Re: [PATCH v2 2/2] selftests: liveupdate: add test for double preservation

[Samiullah Khawaja <skhawaja@google.com>]

On Mon, Mar 23, 2026 at 08:31:45PM +0000, Pasha Tatashin wrote:
>Verify that a file can only be preserved once across all active
>sessions. Attempting to preserve it a second time, whether in the same
>or a different session, should fail with EBUSY.
>
>Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
>---
> .../testing/selftests/liveupdate/liveupdate.c | 41 +++++++++++++++++++
> 1 file changed, 41 insertions(+)
>
>diff --git a/tools/testing/selftests/liveupdate/liveupdate.c b/tools/testing/selftests/liveupdate/liveupdate.c
>index c2878e3d5ef9..37c808fbe1e9 100644
>--- a/tools/testing/selftests/liveupdate/liveupdate.c
>+++ b/tools/testing/selftests/liveupdate/liveupdate.c
>@@ -345,4 +345,45 @@ TEST_F(liveupdate_device, preserve_unsupported_fd)
> 	ASSERT_EQ(close(session_fd), 0);
> }
>
>+/*
>+ * Test Case: Prevent Double Preservation
>+ *
>+ * Verifies that a file (memfd) can only be preserved once across all active
>+ * sessions. Attempting to preserve it a second time, whether in the same or
>+ * a different session, should fail with EBUSY.
>+ */
>+TEST_F(liveupdate_device, prevent_double_preservation)
>+{
>+	int session_fd1, session_fd2, mem_fd;
>+	int ret;
>+
>+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
>+	if (self->fd1 < 0 && errno == ENOENT)
>+		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
>+	ASSERT_GE(self->fd1, 0);
>+
>+	session_fd1 = create_session(self->fd1, "double-preserve-session-1");
>+	ASSERT_GE(session_fd1, 0);
>+	session_fd2 = create_session(self->fd1, "double-preserve-session-2");
>+	ASSERT_GE(session_fd2, 0);
>+
>+	mem_fd = memfd_create("test-memfd", 0);
>+	ASSERT_GE(mem_fd, 0);
>+
>+	/* First preservation should succeed */
>+	ASSERT_EQ(preserve_fd(session_fd1, mem_fd, 0x1111), 0);
>+
>+	/* Second preservation in a different session should fail with EBUSY */
>+	ret = preserve_fd(session_fd2, mem_fd, 0x2222);
>+	EXPECT_EQ(ret, -EBUSY);
>+
>+	/* Second preservation in the same session (different token) should fail with EBUSY */
>+	ret = preserve_fd(session_fd1, mem_fd, 0x3333);
>+	EXPECT_EQ(ret, -EBUSY);
>+
>+	ASSERT_EQ(close(mem_fd), 0);
>+	ASSERT_EQ(close(session_fd1), 0);
>+	ASSERT_EQ(close(session_fd2), 0);
>+}
>+
> TEST_HARNESS_MAIN
>-- 
>2.43.0
>

Reviewed-by: Samiullah Khawaja <skhawaja@google.com>