Merge branch 'mptcp-implement-read_sock-and-splice_read'

Matthieu Baerts says:

====================
mptcp: implement .read_sock and .splice_read

This series is a preparation work for future in-kernel MPTCP sockets
usage. Here, two interfaces are implemented: read_sock and splice_read.
As a result of this series, splice() with MPTCP sockets -- which was
already supported -- is now improved.

- Patches 1-2: .read_sock implementation

- Patches 3-4: .splice_read implementation

- Patches 5-6: validate splice() support with MPTCP sockets.
====================

Link: https://patch.msgid.link/20260130-net-next-mptcp-splice-v2-0-31332ba70d7f@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

3 files changed, 84 insertions, 1 deletions

diff --git a/tools/testing/selftests/net/mptcp/Makefile b/tools/testing/selftests/net/mptcp/Makefile
index 4dd6278cd3dd..22ba0da2adb8 100644
--- a/tools/testing/selftests/net/mptcp/Makefile
+++ b/tools/testing/selftests/net/mptcp/Makefile
@@ -11,6 +11,7 @@ TEST_PROGS := \
 	mptcp_connect_checksum.sh \
 	mptcp_connect_mmap.sh \
 	mptcp_connect_sendfile.sh \
+	mptcp_connect_splice.sh \
 	mptcp_join.sh \
 	mptcp_sockopt.sh \
 	pm_netlink.sh \
diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.c b/tools/testing/selftests/net/mptcp/mptcp_connect.c
index 10f6f99cfd4e..a74b13e42ecd 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_connect.c
+++ b/tools/testing/selftests/net/mptcp/mptcp_connect.c
@@ -52,6 +52,7 @@ enum cfg_mode {
 	CFG_MODE_POLL,
 	CFG_MODE_MMAP,
 	CFG_MODE_SENDFILE,
+	CFG_MODE_SPLICE,
 };
 
 enum cfg_peek {
@@ -124,7 +125,7 @@ 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");
@@ -935,6 +936,71 @@ 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)
+{
+	ssize_t in_bytes, out_bytes;
+	int pipefd[2];
+	int err;
+
+	err = pipe(pipefd);
+	if (err) {
+		perror("pipe");
+		return 2;
+	}
+
+again:
+	in_bytes = splice(infd, NULL, pipefd[1], NULL, len - winfo->total_len,
+			  SPLICE_F_MOVE | SPLICE_F_MORE);
+	if (in_bytes < 0) {
+		perror("splice in");
+		err = 3;
+	} else if (in_bytes > 0) {
+		out_bytes = splice(pipefd[0], NULL, outfd, NULL, in_bytes,
+				   SPLICE_F_MOVE | SPLICE_F_MORE);
+		if (out_bytes < 0) {
+			perror("splice out");
+			err = 4;
+		} else if (in_bytes != out_bytes) {
+			fprintf(stderr, "Unexpected transfer: %zu vs %zu\n",
+				in_bytes, out_bytes);
+			err = 5;
+		} else {
+			goto again;
+		}
+	}
+
+	close(pipefd[0]);
+	close(pipefd[1]);
+
+	return err;
+}
+
+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;
@@ -967,6 +1033,14 @@ 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);
 
@@ -1380,12 +1454,15 @@ 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();
 
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 000000000000..241254a966c9
--- /dev/null
+++ b/tools/testing/selftests/net/mptcp/mptcp_connect_splice.sh
@@ -0,0 +1,5 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+MPTCP_LIB_KSFT_TEST="$(basename "${0}" .sh)" \
+	"$(dirname "${0}")/mptcp_connect.sh" -m splice "${@}"