tracing: Remove get_trigger_ops() and add count_func() from trigger ops

The struct event_command has a callback function called get_trigger_ops().
This callback returns the "trigger_ops" to use for the trigger. These ops
define the trigger function, how to init the trigger, how to print the
trigger and how to free it.

The only reason there's a callback function to get these ops is because
some triggers have two types of operations. One is an "always on"
operation, and the other is a "count down" operation. If a user passes in
a parameter to say how many times the trigger should execute. For example:

  echo stacktrace:5 > events/kmem/kmem_cache_alloc/trigger

It will trigger the stacktrace for the first 5 times the kmem_cache_alloc
event is hit.

Instead of having two different trigger_ops since the only difference
between them is the tigger itself (the print, init and free functions are
all the same), just use a single ops that the event_command points to and
add a function field to the trigger_ops to have a count_func.

When a trigger is added to an event, if there's a count attached to it and
the trigger ops has the count_func field, the data allocated to represent
this trigger will have a new flag set called COUNT.

Then when the trigger executes, it will check if the COUNT data flag is
set, and if so, it will call the ops count_func(). If that returns false,
it returns without executing the trigger.

This removes the need for duplicate event_trigger_ops structures.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://patch.msgid.link/20251125200932.274566147@kernel.org
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

1 files changed, 5 insertions, 55 deletions

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 1d536219b624..f9cc8d6a215b 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -6363,12 +6363,6 @@ static const struct event_trigger_ops event_hist_trigger_named_ops = {
 	.free			= event_hist_trigger_named_free,
 };
 
-static const struct event_trigger_ops *event_hist_get_trigger_ops(char *cmd,
-								  char *param)
-{
-	return &event_hist_trigger_ops;
-}
-
 static void hist_clear(struct event_trigger_data *data)
 {
 	struct hist_trigger_data *hist_data = data->private_data;
@@ -6908,11 +6902,11 @@ static struct event_command trigger_hist_cmd = {
 	.name			= "hist",
 	.trigger_type		= ETT_EVENT_HIST,
 	.flags			= EVENT_CMD_FL_NEEDS_REC,
+	.trigger_ops		= &event_hist_trigger_ops,
 	.parse			= event_hist_trigger_parse,
 	.reg			= hist_register_trigger,
 	.unreg			= hist_unregister_trigger,
 	.unreg_all		= hist_unreg_all,
-	.get_trigger_ops	= event_hist_get_trigger_ops,
 	.set_filter		= set_trigger_filter,
 };
 
@@ -6945,29 +6939,9 @@ hist_enable_trigger(struct event_trigger_data *data,
 	}
 }
 
-static void
-hist_enable_count_trigger(struct event_trigger_data *data,
-			  struct trace_buffer *buffer,  void *rec,
-			  struct ring_buffer_event *event)
-{
-	if (!data->count)
-		return;
-
-	if (data->count != -1)
-		(data->count)--;
-
-	hist_enable_trigger(data, buffer, rec, event);
-}
-
 static const struct event_trigger_ops hist_enable_trigger_ops = {
 	.trigger		= hist_enable_trigger,
-	.print			= event_enable_trigger_print,
-	.init			= event_trigger_init,
-	.free			= event_enable_trigger_free,
-};
-
-static const struct event_trigger_ops hist_enable_count_trigger_ops = {
-	.trigger		= hist_enable_count_trigger,
+	.count_func		= event_trigger_count,
 	.print			= event_enable_trigger_print,
 	.init			= event_trigger_init,
 	.free			= event_enable_trigger_free,
@@ -6975,36 +6949,12 @@ static const struct event_trigger_ops hist_enable_count_trigger_ops = {
 
 static const struct event_trigger_ops hist_disable_trigger_ops = {
 	.trigger		= hist_enable_trigger,
+	.count_func		= event_trigger_count,
 	.print			= event_enable_trigger_print,
 	.init			= event_trigger_init,
 	.free			= event_enable_trigger_free,
 };
 
-static const struct event_trigger_ops hist_disable_count_trigger_ops = {
-	.trigger		= hist_enable_count_trigger,
-	.print			= event_enable_trigger_print,
-	.init			= event_trigger_init,
-	.free			= event_enable_trigger_free,
-};
-
-static const struct event_trigger_ops *
-hist_enable_get_trigger_ops(char *cmd, char *param)
-{
-	const struct event_trigger_ops *ops;
-	bool enable;
-
-	enable = (strcmp(cmd, ENABLE_HIST_STR) == 0);
-
-	if (enable)
-		ops = param ? &hist_enable_count_trigger_ops :
-			&hist_enable_trigger_ops;
-	else
-		ops = param ? &hist_disable_count_trigger_ops :
-			&hist_disable_trigger_ops;
-
-	return ops;
-}
-
 static void hist_enable_unreg_all(struct trace_event_file *file)
 {
 	struct event_trigger_data *test, *n;
@@ -7023,22 +6973,22 @@ static void hist_enable_unreg_all(struct trace_event_file *file)
 static struct event_command trigger_hist_enable_cmd = {
 	.name			= ENABLE_HIST_STR,
 	.trigger_type		= ETT_HIST_ENABLE,
+	.trigger_ops		= &hist_enable_trigger_ops,
 	.parse			= event_enable_trigger_parse,
 	.reg			= event_enable_register_trigger,
 	.unreg			= event_enable_unregister_trigger,
 	.unreg_all		= hist_enable_unreg_all,
-	.get_trigger_ops	= hist_enable_get_trigger_ops,
 	.set_filter		= set_trigger_filter,
 };
 
 static struct event_command trigger_hist_disable_cmd = {
 	.name			= DISABLE_HIST_STR,
 	.trigger_type		= ETT_HIST_ENABLE,
+	.trigger_ops		= &hist_disable_trigger_ops,
 	.parse			= event_enable_trigger_parse,
 	.reg			= event_enable_register_trigger,
 	.unreg			= event_enable_unregister_trigger,
 	.unreg_all		= hist_enable_unreg_all,
-	.get_trigger_ops	= hist_enable_get_trigger_ops,
 	.set_filter		= set_trigger_filter,
 };