cfg80211: add support for flushing old scan results

Add an NL80211_SCAN_FLAG_FLUSH flag that causes old bss cache
entries to be flushed on scan completion. This is useful for
collecting guaranteed fresh scan/survey result (e.g. on resume).

For normal scan, flushing only happens on successful completion
of a scan; i.e. it does not happen if the scan is aborted.
For scheduled scan, previous scan results are flushed everytime
when we get new scan results.

This feature is enabled by default. Drivers can disable it by
unsetting the NL80211_FEATURE_SCAN_FLUSH flag.

Signed-off-by: Sam Leffler <sleffler@chromium.org>
Tested-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
[invert polarity of feature flag to account for old kernels]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

2 files changed, 7 insertions, 0 deletions

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index d95da8f55f6e..aa0e4a12308c 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -1005,6 +1005,7 @@ struct cfg80211_ssid {
  * @flags: bit field of flags controlling operation
  * @rates: bitmap of rates to advertise for each band
  * @wiphy: the wiphy this was for
+ * @scan_start: time (in jiffies) when the scan started
  * @wdev: the wireless device to scan for
  * @aborted: (internal) scan request was notified as aborted
  * @no_cck: used to send probe requests at non CCK rate in 2GHz band
@@ -1023,6 +1024,7 @@ struct cfg80211_scan_request {
 
         /* internal */
         struct wiphy *wiphy;
+        unsigned long scan_start;
         bool aborted;
         bool no_cck;
 
@@ -1074,6 +1076,7 @@ struct cfg80211_sched_scan_request {
         /* internal */
         struct wiphy *wiphy;
         struct net_device *dev;
+        unsigned long scan_start;
 
         /* keep last */
         struct ieee80211_channel *channels[0];
diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index c68e15e41321..0e6277a06c29 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -3049,6 +3049,7 @@ enum nl80211_ap_sme_features {
  *      equals (SAE) with user space SME (NL80211_CMD_AUTHENTICATE) in station
  *      mode
  * @NL80211_FEATURE_LOW_PRIORITY_SCAN: This driver supports low priority scan
+ * @NL80211_FEATURE_SCAN_FLUSH: Scan flush is supported
  */
 enum nl80211_feature_flags {
         NL80211_FEATURE_SK_TX_STATUS                    = 1 << 0,
@@ -3058,6 +3059,7 @@ enum nl80211_feature_flags {
         NL80211_FEATURE_P2P_DEVICE_NEEDS_CHANNEL        = 1 << 4,
         NL80211_FEATURE_SAE                             = 1 << 5,
         NL80211_FEATURE_LOW_PRIORITY_SCAN               = 1 << 6,
+        NL80211_FEATURE_SCAN_FLUSH                      = 1 << 7,
 };
 
 /**
@@ -3100,9 +3102,11 @@ enum nl80211_connect_failed_reason {
  * requests.
  *
  * @NL80211_SCAN_FLAG_LOW_PRIORITY: scan request has low priority
+ * @NL80211_SCAN_FLAG_FLUSH: flush cache before scanning
  */
 enum nl80211_scan_flags {
         NL80211_SCAN_FLAG_LOW_PRIORITY                  = 1<<0,
+        NL80211_SCAN_FLAG_FLUSH                         = 1<<1,
 };
 
 #endif /* __LINUX_NL80211_H */