mac80211: Add support to trigger sta disconnect on hardware restart

Currently in case of target hardware restart, we just reconfig and
re-enable the security keys and enable the network queues to start
data traffic back from where it was interrupted.

Many ath10k wifi chipsets have sequence numbers for the data
packets assigned by firmware and the mac sequence number will
restart from zero after target hardware restart leading to mismatch
in the sequence number expected by the remote peer vs the sequence
number of the frame sent by the target firmware.

This mismatch in sequence number will cause out-of-order packets
on the remote peer and all the frames sent by the device are dropped
until we reach the sequence number which was sent before we restarted
the target hardware

In order to fix this, we trigger a sta disconnect, in case of target
hw restart. After this there will be a fresh connection and thereby
avoiding the dropping of frames by remote peer.

The right fix would be to pull the entire data path into the host
which is not feasible or would need lots of complex changes and
will still be inefficient.

Tested on ath10k using WCN3990, QCA6174

Signed-off-by: Youghandhar Chintala <youghand@codeaurora.org>
Link: https://lore.kernel.org/r/20220308115325.5246-2-youghand@codeaurora.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

3 files changed, 45 insertions, 3 deletions

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 6a2421a066fb..b07ccfc44115 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -767,6 +767,8 @@ struct ieee80211_if_mesh {
  *	back to wireless media and to the local net stack.
  * @IEEE80211_SDATA_DISCONNECT_RESUME: Disconnect after resume.
  * @IEEE80211_SDATA_IN_DRIVER: indicates interface was added to driver
+ * @IEEE80211_SDATA_DISCONNECT_HW_RESTART: Disconnect after hardware restart
+ *  recovery
  */
 enum ieee80211_sub_if_data_flags {
 	IEEE80211_SDATA_ALLMULTI		= BIT(0),
@@ -774,6 +776,7 @@ enum ieee80211_sub_if_data_flags {
 	IEEE80211_SDATA_DONT_BRIDGE_PACKETS	= BIT(3),
 	IEEE80211_SDATA_DISCONNECT_RESUME	= BIT(4),
 	IEEE80211_SDATA_IN_DRIVER		= BIT(5),
+	IEEE80211_SDATA_DISCONNECT_HW_RESTART	= BIT(6),
 };
 
 /**
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 197cad4a2768..29bfce6b3561 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -4934,6 +4934,18 @@ void ieee80211_sta_restart(struct ieee80211_sub_if_data *sdata)
 		sdata_unlock(sdata);
 		return;
 	}
+
+	if (sdata->flags & IEEE80211_SDATA_DISCONNECT_HW_RESTART) {
+		sdata->flags &= ~IEEE80211_SDATA_DISCONNECT_HW_RESTART;
+		mlme_dbg(sdata, "driver requested disconnect after hardware restart\n");
+		ieee80211_sta_connection_lost(sdata,
+					      ifmgd->associated->bssid,
+					      WLAN_REASON_UNSPECIFIED,
+					      true);
+		sdata_unlock(sdata);
+		return;
+	}
+
 	sdata_unlock(sdata);
 }
 #endif
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index caea8dbd1d9b..682a164f795a 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -2347,6 +2347,7 @@ int ieee80211_reconfig(struct ieee80211_local *local)
 	struct cfg80211_sched_scan_request *sched_scan_req;
 	bool sched_scan_stopped = false;
 	bool suspended = local->suspended;
+	bool in_reconfig = false;
 
 	/* nothing to do if HW shouldn't run */
 	if (!local->open_count)
@@ -2698,6 +2699,7 @@ int ieee80211_reconfig(struct ieee80211_local *local)
 		drv_reconfig_complete(local, IEEE80211_RECONFIG_TYPE_RESTART);
 
 	if (local->in_reconfig) {
+		in_reconfig = local->in_reconfig;
 		local->in_reconfig = false;
 		barrier();
 
@@ -2715,6 +2717,15 @@ int ieee80211_reconfig(struct ieee80211_local *local)
 					IEEE80211_QUEUE_STOP_REASON_SUSPEND,
 					false);
 
+	if (in_reconfig) {
+		list_for_each_entry(sdata, &local->interfaces, list) {
+			if (!ieee80211_sdata_running(sdata))
+				continue;
+			if (sdata->vif.type == NL80211_IFTYPE_STATION)
+				ieee80211_sta_restart(sdata);
+		}
+	}
+
 	if (!suspended)
 		return 0;
 
@@ -2744,7 +2755,7 @@ int ieee80211_reconfig(struct ieee80211_local *local)
 	return 0;
 }
 
-void ieee80211_resume_disconnect(struct ieee80211_vif *vif)
+static void ieee80211_reconfig_disconnect(struct ieee80211_vif *vif, u8 flag)
 {
 	struct ieee80211_sub_if_data *sdata;
 	struct ieee80211_local *local;
@@ -2756,19 +2767,35 @@ void ieee80211_resume_disconnect(struct ieee80211_vif *vif)
 	sdata = vif_to_sdata(vif);
 	local = sdata->local;
 
-	if (WARN_ON(!local->resuming))
+	if (WARN_ON(flag & IEEE80211_SDATA_DISCONNECT_RESUME &&
+		    !local->resuming))
+		return;
+
+	if (WARN_ON(flag & IEEE80211_SDATA_DISCONNECT_HW_RESTART &&
+		    !local->in_reconfig))
 		return;
 
 	if (WARN_ON(vif->type != NL80211_IFTYPE_STATION))
 		return;
 
-	sdata->flags |= IEEE80211_SDATA_DISCONNECT_RESUME;
+	sdata->flags |= flag;
 
 	mutex_lock(&local->key_mtx);
 	list_for_each_entry(key, &sdata->key_list, list)
 		key->flags |= KEY_FLAG_TAINTED;
 	mutex_unlock(&local->key_mtx);
 }
+
+void ieee80211_hw_restart_disconnect(struct ieee80211_vif *vif)
+{
+	ieee80211_reconfig_disconnect(vif, IEEE80211_SDATA_DISCONNECT_HW_RESTART);
+}
+EXPORT_SYMBOL_GPL(ieee80211_hw_restart_disconnect);
+
+void ieee80211_resume_disconnect(struct ieee80211_vif *vif)
+{
+	ieee80211_reconfig_disconnect(vif, IEEE80211_SDATA_DISCONNECT_RESUME);
+}
 EXPORT_SYMBOL_GPL(ieee80211_resume_disconnect);
 
 void ieee80211_recalc_smps(struct ieee80211_sub_if_data *sdata)