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>

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index d95da8f55f6e4cf8dcd17537f4edd3245c6b1394..aa0e4a12308c3568a496263bbbdc4da82df71872 100644 (file)
--- 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 c68e15e4132121f12c01c74f63dffe4956dfe40c..0e6277a06c29076b30e2e40098c905a1c97cdfb0 100644 (file)
--- 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 */

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 443d4d7deea299c7e997045d22d8b2b146d2c877..48c2ea4712e9d292fbed68a3a05d5e77ce7ddfab 100644 (file)
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -370,6 +370,8 @@ struct wiphy *wiphy_new(const struct cfg80211_ops *ops, int sizeof_priv)
        rdev->wiphy.rts_threshold = (u32) -1;
        rdev->wiphy.coverage_class = 0;
 
+       rdev->wiphy.features = NL80211_FEATURE_SCAN_FLUSH;
+
        return &rdev->wiphy;
 }
 EXPORT_SYMBOL(wiphy_new);

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index aee252d65b8f7ff0e06e8569c23c8c127d5fab13..9e5a7206b0b467b872920cacd36083ab2cfbd6a0 100644 (file)
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -4371,8 +4371,10 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
        if (info->attrs[NL80211_ATTR_SCAN_FLAGS]) {
                request->flags = nla_get_u32(
                        info->attrs[NL80211_ATTR_SCAN_FLAGS]);
-               if ((request->flags & NL80211_SCAN_FLAG_LOW_PRIORITY) &&
-                   !(wiphy->features & NL80211_FEATURE_LOW_PRIORITY_SCAN)) {
+               if (((request->flags & NL80211_SCAN_FLAG_LOW_PRIORITY) &&
+                    !(wiphy->features & NL80211_FEATURE_LOW_PRIORITY_SCAN)) ||
+                   ((request->flags & NL80211_SCAN_FLAG_FLUSH) &&
+                    !(wiphy->features & NL80211_FEATURE_SCAN_FLUSH))) {
                        err = -EOPNOTSUPP;
                        goto out_free;
                }
@@ -4383,6 +4385,7 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
 
        request->wdev = wdev;
        request->wiphy = &rdev->wiphy;
+       request->scan_start = jiffies;
 
        rdev->scan_req = request;
        err = rdev->ops->scan(&rdev->wiphy, request);
@@ -4612,8 +4615,10 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
        if (info->attrs[NL80211_ATTR_SCAN_FLAGS]) {
                request->flags = nla_get_u32(
                        info->attrs[NL80211_ATTR_SCAN_FLAGS]);
-               if ((request->flags & NL80211_SCAN_FLAG_LOW_PRIORITY) &&
-                   !(wiphy->features & NL80211_FEATURE_LOW_PRIORITY_SCAN)) {
+               if (((request->flags & NL80211_SCAN_FLAG_LOW_PRIORITY) &&
+                    !(wiphy->features & NL80211_FEATURE_LOW_PRIORITY_SCAN)) ||
+                   ((request->flags & NL80211_SCAN_FLAG_FLUSH) &&
+                    !(wiphy->features & NL80211_FEATURE_SCAN_FLUSH))) {
                        err = -EOPNOTSUPP;
                        goto out_free;
                }
@@ -4622,6 +4627,7 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
        request->dev = dev;
        request->wiphy = &rdev->wiphy;
        request->interval = interval;
+       request->scan_start = jiffies;
 
        err = rdev->ops->sched_scan_start(&rdev->wiphy, dev, request);
        if (!err) {

diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 20050965abca79c8be9fd8459224366eec4df236..a8d5a9a07e491aa145d71ffc911765b48000ef04 100644 (file)
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -47,6 +47,27 @@ static void __cfg80211_unlink_bss(struct cfg80211_registered_device *dev,
        kref_put(&bss->ref, bss_release);
 }
 
+/* must hold dev->bss_lock! */
+static void __cfg80211_bss_expire(struct cfg80211_registered_device *dev,
+                                 unsigned long expire_time)
+{
+       struct cfg80211_internal_bss *bss, *tmp;
+       bool expired = false;
+
+       list_for_each_entry_safe(bss, tmp, &dev->bss_list, list) {
+               if (atomic_read(&bss->hold))
+                       continue;
+               if (!time_after(expire_time, bss->ts))
+                       continue;
+
+               __cfg80211_unlink_bss(dev, bss);
+               expired = true;
+       }
+
+       if (expired)
+               dev->bss_generation++;
+}
+
 void ___cfg80211_scan_done(struct cfg80211_registered_device *rdev, bool leak)
 {
        struct cfg80211_scan_request *request;
@@ -72,10 +93,17 @@ void ___cfg80211_scan_done(struct cfg80211_registered_device *rdev, bool leak)
        if (wdev->netdev)
                cfg80211_sme_scan_done(wdev->netdev);
 
-       if (request->aborted)
+       if (request->aborted) {
                nl80211_send_scan_aborted(rdev, wdev);
-       else
+       } else {
+               if (request->flags & NL80211_SCAN_FLAG_FLUSH) {
+                       /* flush entries from previous scans */
+                       spin_lock_bh(&rdev->bss_lock);
+                       __cfg80211_bss_expire(rdev, request->scan_start);
+                       spin_unlock_bh(&rdev->bss_lock);
+               }
                nl80211_send_scan_done(rdev, wdev);
+       }
 
 #ifdef CONFIG_CFG80211_WEXT
        if (wdev->netdev && !request->aborted) {
@@ -126,16 +154,27 @@ EXPORT_SYMBOL(cfg80211_scan_done);
 void __cfg80211_sched_scan_results(struct work_struct *wk)
 {
        struct cfg80211_registered_device *rdev;
+       struct cfg80211_sched_scan_request *request;
 
        rdev = container_of(wk, struct cfg80211_registered_device,
                            sched_scan_results_wk);
 
+       request = rdev->sched_scan_req;
+
        mutex_lock(&rdev->sched_scan_mtx);
 
        /* we don't have sched_scan_req anymore if the scan is stopping */
-       if (rdev->sched_scan_req)
-               nl80211_send_sched_scan_results(rdev,
-                                               rdev->sched_scan_req->dev);
+       if (request) {
+               if (request->flags & NL80211_SCAN_FLAG_FLUSH) {
+                       /* flush entries from previous scans */
+                       spin_lock_bh(&rdev->bss_lock);
+                       __cfg80211_bss_expire(rdev, request->scan_start);
+                       spin_unlock_bh(&rdev->bss_lock);
+                       request->scan_start =
+                               jiffies + msecs_to_jiffies(request->interval);
+               }
+               nl80211_send_sched_scan_results(rdev, request->dev);
+       }
 
        mutex_unlock(&rdev->sched_scan_mtx);
 }
@@ -197,23 +236,9 @@ void cfg80211_bss_age(struct cfg80211_registered_device *dev,
        }
 }
 
-/* must hold dev->bss_lock! */
 void cfg80211_bss_expire(struct cfg80211_registered_device *dev)
 {
-       struct cfg80211_internal_bss *bss, *tmp;
-       bool expired = false;
-
-       list_for_each_entry_safe(bss, tmp, &dev->bss_list, list) {
-               if (atomic_read(&bss->hold))
-                       continue;
-               if (!time_after(jiffies, bss->ts + IEEE80211_SCAN_RESULT_EXPIRE))
-                       continue;
-               __cfg80211_unlink_bss(dev, bss);
-               expired = true;
-       }
-
-       if (expired)
-               dev->bss_generation++;
+       __cfg80211_bss_expire(dev, jiffies - IEEE80211_SCAN_RESULT_EXPIRE);
 }
 
 const u8 *cfg80211_find_ie(u8 eid, const u8 *ies, int len)
@@ -962,6 +987,7 @@ int cfg80211_wext_siwscan(struct net_device *dev,
        creq->ssids = (void *)&creq->channels[n_channels];
        creq->n_channels = n_channels;
        creq->n_ssids = 1;
+       creq->scan_start = jiffies;
 
        /* translate "Scan on frequencies" request */
        i = 0;

diff --git a/net/wireless/sme.c b/net/wireless/sme.c
index 055d596436161304303fff2a73ba520968df8501..07d717eb9e2a4cdc1f65a7383ba4fce04698edcb 100644 (file)
--- a/net/wireless/sme.c
+++ b/net/wireless/sme.c
@@ -138,6 +138,7 @@ static int cfg80211_conn_scan(struct wireless_dev *wdev)
 
        request->wdev = wdev;
        request->wiphy = &rdev->wiphy;
+       request->scan_start = jiffies;
 
        rdev->scan_req = request;