netdev - [PATCH v1 net] selftests: af_unix: drain after peek and verify SO_PEEK

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Message-ID: <20260122033605.148626-1-the.latticeheart@gmail.com>
Date: Thu, 22 Jan 2026 12:36:05 +0900
From: Soichiro Ueda <the.latticeheart@...il.com>
To: Kuniyuki Iwashima <kuniyu@...gle.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	netdev@...r.kernel.org
Cc: Simon Horman <horms@...nel.org>,
	Soichiro Ueda <the.latticeheart@...il.com>,
	Miao Wang <shankerwangmiao@...il.com>
Subject: [PATCH v1 net] selftests: af_unix: drain after peek and verify SO_PEEK_OFF reset

Extend the so_peek_off selftest to validate behavior after MSG_PEEK.

After exercising SO_PEEK_OFF via MSG_PEEK, drain the receive queue with a
non-peek recv() and verify that it can receive all the content in the
buffer and SO_PEEK_OFF returns back to 0.

This improvement is suggested by Miao Wang when the so_peek_off selftest
was added.

Link: https://lore.kernel.org/all/7B657CC7-B5CA-46D2-8A4B-8AB5FB83C6DA@gmail.com/
Suggested-by: Miao Wang <shankerwangmiao@...il.com>
Signed-off-by: Soichiro Ueda <the.latticeheart@...il.com>
---
 .../selftests/net/af_unix/so_peek_off.c       | 49 +++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/tools/testing/selftests/net/af_unix/so_peek_off.c b/tools/testing/selftests/net/af_unix/so_peek_off.c
index 86e7b0fb522d..813e3b3655d3 100644
--- a/tools/testing/selftests/net/af_unix/so_peek_off.c
+++ b/tools/testing/selftests/net/af_unix/so_peek_off.c
@@ -76,6 +76,19 @@ FIXTURE_TEARDOWN(so_peek_off)
 		ASSERT_STREQ(str, buf);				\
 	} while (0)
 
+#define peekoffeq(fd, expected)					\
+	do {							\
+		int off = -1;					\
+		socklen_t optlen = sizeof(off);		\
+		int ret;					\
+								\
+		ret = getsockopt(fd, SOL_SOCKET, SO_PEEK_OFF,	\
+				 &off, &optlen);		\
+		ASSERT_EQ(0, ret);				\
+		ASSERT_EQ((socklen_t)sizeof(off), optlen);	\
+		ASSERT_EQ(expected, off);			\
+	} while (0)
+
 #define async							\
 	for (pid_t pid = (pid = fork(),				\
 			  pid < 0 ?				\
@@ -92,6 +105,14 @@ TEST_F(so_peek_off, single_chunk)
 
 	recveq(self->fd[1], "aaaa", 4, MSG_PEEK);
 	recveq(self->fd[1], "bbbb", 100, MSG_PEEK);
+
+	if (variant->type == SOCK_STREAM) {
+		recveq(self->fd[1], "aaaa", 4, 0);
+		recveq(self->fd[1], "bbbb", 100, 0);
+	} else {
+		recveq(self->fd[1], "aaaabbbb", 100, 0);
+	}
+	peekoffeq(self->fd[1], 0);
 }
 
 TEST_F(so_peek_off, two_chunks)
@@ -101,6 +122,13 @@ TEST_F(so_peek_off, two_chunks)
 
 	recveq(self->fd[1], "aaaa", 4, MSG_PEEK);
 	recveq(self->fd[1], "bbbb", 100, MSG_PEEK);
+
+	if (variant->type == SOCK_STREAM)
+		recveq(self->fd[1], "aaaa", 4, 0);
+	else
+		recveq(self->fd[1], "aaaa", 100, 0);
+	recveq(self->fd[1], "bbbb", 100, 0);
+	peekoffeq(self->fd[1], 0);
 }
 
 TEST_F(so_peek_off, two_chunks_blocking)
@@ -119,6 +147,13 @@ TEST_F(so_peek_off, two_chunks_blocking)
 
 	/* goto again; -> goto redo; in unix_stream_read_generic(). */
 	recveq(self->fd[1], "bbbb", 100, MSG_PEEK);
+
+	if (variant->type == SOCK_STREAM)
+		recveq(self->fd[1], "aaaa", 4, 0);
+	else
+		recveq(self->fd[1], "aaaa", 100, 0);
+	recveq(self->fd[1], "bbbb", 100, 0);
+	peekoffeq(self->fd[1], 0);
 }
 
 TEST_F(so_peek_off, two_chunks_overlap)
@@ -137,6 +172,13 @@ TEST_F(so_peek_off, two_chunks_overlap)
 		recveq(self->fd[1], "aa", 100, MSG_PEEK);
 		recveq(self->fd[1], "bbbb", 100, MSG_PEEK);
 	}
+
+	if (variant->type == SOCK_STREAM)
+		recveq(self->fd[1], "aaaa", 4, 0);
+	else
+		recveq(self->fd[1], "aaaa", 100, 0);
+	recveq(self->fd[1], "bbbb", 100, 0);
+	peekoffeq(self->fd[1], 0);
 }
 
 TEST_F(so_peek_off, two_chunks_overlap_blocking)
@@ -157,6 +199,13 @@ TEST_F(so_peek_off, two_chunks_overlap_blocking)
 	recveq(self->fd[1], "aa", 100, MSG_PEEK);
 
 	recveq(self->fd[1], "bbbb", 100, MSG_PEEK);
+
+	if (variant->type == SOCK_STREAM)
+		recveq(self->fd[1], "aaaa", 4, 0);
+	else
+		recveq(self->fd[1], "aaaa", 100, 0);
+	recveq(self->fd[1], "bbbb", 100, 0);
+	peekoffeq(self->fd[1], 0);
 }
 
 TEST_HARNESS_MAIN
-- 
2.52.0