Bluetooth: host: Improve multiple DHKey handling

Improve multiple DHKey handling by allowing the next DHKey calculation
to be started in the dhkey ready callback.
Return error code EALREADY if the provided callback is the current
callback generating the DHKey.

Signed-off-by: Joakim Andersson <[email protected]>

Author: joerchan

subsys/bluetooth/host/hci_core.c

@@ -3860,8 +3860,10 @@ static void le_dhkey_complete(struct net_buf *buf)
 	BT_DBG("status: 0x%02x", evt->status);
 
 	if (dh_key_cb) {
-		dh_key_cb(evt->status ? NULL : evt->dhkey);
+		bt_dh_key_cb_t cb = dh_key_cb;
+
 		dh_key_cb = NULL;
+		cb(evt->status ? NULL : evt->dhkey);
 	}
 }
 #endif /* CONFIG_BT_ECC */
@@ -9326,6 +9328,10 @@ int bt_dh_key_gen(const uint8_t remote_pk[64], bt_dh_key_cb_t cb)
 	struct net_buf *buf;
 	int err;
 
+	if (dh_key_cb == cb) {
+		return -EALREADY;
+	}
+
 	if (dh_key_cb || atomic_test_bit(bt_dev.flags, BT_DEV_PUB_KEY_BUSY)) {
 		return -EBUSY;
 	}