tracing: Remove usage of list iterator after the loop body

In preparation to limit the scope of the list iterator variable to the
traversal loop, use a dedicated pointer to point to the found element
[1].

Before, the code implicitly used the head when no element was found
when using &pos->list. Since the new variable is only set if an
element was found, the head needs to be used explicitly if the
variable is NULL.

Link: https://lkml.kernel.org/r/20220427170734.819891-2-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_output.c b/kernel/trace/trace_output.c
index d89e3f7..67f47ea 100644 (file)
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -692,7 +692,7 @@ static LIST_HEAD(ftrace_event_list);
 
 static int trace_search_list(struct list_head **list)
 {
-       struct trace_event *e;
+       struct trace_event *e = NULL, *iter;
        int next = __TRACE_LAST_TYPE;
 
        if (list_empty(&ftrace_event_list)) {
@@ -704,9 +704,11 @@ static int trace_search_list(struct list_head **list)
         * We used up all possible max events,
         * lets see if somebody freed one.
         */
-       list_for_each_entry(e, &ftrace_event_list, list) {
-               if (e->type != next)
+       list_for_each_entry(iter, &ftrace_event_list, list) {
+               if (iter->type != next) {
+                       e = iter;
                        break;
+               }
                next++;
        }
 
@@ -714,7 +716,10 @@ static int trace_search_list(struct list_head **list)
        if (next > TRACE_EVENT_TYPE_MAX)
                return 0;
 
-       *list = &e->list;
+       if (e)
+               *list = &e->list;
+       else
+               *list = &ftrace_event_list;
        return next;
 }