The get_next_frame() function in psock_tpacket.c was missing a return
statement in its default switch case, leading to a compiler warning.

This was caused by a `bug_on(1)` call, which is defined as an
`assert()`, being compiled out because NDEBUG is defined during the
build.

Instead of adding a `return NULL;` which would silently hide the error
and could lead to crashes later, this change restores the original
author's intent. By adding `#undef NDEBUG` before including <assert.h>,
we ensure the assertion is active and will cause the test to abort if
this unreachable code is ever executed.

Signed-off-by: Wake Liu <wakel@google.com>
---
 tools/testing/selftests/net/psock_tpacket.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/net/psock_tpacket.c b/tools/testing/selftests/net/psock_tpacket.c
index 0dd909e325d9..a54f2eb754ce 100644
--- a/tools/testing/selftests/net/psock_tpacket.c
+++ b/tools/testing/selftests/net/psock_tpacket.c
@@ -38,6 +38,7 @@
 #include <arpa/inet.h>
 #include <stdint.h>
 #include <string.h>
+#undef NDEBUG
 #include <assert.h>
 #include <net/if.h>
 #include <inttypes.h>
-- 
2.50.1.703.g449372360f-goog