[PATCH v8 4/4] tracing: Separate hist state updates from hist registration

Tom Zanussi
2022-02-04T22:12:31Z

hist_register_trigger() handles both new hist registration as well as
existing hist registration through event_command.reg().

Adding a new function, existing_hist_update_only(), that checks and
updates existing histograms and exits after doing so allows the
confusing logic in event_hist_trigger_parse() to be simplified.

Signed-off-by: Tom Zanussi <zanussi@kernel.org>
---
kernel/trace/trace_events_hist.c | 66 +++++++++++++++++++++++---------
1 file changed, 48 insertions(+), 18 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 28604e17bc73..bc52b03be11a 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -5926,6 +5926,48 @@ static bool hist_trigger_match(struct event_trigger_data *data,
return true;
}

+static bool existing_hist_update_only(char *glob,
+ struct event_trigger_data *data,
+ struct trace_event_file *file)
+{
+ struct hist_trigger_data *hist_data = data->private_data;
+ struct event_trigger_data *test, *named_data = NULL;
+ bool updated = false;
+
+ if (!hist_data->attrs->pause && !hist_data->attrs->cont &&
+ !hist_data->attrs->clear)
+ goto out;
+
+ if (hist_data->attrs->name) {
+ named_data = find_named_trigger(hist_data->attrs->name);
+ if (named_data) {
+ if (!hist_trigger_match(data, named_data, named_data,
+ true))
+ goto out;
+ }
+ }
+
+ if (hist_data->attrs->name && !named_data)
+ goto out;
+
+ list_for_each_entry(test, &file->triggers, list) {
+ if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+ if (!hist_trigger_match(data, test, named_data, false))
+ continue;
+ if (hist_data->attrs->pause)
+ test->paused = true;
+ else if (hist_data->attrs->cont)
+ test->paused = false;
+ else if (hist_data->attrs->clear)
+ hist_clear(test);
+ updated = true;
+ goto out;
+ }
+ }
+ out:
+ return updated;
+}
+
static int hist_register_trigger(char *glob,
struct event_trigger_data *data,
struct trace_event_file *file)
@@ -5954,19 +5996,11 @@ static int hist_register_trigger(char *glob,

list_for_each_entry(test, &file->triggers, list) {
if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
- if (!hist_trigger_match(data, test, named_data, false))
- continue;
- if (hist_data->attrs->pause)
- test->paused = true;
- else if (hist_data->attrs->cont)
- test->paused = false;
- else if (hist_data->attrs->clear)
- hist_clear(test);
- else {
+ if (hist_trigger_match(data, test, named_data, false)) {
hist_err(tr, HIST_ERR_TRIGGER_EEXIST, 0);
ret = -EEXIST;
+ goto out;
}
- goto out;
}
}
new:
@@ -6005,8 +6039,6 @@ static int hist_register_trigger(char *glob,

if (named_data)
destroy_hist_data(hist_data);
-
- ret++;
out:
return ret;
}
@@ -6274,14 +6306,12 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops,
goto out_free;
}

- ret = event_trigger_register(cmd_ops, file, glob, trigger_data);
- if (ret)
+ if (existing_hist_update_only(glob, trigger_data, file))
goto out_free;
- if (ret == 0) {
- if (!(attrs->pause || attrs->cont || attrs->clear))
- ret = -ENOENT;
+
+ ret = event_trigger_register(cmd_ops, file, glob, trigger_data);
+ if (ret < 0)
goto out_free;
- }

if (get_named_trigger_data(trigger_data))
goto enable;
--
2.17.1