[PATCH 0/4] tracing: Small updates on tracing/set_graph_notrace file

[PATCH 0/4] tracing: Small updates on tracing/set_graph_notrace file

[Namhyung Kim]

Hello,

This is an update of recent notrace filter change in the function graph
tracer.  It adds a new kernel boot parameter and also adds description of
the file to the tracing/README in debugfs.  Finally it changes message
when the (both of) notrace filter hash is empty.  They'll print below
message when there's no entry:

  # cat /sys/kernel/debug/tracing/set_graph_notrace
  #### no functions disabled ####


It's also available at 'ftrace/nograph-v3' branch in my tree

  git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git

Thanks,
Namhyung


Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>

Namhyung Kim (4):
  tracing: Add ftrace_graph_notrace boot parameter
  tracing: Improve message of empty set_graph_notrace file
  tracing: Improve message of empty set_ftrace_notrace file
  tracing: Add description of set_graph_notrace to tracing/README

 Documentation/kernel-parameters.txt |    6 +++++
 kernel/trace/ftrace.c               |   46 ++++++++++++++++++++++++++++++-----
 kernel/trace/trace.c                |    1 +
 3 files changed, 47 insertions(+), 6 deletions(-)

-- 
1.7.9.2

[PATCH 1/4] tracing: Add ftrace_graph_notrace boot parameter

[Namhyung Kim]

The ftrace_graph_notrace option is for specifying notrace filter for
function graph tracer at boot time.  It can be altered after boot
using set_graph_notrace file on the debugfs.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 Documentation/kernel-parameters.txt |    6 ++++++
 kernel/trace/ftrace.c               |   24 ++++++++++++++++++++----
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 43842177b771..40cf0caf92a9 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1062,6 +1062,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			that can be changed at run time by the
 			set_graph_function file in the debugfs tracing directory.
 
+	ftrace_graph_notrace=[function-list]
+			[FTRACE] Do not trace from the functions specified in
+			function-list.  This list is a comma separated list of
+			functions that can be changed at run time by the
+			set_graph_notrace file in the debugfs tracing directory.
+
 	gamecon.map[2|3]=
 			[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
 			support via parallel port (up to 5 devices per port)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 071908f58e7a..f08edd7125c6 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3628,6 +3628,7 @@ __setup("ftrace_filter=", set_ftrace_filter);
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 static char ftrace_graph_buf[FTRACE_FILTER_SIZE] __initdata;
+static char ftrace_graph_notrace_buf[FTRACE_FILTER_SIZE] __initdata;
 static int ftrace_set_func(unsigned long *array, int *idx, int size, char *buffer);
 
 static int __init set_graph_function(char *str)
@@ -3637,16 +3638,29 @@ static int __init set_graph_function(char *str)
 }
 __setup("ftrace_graph_filter=", set_graph_function);
 
-static void __init set_ftrace_early_graph(char *buf)
+static int __init set_graph_notrace_function(char *str)
+{
+	strlcpy(ftrace_graph_notrace_buf, str, FTRACE_FILTER_SIZE);
+	return 1;
+}
+__setup("ftrace_graph_notrace=", set_graph_notrace_function);
+
+static void __init set_ftrace_early_graph(char *buf, int enable)
 {
 	int ret;
 	char *func;
+	unsigned long *table = ftrace_graph_funcs;
+	int *count = &ftrace_graph_count;
+
+	if (!enable) {
+		table = ftrace_graph_notrace_funcs;
+		count = &ftrace_graph_notrace_count;
+	}
 
 	while (buf) {
 		func = strsep(&buf, ",");
 		/* we allow only one expression at a time */
-		ret = ftrace_set_func(ftrace_graph_funcs, &ftrace_graph_count,
-				      FTRACE_GRAPH_MAX_FUNCS, func);
+		ret = ftrace_set_func(table, count, FTRACE_GRAPH_MAX_FUNCS, func);
 		if (ret)
 			printk(KERN_DEBUG "ftrace: function %s not "
 					  "traceable\n", func);
@@ -3675,7 +3689,9 @@ static void __init set_ftrace_early_filters(void)
 		ftrace_set_early_filter(&global_ops, ftrace_notrace_buf, 0);
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 	if (ftrace_graph_buf[0])
-		set_ftrace_early_graph(ftrace_graph_buf);
+		set_ftrace_early_graph(ftrace_graph_buf, 1);
+	if (ftrace_graph_notrace_buf[0])
+		set_ftrace_early_graph(ftrace_graph_notrace_buf, 0);
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 }
 
-- 
1.7.9.2

[PATCH 2/4] tracing: Improve message of empty set_graph_notrace file

[Namhyung Kim]

When there's no entry in set_graph_notrace, it'll print below message

  #### all functions enabled ####

While this is technically correct, it's better to print like below:

  #### no functions disabled ####

Reported-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 kernel/trace/ftrace.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index f08edd7125c6..b375cf2cd786 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3833,7 +3833,12 @@ static int g_show(struct seq_file *m, void *v)
 		return 0;
 
 	if (ptr == (unsigned long *)1) {
-		seq_printf(m, "#### all functions enabled ####\n");
+		struct ftrace_graph_data *fgd = m->private;
+
+		if (fgd->table == ftrace_graph_funcs)
+			seq_printf(m, "#### all functions enabled ####\n");
+		else
+			seq_printf(m, "#### no functions disabled ####\n");
 		return 0;
 	}
 
-- 
1.7.9.2

[PATCH 3/4] tracing: Improve message of empty set_ftrace_notrace file

[Namhyung Kim]

When there's no entry in set_ftrace_notrace, it'll print nothing, but
it's better to print something like below like set_graph_notrace does:

  #### no functions disabled ####

Reported-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 kernel/trace/ftrace.c |   15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index b375cf2cd786..566ffa0f3442 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2603,6 +2603,16 @@ static void *t_start(struct seq_file *m, loff_t *pos)
 		return iter;
 	}
 
+	if (iter->flags & FTRACE_ITER_NOTRACE &&
+	    ftrace_hash_empty(ops->notrace_hash)) {
+		if (*pos > 0)
+			return t_hash_start(m, pos);
+		iter->flags |= FTRACE_ITER_PRINTALL;
+		/* reset in case of seek/pread */
+		iter->flags &= ~FTRACE_ITER_HASH;
+		return iter;
+	}
+
 	if (iter->flags & FTRACE_ITER_HASH)
 		return t_hash_start(m, pos);
 
@@ -2639,7 +2649,10 @@ static int t_show(struct seq_file *m, void *v)
 		return t_hash_show(m, iter);
 
 	if (iter->flags & FTRACE_ITER_PRINTALL) {
-		seq_printf(m, "#### all functions enabled ####\n");
+		if (iter->flags & FTRACE_ITER_NOTRACE)
+			seq_printf(m, "#### no functions disabled ####\n");
+		else
+			seq_printf(m, "#### all functions enabled ####\n");
 		return 0;
 	}
 
-- 
1.7.9.2

[PATCH 4/4] tracing: Add description of set_graph_notrace to tracing/README

[Namhyung Kim]

It was missing the description of set_graph_notrace file.  Add it.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 kernel/trace/trace.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 384ede311717..a5f1f8f10645 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3687,6 +3687,7 @@ static const char readme_msg[] =
 #endif
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 	"  set_graph_function\t- Trace the nested calls of a function (function_graph)\n"
+	"  set_graph_notrace\t- Do not trace the nested calls of a function (function_graph)\n"
 	"  max_graph_depth\t- Trace a limited depth of nested calls (0 is unlimited)\n"
 #endif
 #ifdef CONFIG_TRACER_SNAPSHOT
-- 
1.7.9.2

Re: [PATCH 3/4] tracing: Improve message of empty set_ftrace_notrace file

[Steven Rostedt]

On Fri, 13 Jun 2014 01:23:52 +0900
Namhyung Kim <namhyung@kernel.org> wrote:

> When there's no entry in set_ftrace_notrace, it'll print nothing, but
> it's better to print something like below like set_graph_notrace does:
> 
>   #### no functions disabled ####
> 
> Reported-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
>  kernel/trace/ftrace.c |   15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index b375cf2cd786..566ffa0f3442 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -2603,6 +2603,16 @@ static void *t_start(struct seq_file *m, loff_t *pos)
>  		return iter;
>  	}
>  
> +	if (iter->flags & FTRACE_ITER_NOTRACE &&
> +	    ftrace_hash_empty(ops->notrace_hash)) {
> +		if (*pos > 0)
> +			return t_hash_start(m, pos);
> +		iter->flags |= FTRACE_ITER_PRINTALL;
> +		/* reset in case of seek/pread */
> +		iter->flags &= ~FTRACE_ITER_HASH;
> +		return iter;
> +	}

This contains the exact if block as the condition before it. Why not
join the two:

	if ((iter->flags & FTRACE_ITER_FILTER &&
	     ftrace_hash_empty(ops->filter_hash))
	  ||
	    (iter->flags & FTRACE_ITER_NOTRACE &&
	     ftrace_hash_empty(ops->notrace_hash))) {

-- Steve

> +
>  	if (iter->flags & FTRACE_ITER_HASH)
>  		return t_hash_start(m, pos);
>  
> @@ -2639,7 +2649,10 @@ static int t_show(struct seq_file *m, void *v)
>  		return t_hash_show(m, iter);
>  
>  	if (iter->flags & FTRACE_ITER_PRINTALL) {
> -		seq_printf(m, "#### all functions enabled ####\n");
> +		if (iter->flags & FTRACE_ITER_NOTRACE)
> +			seq_printf(m, "#### no functions disabled ####\n");
> +		else
> +			seq_printf(m, "#### all functions enabled ####\n");
>  		return 0;
>  	}
>  

[PATCH v2 3/4] tracing: Improve message of empty set_ftrace_notrace file

[Namhyung Kim]

When there's no entry in set_ftrace_notrace, it'll print nothing, but
it's better to print something like below like set_graph_notrace does:

  #### no functions disabled ####

Reported-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
also updated the ftrace/nograph-v3 branch..

 kernel/trace/ftrace.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index b375cf2cd786..ff402e092df1 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2593,8 +2593,10 @@ static void *t_start(struct seq_file *m, loff_t *pos)
 	 * off, we can short cut and just print out that all
 	 * functions are enabled.
 	 */
-	if (iter->flags & FTRACE_ITER_FILTER &&
-	    ftrace_hash_empty(ops->filter_hash)) {
+	if ((iter->flags & FTRACE_ITER_FILTER &&
+	     ftrace_hash_empty(ops->filter_hash)) ||
+	    (iter->flags & FTRACE_ITER_NOTRACE &&
+	     ftrace_hash_empty(ops->notrace_hash))) {
 		if (*pos > 0)
 			return t_hash_start(m, pos);
 		iter->flags |= FTRACE_ITER_PRINTALL;
@@ -2639,7 +2641,10 @@ static int t_show(struct seq_file *m, void *v)
 		return t_hash_show(m, iter);
 
 	if (iter->flags & FTRACE_ITER_PRINTALL) {
-		seq_printf(m, "#### all functions enabled ####\n");
+		if (iter->flags & FTRACE_ITER_NOTRACE)
+			seq_printf(m, "#### no functions disabled ####\n");
+		else
+			seq_printf(m, "#### all functions enabled ####\n");
 		return 0;
 	}
 
-- 
1.7.9.2