When the cfg80211 option "bss_entries_limit" is set to 1, routine cfg80211_bss_expire_oldest() fails by issuing repeated warnings. The problem could also occur in the unlikely event that a scan only finds a single SSID. In the first case, the warning is avoided by testing for the special ivalue for the option before scanning for the oldest entry. The second case is handled by converting the WARN_ON() to a WARN_ON_ONCE(). These changes fix commit 9853a55ef1bb ("cfg80211: limit scan results cache size").

Reported-by: Maxim Klimenko Sergievich klimenkomaximsergievich@gmail.com Fixes: 9853a55ef1bb ("cfg80211: limit scan results cache size"). Cc: stable@vger.kernel.org # 4.9+ Cc: Johannes Berg johannes@sipsolutions.net Signed-off-by: Larry Finger Larry.Finger@lwfinger.net --- net/wireless/scan.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/net/wireless/scan.c b/net/wireless/scan.c index 22e92be61938..d7aa38445fe6 100644 --- a/net/wireless/scan.c +++ b/net/wireless/scan.c @@ -463,6 +463,12 @@ static bool cfg80211_bss_expire_oldest(struct cfg80211_registered_device *rdev)

lockdep_assert_held(&rdev->bss_lock);

+ /* If the user has set cfg80211 option bss_entries_limit to 1, + * there cannot be an oldest BSS. Skip the scan. + */ + if (unlikely(rdev->bss_entries == 1)) + return false; + list_for_each_entry(bss, &rdev->bss_list, list) { if (atomic_read(&bss->hold)) continue; @@ -476,7 +482,7 @@ static bool cfg80211_bss_expire_oldest(struct cfg80211_registered_device *rdev) oldest = bss; }

- if (WARN_ON(!oldest)) + if (WARN_ON_ONCE(!oldest)) return false;

/*