, &offset);
+		mptcp_cleanup_rbuf(msk, copied);
+	}
+
+	return copied;
+}
+
 static const struct proto_ops mptcp_stream_ops = {
 	.family		   = PF_INET,
 	.owner		   = THIS_MODULE,
@@ -XXX,XX +XXX,XX @@ static const struct proto_ops mptcp_stream_ops = {
 	.recvmsg	   = inet_recvmsg,
 	.mmap		   = sock_no_mmap,
 	.set_rcvlowat	   = mptcp_set_rcvlowat,
+	.read_sock	   = mptcp_read_sock,
 };
 
 static struct inet_protosw mptcp_protosw = {
@@ -XXX,XX +XXX,XX @@ static const struct proto_ops mptcp_v6_stream_ops = {
 	.compat_ioctl	   = inet6_compat_ioctl,
 #endif
 	.set_rcvlowat	   = mptcp_set_rcvlowat,
+	.read_sock	   = mptcp_read_sock,
 };
 
 static struct proto mptcp_v6_prot;
-- 
2.43.0

From: Geliang Tang <tanggeliang@kylinos.cn>

Export struct tcp_splice_state and tcp_splice_data_recv() in net/tcp.h so
that they can be used by MPTCP.

From: Geliang Tang <tanggeliang@kylinos.cn>

Factor out a new helper tcp_recv_should_stop() from tcp_recvmsg_locked()
and tcp_splice_read() to check whether to stop receiving. It will be used
for MPTCP too.

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 include/net/tcp.h | 23 +++++++++++++++
 net/ipv4/tcp.c    | 73 ++++++++---------------------------------------
 2 files changed, 35 insertions(+), 61 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index XXXXXXX..XXXXXXX 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -XXX,XX +XXX,XX @@ struct tcp_splice_state {
 int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
 			 unsigned int offset, size_t len);
 
+static inline int tcp_recv_should_stop(struct sock *sk, long timeo)
+{
+	if (sock_flag(sk, SOCK_DONE))
+		return -ENETDOWN;
+
+	if (sk->sk_err)
+		return sock_error(sk);
+
+	if (sk->sk_shutdown & RCV_SHUTDOWN)
+		return -ESHUTDOWN;
+
+	if (sk->sk_state == TCP_CLOSE)
+		return -ENOTCONN;
+
+	if (!timeo)
+		return -EAGAIN;
+
+	if (signal_pending(current))
+		return sock_intr_errno(timeo);
+
+	return 0;
+}
+
 
 /* sysctl variables for tcp */
 extern int sysctl_tcp_max_orphans;
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index XXXXXXX..XXXXXXX 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -XXX,XX +XXX,XX @@ ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
 		if (ret < 0)
 			break;
 		else if (!ret) {
+			int err;
+
 			if (spliced)
 				break;
-			if (sock_flag(sk, SOCK_DONE))
-				break;
-			if (sk->sk_err) {
-				ret = sock_error(sk);
-				break;
-			}
-			if (sk->sk_shutdown & RCV_SHUTDOWN)
-				break;
-			if (sk->sk_state == TCP_CLOSE) {
-				/*
-				 * This occurs when user tries to read
-				 * from never connected socket.
-				 */
-				ret = -ENOTCONN;
-				break;
-			}
-			if (!timeo) {
-				ret = -EAGAIN;
+			err = tcp_recv_should_stop(sk, timeo);
+			if (err < 0) {
+				if (err != -ENETDOWN && err != -ESHUTDOWN)
+					ret = err;
 				break;
 			}
 			/* if __tcp_splice_read() got nothing while we have
@@ -XXX,XX +XXX,XX @@ ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
 			ret = sk_wait_data(sk, &timeo, NULL);
 			if (ret < 0)
 				break;
-			if (signal_pending(current)) {
-				ret = sock_intr_errno(timeo);
-				break;
-			}
 			continue;
 		}
 		tss.len -= ret;
@@ -XXX,XX +XXX,XX @@ ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
 		release_sock(sk);
 		lock_sock(sk);
 
-		if (sk->sk_err || sk->sk_state == TCP_CLOSE ||
-		    (sk->sk_shutdown & RCV_SHUTDOWN) ||
-		    signal_pending(current))
+		if (tcp_recv_should_stop(sk, timeo))
 			break;
 	}
 
@@ -XXX,XX +XXX,XX @@ static int tcp_recvmsg_locked(struct sock *sk, struct msghdr *msg, size_t len,
 		if (copied >= target && !READ_ONCE(sk->sk_backlog.tail))
 			break;
 
-		if (copied) {
-			if (!timeo ||
-			    sk->sk_err ||
-			    sk->sk_state == TCP_CLOSE ||
-			    (sk->sk_shutdown & RCV_SHUTDOWN) ||
-			    signal_pending(current))
-				break;
-		} else {
-			if (sock_flag(sk, SOCK_DONE))
-				break;
-
-			if (sk->sk_err) {
-				copied = sock_error(sk);
-				break;
-			}
-
-			if (sk->sk_shutdown & RCV_SHUTDOWN)
-				break;
-
-			if (sk->sk_state == TCP_CLOSE) {
-				/* This occurs when user tries to read
-				 * from never connected socket.
-				 */
-				copied = -ENOTCONN;
-				break;
-			}
-
-			if (!timeo) {
-				copied = -EAGAIN;
-				break;
-			}
-
-			if (signal_pending(current)) {
-				copied = sock_intr_errno(timeo);
-				break;
-			}
+		err = tcp_recv_should_stop(sk, timeo);
+		if (err < 0) {
+			if (!copied && err != -ENETDOWN && err != -ESHUTDOWN)
+				copied = err;
+			break;
 		}
 
 		if (copied >= target) {
-- 
2.43.0

From: Geliang Tang <tanggeliang@kylinos.cn>

Use the newly added tcp_recv_should_stop() helper in mptcp_recvmsg() to
check whether to stop receiving.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 net/mptcp/protocol.c | 35 +++++------------------------------
 1 file changed, 5 insertions(+), 30 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index XXXXXXX..XXXXXXX 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -XXX,XX +XXX,XX @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 		if (copied >= target)
 			break;
 
-		if (copied) {
-			if (sk->sk_err ||
-			    sk->sk_state == TCP_CLOSE ||
-			    (sk->sk_shutdown & RCV_SHUTDOWN) ||
-			    !timeo ||
-			    signal_pending(current))
-				break;
-		} else {
-			if (sk->sk_err) {
-				copied = sock_error(sk);
-				break;
-			}
-
-			if (sk->sk_shutdown & RCV_SHUTDOWN)
-				break;
-
-			if (sk->sk_state == TCP_CLOSE) {
-				copied = -ENOTCONN;
-				break;
-			}
-
-			if (!timeo) {
-				copied = -EAGAIN;
-				break;
-			}
-
-			if (signal_pending(current)) {
-				copied = sock_intr_errno(timeo);
-				break;
-			}
+		err = tcp_recv_should_stop(sk, timeo);
+		if (err < 0) {
+			if (!copied && err != -ESHUTDOWN)
+				copied = err;
+			break;
 		}
 
 		pr_debug("block timeout %ld\n", timeo);
-- 
2.43.0

From: Geliang Tang <tanggeliang@kylinos.cn>

This patch implements .splice_read interface of mptcp struct proto_ops
as mptcp_splice_read() with reference to tcp_splice_read().

Corresponding to __tcp_splice_read(), __mptcp_splice_read() is defined,
invoking mptcp_read_sock() instead of tcp_read_sock().

mptcp_splice_read() is almost the same as tcp_splice_read(), except for
sock_rps_record_flow().

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 net/mptcp/protocol.c | 96 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index XXXXXXX..XXXXXXX 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -XXX,XX +XXX,XX @@ static int mptcp_read_sock(struct sock *sk, read_descriptor_t *desc,
 	return copied;
 }
 
+static int __mptcp_splice_read(struct sock *sk, struct tcp_splice_state *tss)
+{
+	/* Store TCP splice context information in read_descriptor_t. */
+	read_descriptor_t rd_desc = {
+		.arg.data = tss,
+		.count	  = tss->len,
+	};
+
+	return mptcp_read_sock(sk, &rd_desc, tcp_splice_data_recv);
+}
+
+/**
+ *  mptcp_splice_read - splice data from MPTCP socket to a pipe
+ * @sock:	socket to splice from
+ * @ppos:	position (not valid)
+ * @pipe:	pipe to splice to
+ * @len:	number of bytes to splice
+ * @flags:	splice modifier flags
+ *
+ * Description:
+ *    Will read pages from given socket and fill them into a pipe.
+ *
+ **/
+static ssize_t mptcp_splice_read(struct socket *sock, loff_t *ppos,
+				 struct pipe_inode_info *pipe, size_t len,
+				 unsigned int flags)
+{
+	struct tcp_splice_state tss = {
+		.pipe	= pipe,
+		.len	= len,
+		.flags	= flags,
+	};
+	struct sock *sk = sock->sk;
+	ssize_t spliced = 0;
+	int ret = 0;
+	long timeo;
+
+	/*
+	 * We can't seek on a socket input
+	 */
+	if (unlikely(*ppos))
+		return -ESPIPE;
+
+	lock_sock(sk);
+
+	mptcp_rps_record_subflows(mptcp_sk(sk));
+
+	timeo = sock_rcvtimeo(sk, sock->file->f_flags & O_NONBLOCK);
+	while (tss.len) {
+		ret = __mptcp_splice_read(sk, &tss);
+		if (ret < 0) {
+			break;
+		} else if (!ret) {
+			int err;
+
+			if (spliced)
+				break;
+			err = tcp_recv_should_stop(sk, timeo);
+			if (err < 0) {
+				if (err != -ESHUTDOWN)
+					ret = err;
+				break;
+			}
+			/* if __mptcp_splice_read() got nothing while we have
+			 * an skb in receive queue, we do not want to loop.
+			 * This might happen with URG data.
+			 */
+			if (!skb_queue_empty(&sk->sk_receive_queue))
+				break;
+			ret = sk_wait_data(sk, &timeo, NULL);
+			if (ret < 0)
+				break;
+			continue;
+		}
+		tss.len -= ret;
+		spliced += ret;
+
+		if (!tss.len || !timeo)
+			break;
+		release_sock(sk);
+		lock_sock(sk);
+
+		if (tcp_recv_should_stop(sk, timeo))
+			break;
+	}
+
+	release_sock(sk);
+
+	if (spliced)
+		return spliced;
+
+	return ret;
+}
+
 static const struct proto_ops mptcp_stream_ops = {
 	.family		   = PF_INET,
 	.owner		   = THIS_MODULE,
@@ -XXX,XX +XXX,XX @@ static const struct proto_ops mptcp_stream_ops = {
 	.mmap		   = sock_no_mmap,
 	.set_rcvlowat	   = mptcp_set_rcvlowat,
 	.read_sock	   = mptcp_read_sock,
+	.splice_read	   = mptcp_splice_read,
 };
 
 static struct inet_protosw mptcp_protosw = {
@@ -XXX,XX +XXX,XX @@ static const struct proto_ops mptcp_v6_stream_ops = {
 #endif
 	.set_rcvlowat	   = mptcp_set_rcvlowat,
 	.read_sock	   = mptcp_read_sock,
+	.splice_read	   = mptcp_splice_read,
 };
 
 static struct proto mptcp_v6_prot;
-- 
2.43.0

From: Geliang Tang <tanggeliang@kylinos.cn>

This patch adds a new 'splice' io mode for mptcp_connect to test
the newly added read_sock() and splice_read() functions of MPTCP.

do_splice() efficiently transfers data directly between two file
descriptors (infd and outfd) without copying to userspace, using
Linux's splice() system call.

Usage:
	./mptcp_connect.sh -m splice

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 .../selftests/net/mptcp/mptcp_connect.c       | 63 ++++++++++++++++++-
 1 file changed, 62 insertions(+), 1 deletion(-)

From: Geliang Tang <tanggeliang@kylinos.cn>

The "splice" alternate mode for mptcp_connect.sh/.c is available now,
this patch adds mptcp_connect_splice.sh to test it in the MPTCP CI by
default.

Suggested-by: Matthieu Baerts <matttbe@kernel.org>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 tools/testing/selftests/net/mptcp/Makefile                | 1 +
 tools/testing/selftests/net/mptcp/mptcp_connect_splice.sh | 5 +++++
 2 files changed, 6 insertions(+)
 create mode 100755 tools/testing/selftests/net/mptcp/mptcp_connect_splice.sh

diff --git a/tools/testing/selftests/net/mptcp/Makefile b/tools/testing/selftests/net/mptcp/Makefile
index XXXXXXX..XXXXXXX 100644
--- a/tools/testing/selftests/net/mptcp/Makefile
+++ b/tools/testing/selftests/net/mptcp/Makefile
@@ -XXX,XX +XXX,XX @@ top_srcdir = ../../../../..
 CFLAGS += -Wall -Wl,--no-as-needed -O2 -g -I$(top_srcdir)/usr/include $(KHDR_INCLUDES)
 
 TEST_PROGS := mptcp_connect.sh mptcp_connect_mmap.sh mptcp_connect_sendfile.sh \
+	      mptcp_connect_splice.sh \
 	      mptcp_connect_checksum.sh pm_netlink.sh mptcp_join.sh diag.sh \
 	      simult_flows.sh mptcp_sockopt.sh userspace_pm.sh
 
diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect_splice.sh b/tools/testing/selftests/net/mptcp/mptcp_connect_splice.sh
new file mode 100755
index XXXXXXX..XXXXXXX
--- /dev/null
+++ b/tools/testing/selftests/net/mptcp/mptcp_connect_splice.sh
@@ -XXX,XX +XXX,XX @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+MPTCP_LIB_KSFT_TEST="$(basename "${0}" .sh)" \
+	"$(dirname "${0}")/mptcp_connect.sh" -m splice "${@}"
-- 
2.43.0