Bluetooth: Sort to-be-resolved devices by RSSI during discovery

This patch makes sure that devices with stronger signal (RSSI closer to
0) are sorted first in the resolve list and will therefore get their
names resolved first during device discovery. Since it's more likely
that the device the user is trying to discover has a strong signal due
to its proximity this ensures that the user gets the "device found"
event for it more quickly.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>

include/net/bluetooth/hci_core.h

@@ -395,6 +395,8 @@ struct inquiry_entry *hci_inquiry_cache_lookup_unknown(struct hci_dev *hdev,
 struct inquiry_entry *hci_inquiry_cache_lookup_resolve(struct hci_dev *hdev,
 							bdaddr_t *bdaddr,
 							int state);
+void hci_inquiry_cache_update_resolve(struct hci_dev *hdev,
+						struct inquiry_entry *ie);
 bool hci_inquiry_cache_update(struct hci_dev *hdev, struct inquiry_data *data,
 							bool name_known);
 

net/bluetooth/hci_core.c

@@ -457,6 +457,25 @@ struct inquiry_entry *hci_inquiry_cache_lookup_resolve(struct hci_dev *hdev,
 	return NULL;
 }
 
+void hci_inquiry_cache_update_resolve(struct hci_dev *hdev,
+						struct inquiry_entry *ie)
+{
+	struct discovery_state *cache = &hdev->discovery;
+	struct list_head *pos = &cache->resolve;
+	struct inquiry_entry *p;
+
+	list_del(&ie->list);
+
+	list_for_each_entry(p, &cache->resolve, list) {
+		if (p->name_state != NAME_PENDING &&
+				abs(p->data.rssi) >= abs(ie->data.rssi))
+			break;
+		pos = &p->list;
+	}
+
+	list_add(&ie->list, pos);
+}
+
 bool hci_inquiry_cache_update(struct hci_dev *hdev, struct inquiry_data *data,
 							bool name_known)
 {
@@ -466,8 +485,15 @@ bool hci_inquiry_cache_update(struct hci_dev *hdev, struct inquiry_data *data,
 	BT_DBG("cache %p, %s", cache, batostr(&data->bdaddr));
 
 	ie = hci_inquiry_cache_lookup(hdev, &data->bdaddr);
-	if (ie)
+	if (ie) {
+		if (ie->name_state == NAME_NEEDED &&
+						data->rssi != ie->data.rssi) {
+			ie->data.rssi = data->rssi;
+			hci_inquiry_cache_update_resolve(hdev, ie);
+		}
+
 		goto update;
+	}
 
 	/* Entry not in the cache. Add new one. */
 	ie = kzalloc(sizeof(struct inquiry_entry), GFP_ATOMIC);

net/bluetooth/mgmt.c

@@ -2043,7 +2043,7 @@ static int confirm_name(struct sock *sk, u16 index, unsigned char *data,
 		list_del(&e->list);
 	} else {
 		e->name_state = NAME_NEEDED;
-		list_move(&e->list, &hdev->discovery.resolve);
+		hci_inquiry_cache_update_resolve(hdev, e);
 	}
 
 	err = 0;