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Subject[PATCH v2 1/4] tracing: Remove usage of list iterator after the loop body
Date
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://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
---
kernel/trace/trace_output.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 8aa493d25c73..733a4d6c20e2 100644
--- 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;
}

--
2.25.1
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