[PATCH v13 06/29] tracing: Add needs_rec flag to event triggers

From: Tom Zanussi
Date: Thu Dec 10 2015 - 13:52:51 EST


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>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Reviewed-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
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 5e23a97..300add5 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1293,6 +1293,12 @@ 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.
*
@@ -1333,6 +1339,7 @@ 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

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