[for-next][PATCH 30/32] tracing: let user specify tracing_thresh after selecting function_graph

Steven Rostedt
2014-07-19T13:17:16Z

[-- Attachment #1: 0030-tracing-let-user-specify-tracing_thresh-after-select.patch --]
[-- Type: text/plain, Size: 5629 bytes --]

From: Stanislav Fomichev <stfomichev@yandex-team.ru>

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: Stanislav Fomichev <stfomichev@yandex-team.ru>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace.c | 65 ++++++++++++++++++++++++++++++++----
kernel/trace/trace.h | 2 ++
kernel/trace/trace_functions_graph.c | 7 ++++
3 files changed, 67 insertions(+), 7 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 4a343db45d4e..2752147ed317 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -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,
- size_t cnt, loff_t *ppos)
+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,
- size_t cnt, loff_t *ppos)
+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);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 9258f5a815db..385391fb1d3b 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -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);
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 2c944e6c4a9d..74d98820497c 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -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,
--
2.0.1