tracing: Fix regression with tracing_on (348f0fc2) · Commits · 戴 / test

The change to make tracing_on affect only the ftrace ring buffer, caused a bug where it wont affect any ring buffer. The problem was that the buffer of the trace_array was passed to the write function and not the trace array itself. The trace_array can change the buffer when running a latency tracer. If this happens, then the buffer being disabled may not be the buffer currently used by ftrace. This will cause the tracing_on file to become useless. The simple fix is to pass the trace_array to the write function instead of the buffer. Then the actual buffer may be changed. Signed-off-by:

Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace.c

+5 −3

Original line number	Diff line number	Diff line
		@@ -4629,7 +4629,8 @@ static ssize_t
		rb_simple_read(struct file filp, char __user ubuf,
		size_t cnt, loff_t *ppos)
		{
		struct ring_buffer *buffer = filp->private_data;
		struct trace_array *tr = filp->private_data;
		struct ring_buffer *buffer = tr->buffer;
		char buf[64];
		int r;

		@@ -4647,7 +4648,8 @@ static ssize_t
		rb_simple_write(struct file filp, const char __user ubuf,
		size_t cnt, loff_t *ppos)
		{
		struct ring_buffer *buffer = filp->private_data;
		struct trace_array *tr = filp->private_data;
		struct ring_buffer *buffer = tr->buffer;
		unsigned long val;
		int ret;

		@@ -4734,7 +4736,7 @@ static __init int tracer_init_debugfs(void)
		&trace_clock_fops);

		trace_create_file("tracing_on", 0644, d_tracer,
		global_trace.buffer, &rb_simple_fops);
		&global_trace, &rb_simple_fops);

		#ifdef CONFIG_DYNAMIC_FTRACE
		trace_create_file("dyn_ftrace_total_info", 0444, d_tracer,

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