tracing: Remove logic for registering multiple event triggers at a time

Code for registering triggers assumes it's possible to register more
than one trigger at a time.  In fact, it's unimplemented and there
doesn't seem to be a reason to do that.

Remove the n_registered param from event_trigger_register() and fix up
callers.

Doing so simplifies the logic in event_trigger_register to the point
that it just becomes a wrapper calling event_command.reg().

It also removes the problematic call to event_command.unreg() in case
of failure.  A new function, event_trigger_unregister() is also added
for callers to call themselves.

The changes to trace_events_hist.c simply allow compilation; a
separate patch follows which updates the hist triggers to work
correctly with the new changes.

Link: https://lkml.kernel.org/r/6149fec7a139d93e84fa4535672fb5bef88006b0.1644010575.git.zanussi@kernel.org

Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

1 files changed, 6 insertions, 11 deletions

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 44db5ba9cabb..b18d00905eae 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -6287,7 +6287,7 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops,
 			goto out_free;
 		}
 
-		cmd_ops->unreg(glob+1, trigger_data, file);
+		event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);
 		se_name = trace_event_name(file->event_call);
 		se = find_synth_event(se_name);
 		if (se)
@@ -6296,13 +6296,10 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops,
 		goto out_free;
 	}
 
-	ret = cmd_ops->reg(glob, trigger_data, file);
-	/*
-	 * The above returns on success the # of triggers registered,
-	 * but if it didn't register any it returns zero.  Consider no
-	 * triggers registered a failure too.
-	 */
-	if (!ret) {
+	ret = event_trigger_register(cmd_ops, file, glob, trigger_data);
+	if (ret)
+		goto out_free;
+	if (ret == 0) {
 		if (!(attrs->pause || attrs->cont || attrs->clear))
 			ret = -ENOENT;
 		goto out_free;
@@ -6331,15 +6328,13 @@ enable:
 	se = find_synth_event(se_name);
 	if (se)
 		se->ref++;
-	/* Just return zero, not the number of registered triggers */
-	ret = 0;
  out:
 	if (ret == 0)
 		hist_err_clear();
 
 	return ret;
  out_unreg:
-	cmd_ops->unreg(glob+1, trigger_data, file);
+	event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);
  out_free:
 	if (cmd_ops->set_filter)
 		cmd_ops->set_filter(NULL, trigger_data, NULL);