nl80211: report age of scan results

Linux keeps scan results up to 15 seconds. This can be a problem for fast
moving clients: they get back stale data. But if the kernel reports the age
of the BSS items, then user-space can simply weed out old entries by itself.

Signed-off-by: Holger Schurig <hs4233@mail.mn-solutions.de>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h
index a8d71ed..50afca3 100644 (file)
--- a/include/linux/nl80211.h
+++ b/include/linux/nl80211.h
@@ -1277,6 +1277,7 @@ enum nl80211_channel_type {
  * @NL80211_BSS_SIGNAL_UNSPEC: signal strength of the probe response/beacon
  *     in unspecified units, scaled to 0..100 (u8)
  * @NL80211_BSS_STATUS: status, if this BSS is "used"
+ * @NL80211_BSS_SEEN_MS_AGO: age of this BSS entry in ms
  * @__NL80211_BSS_AFTER_LAST: internal
  * @NL80211_BSS_MAX: highest BSS attribute
  */
@@ -1291,6 +1292,7 @@ enum nl80211_bss {
        NL80211_BSS_SIGNAL_MBM,
        NL80211_BSS_SIGNAL_UNSPEC,
        NL80211_BSS_STATUS,
+       NL80211_BSS_SEEN_MS_AGO,
 
        /* keep last */
        __NL80211_BSS_AFTER_LAST,

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index eddab09..e0ecc9f 100644 (file)
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -3105,6 +3105,8 @@ static int nl80211_send_bss(struct sk_buff *msg, u32 pid, u32 seq, int flags,
                NLA_PUT_U16(msg, NL80211_BSS_BEACON_INTERVAL, res->beacon_interval);
        NLA_PUT_U16(msg, NL80211_BSS_CAPABILITY, res->capability);
        NLA_PUT_U32(msg, NL80211_BSS_FREQUENCY, res->channel->center_freq);
+       NLA_PUT_U32(msg, NL80211_BSS_SEEN_MS_AGO,
+               jiffies_to_msecs(jiffies - intbss->ts));
 
        switch (rdev->wiphy.signal_type) {
        case CFG80211_SIGNAL_TYPE_MBM: