From c638ebd8232e69daed2f2573365c48cd1e064a89 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 5 May 2025 17:21:06 -0400 Subject: [PATCH] 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 Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Link: https://lore.kernel.org/20250505212234.868972758@goodmis.org Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_functions.c | 16 +++------------- 1 file changed, 3 insertions(+), 13 deletions(-) diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c index 98ccf3f00c519..bd153219a712b 100644 --- a/kernel/trace/trace_functions.c +++ b/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; /* -- 2.50.1