[PATCHSET 0/4] ftrace: Add support to set_graph_notrace filter (v2)

[PATCHSET 0/4] ftrace: Add support to set_graph_notrace filter (v2)

[Namhyung Kim]

Hi Steve,

I broke the patch into pieces so that it can address what you said.
The patch 1 and 2 are cleanup and preparation you mentioned.  Patch 3
is an one more cleanup I found during the work.  Patch 4 is core of
this patchset and main diferrence to prior version is added comments.

This is based on the current linux-trace/for-next.

I also put this on 'ftrace/nograph-v2' branch in my tree

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

Any comments are welcome, thanks.
Namhyung


Namhyung Kim (4):
  ftrace: Get rid of ftrace_graph_filter_enabled
  ftrace: Introduce struct ftrace_graph_data
  ftrace: Narrow down the protected area of graph_lock
  ftrace: Add set_graph_notrace filter

 include/linux/ftrace.h               |   1 +
 kernel/trace/ftrace.c                | 140 ++++++++++++++++++++++++++---------
 kernel/trace/trace.h                 |  25 ++++++-
 kernel/trace/trace_functions_graph.c |  56 +++++++++++++-
 4 files changed, 181 insertions(+), 41 deletions(-)

-- 
1.7.11.7

[PATCH 1/4] ftrace: Get rid of ftrace_graph_filter_enabled

[Namhyung Kim]

From: Namhyung Kim <namhyung.kim@lge.com>

The ftrace_graph_filter_enabled means that user sets function filter
and it always has same meaning of ftrace_graph_count > 0.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 kernel/trace/ftrace.c | 6 +-----
 kernel/trace/trace.h  | 3 +--
 2 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 03cf44ac54d3..a77e4a0142ee 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3776,7 +3776,6 @@ static const struct file_operations ftrace_notrace_fops = {
 static DEFINE_MUTEX(graph_lock);
 
 int ftrace_graph_count;
-int ftrace_graph_filter_enabled;
 unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS] __read_mostly;
 
 static void *
@@ -3799,7 +3798,7 @@ static void *g_start(struct seq_file *m, loff_t *pos)
 	mutex_lock(&graph_lock);
 
 	/* Nothing, tell g_show to print all functions are enabled */
-	if (!ftrace_graph_filter_enabled && !*pos)
+	if (!ftrace_graph_count && !*pos)
 		return (void *)1;
 
 	return __g_next(m, pos);
@@ -3845,7 +3844,6 @@ ftrace_graph_open(struct inode *inode, struct file *file)
 	mutex_lock(&graph_lock);
 	if ((file->f_mode & FMODE_WRITE) &&
 	    (file->f_flags & O_TRUNC)) {
-		ftrace_graph_filter_enabled = 0;
 		ftrace_graph_count = 0;
 		memset(ftrace_graph_funcs, 0, sizeof(ftrace_graph_funcs));
 	}
@@ -3925,8 +3923,6 @@ out:
 	if (fail)
 		return -EINVAL;
 
-	ftrace_graph_filter_enabled = !!(*idx);
-
 	return 0;
 }
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 502fed770751..1ea31a7b1890 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -730,7 +730,6 @@ extern void __trace_graph_return(struct trace_array *tr,
 #ifdef CONFIG_DYNAMIC_FTRACE
 /* TODO: make this variable */
 #define FTRACE_GRAPH_MAX_FUNCS		32
-extern int ftrace_graph_filter_enabled;
 extern int ftrace_graph_count;
 extern unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS];
 
@@ -738,7 +737,7 @@ static inline int ftrace_graph_addr(unsigned long addr)
 {
 	int i;
 
-	if (!ftrace_graph_filter_enabled)
+	if (!ftrace_graph_count)
 		return 1;
 
 	for (i = 0; i < ftrace_graph_count; i++) {
-- 
1.7.11.7

[PATCH 2/4] ftrace: Introduce struct ftrace_graph_data

[Namhyung Kim]

From: Namhyung Kim <namhyung.kim@lge.com>

The struct ftrace_graph_data is for generalizing the access to
set_graph_function file.  This is a preparation for adding support to
set_graph_notrace.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 kernel/trace/ftrace.c | 81 +++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 62 insertions(+), 19 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index a77e4a0142ee..0ff3449b4272 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3641,7 +3641,7 @@ __setup("ftrace_filter=", set_ftrace_filter);
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 static char ftrace_graph_buf[FTRACE_FILTER_SIZE] __initdata;
-static int ftrace_set_func(unsigned long *array, int *idx, char *buffer);
+static int ftrace_set_func(unsigned long *array, int *idx, int size, char *buffer);
 
 static int __init set_graph_function(char *str)
 {
@@ -3659,7 +3659,7 @@ static void __init set_ftrace_early_graph(char *buf)
 		func = strsep(&buf, ",");
 		/* we allow only one expression at a time */
 		ret = ftrace_set_func(ftrace_graph_funcs, &ftrace_graph_count,
-				      func);
+				      FTRACE_GRAPH_MAX_FUNCS, func);
 		if (ret)
 			printk(KERN_DEBUG "ftrace: function %s not "
 					  "traceable\n", func);
@@ -3778,12 +3778,21 @@ static DEFINE_MUTEX(graph_lock);
 int ftrace_graph_count;
 unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS] __read_mostly;
 
+struct ftrace_graph_data {
+	unsigned long *table;
+	size_t size;
+	int *count;
+	const struct seq_operations *seq_ops;
+};
+
 static void *
 __g_next(struct seq_file *m, loff_t *pos)
 {
-	if (*pos >= ftrace_graph_count)
+	struct ftrace_graph_data *fgd = m->private;
+
+	if (*pos >= *fgd->count)
 		return NULL;
-	return &ftrace_graph_funcs[*pos];
+	return &fgd->table[*pos];
 }
 
 static void *
@@ -3795,10 +3804,12 @@ g_next(struct seq_file *m, void *v, loff_t *pos)
 
 static void *g_start(struct seq_file *m, loff_t *pos)
 {
+	struct ftrace_graph_data *fgd = m->private;
+
 	mutex_lock(&graph_lock);
 
 	/* Nothing, tell g_show to print all functions are enabled */
-	if (!ftrace_graph_count && !*pos)
+	if (!*fgd->count && !*pos)
 		return (void *)1;
 
 	return __g_next(m, pos);
@@ -3834,37 +3845,68 @@ static const struct seq_operations ftrace_graph_seq_ops = {
 };
 
 static int
-ftrace_graph_open(struct inode *inode, struct file *file)
+__ftrace_graph_open(struct inode *inode, struct file *file,
+		    struct ftrace_graph_data *fgd)
 {
 	int ret = 0;
 
-	if (unlikely(ftrace_disabled))
-		return -ENODEV;
-
 	mutex_lock(&graph_lock);
 	if ((file->f_mode & FMODE_WRITE) &&
 	    (file->f_flags & O_TRUNC)) {
-		ftrace_graph_count = 0;
-		memset(ftrace_graph_funcs, 0, sizeof(ftrace_graph_funcs));
+		*fgd->count = 0;
+		memset(fgd->table, 0, fgd->size * sizeof(*fgd->table));
 	}
 	mutex_unlock(&graph_lock);
 
-	if (file->f_mode & FMODE_READ)
-		ret = seq_open(file, &ftrace_graph_seq_ops);
+	if (file->f_mode & FMODE_READ) {
+		ret = seq_open(file, fgd->seq_ops);
+		if (!ret) {
+			struct seq_file *m = file->private_data;
+			m->private = fgd;
+		}
+	} else
+		file->private_data = fgd;
 
 	return ret;
 }
 
 static int
+ftrace_graph_open(struct inode *inode, struct file *file)
+{
+	struct ftrace_graph_data *fgd;
+
+	if (unlikely(ftrace_disabled))
+		return -ENODEV;
+
+	fgd = kmalloc(sizeof(*fgd), GFP_KERNEL);
+	if (fgd == NULL)
+		return -ENOMEM;
+
+	fgd->table = ftrace_graph_funcs;
+	fgd->size = FTRACE_GRAPH_MAX_FUNCS;
+	fgd->count = &ftrace_graph_count;
+	fgd->seq_ops = &ftrace_graph_seq_ops;
+
+	return __ftrace_graph_open(inode, file, fgd);
+}
+
+static int
 ftrace_graph_release(struct inode *inode, struct file *file)
 {
-	if (file->f_mode & FMODE_READ)
+	if (file->f_mode & FMODE_READ) {
+		struct seq_file *m = file->private_data;
+
+		kfree(m->private);
 		seq_release(inode, file);
+	} else {
+		kfree(file->private_data);
+	}
+
 	return 0;
 }
 
 static int
-ftrace_set_func(unsigned long *array, int *idx, char *buffer)
+ftrace_set_func(unsigned long *array, int *idx, int size, char *buffer)
 {
 	struct dyn_ftrace *rec;
 	struct ftrace_page *pg;
@@ -3877,7 +3919,7 @@ ftrace_set_func(unsigned long *array, int *idx, char *buffer)
 
 	/* decode regex */
 	type = filter_parse_regex(buffer, strlen(buffer), &search, &not);
-	if (!not && *idx >= FTRACE_GRAPH_MAX_FUNCS)
+	if (!not && *idx >= size)
 		return -EBUSY;
 
 	search_len = strlen(search);
@@ -3905,7 +3947,7 @@ ftrace_set_func(unsigned long *array, int *idx, char *buffer)
 				fail = 0;
 				if (!exists) {
 					array[(*idx)++] = rec->ip;
-					if (*idx >= FTRACE_GRAPH_MAX_FUNCS)
+					if (*idx >= size)
 						goto out;
 				}
 			} else {
@@ -3932,6 +3974,7 @@ ftrace_graph_write(struct file *file, const char __user *ubuf,
 {
 	struct trace_parser parser;
 	ssize_t read, ret;
+	struct ftrace_graph_data *fgd = file->private_data;
 
 	if (!cnt)
 		return 0;
@@ -3949,8 +3992,8 @@ ftrace_graph_write(struct file *file, const char __user *ubuf,
 		parser.buffer[parser.idx] = 0;
 
 		/* we allow only one expression at a time */
-		ret = ftrace_set_func(ftrace_graph_funcs, &ftrace_graph_count,
-					parser.buffer);
+		ret = ftrace_set_func(fgd->table, fgd->count, fgd->size,
+				      parser.buffer);
 		if (ret)
 			goto out_free;
 	}
-- 
1.7.11.7

[PATCH 3/4] ftrace: Narrow down the protected area of graph_lock

[Namhyung Kim]

From: Namhyung Kim <namhyung.kim@lge.com>

It seems that it doesn't need to hold graph_lock during preparation of
the trace_parser.  At least it makes the code a bit simpler IMHO.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 kernel/trace/ftrace.c | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 0ff3449b4272..26a229ab0c19 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3973,37 +3973,33 @@ ftrace_graph_write(struct file *file, const char __user *ubuf,
 		   size_t cnt, loff_t *ppos)
 {
 	struct trace_parser parser;
-	ssize_t read, ret;
+	ssize_t read, ret = 0;
 	struct ftrace_graph_data *fgd = file->private_data;
 
 	if (!cnt)
 		return 0;
 
-	mutex_lock(&graph_lock);
-
-	if (trace_parser_get_init(&parser, FTRACE_BUFF_MAX)) {
-		ret = -ENOMEM;
-		goto out_unlock;
-	}
+	if (trace_parser_get_init(&parser, FTRACE_BUFF_MAX))
+		return -ENOMEM;
 
 	read = trace_get_user(&parser, ubuf, cnt, ppos);
 
 	if (read >= 0 && trace_parser_loaded((&parser))) {
 		parser.buffer[parser.idx] = 0;
 
+		mutex_lock(&graph_lock);
+
 		/* we allow only one expression at a time */
 		ret = ftrace_set_func(fgd->table, fgd->count, fgd->size,
 				      parser.buffer);
-		if (ret)
-			goto out_free;
+
+		mutex_unlock(&graph_lock);
 	}
 
-	ret = read;
+	if (!ret)
+		ret = read;
 
-out_free:
 	trace_parser_put(&parser);
-out_unlock:
-	mutex_unlock(&graph_lock);
 
 	return ret;
 }
-- 
1.7.11.7

[PATCH 4/4] ftrace: Add set_graph_notrace filter

[Namhyung Kim]

From: Namhyung Kim <namhyung.kim@lge.com>

The set_graph_notrace filter is analogous to set_ftrace_notrace and
can be used for eliminating uninteresting part of function graph trace
output.  It also works with set_graph_function nicely.

  # cd /sys/kernel/debug/tracing/
  # echo do_page_fault > set_graph_function
  # perf ftrace live true
   2)               |  do_page_fault() {
   2)               |    __do_page_fault() {
   2)   0.381 us    |      down_read_trylock();
   2)   0.055 us    |      __might_sleep();
   2)   0.696 us    |      find_vma();
   2)               |      handle_mm_fault() {
   2)               |        handle_pte_fault() {
   2)               |          __do_fault() {
   2)               |            filemap_fault() {
   2)               |              find_get_page() {
   2)   0.033 us    |                __rcu_read_lock();
   2)   0.035 us    |                __rcu_read_unlock();
   2)   1.696 us    |              }
   2)   0.031 us    |              __might_sleep();
   2)   2.831 us    |            }
   2)               |            _raw_spin_lock() {
   2)   0.046 us    |              add_preempt_count();
   2)   0.841 us    |            }
   2)   0.033 us    |            page_add_file_rmap();
   2)               |            _raw_spin_unlock() {
   2)   0.057 us    |              sub_preempt_count();
   2)   0.568 us    |            }
   2)               |            unlock_page() {
   2)   0.084 us    |              page_waitqueue();
   2)   0.126 us    |              __wake_up_bit();
   2)   1.117 us    |            }
   2)   7.729 us    |          }
   2)   8.397 us    |        }
   2)   8.956 us    |      }
   2)   0.085 us    |      up_read();
   2) + 12.745 us   |    }
   2) + 13.401 us   |  }
  ...

  # echo handle_mm_fault > set_graph_notrace
  # perf ftrace live true
   1)               |  do_page_fault() {
   1)               |    __do_page_fault() {
   1)   0.205 us    |      down_read_trylock();
   1)   0.041 us    |      __might_sleep();
   1)   0.344 us    |      find_vma();
   1)   0.069 us    |      up_read();
   1)   4.692 us    |    }
   1)   5.311 us    |  }
  ...

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 include/linux/ftrace.h               |  1 +
 kernel/trace/ftrace.c                | 33 +++++++++++++++++++++
 kernel/trace/trace.h                 | 22 ++++++++++++++
 kernel/trace/trace_functions_graph.c | 56 ++++++++++++++++++++++++++++++++++--
 4 files changed, 109 insertions(+), 3 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 9f15c0064c50..ec85d48619e1 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -721,6 +721,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
 extern char __irqentry_text_start[];
 extern char __irqentry_text_end[];
 
+#define FTRACE_NOTRACE_DEPTH 65536
 #define FTRACE_RETFUNC_DEPTH 50
 #define FTRACE_RETSTACK_ALLOC_SIZE 32
 extern int register_ftrace_graph(trace_func_graph_ret_t retfunc,
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 26a229ab0c19..44e826a79665 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3776,7 +3776,9 @@ static const struct file_operations ftrace_notrace_fops = {
 static DEFINE_MUTEX(graph_lock);
 
 int ftrace_graph_count;
+int ftrace_graph_notrace_count;
 unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS] __read_mostly;
+unsigned long ftrace_graph_notrace_funcs[FTRACE_GRAPH_MAX_FUNCS] __read_mostly;
 
 struct ftrace_graph_data {
 	unsigned long *table;
@@ -3891,6 +3893,26 @@ ftrace_graph_open(struct inode *inode, struct file *file)
 }
 
 static int
+ftrace_graph_notrace_open(struct inode *inode, struct file *file)
+{
+	struct ftrace_graph_data *fgd;
+
+	if (unlikely(ftrace_disabled))
+		return -ENODEV;
+
+	fgd = kmalloc(sizeof(*fgd), GFP_KERNEL);
+	if (fgd == NULL)
+		return -ENOMEM;
+
+	fgd->table = ftrace_graph_notrace_funcs;
+	fgd->size = FTRACE_GRAPH_MAX_FUNCS;
+	fgd->count = &ftrace_graph_notrace_count;
+	fgd->seq_ops = &ftrace_graph_seq_ops;
+
+	return __ftrace_graph_open(inode, file, fgd);
+}
+
+static int
 ftrace_graph_release(struct inode *inode, struct file *file)
 {
 	if (file->f_mode & FMODE_READ) {
@@ -4011,6 +4033,14 @@ static const struct file_operations ftrace_graph_fops = {
 	.llseek		= ftrace_filter_lseek,
 	.release	= ftrace_graph_release,
 };
+
+static const struct file_operations ftrace_graph_notrace_fops = {
+	.open		= ftrace_graph_notrace_open,
+	.read		= seq_read,
+	.write		= ftrace_graph_write,
+	.llseek		= ftrace_filter_lseek,
+	.release	= ftrace_graph_release,
+};
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 
 static __init int ftrace_init_dyn_debugfs(struct dentry *d_tracer)
@@ -4032,6 +4062,9 @@ static __init int ftrace_init_dyn_debugfs(struct dentry *d_tracer)
 	trace_create_file("set_graph_function", 0444, d_tracer,
 				    NULL,
 				    &ftrace_graph_fops);
+	trace_create_file("set_graph_notrace", 0444, d_tracer,
+				    NULL,
+				    &ftrace_graph_notrace_fops);
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 
 	return 0;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 1ea31a7b1890..fec2d75a733f 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -732,6 +732,8 @@ extern void __trace_graph_return(struct trace_array *tr,
 #define FTRACE_GRAPH_MAX_FUNCS		32
 extern int ftrace_graph_count;
 extern unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS];
+extern int ftrace_graph_notrace_count;
+extern unsigned long ftrace_graph_notrace_funcs[FTRACE_GRAPH_MAX_FUNCS];
 
 static inline int ftrace_graph_addr(unsigned long addr)
 {
@@ -757,11 +759,31 @@ static inline int ftrace_graph_addr(unsigned long addr)
 
 	return 0;
 }
+
+static inline int ftrace_graph_notrace_addr(unsigned long addr)
+{
+	int i;
+
+	if (!ftrace_graph_notrace_count)
+		return 0;
+
+	for (i = 0; i < ftrace_graph_notrace_count; i++) {
+		if (addr == ftrace_graph_notrace_funcs[i])
+			return 1;
+	}
+
+	return 0;
+}
 #else
 static inline int ftrace_graph_addr(unsigned long addr)
 {
 	return 1;
 }
+
+static inline int ftrace_graph_notrace_addr(unsigned long addr)
+{
+	return 0;
+}
 #endif /* CONFIG_DYNAMIC_FTRACE */
 #else /* CONFIG_FUNCTION_GRAPH_TRACER */
 static inline enum print_line_t
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index b5c09242683d..e08c030b8f38 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -114,16 +114,37 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
 		return -EBUSY;
 	}
 
+	/*
+	 * The curr_ret_stack is an index to ftrace return stack of
+	 * current task.  Its value should be in [0, FTRACE_RETFUNC_
+	 * DEPTH) when the function graph tracer is used.  To support
+	 * filtering out specific functions, it makes the index
+	 * negative by subtracting huge value (FTRACE_NOTRACE_DEPTH)
+	 * so when it sees a negative index the ftrace will ignore
+	 * the record.  And the index gets recovered when returning
+	 * from the filtered function by adding the FTRACE_NOTRACE_
+	 * DEPTH and then it'll continue to record functions normally.
+	 *
+	 * The curr_ret_stack is initialized to -1 and get increased
+	 * in this function.  So it can be less than -1 only if it was
+	 * filtered out via ftrace_graph_notrace_addr() which can be
+	 * set from set_graph_notrace file in debugfs by user.
+	 */
+	if (current->curr_ret_stack < -1)
+		return -EBUSY;
+
 	calltime = trace_clock_local();
 
 	index = ++current->curr_ret_stack;
+	if (ftrace_graph_notrace_addr(func))
+		current->curr_ret_stack -= FTRACE_NOTRACE_DEPTH;
 	barrier();
 	current->ret_stack[index].ret = ret;
 	current->ret_stack[index].func = func;
 	current->ret_stack[index].calltime = calltime;
 	current->ret_stack[index].subtime = 0;
 	current->ret_stack[index].fp = frame_pointer;
-	*depth = index;
+	*depth = current->curr_ret_stack;
 
 	return 0;
 }
@@ -137,7 +158,17 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
 
 	index = current->curr_ret_stack;
 
-	if (unlikely(index < 0)) {
+	/*
+	 * A negative index here means that it's just returned from a
+	 * notrace'd function.  Recover index to get an original
+	 * return address.  See ftrace_push_return_trace().
+	 *
+	 * TODO: Need to check whether the stack gets corrupted.
+	 */
+	if (index < 0)
+		index += FTRACE_NOTRACE_DEPTH;
+
+	if (unlikely(index < 0 || index >= FTRACE_RETFUNC_DEPTH)) {
 		ftrace_graph_stop();
 		WARN_ON(1);
 		/* Might as well panic, otherwise we have no where to go */
@@ -193,6 +224,15 @@ unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
 	trace.rettime = trace_clock_local();
 	barrier();
 	current->curr_ret_stack--;
+	/*
+	 * The curr_ret_stack can be less than -1 only if it was
+	 * filtered out and it's about to return from the function.
+	 * Recover the index and continue to trace normal functions.
+	 */
+	if (current->curr_ret_stack < -1) {
+		current->curr_ret_stack += FTRACE_NOTRACE_DEPTH;
+		return ret;
+	}
 
 	/*
 	 * The trace should run after decrementing the ret counter
@@ -259,10 +299,20 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
 
 	/* trace it when it is-nested-in or is a function enabled. */
 	if ((!(trace->depth || ftrace_graph_addr(trace->func)) ||
-	     ftrace_graph_ignore_irqs()) ||
+	     ftrace_graph_ignore_irqs()) || (trace->depth < 0) ||
 	    (max_depth && trace->depth >= max_depth))
 		return 0;
 
+	/*
+	 * Do not trace a function if it's filtered by set_graph_notrace.
+	 * Make the index of ret stack negative to indicate that it should
+	 * ignore further functions.  But it needs its own ret stack entry
+	 * to recover the original index in order to continue tracing after
+	 * returning from the function.
+	 */
+	if (ftrace_graph_notrace_addr(trace->func))
+		return 1;
+
 	local_irq_save(flags);
 	cpu = raw_smp_processor_id();
 	data = per_cpu_ptr(tr->trace_buffer.data, cpu);
-- 
1.7.11.7