Extend the so_peek_off selftest to ensure the socket peek offset is handled correctly after both MSG_PEEK and actual data consumption. Verify that the peek offset advances by the same amount as the number of bytes read when performing a read with 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. The verification after actual data consumption was suggested by Miao Wang when the original so_peek_off selftest was introduced. Link: https://lore.kernel.org/all/7B657CC7-B5CA-46D2-8A4B-8AB5FB83C6DA@gmail.com/ Suggested-by: Miao Wang Signed-off-by: Soichiro Ueda --- v1 -> v2: - Add peekoffeq checks after MSG_PEEK to verify offset advancement - Unify the length in the non-peek read v1: https://lore.kernel.org/netdev/20260122033605.148626-1-the.latticeheart@gmail.com/ .../selftests/net/af_unix/so_peek_off.c | 46 +++++++++++++++++++ 1 file changed, 46 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..9640a3975aee 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 ? \ @@ -91,7 +104,12 @@ TEST_F(so_peek_off, single_chunk) sendeq(self->fd[0], "aaaabbbb", 0); recveq(self->fd[1], "aaaa", 4, MSG_PEEK); + peekoffeq(self->fd[1], 4); recveq(self->fd[1], "bbbb", 100, MSG_PEEK); + peekoffeq(self->fd[1], 8); + + recveq(self->fd[1], "aaaabbbb", 8, 0); + peekoffeq(self->fd[1], 0); } TEST_F(so_peek_off, two_chunks) @@ -100,7 +118,13 @@ TEST_F(so_peek_off, two_chunks) sendeq(self->fd[0], "bbbb", 0); recveq(self->fd[1], "aaaa", 4, MSG_PEEK); + peekoffeq(self->fd[1], 4); recveq(self->fd[1], "bbbb", 100, MSG_PEEK); + peekoffeq(self->fd[1], 8); + + recveq(self->fd[1], "aaaa", 4, 0); + recveq(self->fd[1], "bbbb", 4, 0); + peekoffeq(self->fd[1], 0); } TEST_F(so_peek_off, two_chunks_blocking) @@ -111,6 +135,7 @@ TEST_F(so_peek_off, two_chunks_blocking) } recveq(self->fd[1], "aaaa", 4, MSG_PEEK); + peekoffeq(self->fd[1], 4); async { usleep(1000); @@ -119,24 +144,38 @@ 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); + peekoffeq(self->fd[1], 8); + + recveq(self->fd[1], "aaaa", 4, 0); + recveq(self->fd[1], "bbbb", 4, 0); + peekoffeq(self->fd[1], 0); } TEST_F(so_peek_off, two_chunks_overlap) { sendeq(self->fd[0], "aaaa", 0); recveq(self->fd[1], "aa", 2, MSG_PEEK); + peekoffeq(self->fd[1], 2); sendeq(self->fd[0], "bbbb", 0); if (variant->type == SOCK_STREAM) { /* SOCK_STREAM tries to fill the buffer. */ recveq(self->fd[1], "aabb", 4, MSG_PEEK); + peekoffeq(self->fd[1], 6); recveq(self->fd[1], "bb", 100, MSG_PEEK); + peekoffeq(self->fd[1], 8); } else { /* SOCK_DGRAM and SOCK_SEQPACKET returns at the skb boundary. */ recveq(self->fd[1], "aa", 100, MSG_PEEK); + peekoffeq(self->fd[1], 4); recveq(self->fd[1], "bbbb", 100, MSG_PEEK); + peekoffeq(self->fd[1], 8); } + + recveq(self->fd[1], "aaaa", 4, 0); + recveq(self->fd[1], "bbbb", 4, 0); + peekoffeq(self->fd[1], 0); } TEST_F(so_peek_off, two_chunks_overlap_blocking) @@ -147,6 +186,7 @@ TEST_F(so_peek_off, two_chunks_overlap_blocking) } recveq(self->fd[1], "aa", 2, MSG_PEEK); + peekoffeq(self->fd[1], 2); async { usleep(1000); @@ -155,8 +195,14 @@ TEST_F(so_peek_off, two_chunks_overlap_blocking) /* Even SOCK_STREAM does not wait if at least one byte is read. */ recveq(self->fd[1], "aa", 100, MSG_PEEK); + peekoffeq(self->fd[1], 4); recveq(self->fd[1], "bbbb", 100, MSG_PEEK); + peekoffeq(self->fd[1], 8); + + recveq(self->fd[1], "aaaa", 4, 0); + recveq(self->fd[1], "bbbb", 4, 0); + peekoffeq(self->fd[1], 0); } TEST_HARNESS_MAIN -- 2.53.0