Re: [PATCH v3 1/2] tracing: Allow tracer to add more than 32 options

On Wed, 15 Oct 2025 17:20:20 -0400
Steven Rostedt [off-list ref] wrote:

On Tue, 30 Sep 2025 07:34:53 +0900
"Masami Hiramatsu (Google)" [off-list ref] wrote:

quoted

--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c

@@ -86,6 +86,11 @@ void __init disable_tracing_selftest(const char *reason)
 #define tracing_selftest_disabled	0
 #endif
 
+/* Define TRACE_ITER_* flags. */
+#undef C
+#define C(a, b) const u64 TRACE_ITER_##a = (1ULL << TRACE_ITER_##a##_BIT);
+TRACE_FLAGS
+

quoted

 #undef C
-#define C(a, b) TRACE_ITER_##a = (1 << TRACE_ITER_##a##_BIT)
+#define C(a, b) extern const u64 TRACE_ITER_##a;
 
-enum trace_iterator_flags { TRACE_FLAGS };
+TRACE_FLAGS
+#undef C

Why all this work when this could have been simply fixed with a:

-enum trace_iterator_flags { TRACE_FLAGS };
+enum64 trace_iterator_flags { TRACE_FLAGS };

With enum64, clang 18 caused this error.

In file included from /home/mhiramat/ksrc/linux/kernel/trace/ring_buffer.c:36:
/home/mhiramat/ksrc/linux/kernel/trace/trace.h:1427:1: error: unknown type name 'enum64'; did you mean 'enum'?
 1427 | enum64 trace_iterator_flags { TRACE_FLAGS };
      | ^~~~~~
      | enum

But below (C++11/C23 or clang/gcc extension) passed.

-enum trace_iterator_flags { TRACE_FLAGS };
+enum trace_iterator_flags : uint64_t { TRACE_FLAGS };


So let's use this.

Thanks,


-- 
Masami Hiramatsu (Google) [off-list ref]