nl80211/cfg80211: add 'scan_cancel' command (INTERNAL)

Mostly from an energy consumption and cpu load perspective,
it can be useful to stop a triggered scan earlier, when one
finds the desired scan results.
Adding the ability to stop a scan from user space by exposing
new NL80211_CMD_SCAN_CANCEL API.

Signed-off-by: Victor Goldenshtein <victorg@ti.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>

include/net/cfg80211.h

@@ -1875,6 +1875,7 @@ struct cfg80211_update_ft_ies_params {
  *	the driver, and will be valid until passed to cfg80211_scan_done().
  *	For scan results, call cfg80211_inform_bss(); you can call this outside
  *	the scan/scan_done bracket too.
+ * @scan_cancel: Stop currently running scan (both sw and hw).
  *
  * @auth: Request to authenticate with the specified peer
  * @assoc: Request to (re)associate with the specified peer
@@ -2098,6 +2099,7 @@ struct cfg80211_ops {
 
 	int	(*scan)(struct wiphy *wiphy,
 			struct cfg80211_scan_request *request);
+	void    (*scan_cancel)(struct wiphy *wiphy, struct net_device *dev);
 
 	int	(*auth)(struct wiphy *wiphy, struct net_device *dev,
 			struct cfg80211_auth_request *req);

include/uapi/linux/nl80211.h

@@ -646,6 +646,11 @@
  * @NL80211_CMD_CRIT_PROTOCOL_STOP: Indicates the connection reliability can
  *	return back to normal.
  *
+ * @NL80211_CMD_SCAN_CANCEL: Stop currently running scan (both sw and hw).
+ *	This operation will eventually invoke %NL80211_CMD_SCAN_ABORTED
+ *	event, partial scan results will be available. Returns -ENOENT
+ *	if scan is not running.
+ *
  * @NL80211_CMD_MAX: highest used command number
  * @__NL80211_CMD_AFTER_LAST: internal use
  */
@@ -808,6 +813,8 @@ enum nl80211_commands {
 	NL80211_CMD_CRIT_PROTOCOL_START,
 	NL80211_CMD_CRIT_PROTOCOL_STOP,
 
+	NL80211_CMD_SCAN_CANCEL,
+
 	/* add new commands above here */
 
 	/* used to define NL80211_CMD_MAX below */

net/wireless/core.h

@@ -419,6 +419,7 @@ void ___cfg80211_scan_done(struct cfg80211_registered_device *rdev, bool leak);
 void __cfg80211_sched_scan_results(struct work_struct *wk);
 int __cfg80211_stop_sched_scan(struct cfg80211_registered_device *rdev,
 			       bool driver_initiated);
+int cfg80211_scan_cancel(struct cfg80211_registered_device *rdev);
 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,

net/wireless/nl80211.c

@@ -5560,6 +5560,11 @@ static int nl80211_start_radar_detection(struct sk_buff *skb,
 	return err;
 }
 
+static int nl80211_scan_cancel(struct sk_buff *skb, struct genl_info *info)
+{
+	return cfg80211_scan_cancel(info->user_ptr[0]);
+}
+
 static int nl80211_send_bss(struct sk_buff *msg, struct netlink_callback *cb,
 			    u32 seq, int flags,
 			    struct cfg80211_registered_device *rdev,
@@ -8603,6 +8608,14 @@ static struct genl_ops nl80211_ops[] = {
 		.internal_flags = NL80211_FLAG_NEED_WDEV_UP |
 				  NL80211_FLAG_NEED_RTNL,
 	},
+	{
+		.cmd = NL80211_CMD_SCAN_CANCEL,
+		.doit = nl80211_scan_cancel,
+		.policy = nl80211_policy,
+		.flags = GENL_ADMIN_PERM,
+		.internal_flags = NL80211_FLAG_NEED_NETDEV_UP |
+				  NL80211_FLAG_NEED_RTNL,
+	},
 	{
 		.cmd = NL80211_CMD_GET_SCAN,
 		.policy = nl80211_policy,

net/wireless/scan.c

@@ -320,6 +320,22 @@ int __cfg80211_stop_sched_scan(struct cfg80211_registered_device *rdev,
 	return err;
 }
 
+int cfg80211_scan_cancel(struct cfg80211_registered_device *rdev)
+{
+	struct net_device *dev;
+
+	ASSERT_RDEV_LOCK(rdev);
+
+	if (!rdev->ops->scan_cancel)
+		return -EOPNOTSUPP;
+	if (!rdev->scan_req)
+		return -ENOENT;
+
+	dev = rdev->scan_req->wdev->netdev;
+	rdev->ops->scan_cancel(&rdev->wiphy, dev);
+	return 0;
+}
+
 void cfg80211_bss_age(struct cfg80211_registered_device *dev,
                       unsigned long age_secs)
 {