tracing: Fix DECLARE_TRACE_CONDITION

Commit 287050d ("tracing: Add TRACE_EVENT_CONDITIONAL()") adds
macros to define conditional trace events (TRACE_EVENT_CONDITIONAL) and
tracepoints (DECLARE_TRACE_CONDITION), but sets up functionality for
direct use only for the former.

Add preprocessor bits in define_trace.h to allow usage of
DECLARE_TRACE_CONDITION just like DECLARE_TRACE.

Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/20250218123121.253551-2-gmonaco@redhat.com
Fixes: 287050d ("tracing: Add TRACE_EVENT_CONDITIONAL()")
Link: https://lore.kernel.org/linux-trace-kernel/20250128111926.303093-1-gmonaco@redhat.com
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Author: glemco

include/trace/define_trace.h

@@ -76,6 +76,10 @@
 #define DECLARE_TRACE(name, proto, args)	\
 	DEFINE_TRACE(name, PARAMS(proto), PARAMS(args))
 
+#undef DECLARE_TRACE_CONDITION
+#define DECLARE_TRACE_CONDITION(name, proto, args, cond)	\
+	DEFINE_TRACE(name, PARAMS(proto), PARAMS(args))
+
 /* If requested, create helpers for calling these tracepoints from Rust. */
 #ifdef CREATE_RUST_TRACE_POINTS
 #undef DEFINE_RUST_DO_TRACE
@@ -108,6 +112,8 @@
 /* Make all open coded DECLARE_TRACE nops */
 #undef DECLARE_TRACE
 #define DECLARE_TRACE(name, proto, args)
+#undef DECLARE_TRACE_CONDITION
+#define DECLARE_TRACE_CONDITION(name, proto, args, cond)
 
 #ifdef TRACEPOINTS_ENABLED
 #include <trace/trace_events.h>
@@ -129,6 +135,7 @@
 #undef DEFINE_EVENT_CONDITION
 #undef TRACE_HEADER_MULTI_READ
 #undef DECLARE_TRACE
+#undef DECLARE_TRACE_CONDITION
 
 /* Only undef what we defined in this file */
 #ifdef UNDEF_TRACE_INCLUDE_FILE