Merge branches 'tracing/kmemtrace2' and 'tracing/ftrace' into tracing/urgent

kernel/trace/Makefile

@@ -19,6 +19,8 @@ obj-$(CONFIG_FUNCTION_TRACER) += libftrace.o
 obj-$(CONFIG_RING_BUFFER) += ring_buffer.o
 
 obj-$(CONFIG_TRACING) += trace.o
+obj-$(CONFIG_TRACING) += trace_output.o
+obj-$(CONFIG_TRACING) += trace_stat.o
 obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
 obj-$(CONFIG_SYSPROF_TRACER) += trace_sysprof.o
 obj-$(CONFIG_FUNCTION_TRACER) += trace_functions.o

kernel/trace/trace.h

@@ -17,7 +17,6 @@ enum trace_type {
 	TRACE_FN,
 	TRACE_CTX,
 	TRACE_WAKE,
-	TRACE_CONT,
 	TRACE_STACK,
 	TRACE_PRINT,
 	TRACE_SPECIAL,
@@ -34,7 +33,7 @@ enum trace_type {
 	TRACE_KMEM_FREE,
 	TRACE_POWER,
 
-	__TRACE_LAST_TYPE
+	__TRACE_LAST_TYPE,
 };
 
 /*
@@ -199,7 +198,6 @@ struct kmemtrace_free_entry {
  *  NEED_RESCED		- reschedule is requested
  *  HARDIRQ		- inside an interrupt handler
  *  SOFTIRQ		- inside a softirq handler
- *  CONT		- multiple entries hold the trace item
  */
 enum trace_flag_type {
 	TRACE_FLAG_IRQS_OFF		= 0x01,
@@ -207,7 +205,6 @@ enum trace_flag_type {
 	TRACE_FLAG_NEED_RESCHED		= 0x04,
 	TRACE_FLAG_HARDIRQ		= 0x08,
 	TRACE_FLAG_SOFTIRQ		= 0x10,
-	TRACE_FLAG_CONT			= 0x20,
 };
 
 #define TRACE_BUF_SIZE		1024
@@ -283,7 +280,6 @@ extern void __ftrace_bad_type(void);
 	do {								\
 		IF_ASSIGN(var, ent, struct ftrace_entry, TRACE_FN);	\
 		IF_ASSIGN(var, ent, struct ctx_switch_entry, 0);	\
-		IF_ASSIGN(var, ent, struct trace_field_cont, TRACE_CONT); \
 		IF_ASSIGN(var, ent, struct stack_entry, TRACE_STACK);	\
 		IF_ASSIGN(var, ent, struct userstack_entry, TRACE_USER_STACK);\
 		IF_ASSIGN(var, ent, struct print_entry, TRACE_PRINT);	\
@@ -365,6 +361,21 @@ struct tracer {
 	struct tracer		*next;
 	int			print_max;
 	struct tracer_flags 	*flags;
+
+	/*
+	 * If you change one of the following on tracing runtime, recall
+	 * init_tracer_stat()
+	 */
+
+	/* Iteration over statistic entries */
+	void			*(*stat_start)(void);
+	void			*(*stat_next)(void *prev, int idx);
+	/* Compare two entries for sorting (optional) for stats */
+	int			(*stat_cmp)(void *p1, void *p2);
+	/* Print a stat entry */
+	int			(*stat_show)(struct seq_file *s, void *p);
+	/* Print the headers of your stat entries */
+	int			(*stat_headers)(struct seq_file *s);
 };
 
 struct trace_seq {
@@ -450,6 +461,8 @@ void tracing_start_sched_switch_record(void);
 int register_tracer(struct tracer *type);
 void unregister_tracer(struct tracer *type);
 
+void init_tracer_stat(struct tracer *trace);
+
 extern unsigned long nsecs_to_usecs(unsigned long nsecs);
 
 extern unsigned long tracing_max_latency;
@@ -481,10 +494,10 @@ struct tracer_switch_ops {
 	void				*private;
 	struct tracer_switch_ops	*next;
 };
-
-char *trace_find_cmdline(int pid);
 #endif /* CONFIG_CONTEXT_SWITCH_TRACER */
 
+extern char *trace_find_cmdline(int pid);
+
 #ifdef CONFIG_DYNAMIC_FTRACE
 extern unsigned long ftrace_update_tot_cnt;
 #define DYN_FTRACE_TEST_NAME trace_selftest_dynamic_test_func
@@ -513,15 +526,6 @@ extern int trace_selftest_startup_branch(struct tracer *trace,
 #endif /* CONFIG_FTRACE_STARTUP_TEST */
 
 extern void *head_page(struct trace_array_cpu *data);
-extern int trace_seq_printf(struct trace_seq *s, const char *fmt, ...);
-extern void trace_seq_print_cont(struct trace_seq *s,
-				 struct trace_iterator *iter);
-
-extern int
-seq_print_ip_sym(struct trace_seq *s, unsigned long ip,
-		unsigned long sym_flags);
-extern ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
-				 size_t cnt);
 extern long ns2usecs(cycle_t nsec);
 extern int
 trace_vprintk(unsigned long ip, int depth, const char *fmt, va_list args);

kernel/trace/trace_boot.c

@@ -11,6 +11,7 @@
 #include <linux/kallsyms.h>
 
 #include "trace.h"
+#include "trace_output.h"
 
 static struct trace_array *boot_trace;
 static bool pre_initcalls_finished;

kernel/trace/trace_branch.c

@@ -14,12 +14,17 @@
 #include <linux/hash.h>
 #include <linux/fs.h>
 #include <asm/local.h>
+
 #include "trace.h"
+#include "trace_output.h"
+
+static struct tracer branch_trace;
 
 #ifdef CONFIG_BRANCH_TRACER
 
 static int branch_tracing_enabled __read_mostly;
 static DEFINE_MUTEX(branch_tracing_mutex);
+
 static struct trace_array *branch_tracer;
 
 static void
@@ -142,22 +147,50 @@ static void branch_trace_reset(struct trace_array *tr)
 	stop_branch_trace(tr);
 }
 
-struct tracer branch_trace __read_mostly =
+static int
+trace_print_print(struct trace_seq *s, struct trace_entry *entry, int flags)
 {
-	.name		= "branch",
-	.init		= branch_trace_init,
-	.reset		= branch_trace_reset,
-#ifdef CONFIG_FTRACE_SELFTEST
-	.selftest	= trace_selftest_startup_branch,
-#endif
-};
+	struct print_entry *field;
 
-__init static int init_branch_trace(void)
+	trace_assign_type(field, entry);
+
+	if (seq_print_ip_sym(s, field->ip, flags))
+		goto partial;
+
+	if (trace_seq_printf(s, ": %s", field->buf))
+		goto partial;
+
+ partial:
+	return TRACE_TYPE_PARTIAL_LINE;
+}
+
+static int
+trace_branch_print(struct trace_seq *s, struct trace_entry *entry, int flags)
 {
-	return register_tracer(&branch_trace);
+	struct trace_branch *field;
+
+	trace_assign_type(field, entry);
+
+	if (trace_seq_printf(s, "[%s] %s:%s:%d\n",
+			     field->correct ? "  ok  " : " MISS ",
+			     field->func,
+			     field->file,
+			     field->line))
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	return 0;
 }
 
-device_initcall(init_branch_trace);
+
+static struct trace_event trace_branch_event = {
+	.type	 	= TRACE_BRANCH,
+	.trace		= trace_branch_print,
+	.latency_trace	= trace_branch_print,
+	.raw		= trace_nop_print,
+	.hex		= trace_nop_print,
+	.binary		= trace_nop_print,
+};
+
 #else
 static inline
 void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)
@@ -183,66 +216,39 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect)
 }
 EXPORT_SYMBOL(ftrace_likely_update);
 
-struct ftrace_pointer {
-	void		*start;
-	void		*stop;
-	int		hit;
-};
+extern unsigned long __start_annotated_branch_profile[];
+extern unsigned long __stop_annotated_branch_profile[];
 
-static void *
-t_next(struct seq_file *m, void *v, loff_t *pos)
+static int annotated_branch_stat_headers(struct seq_file *m)
 {
-	const struct ftrace_pointer *f = m->private;
-	struct ftrace_branch_data *p = v;
-
-	(*pos)++;
-
-	if (v == (void *)1)
-		return f->start;
-
-	++p;
-
-	if ((void *)p >= (void *)f->stop)
-		return NULL;
-
-	return p;
+	seq_printf(m, " correct incorrect  %% ");
+	seq_printf(m, "       Function                "
+			      "  File              Line\n"
+			      " ------- ---------  - "
+			      "       --------                "
+			      "  ----              ----\n");
+	return 0;
 }
 
-static void *t_start(struct seq_file *m, loff_t *pos)
+static inline long get_incorrect_percent(struct ftrace_branch_data *p)
 {
-	void *t = (void *)1;
-	loff_t l = 0;
-
-	for (; t && l < *pos; t = t_next(m, t, &l))
-		;
+	long percent;
 
-	return t;
-}
+	if (p->correct) {
+		percent = p->incorrect * 100;
+		percent /= p->correct + p->incorrect;
+	} else
+		percent = p->incorrect ? 100 : -1;
 
-static void t_stop(struct seq_file *m, void *p)
-{
+	return percent;
 }
 
-static int t_show(struct seq_file *m, void *v)
+static int branch_stat_show(struct seq_file *m, void *v)
 {
-	const struct ftrace_pointer *fp = m->private;
 	struct ftrace_branch_data *p = v;
 	const char *f;
 	long percent;
 
-	if (v == (void *)1) {
-		if (fp->hit)
-			seq_printf(m, "   miss      hit    %% ");
-		else
-			seq_printf(m, " correct incorrect  %% ");
-		seq_printf(m, "       Function                "
-			      "  File              Line\n"
-			      " ------- ---------  - "
-			      "       --------                "
-			      "  ----              ----\n");
-		return 0;
-	}
-
 	/* Only print the file, not the path */
 	f = p->file + strlen(p->file);
 	while (f >= p->file && *f != '/')
@@ -252,11 +258,7 @@ static int t_show(struct seq_file *m, void *v)
 	/*
 	 * The miss is overlayed on correct, and hit on incorrect.
 	 */
-	if (p->correct) {
-		percent = p->incorrect * 100;
-		percent /= p->correct + p->incorrect;
-	} else
-		percent = p->incorrect ? 100 : -1;
+	percent = get_incorrect_percent(p);
 
 	seq_printf(m, "%8lu %8lu ",  p->correct, p->incorrect);
 	if (percent < 0)
@@ -267,76 +269,143 @@ static int t_show(struct seq_file *m, void *v)
 	return 0;
 }
 
-static struct seq_operations tracing_likely_seq_ops = {
-	.start		= t_start,
-	.next		= t_next,
-	.stop		= t_stop,
-	.show		= t_show,
-};
+static void *annotated_branch_stat_start(void)
+{
+	return __start_annotated_branch_profile;
+}
 
-static int tracing_branch_open(struct inode *inode, struct file *file)
+static void *
+annotated_branch_stat_next(void *v, int idx)
 {
-	int ret;
+	struct ftrace_branch_data *p = v;
 
-	ret = seq_open(file, &tracing_likely_seq_ops);
-	if (!ret) {
-		struct seq_file *m = file->private_data;
-		m->private = (void *)inode->i_private;
-	}
+	++p;
 
-	return ret;
+	if ((void *)p >= (void *)__stop_annotated_branch_profile)
+		return NULL;
+
+	return p;
 }
 
-static const struct file_operations tracing_branch_fops = {
-	.open		= tracing_branch_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-};
+static int annotated_branch_stat_cmp(void *p1, void *p2)
+{
+	struct ftrace_branch_data *a = p1;
+	struct ftrace_branch_data *b = p2;
+
+	long percent_a, percent_b;
+
+	percent_a = get_incorrect_percent(a);
+	percent_b = get_incorrect_percent(b);
+
+	if (percent_a < percent_b)
+		return -1;
+	if (percent_a > percent_b)
+		return 1;
+	else
+		return 0;
+}
 
 #ifdef CONFIG_PROFILE_ALL_BRANCHES
-extern unsigned long __start_branch_profile[];
-extern unsigned long __stop_branch_profile[];
+enum {
+	TRACE_BRANCH_OPT_ALL = 0x1
+};
 
-static const struct ftrace_pointer ftrace_branch_pos = {
-	.start			= __start_branch_profile,
-	.stop			= __stop_branch_profile,
-	.hit			= 1,
+static struct tracer_opt branch_opts[] = {
+	{ TRACER_OPT(stat_all_branch, TRACE_BRANCH_OPT_ALL) },
+	{ }
 };
 
-#endif /* CONFIG_PROFILE_ALL_BRANCHES */
+static struct tracer_flags branch_flags = {
+	.val = 0,
+	.opts = branch_opts
+};
 
-extern unsigned long __start_annotated_branch_profile[];
-extern unsigned long __stop_annotated_branch_profile[];
+extern unsigned long __start_branch_profile[];
+extern unsigned long __stop_branch_profile[];
 
-static const struct ftrace_pointer ftrace_annotated_branch_pos = {
-	.start			= __start_annotated_branch_profile,
-	.stop			= __stop_annotated_branch_profile,
-};
+static int all_branch_stat_headers(struct seq_file *m)
+{
+	seq_printf(m, "   miss      hit    %% ");
+	seq_printf(m, "       Function                "
+			      "  File              Line\n"
+			      " ------- ---------  - "
+			      "       --------                "
+			      "  ----              ----\n");
+	return 0;
+}
+
+static void *all_branch_stat_start(void)
+{
+	return __start_branch_profile;
+}
 
-static __init int ftrace_branch_init(void)
+static void *
+all_branch_stat_next(void *v, int idx)
 {
-	struct dentry *d_tracer;
-	struct dentry *entry;
+	struct ftrace_branch_data *p = v;
 
-	d_tracer = tracing_init_dentry();
+	++p;
 
-	entry = debugfs_create_file("profile_annotated_branch", 0444, d_tracer,
-				    (void *)&ftrace_annotated_branch_pos,
-				    &tracing_branch_fops);
-	if (!entry)
-		pr_warning("Could not create debugfs "
-			   "'profile_annotatet_branch' entry\n");
+	if ((void *)p >= (void *)__stop_branch_profile)
+		return NULL;
 
-#ifdef CONFIG_PROFILE_ALL_BRANCHES
-	entry = debugfs_create_file("profile_branch", 0444, d_tracer,
-				    (void *)&ftrace_branch_pos,
-				    &tracing_branch_fops);
-	if (!entry)
-		pr_warning("Could not create debugfs"
-			   " 'profile_branch' entry\n");
-#endif
+	return p;
+}
 
+static int branch_set_flag(u32 old_flags, u32 bit, int set)
+{
+	if (bit == TRACE_BRANCH_OPT_ALL) {
+		if (set) {
+			branch_trace.stat_headers = all_branch_stat_headers;
+			branch_trace.stat_start = all_branch_stat_start;
+			branch_trace.stat_next = all_branch_stat_next;
+			branch_trace.stat_cmp = NULL;
+		} else {
+			branch_trace.stat_headers =
+				annotated_branch_stat_headers;
+			branch_trace.stat_start = annotated_branch_stat_start;
+			branch_trace.stat_next = annotated_branch_stat_next;
+			branch_trace.stat_cmp = annotated_branch_stat_cmp;
+		}
+		init_tracer_stat(&branch_trace);
+	}
 	return 0;
 }
 
-device_initcall(ftrace_branch_init);
+#endif /* CONFIG_PROFILE_ALL_BRANCHES */
+
+static struct tracer branch_trace __read_mostly =
+{
+	.name		= "branch",
+#ifdef CONFIG_BRANCH_TRACER
+	.init		= branch_trace_init,
+	.reset		= branch_trace_reset,
+#ifdef CONFIG_FTRACE_SELFTEST
+	.selftest	= trace_selftest_startup_branch,
+#endif /* CONFIG_FTRACE_SELFTEST */
+#endif /* CONFIG_BRANCH_TRACER */
+	.stat_start	=	annotated_branch_stat_start,
+	.stat_next	= annotated_branch_stat_next,
+	.stat_show	= branch_stat_show,
+	.stat_headers	= annotated_branch_stat_headers,
+	.stat_cmp	= annotated_branch_stat_cmp,
+#ifdef CONFIG_PROFILE_ALL_BRANCHES
+	.flags	= &branch_flags,
+	.set_flag	= branch_set_flag,
+#endif
+};
+
+__init static int init_branch_trace(void)
+{
+#ifdef CONFIG_BRANCH_TRACER
+	int ret;
+	ret = register_ftrace_event(&trace_branch_event);
+	if (!ret) {
+		printk(KERN_WARNING "Warning: could not register branch events\n");
+		return 1;
+	}
+#endif
+
+	return register_tracer(&branch_trace);
+}
+device_initcall(init_branch_trace);

kernel/trace/trace_functions_graph.c

@@ -12,6 +12,7 @@
 #include <linux/fs.h>
 
 #include "trace.h"
+#include "trace_output.h"
 
 #define TRACE_GRAPH_INDENT	2
 
@@ -589,9 +590,6 @@ print_graph_comment(struct print_entry *trace, struct trace_seq *s,
 	if (!ret)
 		return TRACE_TYPE_PARTIAL_LINE;
 
-	if (ent->flags & TRACE_FLAG_CONT)
-		trace_seq_print_cont(s, iter);
-
 	/* Strip ending newline */
 	if (s->buffer[s->len - 1] == '\n') {
 		s->buffer[s->len - 1] = '\0';

kernel/trace/trace_hw_branches.c

@@ -14,6 +14,7 @@
 #include <asm/ds.h>
 
 #include "trace.h"
+#include "trace_output.h"
 
 
 #define SIZEOF_BTS (1 << 13)

kernel/trace/trace_mmiotrace.c

@@ -11,6 +11,7 @@
 #include <linux/pci.h>
 
 #include "trace.h"
+#include "trace_output.h"
 
 struct header_iter {
 	struct pci_dev *dev;
@@ -262,9 +263,6 @@ static enum print_line_t mmio_print_mark(struct trace_iterator *iter)
 	if (!ret)
 		return TRACE_TYPE_PARTIAL_LINE;
 
-	if (entry->flags & TRACE_FLAG_CONT)
-		trace_seq_print_cont(s, iter);
-
 	return TRACE_TYPE_HANDLED;
 }
 

kernel/trace/trace_output.c

+/*
+ * trace_output.c
+ *
+ * Copyright (C) 2008 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/ftrace.h>
+
+#include "trace_output.h"
+
+/* must be a power of 2 */
+#define EVENT_HASHSIZE	128
+
+static DEFINE_MUTEX(trace_event_mutex);
+static struct hlist_head event_hash[EVENT_HASHSIZE] __read_mostly;
+
+static int next_event_type = __TRACE_LAST_TYPE + 1;
+
+/**
+ * trace_seq_printf - sequence printing of trace information
+ * @s: trace sequence descriptor
+ * @fmt: printf format string
+ *
+ * The tracer may use either sequence operations or its own
+ * copy to user routines. To simplify formating of a trace
+ * trace_seq_printf is used to store strings into a special
+ * buffer (@s). Then the output may be either used by
+ * the sequencer or pulled into another buffer.
+ */
+int
+trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
+{
+	int len = (PAGE_SIZE - 1) - s->len;
+	va_list ap;
+	int ret;
+
+	if (!len)
+		return 0;
+
+	va_start(ap, fmt);
+	ret = vsnprintf(s->buffer + s->len, len, fmt, ap);
+	va_end(ap);
+
+	/* If we can't write it all, don't bother writing anything */
+	if (ret >= len)
+		return 0;
+
+	s->len += ret;
+
+	return len;
+}
+
+/**
+ * trace_seq_puts - trace sequence printing of simple string
+ * @s: trace sequence descriptor
+ * @str: simple string to record
+ *
+ * The tracer may use either the sequence operations or its own
+ * copy to user routines. This function records a simple string
+ * into a special buffer (@s) for later retrieval by a sequencer
+ * or other mechanism.
+ */
+int trace_seq_puts(struct trace_seq *s, const char *str)
+{
+	int len = strlen(str);
+
+	if (len > ((PAGE_SIZE - 1) - s->len))
+		return 0;
+
+	memcpy(s->buffer + s->len, str, len);
+	s->len += len;
+
+	return len;
+}
+
+int trace_seq_putc(struct trace_seq *s, unsigned char c)
+{
+	if (s->len >= (PAGE_SIZE - 1))
+		return 0;
+
+	s->buffer[s->len++] = c;
+
+	return 1;
+}
+
+int trace_seq_putmem(struct trace_seq *s, void *mem, size_t len)
+{
+	if (len > ((PAGE_SIZE - 1) - s->len))
+		return 0;
+
+	memcpy(s->buffer + s->len, mem, len);
+	s->len += len;
+
+	return len;
+}
+
+int trace_seq_putmem_hex(struct trace_seq *s, void *mem, size_t len)
+{
+	unsigned char hex[HEX_CHARS];
+	unsigned char *data = mem;
+	int i, j;
+
+#ifdef __BIG_ENDIAN
+	for (i = 0, j = 0; i < len; i++) {
+#else
+	for (i = len-1, j = 0; i >= 0; i--) {
+#endif
+		hex[j++] = hex_asc_hi(data[i]);
+		hex[j++] = hex_asc_lo(data[i]);
+	}
+	hex[j++] = ' ';
+
+	return trace_seq_putmem(s, hex, j);
+}
+
+int trace_seq_path(struct trace_seq *s, struct path *path)
+{
+	unsigned char *p;
+
+	if (s->len >= (PAGE_SIZE - 1))
+		return 0;
+	p = d_path(path, s->buffer + s->len, PAGE_SIZE - s->len);
+	if (!IS_ERR(p)) {
+		p = mangle_path(s->buffer + s->len, p, "\n");
+		if (p) {
+			s->len = p - s->buffer;
+			return 1;
+		}
+	} else {
+		s->buffer[s->len++] = '?';
+		return 1;
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_KRETPROBES
+static inline const char *kretprobed(const char *name)
+{
+	static const char tramp_name[] = "kretprobe_trampoline";
+	int size = sizeof(tramp_name);
+
+	if (strncmp(tramp_name, name, size) == 0)
+		return "[unknown/kretprobe'd]";
+	return name;
+}
+#else
+static inline const char *kretprobed(const char *name)
+{
+	return name;
+}
+#endif /* CONFIG_KRETPROBES */
+
+static int
+seq_print_sym_short(struct trace_seq *s, const char *fmt, unsigned long address)
+{
+#ifdef CONFIG_KALLSYMS
+	char str[KSYM_SYMBOL_LEN];
+	const char *name;
+
+	kallsyms_lookup(address, NULL, NULL, NULL, str);
+
+	name = kretprobed(str);
+
+	return trace_seq_printf(s, fmt, name);
+#endif
+	return 1;
+}
+
+static int
+seq_print_sym_offset(struct trace_seq *s, const char *fmt,
+		     unsigned long address)
+{
+#ifdef CONFIG_KALLSYMS
+	char str[KSYM_SYMBOL_LEN];
+	const char *name;
+
+	sprint_symbol(str, address);
+	name = kretprobed(str);
+
+	return trace_seq_printf(s, fmt, name);
+#endif
+	return 1;
+}
+
+#ifndef CONFIG_64BIT
+# define IP_FMT "%08lx"
+#else
+# define IP_FMT "%016lx"
+#endif
+
+int seq_print_user_ip(struct trace_seq *s, struct mm_struct *mm,
+		      unsigned long ip, unsigned long sym_flags)
+{
+	struct file *file = NULL;
+	unsigned long vmstart = 0;
+	int ret = 1;
+
+	if (mm) {
+		const struct vm_area_struct *vma;
+
+		down_read(&mm->mmap_sem);
+		vma = find_vma(mm, ip);
+		if (vma) {
+			file = vma->vm_file;
+			vmstart = vma->vm_start;
+		}
+		if (file) {
+			ret = trace_seq_path(s, &file->f_path);
+			if (ret)
+				ret = trace_seq_printf(s, "[+0x%lx]",
+						       ip - vmstart);
+		}
+		up_read(&mm->mmap_sem);
+	}
+	if (ret && ((sym_flags & TRACE_ITER_SYM_ADDR) || !file))
+		ret = trace_seq_printf(s, " <" IP_FMT ">", ip);
+	return ret;
+}
+
+int
+seq_print_userip_objs(const struct userstack_entry *entry, struct trace_seq *s,
+		      unsigned long sym_flags)
+{
+	struct mm_struct *mm = NULL;
+	int ret = 1;
+	unsigned int i;
+
+	if (trace_flags & TRACE_ITER_SYM_USEROBJ) {
+		struct task_struct *task;
+		/*
+		 * we do the lookup on the thread group leader,
+		 * since individual threads might have already quit!
+		 */
+		rcu_read_lock();
+		task = find_task_by_vpid(entry->ent.tgid);
+		if (task)
+			mm = get_task_mm(task);
+		rcu_read_unlock();
+	}
+
+	for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
+		unsigned long ip = entry->caller[i];
+
+		if (ip == ULONG_MAX || !ret)
+			break;
+		if (i && ret)
+			ret = trace_seq_puts(s, " <- ");
+		if (!ip) {
+			if (ret)
+				ret = trace_seq_puts(s, "??");
+			continue;
+		}
+		if (!ret)
+			break;
+		if (ret)
+			ret = seq_print_user_ip(s, mm, ip, sym_flags);
+	}
+
+	if (mm)
+		mmput(mm);
+	return ret;
+}
+
+int
+seq_print_ip_sym(struct trace_seq *s, unsigned long ip, unsigned long sym_flags)
+{
+	int ret;
+
+	if (!ip)
+		return trace_seq_printf(s, "0");
+
+	if (sym_flags & TRACE_ITER_SYM_OFFSET)
+		ret = seq_print_sym_offset(s, "%s", ip);
+	else
+		ret = seq_print_sym_short(s, "%s", ip);
+
+	if (!ret)
+		return 0;
+
+	if (sym_flags & TRACE_ITER_SYM_ADDR)
+		ret = trace_seq_printf(s, " <" IP_FMT ">", ip);
+	return ret;
+}
+
+static const char state_to_char[] = TASK_STATE_TO_CHAR_STR;
+
+static int task_state_char(unsigned long state)
+{
+	int bit = state ? __ffs(state) + 1 : 0;
+
+	return bit < sizeof(state_to_char) - 1 ? state_to_char[bit] : '?';
+}
+
+/**
+ * ftrace_find_event - find a registered event
+ * @type: the type of event to look for
+ *
+ * Returns an event of type @type otherwise NULL
+ */
+struct trace_event *ftrace_find_event(int type)
+{
+	struct trace_event *event;
+	struct hlist_node *n;
+	unsigned key;
+
+	key = type & (EVENT_HASHSIZE - 1);
+
+	hlist_for_each_entry_rcu(event, n, &event_hash[key], node) {
+		if (event->type == type)
+			return event;
+	}
+
+	return NULL;
+}
+
+/**
+ * register_ftrace_event - register output for an event type
+ * @event: the event type to register
+ *
+ * Event types are stored in a hash and this hash is used to
+ * find a way to print an event. If the @event->type is set
+ * then it will use that type, otherwise it will assign a
+ * type to use.
+ *
+ * If you assign your own type, please make sure it is added
+ * to the trace_type enum in trace.h, to avoid collisions
+ * with the dynamic types.
+ *
+ * Returns the event type number or zero on error.
+ */
+int register_ftrace_event(struct trace_event *event)
+{
+	unsigned key;
+	int ret = 0;
+
+	mutex_lock(&trace_event_mutex);
+
+	if (!event->type)
+		event->type = next_event_type++;
+	else if (event->type > __TRACE_LAST_TYPE) {
+		printk(KERN_WARNING "Need to add type to trace.h\n");
+		WARN_ON(1);
+	}
+
+	if (ftrace_find_event(event->type))
+		goto out;
+
+	key = event->type & (EVENT_HASHSIZE - 1);
+
+	hlist_add_head_rcu(&event->node, &event_hash[key]);
+
+	ret = event->type;
+ out:
+	mutex_unlock(&trace_event_mutex);
+
+	return ret;
+}
+
+/**
+ * unregister_ftrace_event - remove a no longer used event
+ * @event: the event to remove
+ */
+int unregister_ftrace_event(struct trace_event *event)
+{
+	mutex_lock(&trace_event_mutex);
+	hlist_del(&event->node);
+	mutex_unlock(&trace_event_mutex);
+
+	return 0;
+}
+
+/*
+ * Standard events
+ */
+
+int
+trace_nop_print(struct trace_seq *s, struct trace_entry *entry, int flags)
+{
+	return 0;
+}
+
+/* TRACE_FN */
+static int
+trace_fn_latency(struct trace_seq *s, struct trace_entry *entry, int flags)
+{
+	struct ftrace_entry *field;
+
+	trace_assign_type(field, entry);
+
+	if (!seq_print_ip_sym(s, field->ip, flags))
+		goto partial;
+	if (!trace_seq_puts(s, " ("))
+		goto partial;
+	if (!seq_print_ip_sym(s, field->parent_ip, flags))
+		goto partial;
+	if (!trace_seq_puts(s, ")\n"))
+		goto partial;
+
+	return 0;
+
+ partial:
+	return TRACE_TYPE_PARTIAL_LINE;
+}
+
+static int
+trace_fn_trace(struct trace_seq *s, struct trace_entry *entry, int flags)
+{
+	struct ftrace_entry *field;
+
+	trace_assign_type(field, entry);
+
+	if (!seq_print_ip_sym(s, field->ip, flags))
+		goto partial;
+
+	if ((flags & TRACE_ITER_PRINT_PARENT) && field->parent_ip) {
+		if (!trace_seq_printf(s, " <-"))
+			goto partial;
+		if (!seq_print_ip_sym(s,
+				      field->parent_ip,
+				      flags))
+			goto partial;
+	}
+	if (!trace_seq_printf(s, "\n"))
+		goto partial;
+
+	return 0;
+
+ partial:
+	return TRACE_TYPE_PARTIAL_LINE;
+}
+
+static int
+trace_fn_raw(struct trace_seq *s, struct trace_entry *entry, int flags)
+{
+	struct ftrace_entry *field;
+
+	trace_assign_type(field, entry);
+
+	if (trace_seq_printf(s, "%x %x\n",
+			     field->ip,
+			     field->parent_ip))
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	return 0;
+}
+
+static int
+trace_fn_hex(struct trace_seq *s, struct trace_entry *entry, int flags)
+{
+	struct ftrace_entry *field;
+
+	trace_assign_type(field, entry);
+
+	SEQ_PUT_HEX_FIELD_RET(s, field->ip);
+	SEQ_PUT_HEX_FIELD_RET(s, field->parent_ip);
+
+	return 0;
+}
+
+static int
+trace_fn_bin(struct trace_seq *s, struct trace_entry *entry, int flags)
+{
+	struct ftrace_entry *field;
+
+	trace_assign_type(field, entry);
+
+	SEQ_PUT_FIELD_RET(s, field->ip);
+	SEQ_PUT_FIELD_RET(s, field->parent_ip);
+
+	return 0;
+}
+
+static struct trace_event trace_fn_event = {
+	.type	 	= TRACE_FN,
+	.trace		= trace_fn_trace,
+	.latency_trace	= trace_fn_latency,
+	.raw		= trace_fn_raw,
+	.hex		= trace_fn_hex,
+	.binary		= trace_fn_bin,
+};
+
+/* TRACE_CTX an TRACE_WAKE */
+static int
+trace_ctxwake_print(struct trace_seq *s, struct trace_entry *entry, int flags,
+		    char *delim)
+{
+	struct ctx_switch_entry *field;
+	char *comm;
+	int S, T;
+
+	trace_assign_type(field, entry);
+
+	T = task_state_char(field->next_state);
+	S = task_state_char(field->prev_state);
+	comm = trace_find_cmdline(field->next_pid);
+	if (trace_seq_printf(s, " %5d:%3d:%c %s [%03d] %5d:%3d:%c %s\n",
+			     field->prev_pid,
+			     field->prev_prio,
+			     S, delim,
+			     field->next_cpu,
+			     field->next_pid,
+			     field->next_prio,
+			     T, comm))
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	return 0;
+}
+
+static int
+trace_ctx_print(struct trace_seq *s, struct trace_entry *entry, int flags)
+{
+	return trace_ctxwake_print(s, entry, flags, "==>");
+}
+
+static int
+trace_wake_print(struct trace_seq *s, struct trace_entry *entry, int flags)
+{
+	return trace_ctxwake_print(s, entry, flags, "  +");
+}
+
+static int
+trace_ctxwake_raw(struct trace_seq *s, struct trace_entry *entry, int flags,
+		  char S)
+{
+	struct ctx_switch_entry *field;
+	int T;
+
+	trace_assign_type(field, entry);
+
+	if (!S)
+		task_state_char(field->prev_state);
+	T = task_state_char(field->next_state);
+	if (trace_seq_printf(s, "%d %d %c %d %d %d %c\n",
+			     field->prev_pid,
+			     field->prev_prio,
+			     S,
+			     field->next_cpu,
+			     field->next_pid,
+			     field->next_prio,
+			     T))
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	return 0;
+}
+
+static int
+trace_ctx_raw(struct trace_seq *s, struct trace_entry *entry, int flags)
+{
+	return trace_ctxwake_raw(s, entry, flags, 0);
+}
+
+static int
+trace_wake_raw(struct trace_seq *s, struct trace_entry *entry, int flags)
+{
+	return trace_ctxwake_raw(s, entry, flags, '+');
+}
+
+
+static int
+trace_ctxwake_hex(struct trace_seq *s, struct trace_entry *entry, int flags,
+		  char S)
+{
+	struct ctx_switch_entry *field;
+	int T;
+
+	trace_assign_type(field, entry);
+
+	if (!S)
+		task_state_char(field->prev_state);
+	T = task_state_char(field->next_state);
+
+	SEQ_PUT_HEX_FIELD_RET(s, field->prev_pid);
+	SEQ_PUT_HEX_FIELD_RET(s, field->prev_prio);
+	SEQ_PUT_HEX_FIELD_RET(s, S);
+	SEQ_PUT_HEX_FIELD_RET(s, field->next_cpu);
+	SEQ_PUT_HEX_FIELD_RET(s, field->next_pid);
+	SEQ_PUT_HEX_FIELD_RET(s, field->next_prio);
+	SEQ_PUT_HEX_FIELD_RET(s, T);
+
+	return 0;
+}
+
+static int
+trace_ctx_hex(struct trace_seq *s, struct trace_entry *entry, int flags)
+{
+	return trace_ctxwake_hex(s, entry, flags, 0);
+}
+
+static int
+trace_wake_hex(struct trace_seq *s, struct trace_entry *entry, int flags)
+{
+	return trace_ctxwake_hex(s, entry, flags, '+');
+}
+
+static int
+trace_ctxwake_bin(struct trace_seq *s, struct trace_entry *entry, int flags)
+{
+	struct ctx_switch_entry *field;
+
+	trace_assign_type(field, entry);
+
+	SEQ_PUT_FIELD_RET(s, field->prev_pid);
+	SEQ_PUT_FIELD_RET(s, field->prev_prio);
+	SEQ_PUT_FIELD_RET(s, field->prev_state);
+	SEQ_PUT_FIELD_RET(s, field->next_pid);
+	SEQ_PUT_FIELD_RET(s, field->next_prio);
+	SEQ_PUT_FIELD_RET(s, field->next_state);
+
+	return 0;
+}
+
+static struct trace_event trace_ctx_event = {
+	.type	 	= TRACE_CTX,
+	.trace		= trace_ctx_print,
+	.latency_trace	= trace_ctx_print,
+	.raw		= trace_ctx_raw,
+	.hex		= trace_ctx_hex,
+	.binary		= trace_ctxwake_bin,
+};
+
+static struct trace_event trace_wake_event = {
+	.type	 	= TRACE_WAKE,
+	.trace		= trace_wake_print,
+	.latency_trace	= trace_wake_print,
+	.raw		= trace_wake_raw,
+	.hex		= trace_wake_hex,
+	.binary		= trace_ctxwake_bin,
+};
+
+/* TRACE_SPECIAL */
+static int
+trace_special_print(struct trace_seq *s, struct trace_entry *entry, int flags)
+{
+	struct special_entry *field;
+
+	trace_assign_type(field, entry);
+
+	if (trace_seq_printf(s, "# %ld %ld %ld\n",
+			     field->arg1,
+			     field->arg2,
+			     field->arg3))
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	return 0;
+}
+
+static int
+trace_special_hex(struct trace_seq *s, struct trace_entry *entry, int flags)
+{
+	struct special_entry *field;
+
+	trace_assign_type(field, entry);
+
+	SEQ_PUT_HEX_FIELD_RET(s, field->arg1);
+	SEQ_PUT_HEX_FIELD_RET(s, field->arg2);
+	SEQ_PUT_HEX_FIELD_RET(s, field->arg3);
+
+	return 0;
+}
+
+static int
+trace_special_bin(struct trace_seq *s, struct trace_entry *entry, int flags)
+{
+	struct special_entry *field;
+
+	trace_assign_type(field, entry);
+
+	SEQ_PUT_FIELD_RET(s, field->arg1);
+	SEQ_PUT_FIELD_RET(s, field->arg2);
+	SEQ_PUT_FIELD_RET(s, field->arg3);
+
+	return 0;
+}
+
+static struct trace_event trace_special_event = {
+	.type	 	= TRACE_SPECIAL,
+	.trace		= trace_special_print,
+	.latency_trace	= trace_special_print,
+	.raw		= trace_special_print,
+	.hex		= trace_special_hex,
+	.binary		= trace_special_bin,
+};
+
+/* TRACE_STACK */
+
+static int
+trace_stack_print(struct trace_seq *s, struct trace_entry *entry, int flags)
+{
+	struct stack_entry *field;
+	int i;
+
+	trace_assign_type(field, entry);
+
+	for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
+		if (i) {
+			if (trace_seq_puts(s, " <= "))
+				goto partial;
+
+			if (seq_print_ip_sym(s, field->caller[i], flags))
+				goto partial;
+		}
+		if (trace_seq_puts(s, "\n"))
+			goto partial;
+	}
+
+	return 0;
+
+ partial:
+	return TRACE_TYPE_PARTIAL_LINE;
+}
+
+static struct trace_event trace_stack_event = {
+	.type	 	= TRACE_STACK,
+	.trace		= trace_stack_print,
+	.latency_trace	= trace_stack_print,
+	.raw		= trace_special_print,
+	.hex		= trace_special_hex,
+	.binary		= trace_special_bin,
+};
+
+/* TRACE_USER_STACK */
+static int
+trace_user_stack_print(struct trace_seq *s, struct trace_entry *entry,
+		       int flags)
+{
+	struct userstack_entry *field;
+
+	trace_assign_type(field, entry);
+
+	if (seq_print_userip_objs(field, s, flags))
+		goto partial;
+
+	if (trace_seq_putc(s, '\n'))
+		goto partial;
+
+	return 0;
+
+ partial:
+	return TRACE_TYPE_PARTIAL_LINE;
+}
+
+static struct trace_event trace_user_stack_event = {
+	.type	 	= TRACE_USER_STACK,
+	.trace		= trace_user_stack_print,
+	.latency_trace	= trace_user_stack_print,
+	.raw		= trace_special_print,
+	.hex		= trace_special_hex,
+	.binary		= trace_special_bin,
+};
+
+/* TRACE_PRINT */
+static int
+trace_print_print(struct trace_seq *s, struct trace_entry *entry, int flags)
+{
+	struct print_entry *field;
+
+	trace_assign_type(field, entry);
+
+	if (seq_print_ip_sym(s, field->ip, flags))
+		goto partial;
+
+	if (trace_seq_printf(s, ": %s", field->buf))
+		goto partial;
+
+	return 0;
+
+ partial:
+	return TRACE_TYPE_PARTIAL_LINE;
+}
+
+static int
+trace_print_raw(struct trace_seq *s, struct trace_entry *entry, int flags)
+{
+	struct print_entry *field;
+
+	trace_assign_type(field, entry);
+
+	if (seq_print_ip_sym(s, field->ip, flags))
+		goto partial;
+
+	if (trace_seq_printf(s, "# %lx %s", field->ip, field->buf))
+		goto partial;
+
+	return 0;
+
+ partial:
+	return TRACE_TYPE_PARTIAL_LINE;
+}
+
+static struct trace_event trace_print_event = {
+	.type	 	= TRACE_PRINT,
+	.trace		= trace_print_print,
+	.latency_trace	= trace_print_print,
+	.raw		= trace_print_raw,
+	.hex		= trace_nop_print,
+	.binary		= trace_nop_print,
+};
+
+static struct trace_event *events[] __initdata = {
+	&trace_fn_event,
+	&trace_ctx_event,
+	&trace_wake_event,
+	&trace_special_event,
+	&trace_stack_event,
+	&trace_user_stack_event,
+	&trace_print_event,
+	NULL
+};
+
+__init static int init_events(void)
+{
+	struct trace_event *event;
+	int i, ret;
+
+	for (i = 0; events[i]; i++) {
+		event = events[i];
+
+		ret = register_ftrace_event(event);
+		if (!ret) {
+			printk(KERN_WARNING "event %d failed to register\n",
+			       event->type);
+			WARN_ON_ONCE(1);
+		}
+	}
+
+	return 0;
+}
+device_initcall(init_events);

kernel/trace/trace_output.h

+#ifndef __TRACE_EVENTS_H
+#define __TRACE_EVENTS_H
+
+#include "trace.h"
+
+typedef int (*trace_print_func)(struct trace_seq *s, struct trace_entry *entry,
+				int flags);
+
+struct trace_event {
+	struct hlist_node	node;
+	int			type;
+	trace_print_func	trace;
+	trace_print_func	latency_trace;
+	trace_print_func	raw;
+	trace_print_func	hex;
+	trace_print_func	binary;
+};
+
+extern int trace_seq_printf(struct trace_seq *s, const char *fmt, ...);
+extern int
+seq_print_ip_sym(struct trace_seq *s, unsigned long ip,
+		unsigned long sym_flags);
+extern ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
+				 size_t cnt);
+int trace_seq_puts(struct trace_seq *s, const char *str);
+int trace_seq_putc(struct trace_seq *s, unsigned char c);
+int trace_seq_putmem(struct trace_seq *s, void *mem, size_t len);
+int trace_seq_putmem_hex(struct trace_seq *s, void *mem, size_t len);
+int trace_seq_path(struct trace_seq *s, struct path *path);
+int seq_print_userip_objs(const struct userstack_entry *entry,
+			  struct trace_seq *s, unsigned long sym_flags);
+int seq_print_user_ip(struct trace_seq *s, struct mm_struct *mm,
+		      unsigned long ip, unsigned long sym_flags);
+
+struct trace_event *ftrace_find_event(int type);
+int register_ftrace_event(struct trace_event *event);
+int unregister_ftrace_event(struct trace_event *event);
+
+int
+trace_nop_print(struct trace_seq *s, struct trace_entry *entry, int flags);
+
+#define MAX_MEMHEX_BYTES	8
+#define HEX_CHARS		(MAX_MEMHEX_BYTES*2 + 1)
+
+#define SEQ_PUT_FIELD_RET(s, x)				\
+do {							\
+	if (!trace_seq_putmem(s, &(x), sizeof(x)))	\
+		return 0;				\
+} while (0)
+
+#define SEQ_PUT_HEX_FIELD_RET(s, x)			\
+do {							\
+	BUILD_BUG_ON(sizeof(x) > MAX_MEMHEX_BYTES);	\
+	if (!trace_seq_putmem_hex(s, &(x), sizeof(x)))	\
+		return 0;				\
+} while (0)
+
+#endif
+

kernel/trace/trace_power.c

@@ -16,6 +16,7 @@
 #include <linux/module.h>
 
 #include "trace.h"
+#include "trace_output.h"
 
 static struct trace_array *power_trace;
 static int __read_mostly trace_power_enabled;

kernel/trace/trace_selftest.c

@@ -9,7 +9,6 @@ static inline int trace_valid_entry(struct trace_entry *entry)
 	case TRACE_FN:
 	case TRACE_CTX:
 	case TRACE_WAKE:
-	case TRACE_CONT:
 	case TRACE_STACK:
 	case TRACE_PRINT:
 	case TRACE_SPECIAL:

kernel/trace/trace_stat.c

+/*
+ * Infrastructure for statistic tracing (histogram output).
+ *
+ * Copyright (C) 2008 Frederic Weisbecker <fweisbec@gmail.com>
+ *
+ * Based on the code from trace_branch.c which is
+ * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
+ *
+ */
+
+
+#include <linux/list.h>
+#include <linux/seq_file.h>
+#include <linux/debugfs.h>
+#include "trace.h"
+
+
+/* List of stat entries from a tracer */
+struct trace_stat_list {
+	struct list_head list;
+	void *stat;
+};
+
+static struct trace_stat_list stat_list;
+
+/*
+ * This is a copy of the current tracer to avoid racy
+ * and dangerous output while the current tracer is
+ * switched.
+ */
+static struct tracer current_tracer;
+
+/*
+ * Protect both the current tracer and the global
+ * stat list.
+ */
+static DEFINE_MUTEX(stat_list_mutex);
+
+
+static void reset_stat_list(void)
+{
+	struct trace_stat_list *node;
+	struct list_head *next;
+
+	if (list_empty(&stat_list.list))
+		return;
+
+	node = list_entry(stat_list.list.next, struct trace_stat_list, list);
+	next = node->list.next;
+
+	while (&node->list != next) {
+		kfree(node);
+		node = list_entry(next, struct trace_stat_list, list);
+	}
+	kfree(node);
+
+	INIT_LIST_HEAD(&stat_list.list);
+}
+
+void init_tracer_stat(struct tracer *trace)
+{
+	mutex_lock(&stat_list_mutex);
+	current_tracer = *trace;
+	mutex_unlock(&stat_list_mutex);
+}
+
+/*
+ * For tracers that don't provide a stat_cmp callback.
+ * This one will force an immediate insertion on tail of
+ * the list.
+ */
+static int dummy_cmp(void *p1, void *p2)
+{
+	return 1;
+}
+
+/*
+ * Initialize the stat list at each trace_stat file opening.
+ * All of these copies and sorting are required on all opening
+ * since the stats could have changed between two file sessions.
+ */
+static int stat_seq_init(void)
+{
+	struct trace_stat_list *iter_entry, *new_entry;
+	void *prev_stat;
+	int ret = 0;
+	int i;
+
+	mutex_lock(&stat_list_mutex);
+	reset_stat_list();
+
+	if (!current_tracer.stat_start || !current_tracer.stat_next ||
+					!current_tracer.stat_show)
+		goto exit;
+
+	if (!current_tracer.stat_cmp)
+		current_tracer.stat_cmp = dummy_cmp;
+
+	/*
+	 * The first entry. Actually this is the second, but the first
+	 * one (the stat_list head) is pointless.
+	 */
+	new_entry = kmalloc(sizeof(struct trace_stat_list), GFP_KERNEL);
+	if (!new_entry) {
+		ret = -ENOMEM;
+		goto exit;
+	}
+
+	INIT_LIST_HEAD(&new_entry->list);
+	list_add(&new_entry->list, &stat_list.list);
+	new_entry->stat = current_tracer.stat_start();
+
+	prev_stat = new_entry->stat;
+
+	/*
+	 * Iterate over the tracer stat entries and store them in a sorted
+	 * list.
+	 */
+	for (i = 1; ; i++) {
+		new_entry = kmalloc(sizeof(struct trace_stat_list), GFP_KERNEL);
+		if (!new_entry) {
+			ret = -ENOMEM;
+			goto exit_free_list;
+		}
+
+		INIT_LIST_HEAD(&new_entry->list);
+		new_entry->stat = current_tracer.stat_next(prev_stat, i);
+
+		/* End of insertion */
+		if (!new_entry->stat)
+			break;
+
+		list_for_each_entry(iter_entry, &stat_list.list, list) {
+			/* Insertion with a descendent sorting */
+			if (current_tracer.stat_cmp(new_entry->stat,
+						iter_entry->stat) > 0) {
+
+				list_add_tail(&new_entry->list,
+						&iter_entry->list);
+				break;
+
+			/* The current smaller value */
+			} else if (list_is_last(&iter_entry->list,
+						&stat_list.list)) {
+				list_add(&new_entry->list, &iter_entry->list);
+				break;
+			}
+		}
+
+		prev_stat = new_entry->stat;
+	}
+exit:
+	mutex_unlock(&stat_list_mutex);
+	return ret;
+
+exit_free_list:
+	reset_stat_list();
+	mutex_unlock(&stat_list_mutex);
+	return ret;
+}
+
+
+static void *stat_seq_start(struct seq_file *s, loff_t *pos)
+{
+	struct trace_stat_list *l = (struct trace_stat_list *)s->private;
+
+	/* Prevent from tracer switch or stat_list modification */
+	mutex_lock(&stat_list_mutex);
+
+	/* If we are in the beginning of the file, print the headers */
+	if (!*pos && current_tracer.stat_headers)
+		current_tracer.stat_headers(s);
+
+	return seq_list_start(&l->list, *pos);
+}
+
+static void *stat_seq_next(struct seq_file *s, void *p, loff_t *pos)
+{
+	struct trace_stat_list *l = (struct trace_stat_list *)s->private;
+
+	return seq_list_next(p, &l->list, pos);
+}
+
+static void stat_seq_stop(struct seq_file *m, void *p)
+{
+	mutex_unlock(&stat_list_mutex);
+}
+
+static int stat_seq_show(struct seq_file *s, void *v)
+{
+	struct trace_stat_list *l = list_entry(v, struct trace_stat_list, list);
+	return current_tracer.stat_show(s, l->stat);
+}
+
+static const struct seq_operations trace_stat_seq_ops = {
+	.start = stat_seq_start,
+	.next = stat_seq_next,
+	.stop = stat_seq_stop,
+	.show = stat_seq_show
+};
+
+static int tracing_stat_open(struct inode *inode, struct file *file)
+{
+	int ret;
+
+	ret = seq_open(file, &trace_stat_seq_ops);
+	if (!ret) {
+		struct seq_file *m = file->private_data;
+		m->private = &stat_list;
+		ret = stat_seq_init();
+	}
+
+	return ret;
+}
+
+
+/*
+ * Avoid consuming memory with our now useless list.
+ */
+static int tracing_stat_release(struct inode *i, struct file *f)
+{
+	mutex_lock(&stat_list_mutex);
+	reset_stat_list();
+	mutex_unlock(&stat_list_mutex);
+	return 0;
+}
+
+static const struct file_operations tracing_stat_fops = {
+	.open		= tracing_stat_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= tracing_stat_release
+};
+
+static int __init tracing_stat_init(void)
+{
+	struct dentry *d_tracing;
+	struct dentry *entry;
+
+	INIT_LIST_HEAD(&stat_list.list);
+	d_tracing = tracing_init_dentry();
+
+	entry = debugfs_create_file("trace_stat", 0444, d_tracing,
+					NULL,
+				    &tracing_stat_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs "
+			   "'trace_stat' entry\n");
+	return 0;
+}
+fs_initcall(tracing_stat_init);