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Commit 6508fa76 authored by Stanislav Fomichev's avatar Stanislav Fomichev Committed by Steven Rostedt
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tracing: let user specify tracing_thresh after selecting function_graph 

Currently, tracing_thresh works only if we specify it before selecting
function_graph tracer. If we do the opposite, tracing_thresh will change
it's value, but it will not be applied.
To fix it, we add update_thresh callback which is called whenever
tracing_thresh is updated and for function_graph tracer we register
handler which reinitializes tracer depending on tracing_thresh.

Link: http://lkml.kernel.org/p/20140718111727.GA3206@stfomichev-desktop.yandex.net



Signed-off-by: default avatarStanislav Fomichev <stfomichev@yandex-team.ru>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 021c5b34

kernel/trace/trace.c

+58 −7
Original line number Diff line number Diff line
@@ -4201,10 +4201,9 @@ tracing_set_trace_write(struct file *filp, const char __user *ubuf, 
}



static ssize_t

tracing_max_lat_read(struct file *filp, char __user *ubuf,

tracing_nsecs_read(unsigned long *ptr, char __user *ubuf,

		   size_t cnt, loff_t *ppos)

{

	unsigned long *ptr = filp->private_data;

	char buf[64];

	int r;
@@ -4216,10 +4215,9 @@ tracing_max_lat_read(struct file *filp, char __user *ubuf, 
}



static ssize_t

tracing_max_lat_write(struct file *filp, const char __user *ubuf,

tracing_nsecs_write(unsigned long *ptr, const char __user *ubuf,

		    size_t cnt, loff_t *ppos)

{

	unsigned long *ptr = filp->private_data;

	unsigned long val;

	int ret;
@@ -4232,6 +4230,52 @@ tracing_max_lat_write(struct file *filp, const char __user *ubuf, 
	return cnt;

}



static ssize_t

tracing_thresh_read(struct file *filp, char __user *ubuf,

		    size_t cnt, loff_t *ppos)

{

	return tracing_nsecs_read(&tracing_thresh, ubuf, cnt, ppos);

}



static ssize_t

tracing_thresh_write(struct file *filp, const char __user *ubuf,

		     size_t cnt, loff_t *ppos)

{

	struct trace_array *tr = filp->private_data;

	int ret;



	mutex_lock(&trace_types_lock);

	ret = tracing_nsecs_write(&tracing_thresh, ubuf, cnt, ppos);

	if (ret < 0)

		goto out;



	if (tr->current_trace->update_thresh) {

		ret = tr->current_trace->update_thresh(tr);

		if (ret < 0)

			goto out;

	}



	ret = cnt;

out:

	mutex_unlock(&trace_types_lock);



	return ret;

}



static ssize_t

tracing_max_lat_read(struct file *filp, char __user *ubuf,

		     size_t cnt, loff_t *ppos)

{

	return tracing_nsecs_read(filp->private_data, ubuf, cnt, ppos);

}



static ssize_t

tracing_max_lat_write(struct file *filp, const char __user *ubuf,

		      size_t cnt, loff_t *ppos)

{

	return tracing_nsecs_write(filp->private_data, ubuf, cnt, ppos);

}



static int tracing_open_pipe(struct inode *inode, struct file *filp)

{

	struct trace_array *tr = inode->i_private;
@@ -5133,6 +5177,13 @@ static int snapshot_raw_open(struct inode *inode, struct file *filp) 
#endif /* CONFIG_TRACER_SNAPSHOT */





static const struct file_operations tracing_thresh_fops = {

	.open		= tracing_open_generic,

	.read		= tracing_thresh_read,

	.write		= tracing_thresh_write,

	.llseek		= generic_file_llseek,

};



static const struct file_operations tracing_max_lat_fops = {

	.open		= tracing_open_generic,

	.read		= tracing_max_lat_read,
@@ -6494,7 +6545,7 @@ static __init int tracer_init_debugfs(void) 
	init_tracer_debugfs(&global_trace, d_tracer);



	trace_create_file("tracing_thresh", 0644, d_tracer,

			&tracing_thresh, &tracing_max_lat_fops);

			&global_trace, &tracing_thresh_fops);



	trace_create_file("README", 0444, d_tracer,

			NULL, &tracing_readme_fops);

kernel/trace/trace.h

+2 −0
Original line number Diff line number Diff line
@@ -339,6 +339,7 @@ struct tracer_flags { 
 * @reset: called when one switches to another tracer

 * @start: called when tracing is unpaused (echo 1 > tracing_enabled)

 * @stop: called when tracing is paused (echo 0 > tracing_enabled)

 * @update_thresh: called when tracing_thresh is updated

 * @open: called when the trace file is opened

 * @pipe_open: called when the trace_pipe file is opened

 * @close: called when the trace file is released
@@ -357,6 +358,7 @@ struct tracer { 
	void			(*reset)(struct trace_array *tr);

	void			(*start)(struct trace_array *tr);

	void			(*stop)(struct trace_array *tr);

	int			(*update_thresh)(struct trace_array *tr);

	void			(*open)(struct trace_iterator *iter);

	void			(*pipe_open)(struct trace_iterator *iter);

	void			(*close)(struct trace_iterator *iter);

kernel/trace/trace_functions_graph.c

+7 −0
Original line number Diff line number Diff line
@@ -475,6 +475,12 @@ static void graph_trace_reset(struct trace_array *tr) 
	unregister_ftrace_graph();

}



int graph_trace_update_thresh(struct trace_array *tr)

{

	graph_trace_reset(tr);

	return graph_trace_init(tr);

}



static int max_bytes_for_cpu;



static enum print_line_t
@@ -1525,6 +1531,7 @@ static struct trace_event graph_trace_ret_event = { 


static struct tracer graph_trace __tracer_data = {

	.name		= "function_graph",

	.update_thresh	= graph_trace_update_thresh,

	.open		= graph_trace_open,

	.pipe_open	= graph_trace_open,

	.close		= graph_trace_close,