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Message-ID: <20140715153157.GC5127@stfomichev-desktop.yandex.net>
Date: Tue, 15 Jul 2014 19:31:57 +0400
From: Stanislav Fomichev <stfomichev@...dex-team.ru>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: fweisbec@...il.com, mingo@...hat.com, jovi.zhangwei@...wei.com,
namhyung.kim@....com, tom.zanussi@...ux.intel.com,
linux-kernel@...r.kernel.org
Subject: Re: [PATCHv3] tracing: let user specify tracing_thresh after
selecting function_graph
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.
Signed-off-by: Stanislav Fomichev <stfomichev@...dex-team.ru>
---
kernel/trace/trace.c | 65 ++++++++++++++++++++++++++++++++----
kernel/trace/trace.h | 2 ++
kernel/trace/trace_functions_graph.c | 20 +++++++++--
3 files changed, 77 insertions(+), 10 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index f243444a3772..986e6cad27d7 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4224,10 +4224,9 @@ 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;
@@ -4239,10 +4238,9 @@ 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;
@@ -4255,6 +4253,52 @@ 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;
@@ -5156,6 +5200,13 @@ 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,
@@ -6519,7 +6570,7 @@ 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 4de3e57f723c..10d86cf83cb8 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -279,7 +279,7 @@ static inline int ftrace_graph_ignore_irqs(void)
int trace_graph_entry(struct ftrace_graph_ent *trace)
{
- struct trace_array *tr = graph_array;
+ struct trace_array *tr = ACCESS_ONCE(graph_array);
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
@@ -287,7 +287,7 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
int cpu;
int pc;
- if (!ftrace_trace_task(current))
+ if (!tr || !ftrace_trace_task(current))
return 0;
/* trace it when it is-nested-in or is a function enabled. */
@@ -384,13 +384,16 @@ void __trace_graph_return(struct trace_array *tr,
void trace_graph_return(struct ftrace_graph_ret *trace)
{
- struct trace_array *tr = graph_array;
+ struct trace_array *tr = ACCESS_ONCE(graph_array);
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
int cpu;
int pc;
+ if (!tr)
+ return;
+
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = per_cpu_ptr(tr->trace_buffer.data, cpu);
@@ -443,6 +446,16 @@ static void graph_trace_reset(struct trace_array *tr)
{
tracing_stop_cmdline_record();
unregister_ftrace_graph();
+ set_graph_array(NULL);
+}
+
+int graph_trace_update_thresh(struct trace_array *tr)
+{
+ if (graph_array) {
+ graph_trace_reset(tr);
+ return graph_trace_init(tr);
+ }
+ return 0;
}
static int max_bytes_for_cpu;
@@ -1495,6 +1508,7 @@ 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,
--
1.9.1
--
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