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Commit a8259075 authored by Steven Rostedt's avatar Steven Rostedt
Browse files

tracing: add options directory and core option files 



This patch creates an options directory in the debugfs, that contains
the available tracing options. These files contain 1 or 0, where 1
is the option is enabled and 0 it is disabled.

Simply echoing in 1 will enable the option and 0 will disable it.
This patch only contains the core options, not the tracer options.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
parent 5d0859ce

kernel/trace/trace.c

+117 −0
Original line number Original line Diff line number Diff line
@@ -3093,6 +3093,121 @@ static void tracing_init_debugfs_percpu(long cpu) 
#include "trace_selftest.c"

#include "trace_selftest.c"

#endif

#endif





static ssize_t

trace_options_core_read(struct file *filp, char __user *ubuf, size_t cnt,

			loff_t *ppos)

{

	long index = (long)filp->private_data;

	char *buf;



	if (trace_flags & (1 << index))

		buf = "1\n";

	else

		buf = "0\n";



	return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);

}



static ssize_t

trace_options_core_write(struct file *filp, const char __user *ubuf, size_t cnt,

			 loff_t *ppos)

{

	long index = (long)filp->private_data;

	char buf[64];

	unsigned long val;

	int ret;



	if (cnt >= sizeof(buf))

		return -EINVAL;



	if (copy_from_user(&buf, ubuf, cnt))

		return -EFAULT;



	buf[cnt] = 0;



	ret = strict_strtoul(buf, 10, &val);

	if (ret < 0)

		return ret;



	switch (val) {

	case 0:

		trace_flags &= ~(1 << index);

		break;

	case 1:

		trace_flags |= 1 << index;

		break;



	default:

		return -EINVAL;

	}



	*ppos += cnt;



	return cnt;

}





static const struct file_operations trace_options_core_fops = {

	.open = tracing_open_generic,

	.read = trace_options_core_read,

	.write = trace_options_core_write,

};



static struct dentry *trace_options_init_dentry(void)

{

	struct dentry *d_tracer;

	static struct dentry *t_options;



	if (t_options)

		return t_options;



	d_tracer = tracing_init_dentry();

	if (!d_tracer)

		return NULL;



	t_options = debugfs_create_dir("options", d_tracer);

	if (!t_options) {

		pr_warning("Could not create debugfs directory 'options'\n");

		return NULL;

	}



	return t_options;

}



static struct dentry *

create_trace_option_core_file(const char *option, long index)

{

	struct dentry *t_options;

	struct dentry *entry;



	t_options = trace_options_init_dentry();

	if (!t_options)

		return NULL;



	entry = debugfs_create_file(option, 0644, t_options, (void *)index,

				    &trace_options_core_fops);



	return entry;

}



static __init void create_trace_options_dir(void)

{

	struct dentry *t_options;

	struct dentry *entry;

	int i;



	t_options = trace_options_init_dentry();

	if (!t_options)

		return;



	for (i = 0; trace_options[i]; i++) {

		entry = create_trace_option_core_file(trace_options[i], i);

		if (!entry)

			pr_warning("Could not create debugfs %s entry\n",

				   trace_options[i]);

	}

}



static __init int tracer_init_debugfs(void)

static __init int tracer_init_debugfs(void)

{

{

	struct dentry *d_tracer;

	struct dentry *d_tracer;
@@ -3111,6 +3226,8 @@ static __init int tracer_init_debugfs(void) 
	if (!entry)

	if (!entry)

		pr_warning("Could not create debugfs 'trace_options' entry\n");

		pr_warning("Could not create debugfs 'trace_options' entry\n");





	create_trace_options_dir();



	entry = debugfs_create_file("tracing_cpumask", 0644, d_tracer,

	entry = debugfs_create_file("tracing_cpumask", 0644, d_tracer,

				    NULL, &tracing_cpumask_fops);

				    NULL, &tracing_cpumask_fops);

	if (!entry)

	if (!entry)