[PATCH] tracing: Create output file from cmd_check_undefined

["Thomas Weißschuh" <linux@weissschuh.net>]

As the output file is currently never created, the check will run every
time, even if the inputs have not changed.

Create an empty output file which allows make to skip the execution when
it is not necessary.

Fixes: 1211907ac0b5 ("tracing: Generate undef symbols allowlist for simple_ring_buffer")
Fixes: 58b4bd18390e ("tracing: Adjust cmd_check_undefined to show unexpected undefined symbols")
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
 kernel/trace/Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 1decdce8cbef..b5797457f9f4 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -154,7 +154,8 @@ quiet_cmd_check_undefined = NM      $<
               echo "Unexpected symbols in $<:" >&2; \
               echo "$$undefsyms" >&2; \
               false; \
-          fi
+          fi; \
+          touch $@
 
 $(obj)/%.o.checked: $(obj)/%.o $(obj)/undefsyms_base.o FORCE
 	$(call if_changed,check_undefined)

---
base-commit: 254f49634ee16a731174d2ae34bc50bd5f45e731
change-id: 20260520-tracing-ringbuffer-check-3a6e748d37b7

Best regards,
--  
Thomas Weißschuh <linux@weissschuh.net>