nl80211: allow multiple active scheduled scan requests

This patch implements the idea to have multiple scheduled scan requests
running concurrently. It mainly illustrates how to deal with the incoming
request from user-space in terms of backward compatibility. In order to
use multiple scheduled scans user-space needs to provide a flag attribute
NL80211_ATTR_SCHED_SCAN_MULTI to indicate support. If not the request is
treated as a legacy scan.

Drivers currently supporting scheduled scan are now indicating they support
a single scheduled scan request. This obsoletes WIPHY_FLAG_SUPPORTS_SCHED_SCAN.

Reviewed-by: Hante Meuleman <hante.meuleman@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieter-paul.giesberts@broadcom.com>
Reviewed-by: Franky Lin <franky.lin@broadcom.com>
Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
[clean up netlink destroy path to avoid allocations, code cleanups]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

6 files changed, 181 insertions, 57 deletions

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 4ea28de3a636..a3c0c48afb85 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -330,14 +330,16 @@ static void cfg80211_destroy_iface_wk(struct work_struct *work)
 static void cfg80211_sched_scan_stop_wk(struct work_struct *work)
 {
 	struct cfg80211_registered_device *rdev;
+	struct cfg80211_sched_scan_request *req, *tmp;
 
 	rdev = container_of(work, struct cfg80211_registered_device,
 			   sched_scan_stop_wk);
 
 	rtnl_lock();
-
-	__cfg80211_stop_sched_scan(rdev, false);
-
+	list_for_each_entry_safe(req, tmp, &rdev->sched_scan_req_list, list) {
+		if (req->nl_owner_dead)
+			cfg80211_stop_sched_scan_req(rdev, req, false);
+	}
 	rtnl_unlock();
 }
 
@@ -452,6 +454,7 @@ use_default_name:
 	spin_lock_init(&rdev->beacon_registrations_lock);
 	spin_lock_init(&rdev->bss_lock);
 	INIT_LIST_HEAD(&rdev->bss_list);
+	INIT_LIST_HEAD(&rdev->sched_scan_req_list);
 	INIT_WORK(&rdev->scan_done_wk, __cfg80211_scan_done);
 	INIT_WORK(&rdev->sched_scan_results_wk, __cfg80211_sched_scan_results);
 	INIT_LIST_HEAD(&rdev->mlme_unreg);
@@ -1028,7 +1031,7 @@ void __cfg80211_leave(struct cfg80211_registered_device *rdev,
 		      struct wireless_dev *wdev)
 {
 	struct net_device *dev = wdev->netdev;
-	struct cfg80211_sched_scan_request *sched_scan_req;
+	struct cfg80211_sched_scan_request *pos, *tmp;
 
 	ASSERT_RTNL();
 	ASSERT_WDEV_LOCK(wdev);
@@ -1039,9 +1042,11 @@ void __cfg80211_leave(struct cfg80211_registered_device *rdev,
 		break;
 	case NL80211_IFTYPE_P2P_CLIENT:
 	case NL80211_IFTYPE_STATION:
-		sched_scan_req = rtnl_dereference(rdev->sched_scan_req);
-		if (sched_scan_req && dev == sched_scan_req->dev)
-			__cfg80211_stop_sched_scan(rdev, false);
+		list_for_each_entry_safe(pos, tmp, &rdev->sched_scan_req_list,
+					 list) {
+			if (dev == pos->dev)
+				cfg80211_stop_sched_scan_req(rdev, pos, false);
+		}
 
 #ifdef CONFIG_CFG80211_WEXT
 		kfree(wdev->wext.ie);
@@ -1116,7 +1121,7 @@ static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 	struct wireless_dev *wdev = dev->ieee80211_ptr;
 	struct cfg80211_registered_device *rdev;
-	struct cfg80211_sched_scan_request *sched_scan_req;
+	struct cfg80211_sched_scan_request *pos, *tmp;
 
 	if (!wdev)
 		return NOTIFY_DONE;
@@ -1193,10 +1198,10 @@ static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
 			___cfg80211_scan_done(rdev, false);
 		}
 
-		sched_scan_req = rtnl_dereference(rdev->sched_scan_req);
-		if (WARN_ON(sched_scan_req &&
-			    sched_scan_req->dev == wdev->netdev)) {
-			__cfg80211_stop_sched_scan(rdev, false);
+		list_for_each_entry_safe(pos, tmp,
+					 &rdev->sched_scan_req_list, list) {
+			if (WARN_ON(pos && pos->dev == wdev->netdev))
+				cfg80211_stop_sched_scan_req(rdev, pos, false);
 		}
 
 		rdev->opencount--;
diff --git a/net/wireless/core.h b/net/wireless/core.h
index f9b748e3425a..06eaf96053a8 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -74,7 +74,7 @@ struct cfg80211_registered_device {
 	u32 bss_entries;
 	struct cfg80211_scan_request *scan_req; /* protected by RTNL */
 	struct sk_buff *scan_msg;
-	struct cfg80211_sched_scan_request __rcu *sched_scan_req;
+	struct list_head sched_scan_req_list;
 	unsigned long suspend_at;
 	struct work_struct scan_done_wk;
 	struct work_struct sched_scan_results_wk;
@@ -416,9 +416,16 @@ int cfg80211_validate_key_settings(struct cfg80211_registered_device *rdev,
 void __cfg80211_scan_done(struct work_struct *wk);
 void ___cfg80211_scan_done(struct cfg80211_registered_device *rdev,
 			   bool send_message);
+void cfg80211_add_sched_scan_req(struct cfg80211_registered_device *rdev,
+				 struct cfg80211_sched_scan_request *req);
+int cfg80211_sched_scan_req_possible(struct cfg80211_registered_device *rdev,
+				     bool want_multi);
 void __cfg80211_sched_scan_results(struct work_struct *wk);
+int cfg80211_stop_sched_scan_req(struct cfg80211_registered_device *rdev,
+				 struct cfg80211_sched_scan_request *req,
+				 bool driver_initiated);
 int __cfg80211_stop_sched_scan(struct cfg80211_registered_device *rdev,
-			       bool driver_initiated);
+			       u64 reqid, bool driver_initiated);
 void cfg80211_upload_connect_keys(struct wireless_dev *wdev);
 int cfg80211_change_iface(struct cfg80211_registered_device *rdev,
 			  struct net_device *dev, enum nl80211_iftype ntype,
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 45f5f418e562..ac7e2314f9ec 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -419,6 +419,7 @@ static const struct nla_policy nl80211_policy[NUM_NL80211_ATTR] = {
 					.len = FILS_ERP_MAX_RRK_LEN },
 	[NL80211_ATTR_FILS_CACHE_ID] = { .len = 2 },
 	[NL80211_ATTR_PMK] = { .type = NLA_BINARY, .len = PMK_MAX_LEN },
+	[NL80211_ATTR_SCHED_SCAN_MULTI] = { .type = NLA_FLAG },
 };
 
 /* policy for the key attributes */
@@ -1376,7 +1377,7 @@ static int nl80211_add_commands_unsplit(struct cfg80211_registered_device *rdev,
 		CMD(tdls_mgmt, TDLS_MGMT);
 		CMD(tdls_oper, TDLS_OPER);
 	}
-	if (rdev->wiphy.flags & WIPHY_FLAG_SUPPORTS_SCHED_SCAN)
+	if (rdev->wiphy.max_sched_scan_reqs)
 		CMD(sched_scan_start, START_SCHED_SCAN);
 	CMD(probe_client, PROBE_CLIENT);
 	CMD(set_noack_map, SET_NOACK_MAP);
@@ -1815,6 +1816,11 @@ static int nl80211_send_wiphy(struct cfg80211_registered_device *rdev,
 		    nla_put_flag(msg, NL80211_ATTR_WIPHY_SELF_MANAGED_REG))
 			goto nla_put_failure;
 
+		if (rdev->wiphy.max_sched_scan_reqs &&
+		    nla_put_u32(msg, NL80211_ATTR_SCHED_SCAN_MAX_REQS,
+				rdev->wiphy.max_sched_scan_reqs))
+			goto nla_put_failure;
+
 		if (nla_put(msg, NL80211_ATTR_EXT_FEATURES,
 			    sizeof(rdev->wiphy.ext_features),
 			    rdev->wiphy.ext_features))
@@ -7336,14 +7342,16 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
 	struct net_device *dev = info->user_ptr[1];
 	struct wireless_dev *wdev = dev->ieee80211_ptr;
 	struct cfg80211_sched_scan_request *sched_scan_req;
+	bool want_multi;
 	int err;
 
-	if (!(rdev->wiphy.flags & WIPHY_FLAG_SUPPORTS_SCHED_SCAN) ||
-	    !rdev->ops->sched_scan_start)
+	if (!rdev->wiphy.max_sched_scan_reqs || !rdev->ops->sched_scan_start)
 		return -EOPNOTSUPP;
 
-	if (rdev->sched_scan_req)
-		return -EINPROGRESS;
+	want_multi = info->attrs[NL80211_ATTR_SCHED_SCAN_MULTI];
+	err = cfg80211_sched_scan_req_possible(rdev, want_multi);
+	if (err)
+		return err;
 
 	sched_scan_req = nl80211_parse_sched_scan(&rdev->wiphy, wdev,
 						  info->attrs,
@@ -7353,6 +7361,14 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
 	if (err)
 		goto out_err;
 
+	/* leave request id zero for legacy request
+	 * or if driver does not support multi-scheduled scan
+	 */
+	if (want_multi && rdev->wiphy.max_sched_scan_reqs > 1) {
+		while (!sched_scan_req->reqid)
+			sched_scan_req->reqid = rdev->wiphy.cookie_counter++;
+	}
+
 	err = rdev_sched_scan_start(rdev, dev, sched_scan_req);
 	if (err)
 		goto out_free;
@@ -7363,7 +7379,7 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
 	if (info->attrs[NL80211_ATTR_SOCKET_OWNER])
 		sched_scan_req->owner_nlportid = info->snd_portid;
 
-	rcu_assign_pointer(rdev->sched_scan_req, sched_scan_req);
+	cfg80211_add_sched_scan_req(rdev, sched_scan_req);
 
 	nl80211_send_sched_scan(sched_scan_req, NL80211_CMD_START_SCHED_SCAN);
 	return 0;
@@ -7377,13 +7393,27 @@ out_err:
 static int nl80211_stop_sched_scan(struct sk_buff *skb,
 				   struct genl_info *info)
 {
+	struct cfg80211_sched_scan_request *req;
 	struct cfg80211_registered_device *rdev = info->user_ptr[0];
+	u64 cookie;
 
-	if (!(rdev->wiphy.flags & WIPHY_FLAG_SUPPORTS_SCHED_SCAN) ||
-	    !rdev->ops->sched_scan_stop)
+	if (!rdev->wiphy.max_sched_scan_reqs || !rdev->ops->sched_scan_stop)
 		return -EOPNOTSUPP;
 
-	return __cfg80211_stop_sched_scan(rdev, false);
+	if (info->attrs[NL80211_ATTR_COOKIE]) {
+		cookie = nla_get_u64(info->attrs[NL80211_ATTR_COOKIE]);
+		return __cfg80211_stop_sched_scan(rdev, cookie, false);
+	}
+
+	req = list_first_or_null_rcu(&rdev->sched_scan_req_list,
+				     struct cfg80211_sched_scan_request,
+				     list);
+	if (!req || req->reqid ||
+	    (req->owner_nlportid &&
+	     req->owner_nlportid != info->snd_portid))
+		return -ENOENT;
+
+	return cfg80211_stop_sched_scan_req(rdev, req, false);
 }
 
 static int nl80211_start_radar_detection(struct sk_buff *skb,
@@ -14883,16 +14913,15 @@ static int nl80211_netlink_notify(struct notifier_block * nb,
 	rcu_read_lock();
 
 	list_for_each_entry_rcu(rdev, &cfg80211_rdev_list, list) {
-		struct cfg80211_sched_scan_request *sched_scan_req =
-			rcu_dereference(rdev->sched_scan_req);
-
-		if (sched_scan_req && notify->portid &&
-		    sched_scan_req->owner_nlportid == notify->portid) {
-			sched_scan_req->owner_nlportid = 0;
+		struct cfg80211_sched_scan_request *sched_scan_req;
 
-			if (rdev->ops->sched_scan_stop &&
-			    rdev->wiphy.flags & WIPHY_FLAG_SUPPORTS_SCHED_SCAN)
+		list_for_each_entry_rcu(sched_scan_req,
+					&rdev->sched_scan_req_list,
+					list) {
+			if (sched_scan_req->owner_nlportid == notify->portid) {
+				sched_scan_req->nl_owner_dead = true;
 				schedule_work(&rdev->sched_scan_stop_wk);
+			}
 		}
 
 		list_for_each_entry_rcu(wdev, &rdev->wiphy.wdev_list, list) {
diff --git a/net/wireless/rdev-ops.h b/net/wireless/rdev-ops.h
index e4a99989dd06..783f89c3e504 100644
--- a/net/wireless/rdev-ops.h
+++ b/net/wireless/rdev-ops.h
@@ -813,7 +813,7 @@ rdev_sched_scan_start(struct cfg80211_registered_device *rdev,
 		      struct cfg80211_sched_scan_request *request)
 {
 	int ret;
-	trace_rdev_sched_scan_start(&rdev->wiphy, dev, request);
+	trace_rdev_sched_scan_start(&rdev->wiphy, dev, request->reqid);
 	ret = rdev->ops->sched_scan_start(&rdev->wiphy, dev, request);
 	trace_rdev_return_int(&rdev->wiphy, ret);
 	return ret;
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 6f4996c0f4df..bd9feed95c1e 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -300,6 +300,70 @@ void cfg80211_scan_done(struct cfg80211_scan_request *request,
 }
 EXPORT_SYMBOL(cfg80211_scan_done);
 
+void cfg80211_add_sched_scan_req(struct cfg80211_registered_device *rdev,
+				 struct cfg80211_sched_scan_request *req)
+{
+	ASSERT_RTNL();
+
+	list_add_rcu(&req->list, &rdev->sched_scan_req_list);
+}
+
+static void cfg80211_del_sched_scan_req(struct cfg80211_registered_device *rdev,
+					struct cfg80211_sched_scan_request *req)
+{
+	ASSERT_RTNL();
+
+	list_del_rcu(&req->list);
+	kfree_rcu(req, rcu_head);
+}
+
+static struct cfg80211_sched_scan_request *
+cfg80211_find_sched_scan_req(struct cfg80211_registered_device *rdev, u64 reqid)
+{
+	struct cfg80211_sched_scan_request *pos;
+
+	ASSERT_RTNL();
+
+	list_for_each_entry(pos, &rdev->sched_scan_req_list, list) {
+		if (pos->reqid == reqid)
+			return pos;
+	}
+	return ERR_PTR(-ENOENT);
+}
+
+/*
+ * Determines if a scheduled scan request can be handled. When a legacy
+ * scheduled scan is running no other scheduled scan is allowed regardless
+ * whether the request is for legacy or multi-support scan. When a multi-support
+ * scheduled scan is running a request for legacy scan is not allowed. In this
+ * case a request for multi-support scan can be handled if resources are
+ * available, ie. struct wiphy::max_sched_scan_reqs limit is not yet reached.
+ */
+int cfg80211_sched_scan_req_possible(struct cfg80211_registered_device *rdev,
+				     bool want_multi)
+{
+	struct cfg80211_sched_scan_request *pos;
+	int i = 0;
+
+	list_for_each_entry(pos, &rdev->sched_scan_req_list, list) {
+		/* request id zero means legacy in progress */
+		if (!i && !pos->reqid)
+			return -EINPROGRESS;
+		i++;
+	}
+
+	if (i) {
+		/* no legacy allowed when multi request(s) are active */
+		if (!want_multi)
+			return -EINPROGRESS;
+
+		/* resource limit reached */
+		if (i == rdev->wiphy.max_sched_scan_reqs)
+			return -ENOSPC;
+	}
+	return 0;
+}
+
 void __cfg80211_sched_scan_results(struct work_struct *wk)
 {
 	struct cfg80211_registered_device *rdev;
@@ -310,10 +374,10 @@ void __cfg80211_sched_scan_results(struct work_struct *wk)
 
 	rtnl_lock();
 
-	request = rtnl_dereference(rdev->sched_scan_req);
+	request = cfg80211_find_sched_scan_req(rdev, 0);
 
 	/* we don't have sched_scan_req anymore if the scan is stopping */
-	if (request) {
+	if (!IS_ERR(request)) {
 		if (request->flags & NL80211_SCAN_FLAG_FLUSH) {
 			/* flush entries from previous scans */
 			spin_lock_bh(&rdev->bss_lock);
@@ -329,10 +393,17 @@ void __cfg80211_sched_scan_results(struct work_struct *wk)
 
 void cfg80211_sched_scan_results(struct wiphy *wiphy)
 {
+	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
+	struct cfg80211_sched_scan_request *request;
+
 	trace_cfg80211_sched_scan_results(wiphy);
 	/* ignore if we're not scanning */
 
-	if (rcu_access_pointer(wiphy_to_rdev(wiphy)->sched_scan_req))
+	rtnl_lock();
+	request = cfg80211_find_sched_scan_req(rdev, 0);
+	rtnl_unlock();
+
+	if (!IS_ERR(request))
 		queue_work(cfg80211_wq,
 			   &wiphy_to_rdev(wiphy)->sched_scan_results_wk);
 }
@@ -346,7 +417,7 @@ void cfg80211_sched_scan_stopped_rtnl(struct wiphy *wiphy)
 
 	trace_cfg80211_sched_scan_stopped(wiphy);
 
-	__cfg80211_stop_sched_scan(rdev, true);
+	__cfg80211_stop_sched_scan(rdev, 0, true);
 }
 EXPORT_SYMBOL(cfg80211_sched_scan_stopped_rtnl);
 
@@ -358,34 +429,40 @@ void cfg80211_sched_scan_stopped(struct wiphy *wiphy)
 }
 EXPORT_SYMBOL(cfg80211_sched_scan_stopped);
 
-int __cfg80211_stop_sched_scan(struct cfg80211_registered_device *rdev,
-			       bool driver_initiated)
+int cfg80211_stop_sched_scan_req(struct cfg80211_registered_device *rdev,
+				 struct cfg80211_sched_scan_request *req,
+				 bool driver_initiated)
 {
-	struct cfg80211_sched_scan_request *sched_scan_req;
-	struct net_device *dev;
-
 	ASSERT_RTNL();
 
-	if (!rdev->sched_scan_req)
-		return -ENOENT;
-
-	sched_scan_req = rtnl_dereference(rdev->sched_scan_req);
-	dev = sched_scan_req->dev;
-
 	if (!driver_initiated) {
-		int err = rdev_sched_scan_stop(rdev, dev);
+		int err = rdev_sched_scan_stop(rdev, req->dev);
 		if (err)
 			return err;
 	}
 
-	nl80211_send_sched_scan(sched_scan_req, NL80211_CMD_SCHED_SCAN_STOPPED);
+	nl80211_send_sched_scan(req, NL80211_CMD_SCHED_SCAN_STOPPED);
 
-	RCU_INIT_POINTER(rdev->sched_scan_req, NULL);
-	kfree_rcu(sched_scan_req, rcu_head);
+	cfg80211_del_sched_scan_req(rdev, req);
 
 	return 0;
 }
 
+int __cfg80211_stop_sched_scan(struct cfg80211_registered_device *rdev,
+			       u64 reqid, bool driver_initiated)
+{
+	struct cfg80211_sched_scan_request *sched_scan_req;
+
+	ASSERT_RTNL();
+
+	sched_scan_req = cfg80211_find_sched_scan_req(rdev, reqid);
+	if (IS_ERR(sched_scan_req))
+		return PTR_ERR(sched_scan_req);
+
+	return cfg80211_stop_sched_scan_req(rdev, sched_scan_req,
+					    driver_initiated);
+}
+
 void cfg80211_bss_age(struct cfg80211_registered_device *rdev,
                       unsigned long age_secs)
 {
diff --git a/net/wireless/trace.h b/net/wireless/trace.h
index fd55786f0462..52935c48b342 100644
--- a/net/wireless/trace.h
+++ b/net/wireless/trace.h
@@ -1610,20 +1610,26 @@ DEFINE_EVENT(tx_rx_evt, rdev_set_antenna,
 	TP_ARGS(wiphy, rx, tx)
 );
 
-TRACE_EVENT(rdev_sched_scan_start,
-	TP_PROTO(struct wiphy *wiphy, struct net_device *netdev,
-		 struct cfg80211_sched_scan_request *request),
-	TP_ARGS(wiphy, netdev, request),
+DECLARE_EVENT_CLASS(wiphy_netdev_id_evt,
+	TP_PROTO(struct wiphy *wiphy, struct net_device *netdev, u64 id),
+	TP_ARGS(wiphy, netdev, id),
 	TP_STRUCT__entry(
 		WIPHY_ENTRY
 		NETDEV_ENTRY
+		__field(u64, id)
 	),
 	TP_fast_assign(
 		WIPHY_ASSIGN;
 		NETDEV_ASSIGN;
+		__entry->id = id;
 	),
-	TP_printk(WIPHY_PR_FMT ", " NETDEV_PR_FMT,
-		  WIPHY_PR_ARG, NETDEV_PR_ARG)
+	TP_printk(WIPHY_PR_FMT ", " NETDEV_PR_FMT ", id: %llu",
+		  WIPHY_PR_ARG, NETDEV_PR_ARG, __entry->id)
+);
+
+DEFINE_EVENT(wiphy_netdev_id_evt, rdev_sched_scan_start,
+	TP_PROTO(struct wiphy *wiphy, struct net_device *netdev, u64 id),
+	TP_ARGS(wiphy, netdev, id)
 );
 
 TRACE_EVENT(rdev_tdls_mgmt,