tracing: Make tracing_update_buffers() take NULL for global_trace

The trace.c file has become a dumping ground for all tracing code and has
become quite large. In order to move the trace_printk functions out of it
these functions can not access global_trace directly, as that is something
that needs to stay static in trace.c.

Have tracing_update_buffers() take NULL for its trace_array to denote it
should work on the global_trace top level trace_array allows that function
to be used outside of trace.c and still update the global_trace
trace_array.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://patch.msgid.link/20260208032450.318864210@kernel.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Author: rostedt

kernel/trace/trace.c

@@ -3234,7 +3234,7 @@ void trace_printk_init_buffers(void)
 	pr_warn("**********************************************************\n");
 
 	/* Expand the buffers to set size */
-	if (tracing_update_buffers(&global_trace) < 0)
+	if (tracing_update_buffers(NULL) < 0)
 		pr_err("Failed to expand tracing buffers for trace_printk() calls\n");
 	else
 		buffers_allocated = 1;
@@ -6186,6 +6186,9 @@ int tracing_update_buffers(struct trace_array *tr)
 {
 	int ret = 0;
 
+	if (!tr)
+		tr = &global_trace;
+
 	guard(mutex)(&trace_types_lock);
 
 	update_last_data(tr);