Commit f27a1c9e authored by Daniel Bristot de Oliveira's avatar Daniel Bristot de Oliveira Committed by Steven Rostedt (VMware)
Browse files

trace/hwlat: Use trace_min_max_param for width and window params 

Use the trace_min_max_param to reduce code duplication.

No functional change.

Link: https://lkml.kernel.org/r/b91accd5a7c6c14ea02d3379aae974ba22b47dd6.1624372313.git.bristot@redhat.com



Cc: Phil Auld <pauld@redhat.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Kate Carcia <kcarcia@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Alexandre Chartre <alexandre.chartre@oracle.com>
Cc: Clark Willaims <williams@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarDaniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent bc87cf0a

kernel/trace/trace_hwlat.c

+24 −121
Original line number Diff line number Diff line
@@ -527,115 +527,6 @@ static int start_per_cpu_kthreads(struct trace_array *tr) 
	return retval;

}



/*

 * hwlat_read - Wrapper read function for reading both window and width

 * @filp: The active open file structure

 * @ubuf: The userspace provided buffer to read value into

 * @cnt: The maximum number of bytes to read

 * @ppos: The current "file" position

 *

 * This function provides a generic read implementation for the global state

 * "hwlat_data" structure filesystem entries.

 */

static ssize_t hwlat_read(struct file *filp, char __user *ubuf,

			  size_t cnt, loff_t *ppos)

{

	char buf[U64STR_SIZE];

	u64 *entry = filp->private_data;

	u64 val;

	int len;



	if (!entry)

		return -EFAULT;



	if (cnt > sizeof(buf))

		cnt = sizeof(buf);



	val = *entry;



	len = snprintf(buf, sizeof(buf), "%llu\n", val);



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

}



/**

 * hwlat_width_write - Write function for "width" entry

 * @filp: The active open file structure

 * @ubuf: The user buffer that contains the value to write

 * @cnt: The maximum number of bytes to write to "file"

 * @ppos: The current position in @file

 *

 * This function provides a write implementation for the "width" interface

 * to the hardware latency detector. It can be used to configure

 * for how many us of the total window us we will actively sample for any

 * hardware-induced latency periods. Obviously, it is not possible to

 * sample constantly and have the system respond to a sample reader, or,

 * worse, without having the system appear to have gone out to lunch. It

 * is enforced that width is less that the total window size.

 */

static ssize_t

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

		  size_t cnt, loff_t *ppos)

{

	u64 val;

	int err;



	err = kstrtoull_from_user(ubuf, cnt, 10, &val);

	if (err)

		return err;



	mutex_lock(&hwlat_data.lock);

	if (val < hwlat_data.sample_window)

		hwlat_data.sample_width = val;

	else

		err = -EINVAL;

	mutex_unlock(&hwlat_data.lock);



	if (err)

		return err;



	return cnt;

}



/**

 * hwlat_window_write - Write function for "window" entry

 * @filp: The active open file structure

 * @ubuf: The user buffer that contains the value to write

 * @cnt: The maximum number of bytes to write to "file"

 * @ppos: The current position in @file

 *

 * This function provides a write implementation for the "window" interface

 * to the hardware latency detector. The window is the total time

 * in us that will be considered one sample period. Conceptually, windows

 * occur back-to-back and contain a sample width period during which

 * actual sampling occurs. Can be used to write a new total window size. It

 * is enforced that any value written must be greater than the sample width

 * size, or an error results.

 */

static ssize_t

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

		   size_t cnt, loff_t *ppos)

{

	u64 val;

	int err;



	err = kstrtoull_from_user(ubuf, cnt, 10, &val);

	if (err)

		return err;



	mutex_lock(&hwlat_data.lock);

	if (hwlat_data.sample_width < val)

		hwlat_data.sample_window = val;

	else

		err = -EINVAL;

	mutex_unlock(&hwlat_data.lock);



	if (err)

		return err;



	return cnt;

}



static void *s_mode_start(struct seq_file *s, loff_t *pos)

{

	int mode = *pos;
@@ -760,16 +651,28 @@ static ssize_t hwlat_mode_write(struct file *filp, const char __user *ubuf, 
	return ret;

}



static const struct file_operations width_fops = {

	.open		= tracing_open_generic,

	.read		= hwlat_read,

	.write		= hwlat_width_write,

/*

 * The width parameter is read/write using the generic trace_min_max_param

 * method. The *val is protected by the hwlat_data lock and is upper

 * bounded by the window parameter.

 */

static struct trace_min_max_param hwlat_width = {

	.lock		= &hwlat_data.lock,

	.val		= &hwlat_data.sample_width,

	.max		= &hwlat_data.sample_window,

	.min		= NULL,

};



static const struct file_operations window_fops = {

	.open		= tracing_open_generic,

	.read		= hwlat_read,

	.write		= hwlat_window_write,

/*

 * The window parameter is read/write using the generic trace_min_max_param

 * method. The *val is protected by the hwlat_data lock and is lower

 * bounded by the width parameter.

 */

static struct trace_min_max_param hwlat_window = {

	.lock		= &hwlat_data.lock,

	.val		= &hwlat_data.sample_window,

	.max		= NULL,

	.min		= &hwlat_data.sample_width,

};



static const struct file_operations thread_mode_fops = {
@@ -802,15 +705,15 @@ static int init_tracefs(void) 


	hwlat_sample_window = tracefs_create_file("window", 0640,

						  top_dir,

						  &hwlat_data.sample_window,

						  &window_fops);

						  &hwlat_window,

						  &trace_min_max_fops);

	if (!hwlat_sample_window)

		goto err;



	hwlat_sample_width = tracefs_create_file("width", 0644,

						 top_dir,

						 &hwlat_data.sample_width,

						 &width_fops);

						 &hwlat_width,

						 &trace_min_max_fops);

	if (!hwlat_sample_width)

		goto err;