1 files changed, 122 insertions, 64 deletions

diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index 06b75bcfc7b8..4d2fde996c0f 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -22,6 +22,46 @@ static struct task_struct *trigger_kthread;
 static struct llist_head trigger_data_free_list;
 static DEFINE_MUTEX(trigger_data_kthread_mutex);
 
+static int trigger_kthread_fn(void *ignore);
+
+static void trigger_create_kthread_locked(void)
+{
+	lockdep_assert_held(&trigger_data_kthread_mutex);
+
+	if (!trigger_kthread) {
+		struct task_struct *kthread;
+
+		kthread = kthread_create(trigger_kthread_fn, NULL,
+					 "trigger_data_free");
+		if (!IS_ERR(kthread))
+			WRITE_ONCE(trigger_kthread, kthread);
+	}
+}
+
+static void trigger_data_free_one(struct event_trigger_data *data)
+{
+	if (data->private_data_free)
+		data->private_data_free(data);
+	kfree(data);
+}
+
+static void trigger_data_free_queued_locked(void)
+{
+	struct event_trigger_data *data, *tmp;
+	struct llist_node *llnodes;
+
+	lockdep_assert_held(&trigger_data_kthread_mutex);
+
+	llnodes = llist_del_all(&trigger_data_free_list);
+	if (!llnodes)
+		return;
+
+	tracepoint_synchronize_unregister();
+
+	llist_for_each_entry_safe(data, tmp, llnodes, llist)
+		trigger_data_free_one(data);
+}
+
 /* Bulk garbage collection of event_trigger_data elements */
 static int trigger_kthread_fn(void *ignore)
 {
@@ -42,7 +82,7 @@ static int trigger_kthread_fn(void *ignore)
 		tracepoint_synchronize_unregister();
 
 		llist_for_each_entry_safe(data, tmp, llnodes, llist)
-			kfree(data);
+			trigger_data_free_one(data);
 	}
 
 	return 0;
@@ -50,33 +90,56 @@ static int trigger_kthread_fn(void *ignore)
 
 void trigger_data_free(struct event_trigger_data *data)
 {
+	if (!data)
+		return;
+
 	if (data->cmd_ops->set_filter)
 		data->cmd_ops->set_filter(NULL, data, NULL);
 
+	/*
+	 * Boot-time trigger registration can fail before kthread creation
+	 * works. Keep the deferred-free semantics during boot and let late
+	 * init start the kthread to drain the list.
+	 */
+	if (system_state == SYSTEM_BOOTING && !trigger_kthread) {
+		llist_add(&data->llist, &trigger_data_free_list);
+		return;
+	}
+
 	if (unlikely(!trigger_kthread)) {
 		guard(mutex)(&trigger_data_kthread_mutex);
+
+		trigger_create_kthread_locked();
 		/* Check again after taking mutex */
 		if (!trigger_kthread) {
-			struct task_struct *kthread;
-
-			kthread = kthread_create(trigger_kthread_fn, NULL,
-						 "trigger_data_free");
-			if (!IS_ERR(kthread))
-				WRITE_ONCE(trigger_kthread, kthread);
+			llist_add(&data->llist, &trigger_data_free_list);
+			/* Drain the queued frees synchronously if creation failed. */
+			trigger_data_free_queued_locked();
+			return;
 		}
 	}
 
-	if (!trigger_kthread) {
-		/* Do it the slow way */
-		tracepoint_synchronize_unregister();
-		kfree(data);
-		return;
-	}
-
 	llist_add(&data->llist, &trigger_data_free_list);
 	wake_up_process(trigger_kthread);
 }
 
+static int __init trigger_data_free_init(void)
+{
+	guard(mutex)(&trigger_data_kthread_mutex);
+
+	if (llist_empty(&trigger_data_free_list))
+		return 0;
+
+	trigger_create_kthread_locked();
+	if (trigger_kthread)
+		wake_up_process(trigger_kthread);
+	else
+		trigger_data_free_queued_locked();
+
+	return 0;
+}
+late_initcall(trigger_data_free_init);
+
 static inline void data_ops_trigger(struct event_trigger_data *data,
 				    struct trace_buffer *buffer,  void *rec,
 				    struct ring_buffer_event *event)
@@ -914,7 +977,7 @@ struct event_trigger_data *trigger_data_alloc(struct event_command *cmd_ops,
 {
 	struct event_trigger_data *trigger_data;
 
-	trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
+	trigger_data = kzalloc_obj(*trigger_data);
 	if (!trigger_data)
 		return NULL;
 
@@ -1347,18 +1410,13 @@ traceon_trigger(struct event_trigger_data *data,
 {
 	struct trace_event_file *file = data->private_data;
 
-	if (file) {
-		if (tracer_tracing_is_on(file->tr))
-			return;
-
-		tracer_tracing_on(file->tr);
+	if (WARN_ON_ONCE(!file))
 		return;
-	}
 
-	if (tracing_is_on())
+	if (tracer_tracing_is_on(file->tr))
 		return;
 
-	tracing_on();
+	tracer_tracing_on(file->tr);
 }
 
 static bool
@@ -1368,13 +1426,11 @@ traceon_count_func(struct event_trigger_data *data,
 {
 	struct trace_event_file *file = data->private_data;
 
-	if (file) {
-		if (tracer_tracing_is_on(file->tr))
-			return false;
-	} else {
-		if (tracing_is_on())
-			return false;
-	}
+	if (WARN_ON_ONCE(!file))
+		return false;
+
+	if (tracer_tracing_is_on(file->tr))
+		return false;
 
 	if (!data->count)
 		return false;
@@ -1392,18 +1448,13 @@ traceoff_trigger(struct event_trigger_data *data,
 {
 	struct trace_event_file *file = data->private_data;
 
-	if (file) {
-		if (!tracer_tracing_is_on(file->tr))
-			return;
-
-		tracer_tracing_off(file->tr);
+	if (WARN_ON_ONCE(!file))
 		return;
-	}
 
-	if (!tracing_is_on())
+	if (!tracer_tracing_is_on(file->tr))
 		return;
 
-	tracing_off();
+	tracer_tracing_off(file->tr);
 }
 
 static bool
@@ -1413,13 +1464,11 @@ traceoff_count_func(struct event_trigger_data *data,
 {
 	struct trace_event_file *file = data->private_data;
 
-	if (file) {
-		if (!tracer_tracing_is_on(file->tr))
-			return false;
-	} else {
-		if (!tracing_is_on())
-			return false;
-	}
+	if (WARN_ON_ONCE(!file))
+		return false;
+
+	if (!tracer_tracing_is_on(file->tr))
+		return false;
 
 	if (!data->count)
 		return false;
@@ -1481,10 +1530,10 @@ snapshot_trigger(struct event_trigger_data *data,
 {
 	struct trace_event_file *file = data->private_data;
 
-	if (file)
-		tracing_snapshot_instance(file->tr);
-	else
-		tracing_snapshot();
+	if (WARN_ON_ONCE(!file))
+		return;
+
+	tracing_snapshot_instance(file->tr);
 }
 
 static int
@@ -1570,10 +1619,10 @@ stacktrace_trigger(struct event_trigger_data *data,
 {
 	struct trace_event_file *file = data->private_data;
 
-	if (file)
-		__trace_stack(file->tr, tracing_gen_ctx_dec(), STACK_SKIP);
-	else
-		trace_dump_stack(STACK_SKIP);
+	if (WARN_ON_ONCE(!file))
+		return;
+
+	__trace_stack(file->tr, tracing_gen_ctx_dec(), STACK_SKIP);
 }
 
 static int
@@ -1675,6 +1724,15 @@ int event_enable_trigger_print(struct seq_file *m,
 	return 0;
 }
 
+static void enable_trigger_private_data_free(struct event_trigger_data *data)
+{
+	struct enable_trigger_data *enable_data = data->private_data;
+
+	/* The file may already be freed here, only the call is kept alive */
+	trace_event_put_ref(enable_data->call);
+	kfree(enable_data);
+}
+
 void event_enable_trigger_free(struct event_trigger_data *data)
 {
 	struct enable_trigger_data *enable_data = data->private_data;
@@ -1686,9 +1744,8 @@ void event_enable_trigger_free(struct event_trigger_data *data)
 	if (!data->ref) {
 		/* Remove the SOFT_MODE flag */
 		trace_event_enable_disable(enable_data->file, 0, 1);
-		trace_event_put_ref(enable_data->file->event_call);
+		data->private_data_free = enable_trigger_private_data_free;
 		trigger_data_free(data);
-		kfree(enable_data);
 	}
 }
 
@@ -1697,7 +1754,7 @@ int event_enable_trigger_parse(struct event_command *cmd_ops,
 			       char *glob, char *cmd, char *param_and_filter)
 {
 	struct trace_event_file *event_enable_file;
-	struct enable_trigger_data *enable_data;
+	struct enable_trigger_data *enable_data __free(kfree) = NULL;
 	struct event_trigger_data *trigger_data;
 	struct trace_array *tr = file->tr;
 	char *param, *filter;
@@ -1738,26 +1795,23 @@ int event_enable_trigger_parse(struct event_command *cmd_ops,
 #endif
 	ret = -ENOMEM;
 
-	enable_data = kzalloc(sizeof(*enable_data), GFP_KERNEL);
+	enable_data = kzalloc_obj(*enable_data);
 	if (!enable_data)
 		return ret;
 
 	enable_data->hist = hist;
 	enable_data->enable = enable;
 	enable_data->file = event_enable_file;
+	enable_data->call = event_enable_file->event_call;
 
 	trigger_data = trigger_data_alloc(cmd_ops, cmd, param, enable_data);
-	if (!trigger_data) {
-		kfree(enable_data);
+	if (!trigger_data)
 		return ret;
-	}
 
 	if (remove) {
 		event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);
 		kfree(trigger_data);
-		kfree(enable_data);
-		ret = 0;
-		return ret;
+		return 0;
 	}
 
 	/* Up the trigger_data count to make sure nothing frees it on failure */
@@ -1786,7 +1840,12 @@ int event_enable_trigger_parse(struct event_command *cmd_ops,
 	if (ret)
 		goto out_disable;
 
+	/* It's now safe to free the reference taken earlier */
 	event_trigger_free(trigger_data);
+
+	/* The enabled_data is assigned to trigger_data->private_data */
+	retain_and_null_ptr(enable_data);
+
 	return ret;
  out_disable:
 	trace_event_enable_disable(event_enable_file, 0, 1);
@@ -1795,7 +1854,6 @@ int event_enable_trigger_parse(struct event_command *cmd_ops,
  out_free:
 	event_trigger_reset_filter(cmd_ops, trigger_data);
 	event_trigger_free(trigger_data);
-	kfree(enable_data);
 
 	return ret;
 }