[PATCH v10 07/26] tracing: Add needs_rec flag to event triggers

[Tom Zanussi]

Add a new needs_rec flag for triggers that require unconditional
access to trace records in order to function.

Normally a trigger requires access to the contents of a trace record
only if it has a filter associated with it (since filters need the
contents of a record in order to make a filtering decision).  Some
types of triggers, such as 'hist' triggers, require access to trace
record contents independent of the presence of filters, so add a new
flag for those triggers.

Signed-off-by: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>
---
 kernel/trace/trace.h                | 7 +++++++
 kernel/trace/trace_events_trigger.c | 3 ++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 71cf384..4b4a053 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1231,6 +1231,12 @@ struct event_trigger_ops {
  *	itself logs to the trace buffer, this flag should be set,
  *	otherwise it can be left unspecified.
  *
+ * @needs_rec: A flag that says whether or not this command needs
+ *	access to the trace record in order to perform its function,
+ *	regardless of whether or not it has a filter associated with
+ *	it (filters make a trigger require access to the trace record
+ *	but are not always present).
+ *
  * All the methods below, except for @set_filter(), must be
  * implemented.
  *
@@ -1271,6 +1277,7 @@ struct event_command {
 	char			*name;
 	enum event_trigger_type	trigger_type;
 	bool			post_trigger;
+	bool			needs_rec;
 	int			(*func)(struct event_command *cmd_ops,
 					struct trace_event_file *file,
 					char *glob, char *cmd, char *params);
diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index 8375d29..2f881e9 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -498,7 +498,8 @@ void update_cond_flag(struct trace_event_file *file)
 	bool set_cond = false;
 
 	list_for_each_entry_rcu(data, &file->triggers, list) {
-		if (data->filter || data->cmd_ops->post_trigger) {
+		if (data->filter || data->cmd_ops->post_trigger ||
+		    data->cmd_ops->needs_rec) {
 			set_cond = true;
 			break;
 		}
-- 
1.9.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/