Merge tag 'trace-v4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracking updates from Steven Rostedt:
 "Most of the changes are clean ups and small fixes.  Some of them have
  stable tags to them.  I searched through my INBOX just as the merge
  window opened and found lots of patches to pull.  I ran them through
  all my tests and they were in linux-next for a few days.

  Features added this release:
  ----------------------------

   - Module globbing.  You can now filter function tracing to several
     modules.  # echo '*:mod:*snd*' > set_ftrace_filter (Dmitry Safonov)

   - Tracer specific options are now visible even when the tracer is not
     active.  It was rather annoying that you can only see and modify
     tracer options after enabling the tracer.  Now they are in the
     options/ directory even when the tracer is not active.  Although
     they are still only visible when the tracer is active in the
     trace_options file.

   - Trace options are now per instance (although some of the tracer
     specific options are global)

   - New tracefs file: set_event_pid.  If any pid is added to this file,
     then all events in the instance will filter out events that are not
     part of this pid.  sched_switch and sched_wakeup events handle next
     and the wakee pids"

* tag 'trace-v4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (68 commits)
  tracefs: Fix refcount imbalance in start_creating()
  tracing: Put back comma for empty fields in boot string parsing
  tracing: Apply tracer specific options from kernel command line.
  tracing: Add some documentation about set_event_pid
  ring_buffer: Remove unneeded smp_wmb() before wakeup of reader benchmark
  tracing: Allow dumping traces without tracking trace started cpus
  ring_buffer: Fix more races when terminating the producer in the benchmark
  ring_buffer: Do no not complete benchmark reader too early
  tracing: Remove redundant TP_ARGS redefining
  tracing: Rename max_stack_lock to stack_trace_max_lock
  tracing: Allow arch-specific stack tracer
  recordmcount: arm64: Replace the ignored mcount call into nop
  recordmcount: Fix endianness handling bug for nop_mcount
  tracepoints: Fix documentation of RCU lockdep checks
  tracing: ftrace_event_is_function() can return boolean
  tracing: is_legal_op() can return boolean
  ring-buffer: rb_event_is_commit() can return boolean
  ring-buffer: rb_per_cpu_empty() can return boolean
  ring_buffer: ring_buffer_empty{cpu}() can return boolean
  ring-buffer: rb_is_reader_page() can return boolean
  ...

1 files changed, 479 insertions, 27 deletions

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 7ca09cdc20c2..6bbc5f652355 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -15,11 +15,15 @@
 #include <linux/kthread.h>
 #include <linux/tracefs.h>
 #include <linux/uaccess.h>
+#include <linux/bsearch.h>
 #include <linux/module.h>
 #include <linux/ctype.h>
+#include <linux/sort.h>
 #include <linux/slab.h>
 #include <linux/delay.h>
 
+#include <trace/events/sched.h>
+
 #include <asm/setup.h>
 
 #include "trace_output.h"
@@ -38,21 +42,19 @@ static LIST_HEAD(ftrace_common_fields);
 static struct kmem_cache *field_cachep;
 static struct kmem_cache *file_cachep;
 
-#define SYSTEM_FL_FREE_NAME		(1 << 31)
-
 static inline int system_refcount(struct event_subsystem *system)
 {
-	return system->ref_count & ~SYSTEM_FL_FREE_NAME;
+	return system->ref_count;
 }
 
 static int system_refcount_inc(struct event_subsystem *system)
 {
-	return (system->ref_count++) & ~SYSTEM_FL_FREE_NAME;
+	return system->ref_count++;
 }
 
 static int system_refcount_dec(struct event_subsystem *system)
 {
-	return (--system->ref_count) & ~SYSTEM_FL_FREE_NAME;
+	return --system->ref_count;
 }
 
 /* Double loops, do not use break, only goto's work */
@@ -212,12 +214,32 @@ int trace_event_raw_init(struct trace_event_call *call)
 }
 EXPORT_SYMBOL_GPL(trace_event_raw_init);
 
+bool trace_event_ignore_this_pid(struct trace_event_file *trace_file)
+{
+	struct trace_array *tr = trace_file->tr;
+	struct trace_array_cpu *data;
+	struct trace_pid_list *pid_list;
+
+	pid_list = rcu_dereference_sched(tr->filtered_pids);
+	if (!pid_list)
+		return false;
+
+	data = this_cpu_ptr(tr->trace_buffer.data);
+
+	return data->ignore_pid;
+}
+EXPORT_SYMBOL_GPL(trace_event_ignore_this_pid);
+
 void *trace_event_buffer_reserve(struct trace_event_buffer *fbuffer,
 				 struct trace_event_file *trace_file,
 				 unsigned long len)
 {
 	struct trace_event_call *event_call = trace_file->event_call;
 
+	if ((trace_file->flags & EVENT_FILE_FL_PID_FILTER) &&
+	    trace_event_ignore_this_pid(trace_file))
+		return NULL;
+
 	local_save_flags(fbuffer->flags);
 	fbuffer->pc = preempt_count();
 	fbuffer->trace_file = trace_file;
@@ -338,6 +360,7 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 					 int enable, int soft_disable)
 {
 	struct trace_event_call *call = file->event_call;
+	struct trace_array *tr = file->tr;
 	int ret = 0;
 	int disable;
 
@@ -401,7 +424,7 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 			if (soft_disable)
 				set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &file->flags);
 
-			if (trace_flags & TRACE_ITER_RECORD_CMD) {
+			if (tr->trace_flags & TRACE_ITER_RECORD_CMD) {
 				tracing_start_cmdline_record();
 				set_bit(EVENT_FILE_FL_RECORDED_CMD_BIT, &file->flags);
 			}
@@ -446,6 +469,142 @@ static void ftrace_clear_events(struct trace_array *tr)
 	mutex_unlock(&event_mutex);
 }
 
+static int cmp_pid(const void *key, const void *elt)
+{
+	const pid_t *search_pid = key;
+	const pid_t *pid = elt;
+
+	if (*search_pid == *pid)
+		return 0;
+	if (*search_pid < *pid)
+		return -1;
+	return 1;
+}
+
+static bool
+check_ignore_pid(struct trace_pid_list *filtered_pids, struct task_struct *task)
+{
+	pid_t search_pid;
+	pid_t *pid;
+
+	/*
+	 * Return false, because if filtered_pids does not exist,
+	 * all pids are good to trace.
+	 */
+	if (!filtered_pids)
+		return false;
+
+	search_pid = task->pid;
+
+	pid = bsearch(&search_pid, filtered_pids->pids,
+		      filtered_pids->nr_pids, sizeof(pid_t),
+		      cmp_pid);
+	if (!pid)
+		return true;
+
+	return false;
+}
+
+static void
+event_filter_pid_sched_switch_probe_pre(void *data, bool preempt,
+		    struct task_struct *prev, struct task_struct *next)
+{
+	struct trace_array *tr = data;
+	struct trace_pid_list *pid_list;
+
+	pid_list = rcu_dereference_sched(tr->filtered_pids);
+
+	this_cpu_write(tr->trace_buffer.data->ignore_pid,
+		       check_ignore_pid(pid_list, prev) &&
+		       check_ignore_pid(pid_list, next));
+}
+
+static void
+event_filter_pid_sched_switch_probe_post(void *data, bool preempt,
+		    struct task_struct *prev, struct task_struct *next)
+{
+	struct trace_array *tr = data;
+	struct trace_pid_list *pid_list;
+
+	pid_list = rcu_dereference_sched(tr->filtered_pids);
+
+	this_cpu_write(tr->trace_buffer.data->ignore_pid,
+		       check_ignore_pid(pid_list, next));
+}
+
+static void
+event_filter_pid_sched_wakeup_probe_pre(void *data, struct task_struct *task)
+{
+	struct trace_array *tr = data;
+	struct trace_pid_list *pid_list;
+
+	/* Nothing to do if we are already tracing */
+	if (!this_cpu_read(tr->trace_buffer.data->ignore_pid))
+		return;
+
+	pid_list = rcu_dereference_sched(tr->filtered_pids);
+
+	this_cpu_write(tr->trace_buffer.data->ignore_pid,
+		       check_ignore_pid(pid_list, task));
+}
+
+static void
+event_filter_pid_sched_wakeup_probe_post(void *data, struct task_struct *task)
+{
+	struct trace_array *tr = data;
+	struct trace_pid_list *pid_list;
+
+	/* Nothing to do if we are not tracing */
+	if (this_cpu_read(tr->trace_buffer.data->ignore_pid))
+		return;
+
+	pid_list = rcu_dereference_sched(tr->filtered_pids);
+
+	/* Set tracing if current is enabled */
+	this_cpu_write(tr->trace_buffer.data->ignore_pid,
+		       check_ignore_pid(pid_list, current));
+}
+
+static void __ftrace_clear_event_pids(struct trace_array *tr)
+{
+	struct trace_pid_list *pid_list;
+	struct trace_event_file *file;
+	int cpu;
+
+	pid_list = rcu_dereference_protected(tr->filtered_pids,
+					     lockdep_is_held(&event_mutex));
+	if (!pid_list)
+		return;
+
+	unregister_trace_sched_switch(event_filter_pid_sched_switch_probe_pre, tr);
+	unregister_trace_sched_switch(event_filter_pid_sched_switch_probe_post, tr);
+
+	unregister_trace_sched_wakeup(event_filter_pid_sched_wakeup_probe_pre, tr);
+	unregister_trace_sched_wakeup(event_filter_pid_sched_wakeup_probe_post, tr);
+
+	list_for_each_entry(file, &tr->events, list) {
+		clear_bit(EVENT_FILE_FL_PID_FILTER_BIT, &file->flags);
+	}
+
+	for_each_possible_cpu(cpu)
+		per_cpu_ptr(tr->trace_buffer.data, cpu)->ignore_pid = false;
+
+	rcu_assign_pointer(tr->filtered_pids, NULL);
+
+	/* Wait till all users are no longer using pid filtering */
+	synchronize_sched();
+
+	free_pages((unsigned long)pid_list->pids, pid_list->order);
+	kfree(pid_list);
+}
+
+static void ftrace_clear_event_pids(struct trace_array *tr)
+{
+	mutex_lock(&event_mutex);
+	__ftrace_clear_event_pids(tr);
+	mutex_unlock(&event_mutex);
+}
+
 static void __put_system(struct event_subsystem *system)
 {
 	struct event_filter *filter = system->filter;
@@ -460,8 +619,7 @@ static void __put_system(struct event_subsystem *system)
 		kfree(filter->filter_string);
 		kfree(filter);
 	}
-	if (system->ref_count & SYSTEM_FL_FREE_NAME)
-		kfree(system->name);
+	kfree_const(system->name);
 	kfree(system);
 }
 
@@ -779,6 +937,58 @@ static void t_stop(struct seq_file *m, void *p)
 	mutex_unlock(&event_mutex);
 }
 
+static void *p_start(struct seq_file *m, loff_t *pos)
+	__acquires(RCU)
+{
+	struct trace_pid_list *pid_list;
+	struct trace_array *tr = m->private;
+
+	/*
+	 * Grab the mutex, to keep calls to p_next() having the same
+	 * tr->filtered_pids as p_start() has.
+	 * If we just passed the tr->filtered_pids around, then RCU would
+	 * have been enough, but doing that makes things more complex.
+	 */
+	mutex_lock(&event_mutex);
+	rcu_read_lock_sched();
+
+	pid_list = rcu_dereference_sched(tr->filtered_pids);
+
+	if (!pid_list || *pos >= pid_list->nr_pids)
+		return NULL;
+
+	return (void *)&pid_list->pids[*pos];
+}
+
+static void p_stop(struct seq_file *m, void *p)
+	__releases(RCU)
+{
+	rcu_read_unlock_sched();
+	mutex_unlock(&event_mutex);
+}
+
+static void *
+p_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	struct trace_array *tr = m->private;
+	struct trace_pid_list *pid_list = rcu_dereference_sched(tr->filtered_pids);
+
+	(*pos)++;
+
+	if (*pos >= pid_list->nr_pids)
+		return NULL;
+
+	return (void *)&pid_list->pids[*pos];
+}
+
+static int p_show(struct seq_file *m, void *v)
+{
+	pid_t *pid = v;
+
+	seq_printf(m, "%d\n", *pid);
+	return 0;
+}
+
 static ssize_t
 event_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
 		  loff_t *ppos)
@@ -1336,8 +1546,209 @@ show_header(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
 	return r;
 }
 
+static int max_pids(struct trace_pid_list *pid_list)
+{
+	return (PAGE_SIZE << pid_list->order) / sizeof(pid_t);
+}
+
+static void ignore_task_cpu(void *data)
+{
+	struct trace_array *tr = data;
+	struct trace_pid_list *pid_list;
+
+	/*
+	 * This function is called by on_each_cpu() while the
+	 * event_mutex is held.
+	 */
+	pid_list = rcu_dereference_protected(tr->filtered_pids,
+					     mutex_is_locked(&event_mutex));
+
+	this_cpu_write(tr->trace_buffer.data->ignore_pid,
+		       check_ignore_pid(pid_list, current));
+}
+
+static ssize_t
+ftrace_event_pid_write(struct file *filp, const char __user *ubuf,
+		       size_t cnt, loff_t *ppos)
+{
+	struct seq_file *m = filp->private_data;
+	struct trace_array *tr = m->private;
+	struct trace_pid_list *filtered_pids = NULL;
+	struct trace_pid_list *pid_list = NULL;
+	struct trace_event_file *file;
+	struct trace_parser parser;
+	unsigned long val;
+	loff_t this_pos;
+	ssize_t read = 0;
+	ssize_t ret = 0;
+	pid_t pid;
+	int i;
+
+	if (!cnt)
+		return 0;
+
+	ret = tracing_update_buffers();
+	if (ret < 0)
+		return ret;
+
+	if (trace_parser_get_init(&parser, EVENT_BUF_SIZE + 1))
+		return -ENOMEM;
+
+	mutex_lock(&event_mutex);
+	/*
+	 * Load as many pids into the array before doing a
+	 * swap from the tr->filtered_pids to the new list.
+	 */
+	while (cnt > 0) {
+
+		this_pos = 0;
+
+		ret = trace_get_user(&parser, ubuf, cnt, &this_pos);
+		if (ret < 0 || !trace_parser_loaded(&parser))
+			break;
+
+		read += ret;
+		ubuf += ret;
+		cnt -= ret;
+
+		parser.buffer[parser.idx] = 0;
+
+		ret = -EINVAL;
+		if (kstrtoul(parser.buffer, 0, &val))
+			break;
+		if (val > INT_MAX)
+			break;
+
+		pid = (pid_t)val;
+
+		ret = -ENOMEM;
+		if (!pid_list) {
+			pid_list = kmalloc(sizeof(*pid_list), GFP_KERNEL);
+			if (!pid_list)
+				break;
+
+			filtered_pids = rcu_dereference_protected(tr->filtered_pids,
+							lockdep_is_held(&event_mutex));
+			if (filtered_pids)
+				pid_list->order = filtered_pids->order;
+			else
+				pid_list->order = 0;
+
+			pid_list->pids = (void *)__get_free_pages(GFP_KERNEL,
+								  pid_list->order);
+			if (!pid_list->pids)
+				break;
+
+			if (filtered_pids) {
+				pid_list->nr_pids = filtered_pids->nr_pids;
+				memcpy(pid_list->pids, filtered_pids->pids,
+				       pid_list->nr_pids * sizeof(pid_t));
+			} else
+				pid_list->nr_pids = 0;
+		}
+
+		if (pid_list->nr_pids >= max_pids(pid_list)) {
+			pid_t *pid_page;
+
+			pid_page = (void *)__get_free_pages(GFP_KERNEL,
+							    pid_list->order + 1);
+			if (!pid_page)
+				break;
+			memcpy(pid_page, pid_list->pids,
+			       pid_list->nr_pids * sizeof(pid_t));
+			free_pages((unsigned long)pid_list->pids, pid_list->order);
+
+			pid_list->order++;
+			pid_list->pids = pid_page;
+		}
+
+		pid_list->pids[pid_list->nr_pids++] = pid;
+		trace_parser_clear(&parser);
+		ret = 0;
+	}
+	trace_parser_put(&parser);
+
+	if (ret < 0) {
+		if (pid_list)
+			free_pages((unsigned long)pid_list->pids, pid_list->order);
+		kfree(pid_list);
+		mutex_unlock(&event_mutex);
+		return ret;
+	}
+
+	if (!pid_list) {
+		mutex_unlock(&event_mutex);
+		return ret;
+	}
+
+	sort(pid_list->pids, pid_list->nr_pids, sizeof(pid_t), cmp_pid, NULL);
+
+	/* Remove duplicates */
+	for (i = 1; i < pid_list->nr_pids; i++) {
+		int start = i;
+
+		while (i < pid_list->nr_pids &&
+		       pid_list->pids[i - 1] == pid_list->pids[i])
+			i++;
+
+		if (start != i) {
+			if (i < pid_list->nr_pids) {
+				memmove(&pid_list->pids[start], &pid_list->pids[i],
+					(pid_list->nr_pids - i) * sizeof(pid_t));
+				pid_list->nr_pids -= i - start;
+				i = start;
+			} else
+				pid_list->nr_pids = start;
+		}
+	}
+
+	rcu_assign_pointer(tr->filtered_pids, pid_list);
+
+	list_for_each_entry(file, &tr->events, list) {
+		set_bit(EVENT_FILE_FL_PID_FILTER_BIT, &file->flags);
+	}
+
+	if (filtered_pids) {
+		synchronize_sched();
+
+		free_pages((unsigned long)filtered_pids->pids, filtered_pids->order);
+		kfree(filtered_pids);
+	} else {
+		/*
+		 * Register a probe that is called before all other probes
+		 * to set ignore_pid if next or prev do not match.
+		 * Register a probe this is called after all other probes
+		 * to only keep ignore_pid set if next pid matches.
+		 */
+		register_trace_prio_sched_switch(event_filter_pid_sched_switch_probe_pre,
+						 tr, INT_MAX);
+		register_trace_prio_sched_switch(event_filter_pid_sched_switch_probe_post,
+						 tr, 0);
+
+		register_trace_prio_sched_wakeup(event_filter_pid_sched_wakeup_probe_pre,
+						 tr, INT_MAX);
+		register_trace_prio_sched_wakeup(event_filter_pid_sched_wakeup_probe_post,
+						 tr, 0);
+	}
+
+	/*
+	 * Ignoring of pids is done at task switch. But we have to
+	 * check for those tasks that are currently running.
+	 * Always do this in case a pid was appended or removed.
+	 */
+	on_each_cpu(ignore_task_cpu, tr, 1);
+
+	mutex_unlock(&event_mutex);
+
+	ret = read;
+	*ppos += read;
+
+	return ret;
+}
+
 static int ftrace_event_avail_open(struct inode *inode, struct file *file);
 static int ftrace_event_set_open(struct inode *inode, struct file *file);
+static int ftrace_event_set_pid_open(struct inode *inode, struct file *file);
 static int ftrace_event_release(struct inode *inode, struct file *file);
 
 static const struct seq_operations show_event_seq_ops = {
@@ -1354,6 +1765,13 @@ static const struct seq_operations show_set_event_seq_ops = {
 	.stop = t_stop,
 };
 
+static const struct seq_operations show_set_pid_seq_ops = {
+	.start = p_start,
+	.next = p_next,
+	.show = p_show,
+	.stop = p_stop,
+};
+
 static const struct file_operations ftrace_avail_fops = {
 	.open = ftrace_event_avail_open,
 	.read = seq_read,
@@ -1369,6 +1787,14 @@ static const struct file_operations ftrace_set_event_fops = {
 	.release = ftrace_event_release,
 };
 
+static const struct file_operations ftrace_set_event_pid_fops = {
+	.open = ftrace_event_set_pid_open,
+	.read = seq_read,
+	.write = ftrace_event_pid_write,
+	.llseek = seq_lseek,
+	.release = ftrace_event_release,
+};
+
 static const struct file_operations ftrace_enable_fops = {
 	.open = tracing_open_generic,
 	.read = event_enable_read,
@@ -1479,6 +1905,26 @@ ftrace_event_set_open(struct inode *inode, struct file *file)
 	return ret;
 }
 
+static int
+ftrace_event_set_pid_open(struct inode *inode, struct file *file)
+{
+	const struct seq_operations *seq_ops = &show_set_pid_seq_ops;
+	struct trace_array *tr = inode->i_private;
+	int ret;
+
+	if (trace_array_get(tr) < 0)
+		return -ENODEV;
+
+	if ((file->f_mode & FMODE_WRITE) &&
+	    (file->f_flags & O_TRUNC))
+		ftrace_clear_event_pids(tr);
+
+	ret = ftrace_event_open(inode, file, seq_ops);
+	if (ret < 0)
+		trace_array_put(tr);
+	return ret;
+}
+
 static struct event_subsystem *
 create_new_subsystem(const char *name)
 {
@@ -1492,13 +1938,9 @@ create_new_subsystem(const char *name)
 	system->ref_count = 1;
 
 	/* Only allocate if dynamic (kprobes and modules) */
-	if (!core_kernel_data((unsigned long)name)) {
-		system->ref_count |= SYSTEM_FL_FREE_NAME;
-		system->name = kstrdup(name, GFP_KERNEL);
-		if (!system->name)
-			goto out_free;
-	} else
-		system->name = name;
+	system->name = kstrdup_const(name, GFP_KERNEL);
+	if (!system->name)
+		goto out_free;
 
 	system->filter = NULL;
 
@@ -1511,8 +1953,7 @@ create_new_subsystem(const char *name)
 	return system;
 
  out_free:
-	if (system->ref_count & SYSTEM_FL_FREE_NAME)
-		kfree(system->name);
+	kfree_const(system->name);
 	kfree(system);
 	return NULL;
 }
@@ -2478,6 +2919,9 @@ create_event_toplevel_files(struct dentry *parent, struct trace_array *tr)
 		return -ENOMEM;
 	}
 
+	entry = tracefs_create_file("set_event_pid", 0644, parent,
+				    tr, &ftrace_set_event_pid_fops);
+
 	/* ring buffer internal formats */
 	trace_create_file("header_page", 0444, d_events,
 			  ring_buffer_print_page_header,
@@ -2558,6 +3002,9 @@ int event_trace_del_tracer(struct trace_array *tr)
 	/* Disable any event triggers and associated soft-disabled events */
 	clear_event_triggers(tr);
 
+	/* Clear the pid list */
+	__ftrace_clear_event_pids(tr);
+
 	/* Disable any running events */
 	__ftrace_set_clr_event_nolock(tr, NULL, NULL, NULL, 0);
 
@@ -2595,16 +3042,16 @@ early_enable_events(struct trace_array *tr, bool disable_first)
 
 		if (!token)
 			break;
-		if (!*token)
-			continue;
 
-		/* Restarting syscalls requires that we stop them first */
-		if (disable_first)
-			ftrace_set_clr_event(tr, token, 0);
+		if (*token) {
+			/* Restarting syscalls requires that we stop them first */
+			if (disable_first)
+				ftrace_set_clr_event(tr, token, 0);
 
-		ret = ftrace_set_clr_event(tr, token, 1);
-		if (ret)
-			pr_warn("Failed to enable trace event: %s\n", token);
+			ret = ftrace_set_clr_event(tr, token, 1);
+			if (ret)
+				pr_warn("Failed to enable trace event: %s\n", token);
+		}
 
 		/* Put back the comma to allow this to be called again */
 		if (buf)
@@ -2891,7 +3338,9 @@ static __init void event_trace_self_tests(void)
 
 static DEFINE_PER_CPU(atomic_t, ftrace_test_event_disable);
 
-static void
+static struct trace_array *event_tr;
+
+static void __init
 function_test_events_call(unsigned long ip, unsigned long parent_ip,
 			  struct ftrace_ops *op, struct pt_regs *pt_regs)
 {
@@ -2922,7 +3371,7 @@ function_test_events_call(unsigned long ip, unsigned long parent_ip,
 	entry->ip			= ip;
 	entry->parent_ip		= parent_ip;
 
-	trace_buffer_unlock_commit(buffer, event, flags, pc);
+	trace_buffer_unlock_commit(event_tr, buffer, event, flags, pc);
 
  out:
 	atomic_dec(&per_cpu(ftrace_test_event_disable, cpu));
@@ -2938,6 +3387,9 @@ static struct ftrace_ops trace_ops __initdata  =
 static __init void event_trace_self_test_with_function(void)
 {
 	int ret;
+	event_tr = top_trace_array();
+	if (WARN_ON(!event_tr))
+		return;
 	ret = register_ftrace_function(&trace_ops);
 	if (WARN_ON(ret < 0)) {
 		pr_info("Failed to enable function tracer for event tests\n");