[PATCH 4.19.y 01/13] tracing: Simplify creation and deletion of synthetic events

George Guo
2024-05-09T02:30:06Z

From: Masami Hiramatsu <mhiramat@kernel.org>

commit faacb361f271be4baf2d807e2eeaba87e059225f upstream.

Since the event_mutex and synth_event_mutex ordering issue
is gone, we can skip existing event check when adding or
deleting events, and some redundant code in error path.

This changes release_all_synth_events() to abort the process
when it hits any error and returns the error code. It succeeds
only if it has no error.

Link: http://lkml.kernel.org/r/154140847194.17322.17960275728005067803.stgit@devbox

Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: George Guo <guodongtai@kylinos.cn>
---
kernel/trace/trace_events_hist.c | 53 +++++++++++---------------------
1 file changed, 18 insertions(+), 35 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index ede370225245..efba381dbc60 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1028,18 +1028,6 @@ struct hist_var_data {
struct hist_trigger_data *hist_data;
};

-static void add_or_delete_synth_event(struct synth_event *event, int delete)
-{
- if (delete)
- free_synth_event(event);
- else {
- if (!find_synth_event(event->name))
- list_add(&event->list, &synth_event_list);
- else
- free_synth_event(event);
- }
-}
-
static int create_synth_event(int argc, char **argv)
{
struct synth_field *field, *fields[SYNTH_FIELDS_MAX];
@@ -1072,15 +1060,16 @@ static int create_synth_event(int argc, char **argv)
if (event) {
if (delete_event) {
if (event->ref) {
- event = NULL;
ret = -EBUSY;
goto out;
}
- list_del(&event->list);
- goto out;
- }
- event = NULL;
- ret = -EEXIST;
+ ret = unregister_synth_event(event);
+ if (!ret) {
+ list_del(&event->list);
+ free_synth_event(event);
+ }
+ } else
+ ret = -EEXIST;
goto out;
} else if (delete_event) {
ret = -ENOENT;
@@ -1120,29 +1109,21 @@ static int create_synth_event(int argc, char **argv)
event = NULL;
goto err;
}
+ ret = register_synth_event(event);
+ if (!ret)
+ list_add(&event->list, &synth_event_list);
+ else
+ free_synth_event(event);
out:
- if (event) {
- if (delete_event) {
- ret = unregister_synth_event(event);
- add_or_delete_synth_event(event, !ret);
- } else {
- ret = register_synth_event(event);
- add_or_delete_synth_event(event, ret);
- }
- }
mutex_unlock(&synth_event_mutex);
mutex_unlock(&event_mutex);

return ret;
err:
- mutex_unlock(&synth_event_mutex);
- mutex_unlock(&event_mutex);
-
for (i = 0; i < n_fields; i++)
free_synth_field(fields[i]);
- free_synth_event(event);

- return ret;
+ goto out;
}

static int release_all_synth_events(void)
@@ -1161,10 +1142,12 @@ static int release_all_synth_events(void)
}

list_for_each_entry_safe(event, e, &synth_event_list, list) {
- list_del(&event->list);
-
ret = unregister_synth_event(event);
- add_or_delete_synth_event(event, !ret);
+ if (!ret) {
+ list_del(&event->list);
+ free_synth_event(event);
+ } else
+ break;
}
mutex_unlock(&synth_event_mutex);
mutex_unlock(&event_mutex);
--
2.34.1