tracing: Pass buffer of event to trigger operations

The ring_buffer_event_time_stamp() is going to be updated to extract the
time stamp for the event without needing it to be set to have absolute
values for all events. But to do so, it needs the buffer that the event is
on as the buffer saves information for the event before it is committed to
the buffer.

If the trace buffer is disabled, a temporary buffer is used, and there's
no access to this buffer from the current histogram triggers, even though
it is passed to the trace event code.

Pass the buffer that the event is on all the way down to the histogram
triggers.

Link: https://lkml.kernel.org/r/20210316164113.542448131@goodmis.orgReviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

include/linux/trace_events.h

@@ -640,7 +640,8 @@ enum event_trigger_type {
 extern int filter_match_preds(struct event_filter *filter, void *rec);
 
 extern enum event_trigger_type
-event_triggers_call(struct trace_event_file *file, void *rec,
+event_triggers_call(struct trace_event_file *file,
+		    struct trace_buffer *buffer, void *rec,
 		    struct ring_buffer_event *event);
 extern void
 event_triggers_post_call(struct trace_event_file *file,
@@ -664,7 +665,7 @@ trace_trigger_soft_disabled(struct trace_event_file *file)
 
 	if (!(eflags & EVENT_FILE_FL_TRIGGER_COND)) {
 		if (eflags & EVENT_FILE_FL_TRIGGER_MODE)
-			event_triggers_call(file, NULL, NULL);
+			event_triggers_call(file, NULL, NULL, NULL);
 		if (eflags & EVENT_FILE_FL_SOFT_DISABLED)
 			return true;
 		if (eflags & EVENT_FILE_FL_PID_FILTER)

kernel/trace/trace.c

@@ -6763,7 +6763,7 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
 	if (tr->trace_marker_file && !list_empty(&tr->trace_marker_file->triggers)) {
 		/* do not add \n before testing triggers, but add \0 */
 		entry->buf[cnt] = '\0';
-		tt = event_triggers_call(tr->trace_marker_file, entry, event);
+		tt = event_triggers_call(tr->trace_marker_file, buffer, entry, event);
 	}
 
 	if (entry->buf[cnt - 1] != '\n') {

kernel/trace/trace.h

@@ -1329,7 +1329,7 @@ __event_trigger_test_discard(struct trace_event_file *file,
 	unsigned long eflags = file->flags;
 
 	if (eflags & EVENT_FILE_FL_TRIGGER_COND)
-		*tt = event_triggers_call(file, entry, event);
+		*tt = event_triggers_call(file, buffer, entry, event);
 
 	if (test_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &file->flags) ||
 	    (unlikely(file->flags & EVENT_FILE_FL_FILTERED) &&
@@ -1626,7 +1626,7 @@ extern int register_trigger_hist_enable_disable_cmds(void);
  */
 struct event_trigger_ops {
 	void			(*func)(struct event_trigger_data *data,
-					void *rec,
+					struct trace_buffer *buffer, void *rec,
 					struct ring_buffer_event *rbe);
 	int			(*init)(struct event_trigger_ops *ops,
 					struct event_trigger_data *data);

kernel/trace/trace_events_trigger.c

@@ -53,7 +53,8 @@ void trigger_data_free(struct event_trigger_data *data)
  * any trigger that should be deferred, ETT_NONE if nothing to defer.
  */
 enum event_trigger_type
-event_triggers_call(struct trace_event_file *file, void *rec,
+event_triggers_call(struct trace_event_file *file,
+		    struct trace_buffer *buffer, void *rec,
 		    struct ring_buffer_event *event)
 {
 	struct event_trigger_data *data;
@@ -67,7 +68,7 @@ event_triggers_call(struct trace_event_file *file, void *rec,
 		if (data->paused)
 			continue;
 		if (!rec) {
-			data->ops->func(data, rec, event);
+			data->ops->func(data, buffer, rec, event);
 			continue;
 		}
 		filter = rcu_dereference_sched(data->filter);
@@ -77,7 +78,7 @@ event_triggers_call(struct trace_event_file *file, void *rec,
 			tt |= data->cmd_ops->trigger_type;
 			continue;
 		}
-		data->ops->func(data, rec, event);
+		data->ops->func(data, buffer, rec, event);
 	}
 	return tt;
 }
@@ -105,7 +106,7 @@ event_triggers_post_call(struct trace_event_file *file,
 		if (data->paused)
 			continue;
 		if (data->cmd_ops->trigger_type & tt)
-			data->ops->func(data, NULL, NULL);
+			data->ops->func(data, NULL, NULL, NULL);
 	}
 }
 EXPORT_SYMBOL_GPL(event_triggers_post_call);
@@ -937,7 +938,8 @@ get_named_trigger_data(struct event_trigger_data *data)
 }
 
 static void
-traceon_trigger(struct event_trigger_data *data, void *rec,
+traceon_trigger(struct event_trigger_data *data,
+		struct trace_buffer *buffer, void *rec,
 		struct ring_buffer_event *event)
 {
 	if (tracing_is_on())
@@ -947,7 +949,8 @@ traceon_trigger(struct event_trigger_data *data, void *rec,
 }
 
 static void
-traceon_count_trigger(struct event_trigger_data *data, void *rec,
+traceon_count_trigger(struct event_trigger_data *data,
+		      struct trace_buffer *buffer, void *rec,
 		      struct ring_buffer_event *event)
 {
 	if (tracing_is_on())
@@ -963,7 +966,8 @@ traceon_count_trigger(struct event_trigger_data *data, void *rec,
 }
 
 static void
-traceoff_trigger(struct event_trigger_data *data, void *rec,
+traceoff_trigger(struct event_trigger_data *data,
+		 struct trace_buffer *buffer, void *rec,
 		 struct ring_buffer_event *event)
 {
 	if (!tracing_is_on())
@@ -973,7 +977,8 @@ traceoff_trigger(struct event_trigger_data *data, void *rec,
 }
 
 static void
-traceoff_count_trigger(struct event_trigger_data *data, void *rec,
+traceoff_count_trigger(struct event_trigger_data *data,
+		       struct trace_buffer *buffer, void *rec,
 		       struct ring_buffer_event *event)
 {
 	if (!tracing_is_on())
@@ -1071,7 +1076,8 @@ static struct event_command trigger_traceoff_cmd = {
 
 #ifdef CONFIG_TRACER_SNAPSHOT
 static void
-snapshot_trigger(struct event_trigger_data *data, void *rec,
+snapshot_trigger(struct event_trigger_data *data,
+		 struct trace_buffer *buffer, void *rec,
 		 struct ring_buffer_event *event)
 {
 	struct trace_event_file *file = data->private_data;
@@ -1083,7 +1089,8 @@ snapshot_trigger(struct event_trigger_data *data, void *rec,
 }
 
 static void
-snapshot_count_trigger(struct event_trigger_data *data, void *rec,
+snapshot_count_trigger(struct event_trigger_data *data,
+		       struct trace_buffer *buffer, void *rec,
 		       struct ring_buffer_event *event)
 {
 	if (!data->count)
@@ -1092,7 +1099,7 @@ snapshot_count_trigger(struct event_trigger_data *data, void *rec,
 	if (data->count != -1)
 		(data->count)--;
 
-	snapshot_trigger(data, rec, event);
+	snapshot_trigger(data, buffer, rec, event);
 }
 
 static int
@@ -1176,14 +1183,16 @@ static __init int register_trigger_snapshot_cmd(void) { return 0; }
 #endif
 
 static void
-stacktrace_trigger(struct event_trigger_data *data, void *rec,
+stacktrace_trigger(struct event_trigger_data *data,
+		   struct trace_buffer *buffer,  void *rec,
 		   struct ring_buffer_event *event)
 {
 	trace_dump_stack(STACK_SKIP);
 }
 
 static void
-stacktrace_count_trigger(struct event_trigger_data *data, void *rec,
+stacktrace_count_trigger(struct event_trigger_data *data,
+			 struct trace_buffer *buffer, void *rec,
 			 struct ring_buffer_event *event)
 {
 	if (!data->count)
@@ -1192,7 +1201,7 @@ stacktrace_count_trigger(struct event_trigger_data *data, void *rec,
 	if (data->count != -1)
 		(data->count)--;
 
-	stacktrace_trigger(data, rec, event);
+	stacktrace_trigger(data, buffer, rec, event);
 }
 
 static int
@@ -1254,7 +1263,8 @@ static __init void unregister_trigger_traceon_traceoff_cmds(void)
 }
 
 static void
-event_enable_trigger(struct event_trigger_data *data, void *rec,
+event_enable_trigger(struct event_trigger_data *data,
+		     struct trace_buffer *buffer,  void *rec,
 		     struct ring_buffer_event *event)
 {
 	struct enable_trigger_data *enable_data = data->private_data;
@@ -1266,7 +1276,8 @@ event_enable_trigger(struct event_trigger_data *data, void *rec,
 }
 
 static void
-event_enable_count_trigger(struct event_trigger_data *data, void *rec,
+event_enable_count_trigger(struct event_trigger_data *data,
+			   struct trace_buffer *buffer,  void *rec,
 			   struct ring_buffer_event *event)
 {
 	struct enable_trigger_data *enable_data = data->private_data;
@@ -1281,7 +1292,7 @@ event_enable_count_trigger(struct event_trigger_data *data, void *rec,
 	if (data->count != -1)
 		(data->count)--;
 
-	event_enable_trigger(data, rec, event);
+	event_enable_trigger(data, buffer, rec, event);
 }
 
 int event_enable_trigger_print(struct seq_file *m,