ftrace: Do not bother checking per CPU "disabled" flag

The per CPU "disabled" value was the original way to disable tracing when
the tracing subsystem was first created. Today, the ring buffer
infrastructure has its own way to disable tracing. In fact, things have
changed so much since 2008 that many things ignore the disable flag.

There's no reason for the function tracer to check it, if tracing is
disabled, the ring buffer will not record the event anyway.

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://lore.kernel.org/20250505212234.868972758@goodmis.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Author: rostedt

kernel/trace/trace_functions.c

@@ -209,7 +209,6 @@ function_trace_call(unsigned long ip, unsigned long parent_ip,
 		    struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
 	struct trace_array *tr = op->private;
-	struct trace_array_cpu *data;
 	unsigned int trace_ctx;
 	int bit;
 
@@ -224,9 +223,7 @@ function_trace_call(unsigned long ip, unsigned long parent_ip,
 
 	trace_ctx = tracing_gen_ctx_dec();
 
-	data = this_cpu_ptr(tr->array_buffer.data);
-	if (!atomic_read(&data->disabled))
-		trace_function(tr, ip, parent_ip, trace_ctx, NULL);
+	trace_function(tr, ip, parent_ip, trace_ctx, NULL);
 
 	ftrace_test_recursion_unlock(bit);
 }
@@ -236,10 +233,8 @@ function_args_trace_call(unsigned long ip, unsigned long parent_ip,
 			 struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
 	struct trace_array *tr = op->private;
-	struct trace_array_cpu *data;
 	unsigned int trace_ctx;
 	int bit;
-	int cpu;
 
 	if (unlikely(!tr->function_enabled))
 		return;
@@ -250,10 +245,7 @@ function_args_trace_call(unsigned long ip, unsigned long parent_ip,
 
 	trace_ctx = tracing_gen_ctx();
 
-	cpu = smp_processor_id();
-	data = per_cpu_ptr(tr->array_buffer.data, cpu);
-	if (!atomic_read(&data->disabled))
-		trace_function(tr, ip, parent_ip, trace_ctx, fregs);
+	trace_function(tr, ip, parent_ip, trace_ctx, fregs);
 
 	ftrace_test_recursion_unlock(bit);
 }
@@ -352,7 +344,6 @@ function_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
 {
 	struct trace_func_repeats *last_info;
 	struct trace_array *tr = op->private;
-	struct trace_array_cpu *data;
 	unsigned int trace_ctx;
 	int bit;
 
@@ -364,8 +355,7 @@ function_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
 		return;
 
 	parent_ip = function_get_true_parent_ip(parent_ip, fregs);
-	data = this_cpu_ptr(tr->array_buffer.data);
-	if (atomic_read(&data->disabled))
+	if (!tracer_tracing_is_on(tr))
 		goto out;
 
 	/*