mac80211: allow hardware scan to fall back to software

In some cases, like in the rsi driver hardware scan offload, there
may be scenarios in which hardware scan might not be available or
desirable.

Allow drivers to cope with this by letting them fall back to software
scan by returning the special value 1 from the hardware scan method.

Requested-by: Sushant Kumar Mishra <sushant2k1513@gmail.com>
Requested-by: Siva Rebbagondla <siva.rebbagondla@redpinesignals.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 18 insertions, 4 deletions

diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index 5d2a11777718..95413413f98c 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -356,7 +356,7 @@ static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 {
 	struct ieee80211_local *local = hw_to_local(hw);
-	bool hw_scan = local->ops->hw_scan;
+	bool hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 	bool was_scanning = local->scanning;
 	struct cfg80211_scan_request *scan_req;
 	struct ieee80211_sub_if_data *scan_sdata;
@@ -606,6 +606,7 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 				  struct cfg80211_scan_request *req)
 {
 	struct ieee80211_local *local = sdata->local;
+	bool hw_scan = local->ops->hw_scan;
 	int rc;
 
 	lockdep_assert_held(&local->mtx);
@@ -620,7 +621,8 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 		return 0;
 	}
 
-	if (local->ops->hw_scan) {
+ again:
+	if (hw_scan) {
 		u8 *ies;
 
 		local->hw_scan_ies_bufsize = local->scan_ies_len + req->ie_len;
@@ -679,7 +681,7 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 	else
 		memcpy(local->scan_addr, sdata->vif.addr, ETH_ALEN);
 
-	if (local->ops->hw_scan) {
+	if (hw_scan) {
 		__set_bit(SCAN_HW_SCANNING, &local->scanning);
 	} else if ((req->n_channels == 1) &&
 		   (req->channels[0] == local->_oper_chandef.chan)) {
@@ -722,7 +724,7 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 
 	ieee80211_recalc_idle(local);
 
-	if (local->ops->hw_scan) {
+	if (hw_scan) {
 		WARN_ON(!ieee80211_prep_hw_scan(local));
 		rc = drv_hw_scan(local, sdata, local->hw_scan_req);
 	} else {
@@ -740,6 +742,18 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 		RCU_INIT_POINTER(local->scan_sdata, NULL);
 	}
 
+	if (hw_scan && rc == 1) {
+		/*
+		 * we can't fall back to software for P2P-GO
+		 * as it must update NoA etc.
+		 */
+		if (ieee80211_vif_type_p2p(&sdata->vif) ==
+				NL80211_IFTYPE_P2P_GO)
+			return -EOPNOTSUPP;
+		hw_scan = false;
+		goto again;
+	}
+
 	return rc;
 }