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Date: Fri, 23 Apr 2021 23:05:41 +0200
From: Daniel Bristot de Oliveira <bristot@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Phil Auld <pauld@...hat.com>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
Kate Carcia <kcarcia@...hat.com>,
Daniel Bristot de Oliveira <bristot@...hat.com>,
Jonathan Corbet <corbet@....net>,
Steven Rostedt <rostedt@...dmis.org>,
Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
Alexandre Chartre <alexandre.chartre@...cle.com>,
Clark Willaims <williams@...hat.com>,
John Kacur <jkacur@...hat.com>,
Juri Lelli <juri.lelli@...hat.com>, linux-doc@...r.kernel.org
Subject: [RFC PATCH V2 6/9] tracing/hwlat: Use the generic function to read/write width and window
Use the trace_ull_config generic implementation to reducing the code of
hwlat detector.
Cc: Jonathan Corbet <corbet@....net>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Alexandre Chartre <alexandre.chartre@...cle.com>
Cc: Clark Willaims <williams@...hat.com>
Cc: John Kacur <jkacur@...hat.com>
Cc: Juri Lelli <juri.lelli@...hat.com>
Cc: linux-doc@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@...hat.com>
---
kernel/trace/trace_hwlat.c | 135 ++++---------------------------------
1 file changed, 14 insertions(+), 121 deletions(-)
diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c
index 289ccd56064a..08a39f2e4e65 100644
--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -504,115 +504,6 @@ static int start_per_cpu_kthreads(struct trace_array *tr)
return 0;
}
-/*
- * 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;
@@ -733,16 +624,18 @@ 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,
+static struct trace_ull_config 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,
+static struct trace_ull_config 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 = {
@@ -775,15 +668,15 @@ static int init_tracefs(void)
hwlat_sample_window = tracefs_create_file("window", 0640,
top_dir,
- &hwlat_data.sample_window,
- &window_fops);
+ &hwlat_window,
+ &trace_ull_config_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_ull_config_fops);
if (!hwlat_sample_width)
goto err;
--
2.26.3
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