tracing/ring-buffer: Only have tracing_on disable tracing buffers
As the ring-buffer code is being used by other facilities in the
kernel, having tracing_on file disable *all* buffers is not a desired
affect. It should only disable the ftrace buffers that are being used.
Move the code into the trace.c file and use the buffer disabling
for tracing_on() and tracing_off(). This way only the ftrace buffers
will be affected by them and other kernel utilities will not be
confused to why their output suddenly stopped.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 10d5503..f3c13d6 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -352,6 +352,59 @@
static DECLARE_DELAYED_WORK(wakeup_work, wakeup_work_handler);
/**
+ * tracing_on - enable tracing buffers
+ *
+ * This function enables tracing buffers that may have been
+ * disabled with tracing_off.
+ */
+void tracing_on(void)
+{
+ if (global_trace.buffer)
+ ring_buffer_record_on(global_trace.buffer);
+ /*
+ * This flag is only looked at when buffers haven't been
+ * allocated yet. We don't really care about the race
+ * between setting this flag and actually turning
+ * on the buffer.
+ */
+ global_trace.buffer_disabled = 0;
+}
+EXPORT_SYMBOL_GPL(tracing_on);
+
+/**
+ * tracing_off - turn off tracing buffers
+ *
+ * This function stops the tracing buffers from recording data.
+ * It does not disable any overhead the tracers themselves may
+ * be causing. This function simply causes all recording to
+ * the ring buffers to fail.
+ */
+void tracing_off(void)
+{
+ if (global_trace.buffer)
+ ring_buffer_record_on(global_trace.buffer);
+ /*
+ * This flag is only looked at when buffers haven't been
+ * allocated yet. We don't really care about the race
+ * between setting this flag and actually turning
+ * on the buffer.
+ */
+ global_trace.buffer_disabled = 1;
+}
+EXPORT_SYMBOL_GPL(tracing_off);
+
+/**
+ * tracing_is_on - show state of ring buffers enabled
+ */
+int tracing_is_on(void)
+{
+ if (global_trace.buffer)
+ return ring_buffer_record_is_on(global_trace.buffer);
+ return !global_trace.buffer_disabled;
+}
+EXPORT_SYMBOL_GPL(tracing_is_on);
+
+/**
* trace_wake_up - wake up tasks waiting for trace input
*
* Schedules a delayed work to wake up any task that is blocked on the
@@ -4567,6 +4620,55 @@
create_trace_option_core_file(trace_options[i], i);
}
+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;
+ char buf[64];
+ int r;
+
+ if (buffer)
+ r = ring_buffer_record_is_on(buffer);
+ else
+ r = 0;
+
+ r = sprintf(buf, "%d\n", r);
+
+ return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+}
+
+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;
+ unsigned long val;
+ int ret;
+
+ ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
+ if (ret)
+ return ret;
+
+ if (buffer) {
+ if (val)
+ ring_buffer_record_on(buffer);
+ else
+ ring_buffer_record_off(buffer);
+ }
+
+ (*ppos)++;
+
+ return cnt;
+}
+
+static const struct file_operations rb_simple_fops = {
+ .open = tracing_open_generic,
+ .read = rb_simple_read,
+ .write = rb_simple_write,
+ .llseek = default_llseek,
+};
+
static __init int tracer_init_debugfs(void)
{
struct dentry *d_tracer;
@@ -4626,6 +4728,9 @@
trace_create_file("trace_clock", 0644, d_tracer, NULL,
&trace_clock_fops);
+ trace_create_file("tracing_on", 0644, d_tracer,
+ global_trace.buffer, &rb_simple_fops);
+
#ifdef CONFIG_DYNAMIC_FTRACE
trace_create_file("dyn_ftrace_total_info", 0444, d_tracer,
&ftrace_update_tot_cnt, &tracing_dyn_info_fops);
@@ -4863,6 +4968,8 @@
goto out_free_cpumask;
}
global_trace.entries = ring_buffer_size(global_trace.buffer);
+ if (global_trace.buffer_disabled)
+ tracing_off();
#ifdef CONFIG_TRACER_MAX_TRACE
