tracing: Separate hist state updates from hist registration

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.

Link: https://lkml.kernel.org/r/211b2cd3e3d7e00f4f8ad45ef8b33063da6a7e05.1644010576.git.zanussi@kernel.org
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 1b71bdb0bcb14db16dd8f682c983522ffa3b0973..998dfe2162fceb57e2d5a865baa1cf6745703815 100644 (file)
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -5929,6 +5929,48 @@ 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)
@@ -5957,19 +5999,11 @@ 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:
@@ -6008,8 +6042,6 @@ static int hist_register_trigger(char *glob,
 
        if (named_data)
                destroy_hist_data(hist_data);
-
-       ret++;
  out:
        return ret;
 }
@@ -6277,14 +6309,12 @@ 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;