From: Steven Rostedt <[email protected]> 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. The code already calls tracer_tracing_off() which disables the ring buffer, there's no reason to use the "disabled" flags. Signed-off-by: Steven Rostedt (Google) <[email protected]> --- kernel/trace/trace.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 8ddf6b17215c..bae32778b292 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -10445,7 +10445,7 @@ 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. @@ -10462,10 +10462,6 @@ 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); - } - old_userobj = tr->trace_flags & TRACE_ITER_SYM_USEROBJ; /* don't look at user memory in panic mode */ @@ -10523,9 +10519,6 @@ 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); - } local_irq_restore(flags); } -- 2.47.2
