Merge tag 'trace-v4.17-rc4-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "While writing selftests for a new feature, I triggered two existing
  bugs that deal with triggers and instances.

   - a generic trigger bug where the triggers are not removed from a
     linked list properly when deleting an instance.

   - a bug specific to snapshots, where the snapshot is done in the top
     level buffer, when it is supposed to snapshot the buffer associated
     to the instance the snapshot trigger exists in"

* tag 'trace-v4.17-rc4-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Make the snapshot trigger work with instances
  tracing: Fix crash when freeing instances with event triggers

3 files changed, 28 insertions, 10 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 414d7210b2ec..bcd93031d042 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -893,7 +893,7 @@ int __trace_bputs(unsigned long ip, const char *str)
 EXPORT_SYMBOL_GPL(__trace_bputs);
 
 #ifdef CONFIG_TRACER_SNAPSHOT
-static void tracing_snapshot_instance(struct trace_array *tr)
+void tracing_snapshot_instance(struct trace_array *tr)
 {
 	struct tracer *tracer = tr->current_trace;
 	unsigned long flags;
@@ -949,7 +949,7 @@ static int resize_buffer_duplicate_size(struct trace_buffer *trace_buf,
 					struct trace_buffer *size_buf, int cpu_id);
 static void set_buffer_entries(struct trace_buffer *buf, unsigned long val);
 
-static int alloc_snapshot(struct trace_array *tr)
+int tracing_alloc_snapshot_instance(struct trace_array *tr)
 {
 	int ret;
 
@@ -995,7 +995,7 @@ int tracing_alloc_snapshot(void)
 	struct trace_array *tr = &global_trace;
 	int ret;
 
-	ret = alloc_snapshot(tr);
+	ret = tracing_alloc_snapshot_instance(tr);
 	WARN_ON(ret < 0);
 
 	return ret;
@@ -5408,7 +5408,7 @@ static int tracing_set_tracer(struct trace_array *tr, const char *buf)
 
 #ifdef CONFIG_TRACER_MAX_TRACE
 	if (t->use_max_tr && !had_max_tr) {
-		ret = alloc_snapshot(tr);
+		ret = tracing_alloc_snapshot_instance(tr);
 		if (ret < 0)
 			goto out;
 	}
@@ -6451,7 +6451,7 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt,
 		}
 #endif
 		if (!tr->allocated_snapshot) {
-			ret = alloc_snapshot(tr);
+			ret = tracing_alloc_snapshot_instance(tr);
 			if (ret < 0)
 				break;
 		}
@@ -7179,7 +7179,7 @@ ftrace_trace_snapshot_callback(struct trace_array *tr, struct ftrace_hash *hash,
 		return ret;
 
  out_reg:
-	ret = alloc_snapshot(tr);
+	ret = tracing_alloc_snapshot_instance(tr);
 	if (ret < 0)
 		goto out;
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 6fb46a06c9dc..507954b4e058 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1817,6 +1817,17 @@ static inline void __init trace_event_init(void) { }
 static inline void trace_event_eval_update(struct trace_eval_map **map, int len) { }
 #endif
 
+#ifdef CONFIG_TRACER_SNAPSHOT
+void tracing_snapshot_instance(struct trace_array *tr);
+int tracing_alloc_snapshot_instance(struct trace_array *tr);
+#else
+static inline void tracing_snapshot_instance(struct trace_array *tr) { }
+static inline int tracing_alloc_snapshot_instance(struct trace_array *tr)
+{
+	return 0;
+}
+#endif
+
 extern struct trace_iterator *tracepoint_print_iter;
 
 #endif /* _LINUX_KERNEL_TRACE_H */
diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index d251cabcf69a..8b5bdcf64871 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -483,9 +483,10 @@ clear_event_triggers(struct trace_array *tr)
 	struct trace_event_file *file;
 
 	list_for_each_entry(file, &tr->events, list) {
-		struct event_trigger_data *data;
-		list_for_each_entry_rcu(data, &file->triggers, list) {
+		struct event_trigger_data *data, *n;
+		list_for_each_entry_safe(data, n, &file->triggers, list) {
 			trace_event_trigger_enable_disable(file, 0);
+			list_del_rcu(&data->list);
 			if (data->ops->free)
 				data->ops->free(data->ops, data);
 		}
@@ -642,6 +643,7 @@ event_trigger_callback(struct event_command *cmd_ops,
 	trigger_data->count = -1;
 	trigger_data->ops = trigger_ops;
 	trigger_data->cmd_ops = cmd_ops;
+	trigger_data->private_data = file;
 	INIT_LIST_HEAD(&trigger_data->list);
 	INIT_LIST_HEAD(&trigger_data->named_list);
 
@@ -1053,7 +1055,12 @@ static void
 snapshot_trigger(struct event_trigger_data *data, void *rec,
 		 struct ring_buffer_event *event)
 {
-	tracing_snapshot();
+	struct trace_event_file *file = data->private_data;
+
+	if (file)
+		tracing_snapshot_instance(file->tr);
+	else
+		tracing_snapshot();
 }
 
 static void
@@ -1076,7 +1083,7 @@ register_snapshot_trigger(char *glob, struct event_trigger_ops *ops,
 {
 	int ret = register_trigger(glob, ops, data, file);
 
-	if (ret > 0 && tracing_alloc_snapshot() != 0) {
+	if (ret > 0 && tracing_alloc_snapshot_instance(file->tr) != 0) {
 		unregister_trigger(glob, ops, data, file);
 		ret = 0;
 	}