tracing: Replace usage of found with dedicated list iterator variable

To move the list iterator variable into the list_for_each_entry_*()
macro in the future it should be avoided to use the list iterator
variable after the loop body.

To *never* use the list iterator variable after the loop it was
concluded to use a separate iterator variable instead of a
found boolean [1].

This removes the need to use a found variable and simply checking if
the variable was set, can determine if the break/goto was hit.

Link: https://lkml.kernel.org/r/20220427170734.819891-4-jakobkoschel@gmail.com
Cc: Ingo Molnar <mingo@redhat.com>
Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
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 fe10179..038dc59 100644 (file)
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -6117,20 +6117,19 @@ static void hist_unregister_trigger(char *glob,
                                    struct event_trigger_data *data,
                                    struct trace_event_file *file)
 {
+       struct event_trigger_data *test = NULL, *iter, *named_data = NULL;
        struct hist_trigger_data *hist_data = data->private_data;
-       struct event_trigger_data *test, *named_data = NULL;
-       bool unregistered = false;
 
        lockdep_assert_held(&event_mutex);
 
        if (hist_data->attrs->name)
                named_data = find_named_trigger(hist_data->attrs->name);
 
-       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))
+       list_for_each_entry(iter, &file->triggers, list) {
+               if (iter->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+                       if (!hist_trigger_match(data, iter, named_data, false))
                                continue;
-                       unregistered = true;
+                       test = iter;
                        list_del_rcu(&test->list);
                        trace_event_trigger_enable_disable(file, 0);
                        update_cond_flag(file);
@@ -6138,11 +6137,11 @@ static void hist_unregister_trigger(char *glob,
                }
        }
 
-       if (unregistered && test->ops->free)
+       if (test && test->ops->free)
                test->ops->free(test);
 
        if (hist_data->enable_timestamps) {
-               if (!hist_data->remove || unregistered)
+               if (!hist_data->remove || test)
                        tracing_set_filter_buffering(file->tr, false);
        }
 }

diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index 62c44da..21592be 100644 (file)
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -609,14 +609,13 @@ static void unregister_trigger(char *glob,
                               struct event_trigger_data *test,
                               struct trace_event_file *file)
 {
-       struct event_trigger_data *data;
-       bool unregistered = false;
+       struct event_trigger_data *data = NULL, *iter;
 
        lockdep_assert_held(&event_mutex);
 
-       list_for_each_entry(data, &file->triggers, list) {
-               if (data->cmd_ops->trigger_type == test->cmd_ops->trigger_type) {
-                       unregistered = true;
+       list_for_each_entry(iter, &file->triggers, list) {
+               if (iter->cmd_ops->trigger_type == test->cmd_ops->trigger_type) {
+                       data = iter;
                        list_del_rcu(&data->list);
                        trace_event_trigger_enable_disable(file, 0);
                        update_cond_flag(file);
@@ -624,7 +623,7 @@ static void unregister_trigger(char *glob,
                }
        }
 
-       if (unregistered && data->ops->free)
+       if (data && data->ops->free)
                data->ops->free(data);
 }
 
@@ -1870,19 +1869,18 @@ void event_enable_unregister_trigger(char *glob,
                                     struct trace_event_file *file)
 {
        struct enable_trigger_data *test_enable_data = test->private_data;
+       struct event_trigger_data *data = NULL, *iter;
        struct enable_trigger_data *enable_data;
-       struct event_trigger_data *data;
-       bool unregistered = false;
 
        lockdep_assert_held(&event_mutex);
 
-       list_for_each_entry(data, &file->triggers, list) {
-               enable_data = data->private_data;
+       list_for_each_entry(iter, &file->triggers, list) {
+               enable_data = iter->private_data;
                if (enable_data &&
-                   (data->cmd_ops->trigger_type ==
+                   (iter->cmd_ops->trigger_type ==
                     test->cmd_ops->trigger_type) &&
                    (enable_data->file == test_enable_data->file)) {
-                       unregistered = true;
+                       data = iter;
                        list_del_rcu(&data->list);
                        trace_event_trigger_enable_disable(file, 0);
                        update_cond_flag(file);
@@ -1890,7 +1888,7 @@ void event_enable_unregister_trigger(char *glob,
                }
        }
 
-       if (unregistered && data->ops->free)
+       if (data && data->ops->free)
                data->ops->free(data);
 }