Linux keeps scan results up to 15 seconds. This can be a problem for fast
moving client: they get back stale data. But if the kernel reports the
age of some BSS, then user-space can simply weed out old entries.
Signed-off-by: Holger Schurig <hs4233@xxxxxxxxxxxxxxxxxxxx>
---
One question was if I should specify the age in ms, or if I should specify
an absolute time. In the end I thought age in ms is better suited.
If an absolute time would sent with every BSS item, then user-space would
need an additional call to time() to find out which BSS items are too old.
Now it can use the milliseconds directly.
The case there user-space wants an absolute time ("At what hour did I get
the last probe response from this AP?") seems to be a more theoretical
problem. But if info is wanted, *THEN* you can call time() and substract the
reported bss-item-age from it.
Index: linux-wl/include/linux/nl80211.h
===================================================================
--- linux-wl.orig/include/linux/nl80211.h 2009-09-24 09:19:03.000000000 +0200
+++ linux-wl/include/linux/nl80211.h 2009-09-24 09:19:42.000000000 +0200
@@ -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_AGE_MS: 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_AGE_MS,
/* keep last */
__NL80211_BSS_AFTER_LAST,
Index: linux-wl/net/wireless/nl80211.c
===================================================================
--- linux-wl.orig/net/wireless/nl80211.c 2009-09-24 09:19:03.000000000 +0200
+++ linux-wl/net/wireless/nl80211.c 2009-09-24 09:37:40.000000000 +0200
@@ -3105,6 +3105,7 @@ static int nl80211_send_bss(struct sk_bu
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_AGE_MS, jiffies_to_msecs(jiffies - intbss->ts));
switch (rdev->wiphy.signal_type) {
case CFG80211_SIGNAL_TYPE_MBM:
--
http://www.holgerschurig.de
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