In current linux.git (1954c4f01220), cfg80211_bss_age() is defined
and declared unconditionally. However, its only in-tree caller is within
wiphy_resume() in net/wireless/sysfs.c, which is already guarded by #ifdef 
CONFIG_PM_SLEEP.

Match the helper scope to its caller by wrapping the definition in
CONFIG_PM_SLEEP and providing a no-op stub in the header. This fixes the
config-scope mismatch and avoids unnecessary code inclusion when
system sleep support is disabled.

Signed-off-by: Pengpeng Hou <pengpeng.hou@isrc.iscas.ac.cn>
---
diff --git a/net/wireless/core.h b/net/wireless/core.h
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@
 
 void cfg80211_bss_expire(struct cfg80211_registered_device *rdev);
+#ifdef CONFIG_PM_SLEEP
 void cfg80211_bss_age(struct cfg80211_registered_device *rdev,
                       unsigned long age_secs);
+#else
+static inline void cfg80211_bss_age(struct cfg80211_registered_device *rdev,
+				    unsigned long age_secs) { }
+#endif
 void cfg80211_update_assoc_bss_entry(struct wireless_dev *wdev,
 				     unsigned int link,
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@
-void cfg80211_bss_age(struct cfg80211_registered_device *rdev,
+#ifdef CONFIG_PM_SLEEP
+void cfg80211_bss_age(struct cfg80211_registered_device *rdev,
                       unsigned long age_secs)
 {
 	struct cfg80211_internal_bss *bss;
@@
 	list_for_each_entry(bss, &rdev->bss_list, list)
 		bss->ts -= age_jiffies;
 	spin_unlock_bh(&rdev->bss_lock);
 }
+#endif
 
 void cfg80211_bss_expire(struct cfg80211_registered_device *rdev)
 {