Add test case for resolving family IDs of large Generic Netlink families
(those with 199+ multicast groups):
1. Tests that standard genl_ctrl_resolve() may fail due to:
- Response size exceeding single message limit
- Implementation expecting single response
2. Verifies custom my_genl_ctrl_resolve() works by:
- Using dump mechanism to collect all responses
- Properly handling multi-message replies
- Correctly identifying target family
The test validates that large families can be reliably resolved despite
kernel message size limitations.
Signed-off-by: Yana Bashlykova <yana2...@gmail.com>
---
tools/testing/selftests/net/genetlink.c | 37 +++++++++++++++++++++++++
1 file changed, 37 insertions(+)
diff --git a/tools/testing/selftests/net/genetlink.c
b/tools/testing/selftests/net/genetlink.c
index 0a05402caa20..361840aae918 100644
--- a/tools/testing/selftests/net/genetlink.c
+++ b/tools/testing/selftests/net/genetlink.c
@@ -1142,6 +1142,43 @@ TEST(genl_ctrl_policy)
nl_socket_free(ctrl_sock);
}
+/**
+ * TEST(resolve_large_family_id) - Tests resolution of family ID for
+ * LARGE_GENL Generic Netlink family
+ *
+ * Validates special handling required for families with many multicast groups
(199+):
+ * 1. Standard genl_ctrl_resolve() fails due to message size limitations
+ * 2. Custom my_genl_ctrl_resolve() succeeds by using dump mechanism
+ *
+ * Background:
+ * - Kernel successfully registers large families
+ * - Standard resolution fails because:
+ * * Response doesn't fit in single message
+ * * genl_ctrl_resolve() expects single response
+ * - Custom solution works by:
+ * * Using dump request to get all messages
+ * * Searching for target family in callback
+ *
+ * Verification:
+ * 1. Custom resolver returns valid ID (> 0)
+ * 2. Standard resolver either fails or succeeds (platform-dependent)
+ */
+
+TEST(resolve_large_family_id)
+{
+ int family_id;
+ int no_family_id;
+
+ /* Test custom resolver */
+ family_id = my_genl_ctrl_resolve(LARGE_GENL_FAMILY_NAME);
+ EXPECT_TRUE(family_id > 0);
+
+ /* Test standard resolver (may fail) */
+ no_family_id = genl_ctrl_resolve(socket_alloc_and_conn(),
+ LARGE_GENL_FAMILY_NAME);
+ EXPECT_TRUE(no_family_id > 0);
+}
+
/**
* TEST(capture_end) - Terminates Netlink traffic monitoring session
*
--
2.34.1
