1 files changed, 96 insertions, 10 deletions

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index fcd3975a88d1..f38234ecea18 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -238,7 +238,7 @@ bool trace_event_ignore_this_pid(struct trace_event_file *trace_file)
 	if (!pid_list)
 		return false;
 
-	data = this_cpu_ptr(tr->trace_buffer.data);
+	data = this_cpu_ptr(tr->array_buffer.data);
 
 	return data->ignore_pid;
 }
@@ -273,6 +273,7 @@ void *trace_event_buffer_reserve(struct trace_event_buffer *fbuffer,
 	if (!fbuffer->event)
 		return NULL;
 
+	fbuffer->regs = NULL;
 	fbuffer->entry = ring_buffer_event_data(fbuffer->event);
 	return fbuffer->entry;
 }
@@ -547,7 +548,7 @@ event_filter_pid_sched_switch_probe_pre(void *data, bool preempt,
 
 	pid_list = rcu_dereference_sched(tr->filtered_pids);
 
-	this_cpu_write(tr->trace_buffer.data->ignore_pid,
+	this_cpu_write(tr->array_buffer.data->ignore_pid,
 		       trace_ignore_this_task(pid_list, prev) &&
 		       trace_ignore_this_task(pid_list, next));
 }
@@ -561,7 +562,7 @@ event_filter_pid_sched_switch_probe_post(void *data, bool preempt,
 
 	pid_list = rcu_dereference_sched(tr->filtered_pids);
 
-	this_cpu_write(tr->trace_buffer.data->ignore_pid,
+	this_cpu_write(tr->array_buffer.data->ignore_pid,
 		       trace_ignore_this_task(pid_list, next));
 }
 
@@ -572,12 +573,12 @@ event_filter_pid_sched_wakeup_probe_pre(void *data, struct task_struct *task)
 	struct trace_pid_list *pid_list;
 
 	/* Nothing to do if we are already tracing */
-	if (!this_cpu_read(tr->trace_buffer.data->ignore_pid))
+	if (!this_cpu_read(tr->array_buffer.data->ignore_pid))
 		return;
 
 	pid_list = rcu_dereference_sched(tr->filtered_pids);
 
-	this_cpu_write(tr->trace_buffer.data->ignore_pid,
+	this_cpu_write(tr->array_buffer.data->ignore_pid,
 		       trace_ignore_this_task(pid_list, task));
 }
 
@@ -588,13 +589,13 @@ event_filter_pid_sched_wakeup_probe_post(void *data, struct task_struct *task)
 	struct trace_pid_list *pid_list;
 
 	/* Nothing to do if we are not tracing */
-	if (this_cpu_read(tr->trace_buffer.data->ignore_pid))
+	if (this_cpu_read(tr->array_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,
+	this_cpu_write(tr->array_buffer.data->ignore_pid,
 		       trace_ignore_this_task(pid_list, current));
 }
 
@@ -626,7 +627,7 @@ static void __ftrace_clear_event_pids(struct trace_array *tr)
 	}
 
 	for_each_possible_cpu(cpu)
-		per_cpu_ptr(tr->trace_buffer.data, cpu)->ignore_pid = false;
+		per_cpu_ptr(tr->array_buffer.data, cpu)->ignore_pid = false;
 
 	rcu_assign_pointer(tr->filtered_pids, NULL);
 
@@ -1595,7 +1596,7 @@ static void ignore_task_cpu(void *data)
 	pid_list = rcu_dereference_protected(tr->filtered_pids,
 					     mutex_is_locked(&event_mutex));
 
-	this_cpu_write(tr->trace_buffer.data->ignore_pid,
+	this_cpu_write(tr->array_buffer.data->ignore_pid,
 		       trace_ignore_this_task(pid_list, current));
 }
 
@@ -2553,6 +2554,91 @@ find_event_file(struct trace_array *tr, const char *system, const char *event)
 	return file;
 }
 
+/**
+ * trace_get_event_file - Find and return a trace event file
+ * @instance: The name of the trace instance containing the event
+ * @system: The name of the system containing the event
+ * @event: The name of the event
+ *
+ * Return a trace event file given the trace instance name, trace
+ * system, and trace event name.  If the instance name is NULL, it
+ * refers to the top-level trace array.
+ *
+ * This function will look it up and return it if found, after calling
+ * trace_array_get() to prevent the instance from going away, and
+ * increment the event's module refcount to prevent it from being
+ * removed.
+ *
+ * To release the file, call trace_put_event_file(), which will call
+ * trace_array_put() and decrement the event's module refcount.
+ *
+ * Return: The trace event on success, ERR_PTR otherwise.
+ */
+struct trace_event_file *trace_get_event_file(const char *instance,
+					      const char *system,
+					      const char *event)
+{
+	struct trace_array *tr = top_trace_array();
+	struct trace_event_file *file = NULL;
+	int ret = -EINVAL;
+
+	if (instance) {
+		tr = trace_array_find_get(instance);
+		if (!tr)
+			return ERR_PTR(-ENOENT);
+	} else {
+		ret = trace_array_get(tr);
+		if (ret)
+			return ERR_PTR(ret);
+	}
+
+	mutex_lock(&event_mutex);
+
+	file = find_event_file(tr, system, event);
+	if (!file) {
+		trace_array_put(tr);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* Don't let event modules unload while in use */
+	ret = try_module_get(file->event_call->mod);
+	if (!ret) {
+		trace_array_put(tr);
+		ret = -EBUSY;
+		goto out;
+	}
+
+	ret = 0;
+ out:
+	mutex_unlock(&event_mutex);
+
+	if (ret)
+		file = ERR_PTR(ret);
+
+	return file;
+}
+EXPORT_SYMBOL_GPL(trace_get_event_file);
+
+/**
+ * trace_put_event_file - Release a file from trace_get_event_file()
+ * @file: The trace event file
+ *
+ * If a file was retrieved using trace_get_event_file(), this should
+ * be called when it's no longer needed.  It will cancel the previous
+ * trace_array_get() called by that function, and decrement the
+ * event's module refcount.
+ */
+void trace_put_event_file(struct trace_event_file *file)
+{
+	mutex_lock(&event_mutex);
+	module_put(file->event_call->mod);
+	mutex_unlock(&event_mutex);
+
+	trace_array_put(file->tr);
+}
+EXPORT_SYMBOL_GPL(trace_put_event_file);
+
 #ifdef CONFIG_DYNAMIC_FTRACE
 
 /* Avoid typos */
@@ -3409,8 +3495,8 @@ static void __init
 function_test_events_call(unsigned long ip, unsigned long parent_ip,
 			  struct ftrace_ops *op, struct pt_regs *pt_regs)
 {
+	struct trace_buffer *buffer;
 	struct ring_buffer_event *event;
-	struct ring_buffer *buffer;
 	struct ftrace_entry *entry;
 	unsigned long flags;
 	long disabled;