Commit 1da27a25 authored Apr 27, 2022 by Jakob Koschel Committed by Steven Rostedt (Google) Apr 27, 2022

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/

 [1]
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

parent 4d1257bb

kernel/trace/trace_output.c

+9 −4

Original line number	Diff line number	Diff line
		@@ -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;

		if (e)
		*list = &e->list;
		else
		*list = &ftrace_event_list;
		return next;
		}