tracing/user_events: Optimize safe list traversals

Several of the list traversals in the user_events facility use safe list
traversals where they could be using the unsafe versions instead.

Replace these safe traversals with their unsafe counterparts in the
interest of optimization.

Link: https://lore.kernel.org/linux-trace-kernel/20230810194337.695983-1-ervaughn@linux.microsoft.com
Suggested-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Eric Vaughn <ervaughn@linux.microsoft.com>
Acked-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c
index 33cb6af31f39572c6b7a491a204c85fd68b52ddc..6f046650e52719918fdbb083f6c24df29d947036 100644 (file)
--- a/kernel/trace/trace_events_user.c
+++ b/kernel/trace/trace_events_user.c
@@ -1328,14 +1328,14 @@ static int user_field_set_string(struct ftrace_event_field *field,
 
 static int user_event_set_print_fmt(struct user_event *user, char *buf, int len)
 {
-       struct ftrace_event_field *field, *next;
+       struct ftrace_event_field *field;
        struct list_head *head = &user->fields;
        int pos = 0, depth = 0;
        const char *str_func;
 
        pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
 
-       list_for_each_entry_safe_reverse(field, next, head, link) {
+       list_for_each_entry_reverse(field, head, link) {
                if (depth != 0)
                        pos += snprintf(buf + pos, LEN_OR_ZERO, " ");
 
@@ -1347,7 +1347,7 @@ static int user_event_set_print_fmt(struct user_event *user, char *buf, int len)
 
        pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
 
-       list_for_each_entry_safe_reverse(field, next, head, link) {
+       list_for_each_entry_reverse(field, head, link) {
                if (user_field_is_dyn_string(field->type, &str_func))
                        pos += snprintf(buf + pos, LEN_OR_ZERO,
                                        ", %s(%s)", str_func, field->name);
@@ -1732,7 +1732,7 @@ static int user_event_create(const char *raw_command)
 static int user_event_show(struct seq_file *m, struct dyn_event *ev)
 {
        struct user_event *user = container_of(ev, struct user_event, devent);
-       struct ftrace_event_field *field, *next;
+       struct ftrace_event_field *field;
        struct list_head *head;
        int depth = 0;
 
@@ -1740,7 +1740,7 @@ static int user_event_show(struct seq_file *m, struct dyn_event *ev)
 
        head = trace_get_fields(&user->call);
 
-       list_for_each_entry_safe_reverse(field, next, head, link) {
+       list_for_each_entry_reverse(field, head, link) {
                if (depth == 0)
                        seq_puts(m, " ");
                else
@@ -1816,13 +1816,14 @@ out:
 static bool user_fields_match(struct user_event *user, int argc,
                              const char **argv)
 {
-       struct ftrace_event_field *field, *next;
+       struct ftrace_event_field *field;
        struct list_head *head = &user->fields;
        int i = 0;
 
-       list_for_each_entry_safe_reverse(field, next, head, link)
+       list_for_each_entry_reverse(field, head, link) {
                if (!user_field_match(field, argc, argv, &i))
                        return false;
+       }
 
        if (i != argc)
                return false;