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>

1 files changed, 46 insertions, 17 deletions

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) {