cfg80211: use wiphy DFS domain if it is self-managed

Currently during CAC start or other radar events, the DFS
domain is fetched from cfg based on global DFS domain,
even if the wiphy regdomain disagrees.

But this could be different in case of self managed wiphy's
in case the self managed driver updates its database or supports
regions which has DFS domain set to UNSET in cfg80211 local
regdomain.

So for explicitly self-managed wiphys, just use their DFS
domain.

Signed-off-by: Sriram R <srirrama@codeaurora.org>
Link: https://lore.kernel.org/r/1629934730-16388-1-git-send-email-srirrama@codeaurora.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/reg.c

@@ -171,9 +171,11 @@ enum nl80211_dfs_regions reg_get_dfs_region(struct wiphy *wiphy)
 {
 	const struct ieee80211_regdomain *regd = NULL;
 	const struct ieee80211_regdomain *wiphy_regd = NULL;
+	enum nl80211_dfs_regions dfs_region;
 
 	rcu_read_lock();
 	regd = get_cfg80211_regdom();
+	dfs_region = regd->dfs_region;
 
 	if (!wiphy)
 		goto out;
@@ -182,6 +184,11 @@ enum nl80211_dfs_regions reg_get_dfs_region(struct wiphy *wiphy)
 	if (!wiphy_regd)
 		goto out;
 
+	if (wiphy->regulatory_flags & REGULATORY_WIPHY_SELF_MANAGED) {
+		dfs_region = wiphy_regd->dfs_region;
+		goto out;
+	}
+
 	if (wiphy_regd->dfs_region == regd->dfs_region)
 		goto out;
 
@@ -193,7 +200,7 @@ enum nl80211_dfs_regions reg_get_dfs_region(struct wiphy *wiphy)
 out:
 	rcu_read_unlock();
 
-	return regd->dfs_region;
+	return dfs_region;
 }
 
 static void rcu_free_regdom(const struct ieee80211_regdomain *r)