PM: wakeup: Handle empty list in wakeup_sources_walk_start()

In the case of an empty wakeup_sources list, wakeup_sources_walk_start()
will return an invalid but non-NULL address. This also affects wrappers
of the aforementioned function, like for_each_wakeup_source().

Update wakeup_sources_walk_start() to return NULL in case of an empty
list.

Fixes: b4941adb24c0 ("PM: wakeup: Add routine to help fetch wakeup source object.")
Signed-off-by: Samuel Wu <wusamuel@google.com>
[ rjw: Subject and changelog edits ]
Link: https://patch.msgid.link/20260124012133.2451708-2-wusamuel@google.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
index 1e1a0e7eeac5fa90f159835ff2d35f63ee3fcde9..e69033d16fba04433fee6d0a6cffdf61f6684803 100644 (file)
--- a/drivers/base/power/wakeup.c
+++ b/drivers/base/power/wakeup.c
@@ -275,9 +275,7 @@ EXPORT_SYMBOL_GPL(wakeup_sources_read_unlock);
  */
 struct wakeup_source *wakeup_sources_walk_start(void)
 {
-       struct list_head *ws_head = &wakeup_sources;
-
-       return list_entry_rcu(ws_head->next, struct wakeup_source, entry);
+       return list_first_or_null_rcu(&wakeup_sources, struct wakeup_source, entry);
 }
 EXPORT_SYMBOL_GPL(wakeup_sources_walk_start);