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tracing: let user specify tracing_thresh after selecting function_graph

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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>
This commit is contained in:
Stanislav Fomichev 2014-07-18 15:17:27 +04:00 committed by Steven Rostedt
parent 021c5b3445
commit 6508fa761c
3 changed files with 67 additions and 7 deletions
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65
kernel/trace/trace.c
View File

@ -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);

2
kernel/trace/trace.h
View File

@ -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);

7
kernel/trace/trace_functions_graph.c
View File

@ -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,