mac80211: fix AP reconfiguration on DFS channels in non-ETSI regdomain

Allow grace period for DFS available after shutting down beacons on the channel

Signed-off-by: Felix Fietkau <nbd@nbd.name>

diff --git a/package/kernel/mac80211/patches/subsys/320-cfg80211-allow-grace-period-for-DFS-available-after-.patch b/package/kernel/mac80211/patches/subsys/320-cfg80211-allow-grace-period-for-DFS-available-after-.patch
new file mode 100644 (file)
index 0000000..d04b116
--- /dev/null
+++ b/package/kernel/mac80211/patches/subsys/320-cfg80211-allow-grace-period-for-DFS-available-after-.patch
@@ -0,0 +1,149 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Thu, 14 Sep 2023 13:17:16 +0200
+Subject: [PATCH] cfg80211: allow grace period for DFS available after beacon
+ shutdown
+
+Fixes reconfiguring an AP on a DFS channel in non-ETSI regdomain
+
+Fixes: b35a51c7dd25 ("cfg80211: Make pre-CAC results valid only for ETSI domain")
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/include/net/cfg80211.h
++++ b/include/net/cfg80211.h
+@@ -175,6 +175,8 @@ enum ieee80211_channel_flags {
+  * @dfs_state: current state of this channel. Only relevant if radar is required
+  *    on this channel.
+  * @dfs_state_entered: timestamp (jiffies) when the dfs state was entered.
++ * @dfs_state_last_available: timestamp (jiffies) of the last time when the
++ *    channel was available.
+  * @dfs_cac_ms: DFS CAC time in milliseconds, this is valid for DFS channels.
+  */
+ struct ieee80211_channel {
+@@ -191,6 +193,7 @@ struct ieee80211_channel {
+       int orig_mag, orig_mpwr;
+       enum nl80211_dfs_state dfs_state;
+       unsigned long dfs_state_entered;
++      unsigned long dfs_state_last_available;
+       unsigned int dfs_cac_ms;
+ };
+ 
+--- a/net/wireless/ap.c
++++ b/net/wireless/ap.c
+@@ -30,6 +30,9 @@ static int ___cfg80211_stop_ap(struct cf
+       if (!wdev->links[link_id].ap.beacon_interval)
+               return -ENOENT;
+ 
++      cfg80211_update_last_available(wdev->wiphy,
++                                     &wdev->links[link_id].ap.chandef);
++
+       err = rdev_stop_ap(rdev, dev, link_id);
+       if (!err) {
+               wdev->conn_owner_nlportid = 0;
+@@ -41,9 +44,6 @@ static int ___cfg80211_stop_ap(struct cf
+               if (notify)
+                       nl80211_send_ap_stopped(wdev, link_id);
+ 
+-              /* Should we apply the grace period during beaconing interface
+-               * shutdown also?
+-               */
+               cfg80211_sched_dfs_chan_update(rdev);
+       }
+ 
+--- a/net/wireless/chan.c
++++ b/net/wireless/chan.c
+@@ -461,6 +461,8 @@ static void cfg80211_set_chans_dfs_state
+ 
+               c->dfs_state = dfs_state;
+               c->dfs_state_entered = jiffies;
++              if (dfs_state == NL80211_DFS_AVAILABLE)
++                      c->dfs_state_last_available = jiffies;
+       }
+ }
+ 
+@@ -873,6 +875,49 @@ static bool cfg80211_get_chans_dfs_avail
+       return true;
+ }
+ 
++static void
++__cfg80211_update_last_available(struct wiphy *wiphy,
++                                       u32 center_freq,
++                                       u32 bandwidth)
++{
++      struct ieee80211_channel *c;
++      u32 freq, start_freq, end_freq;
++
++      start_freq = cfg80211_get_start_freq(center_freq, bandwidth);
++      end_freq = cfg80211_get_end_freq(center_freq, bandwidth);
++
++      /*
++       * Check entire range of channels for the bandwidth.
++       * If any channel in between is disabled or has not
++       * had gone through CAC return false
++       */
++      for (freq = start_freq; freq <= end_freq; freq += MHZ_TO_KHZ(20)) {
++              c = ieee80211_get_channel_khz(wiphy, freq);
++              if (!c)
++                      return;
++
++              c->dfs_state_last_available = jiffies;
++      }
++}
++
++void cfg80211_update_last_available(struct wiphy *wiphy,
++                                  const struct cfg80211_chan_def *chandef)
++{
++      int width;
++
++      width = cfg80211_chandef_get_width(chandef);
++      if (width < 0)
++              return;
++
++      __cfg80211_update_last_available(wiphy, MHZ_TO_KHZ(chandef->center_freq1),
++                                               width);
++      if (chandef->width != NL80211_CHAN_WIDTH_80P80)
++          return;
++
++      __cfg80211_update_last_available(wiphy, MHZ_TO_KHZ(chandef->center_freq2),
++                                               width);
++}
++
+ static bool cfg80211_chandef_dfs_available(struct wiphy *wiphy,
+                               const struct cfg80211_chan_def *chandef)
+ {
+--- a/net/wireless/core.h
++++ b/net/wireless/core.h
+@@ -487,6 +487,8 @@ void cfg80211_set_dfs_state(struct wiphy
+                           enum nl80211_dfs_state dfs_state);
+ 
+ void cfg80211_dfs_channels_update_work(struct work_struct *work);
++void cfg80211_update_last_available(struct wiphy *wiphy,
++                                  const struct cfg80211_chan_def *chandef);
+ 
+ unsigned int
+ cfg80211_chandef_dfs_cac_time(struct wiphy *wiphy,
+--- a/net/wireless/mlme.c
++++ b/net/wireless/mlme.c
+@@ -915,6 +915,8 @@ void cfg80211_dfs_channels_update_work(s
+                       if (c->dfs_state == NL80211_DFS_UNAVAILABLE) {
+                               time_dfs_update = IEEE80211_DFS_MIN_NOP_TIME_MS;
+                               radar_event = NL80211_RADAR_NOP_FINISHED;
++                              timeout = c->dfs_state_entered +
++                                        msecs_to_jiffies(time_dfs_update);
+                       } else {
+                               if (regulatory_pre_cac_allowed(wiphy) ||
+                                   cfg80211_any_wiphy_oper_chan(wiphy, c))
+@@ -922,11 +924,10 @@ void cfg80211_dfs_channels_update_work(s
+ 
+                               time_dfs_update = REG_PRE_CAC_EXPIRY_GRACE_MS;
+                               radar_event = NL80211_RADAR_PRE_CAC_EXPIRED;
++                              timeout = c->dfs_state_last_available +
++                                        msecs_to_jiffies(time_dfs_update);
+                       }
+ 
+-                      timeout = c->dfs_state_entered +
+-                                msecs_to_jiffies(time_dfs_update);
+-
+                       if (time_after_eq(jiffies, timeout)) {
+                               c->dfs_state = NL80211_DFS_USABLE;
+                               c->dfs_state_entered = jiffies;