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authorSergey Matyukevich <sergey.matyukevich.os@quantenna.com>2019-07-26 16:39:34 +0000
committerJohannes Berg <johannes.berg@intel.com>2019-07-29 16:23:13 +0200
commit0afd425b1b64251f19b5d8d8b49bf56fefbc643f (patch)
tree631452f22aaad867bc752106de595588f493612e /net/wireless/scan.c
parent3ab8227d3e7d1d2bf1829675d3197e3cb600e9f6 (diff)
cfg80211: fix duplicated scan entries after channel switch
When associated BSS completes channel switch procedure, its channel record needs to be updated. The existing mac80211 solution was extended to cfg80211 in commit 5dc8cdce1d72 ("mac80211/cfg80211: update bss channel on channel switch"). However that solution still appears to be incomplete as it may lead to duplicated scan entries for associated BSS after channel switch. The root cause of the problem is as follows. Each BSS entry is included into the following data structures: - bss list rdev->bss_list - bss search tree rdev->bss_tree Updating BSS channel record without rebuilding bss_tree may break tree search since cmp_bss considers all of the following: channel, bssid, ssid. When BSS channel is updated, but its location in bss_tree is not updated, then subsequent search operations may fail to locate this BSS since they will be traversing bss_tree in wrong direction. As a result, for scan performed after associated BSS channel switch, cfg80211_bss_update may add the second entry for the same BSS to both bss_list and bss_tree, rather then update the existing one. To summarize, if BSS channel needs to be updated, then bss_tree should be rebuilt in order to put updated BSS entry into a proper location. This commit suggests the following straightforward solution: - if new entry has been already created for BSS after channel switch, then use its IEs to update known BSS entry and then remove new entry completely - use rb_erase/rb_insert_bss reinstall updated BSS in bss_tree - for nontransmit BSS entry, the whole transmit BSS hierarchy is updated Signed-off-by: Sergey Matyukevich <sergey.matyukevich.os@quantenna.com> Link: https://lore.kernel.org/r/20190726163922.27509-3-sergey.matyukevich.os@quantenna.com Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Diffstat (limited to 'net/wireless/scan.c')
-rw-r--r--net/wireless/scan.c79
1 files changed, 79 insertions, 0 deletions
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 9119f5ce3677..d313c9befa23 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -2001,6 +2001,85 @@ void cfg80211_bss_iter(struct wiphy *wiphy,
}
EXPORT_SYMBOL(cfg80211_bss_iter);
+void cfg80211_update_assoc_bss_entry(struct wireless_dev *wdev,
+ struct ieee80211_channel *chan)
+{
+ struct wiphy *wiphy = wdev->wiphy;
+ struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
+ struct cfg80211_internal_bss *cbss = wdev->current_bss;
+ struct cfg80211_internal_bss *new = NULL;
+ struct cfg80211_internal_bss *bss;
+ struct cfg80211_bss *nontrans_bss;
+ struct cfg80211_bss *tmp;
+
+ spin_lock_bh(&rdev->bss_lock);
+
+ if (WARN_ON(cbss->pub.channel == chan))
+ goto done;
+
+ /* use transmitting bss */
+ if (cbss->pub.transmitted_bss)
+ cbss = container_of(cbss->pub.transmitted_bss,
+ struct cfg80211_internal_bss,
+ pub);
+
+ cbss->pub.channel = chan;
+
+ list_for_each_entry(bss, &rdev->bss_list, list) {
+ if (!cfg80211_bss_type_match(bss->pub.capability,
+ bss->pub.channel->band,
+ wdev->conn_bss_type))
+ continue;
+
+ if (bss == cbss)
+ continue;
+
+ if (!cmp_bss(&bss->pub, &cbss->pub, BSS_CMP_REGULAR)) {
+ new = bss;
+ break;
+ }
+ }
+
+ if (new) {
+ /* to save time, update IEs for transmitting bss only */
+ if (cfg80211_update_known_bss(rdev, cbss, new, false)) {
+ new->pub.proberesp_ies = NULL;
+ new->pub.beacon_ies = NULL;
+ }
+
+ list_for_each_entry_safe(nontrans_bss, tmp,
+ &new->pub.nontrans_list,
+ nontrans_list) {
+ bss = container_of(nontrans_bss,
+ struct cfg80211_internal_bss, pub);
+ if (__cfg80211_unlink_bss(rdev, bss))
+ rdev->bss_generation++;
+ }
+
+ WARN_ON(atomic_read(&new->hold));
+ if (!WARN_ON(!__cfg80211_unlink_bss(rdev, new)))
+ rdev->bss_generation++;
+ }
+
+ rb_erase(&cbss->rbn, &rdev->bss_tree);
+ rb_insert_bss(rdev, cbss);
+ rdev->bss_generation++;
+
+ list_for_each_entry_safe(nontrans_bss, tmp,
+ &cbss->pub.nontrans_list,
+ nontrans_list) {
+ bss = container_of(nontrans_bss,
+ struct cfg80211_internal_bss, pub);
+ bss->pub.channel = chan;
+ rb_erase(&bss->rbn, &rdev->bss_tree);
+ rb_insert_bss(rdev, bss);
+ rdev->bss_generation++;
+ }
+
+done:
+ spin_unlock_bh(&rdev->bss_lock);
+}
+
#ifdef CONFIG_CFG80211_WEXT
static struct cfg80211_registered_device *
cfg80211_get_dev_from_ifindex(struct net *net, int ifindex)