3 files changed, 88 insertions, 1 deletions

diff --git a/net/wireless/chan.c b/net/wireless/chan.c
index 1d25a462b145..96c97800e247 100644
--- a/net/wireless/chan.c
+++ b/net/wireless/chan.c
@@ -351,6 +351,80 @@ int cfg80211_chandef_dfs_required(struct wiphy *wiphy,
 }
 EXPORT_SYMBOL(cfg80211_chandef_dfs_required);
 
+static int cfg80211_get_chans_dfs_usable(struct wiphy *wiphy,
+                                         u32 center_freq,
+                                         u32 bandwidth)
+{
+        struct ieee80211_channel *c;
+        u32 freq, start_freq, end_freq;
+        int count = 0;
+
+        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.
+         * Check all channels are DFS channels (DFS_USABLE or
+         * DFS_AVAILABLE). Return number of usable channels
+         * (require CAC). Allow DFS and non-DFS channel mix.
+         */
+        for (freq = start_freq; freq <= end_freq; freq += 20) {
+                c = ieee80211_get_channel(wiphy, freq);
+                if (!c)
+                        return -EINVAL;
+
+                if (c->flags & IEEE80211_CHAN_DISABLED)
+                        return -EINVAL;
+
+                if (c->flags & IEEE80211_CHAN_RADAR) {
+                        if (c->dfs_state == NL80211_DFS_UNAVAILABLE)
+                                return -EINVAL;
+
+                        if (c->dfs_state == NL80211_DFS_USABLE)
+                                count++;
+                }
+        }
+
+        return count;
+}
+
+bool cfg80211_chandef_dfs_usable(struct wiphy *wiphy,
+                                 const struct cfg80211_chan_def *chandef)
+{
+        int width;
+        int r1, r2 = 0;
+
+        if (WARN_ON(!cfg80211_chandef_valid(chandef)))
+                return false;
+
+        width = cfg80211_chandef_get_width(chandef);
+        if (width < 0)
+                return false;
+
+        r1 = cfg80211_get_chans_dfs_usable(wiphy, chandef->center_freq1,
+                                          width);
+
+        if (r1 < 0)
+                return false;
+
+        switch (chandef->width) {
+        case NL80211_CHAN_WIDTH_80P80:
+                WARN_ON(!chandef->center_freq2);
+                r2 = cfg80211_get_chans_dfs_usable(wiphy,
+                                                   chandef->center_freq2,
+                                                   width);
+                if (r2 < 0)
+                        return false;
+                break;
+        default:
+                WARN_ON(chandef->center_freq2);
+                break;
+        }
+
+        return (r1 + r2 > 0);
+}
+
+
 static bool cfg80211_secondary_chans_ok(struct wiphy *wiphy,
                                         u32 center_freq, u32 bandwidth,
                                         u32 prohibited_flags)
diff --git a/net/wireless/core.h b/net/wireless/core.h
index eb0f7a3a25a9..2888867ee7c5 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -382,6 +382,19 @@ int cfg80211_can_use_iftype_chan(struct cfg80211_registered_device *rdev,
                                  enum cfg80211_chan_mode chanmode,
                                  u8 radar_detect);
 
+/**
+ * cfg80211_chandef_dfs_usable - checks if chandef is DFS usable
+ * @wiphy: the wiphy to validate against
+ * @chandef: the channel definition to check
+ *
+ * Checks if chandef is usable and we can/need start CAC on such channel.
+ *
+ * Return: Return true if all channels available and at least
+ *         one channel require CAC (NL80211_DFS_USABLE)
+ */
+bool cfg80211_chandef_dfs_usable(struct wiphy *wiphy,
+                                 const struct cfg80211_chan_def *chandef);
+
 void cfg80211_set_dfs_state(struct wiphy *wiphy,
                             const struct cfg80211_chan_def *chandef,
                             enum nl80211_dfs_state dfs_state);
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 41af3a0e9961..e2bb4276af1a 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -5651,7 +5651,7 @@ static int nl80211_start_radar_detection(struct sk_buff *skb,
         if (err == 0)
                 return -EINVAL;
 
-        if (chandef.chan->dfs_state != NL80211_DFS_USABLE)
+        if (!cfg80211_chandef_dfs_usable(wdev->wiphy, &chandef))
                 return -EINVAL;
 
         if (!rdev->ops->start_radar_detection)