From 6ba3e0533fa63bdeb5b3c4c9688a4ecba2705722 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 5 May 2025 17:21:09 -0400 Subject: [PATCH] tracing: Use tracer_tracing_disable() instead of "disabled" field for ftrace_dump_one() 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. The ftrace_dump_one() function iterates over all the current tracing CPUs and increments the "disabled" counter before doing the dump, and decrements it afterward. As the disabled flag can be ignored, doing this today is not reliable. Instead use the new tracer_tracing_disable() that calls into the ring buffer code to do the disabling. Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Link: https://lore.kernel.org/20250505212235.381188238@goodmis.org Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index b691af1c1b5a..bb514e988f22 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -10484,7 +10484,7 @@ static void ftrace_dump_one(struct trace_array *tr, enum ftrace_dump_mode dump_m static struct trace_iterator iter; unsigned int old_userobj; unsigned long flags; - int cnt = 0, cpu; + int cnt = 0; /* * Always turn off tracing when we dump. @@ -10501,9 +10501,8 @@ static void ftrace_dump_one(struct trace_array *tr, enum ftrace_dump_mode dump_m /* Simulate the iterator */ trace_init_iter(&iter, tr); - for_each_tracing_cpu(cpu) { - atomic_inc(&per_cpu_ptr(iter.array_buffer->data, cpu)->disabled); - } + /* While dumping, do not allow the buffer to be enable */ + tracer_tracing_disable(tr); old_userobj = tr->trace_flags & TRACE_ITER_SYM_USEROBJ; @@ -10562,9 +10561,7 @@ static void ftrace_dump_one(struct trace_array *tr, enum ftrace_dump_mode dump_m tr->trace_flags |= old_userobj; - for_each_tracing_cpu(cpu) { - atomic_dec(&per_cpu_ptr(iter.array_buffer->data, cpu)->disabled); - } + tracer_tracing_enable(tr); local_irq_restore(flags); } -- 2.25.1