NFC: Release LLCP SAP when the owner is released

The LLCP SAP should only be freed when the socket owning it is released.
As long as the socket is alive, the SAP should be reserved in order to
e.g. send the right wks array when bringing the MAC up.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

net/nfc/llcp/llcp.c

@@ -131,17 +131,6 @@ int nfc_llcp_local_put(struct nfc_llcp_local *local)
 	return kref_put(&local->ref, local_release);
 }
 
-static void nfc_llcp_clear_sdp(struct nfc_llcp_local *local)
-{
-	mutex_lock(&local->sdp_lock);
-
-	local->local_wks = 0;
-	local->local_sdp = 0;
-	local->local_sap = 0;
-
-	mutex_unlock(&local->sdp_lock);
-}
-
 static void nfc_llcp_timeout_work(struct work_struct *work)
 {
 	struct nfc_llcp_local *local = container_of(work, struct nfc_llcp_local,
@@ -993,8 +982,6 @@ void nfc_llcp_mac_is_down(struct nfc_dev *dev)
 	if (local == NULL)
 		return;
 
-	nfc_llcp_clear_sdp(local);
-
 	/* Close and purge all existing sockets */
 	nfc_llcp_socket_release(local, true);
 }

net/nfc/llcp/llcp.h

@@ -113,6 +113,9 @@ struct nfc_llcp_sock {
 	/* Is the remote peer ready to receive */
 	u8 remote_ready;
 
+	/* Reserved source SAP */
+	u8 reserved_ssap;
+
 	struct sk_buff_head tx_queue;
 	struct sk_buff_head tx_pending_queue;
 	struct sk_buff_head tx_backlog_queue;

net/nfc/llcp/sock.c

@@ -124,6 +124,8 @@ static int llcp_sock_bind(struct socket *sock, struct sockaddr *addr, int alen)
 	if (llcp_sock->ssap == LLCP_MAX_SAP)
 		goto put_dev;
 
+	llcp_sock->reserved_ssap = llcp_sock->ssap;
+
 	nfc_llcp_sock_link(&local->sockets, sk);
 
 	pr_debug("Socket bound to SAP %d\n", llcp_sock->ssap);
@@ -409,7 +411,8 @@ static int llcp_sock_release(struct socket *sock)
 		}
 	}
 
-	nfc_llcp_put_ssap(llcp_sock->local, llcp_sock->ssap);
+	if (llcp_sock->reserved_ssap < LLCP_SAP_MAX)
+		nfc_llcp_put_ssap(llcp_sock->local, llcp_sock->ssap);
 
 	release_sock(sk);
 
@@ -489,6 +492,9 @@ static int llcp_sock_connect(struct socket *sock, struct sockaddr *_addr,
 		ret = -ENOMEM;
 		goto put_dev;
 	}
+
+	llcp_sock->reserved_ssap = llcp_sock->ssap;
+
 	if (addr->service_name_len == 0)
 		llcp_sock->dsap = addr->dsap;
 	else
@@ -690,6 +696,7 @@ struct sock *nfc_llcp_sock_alloc(struct socket *sock, int type, gfp_t gfp)
 	llcp_sock->send_n = llcp_sock->send_ack_n = 0;
 	llcp_sock->recv_n = llcp_sock->recv_ack_n = 0;
 	llcp_sock->remote_ready = 1;
+	llcp_sock->reserved_ssap = LLCP_SAP_MAX;
 	skb_queue_head_init(&llcp_sock->tx_queue);
 	skb_queue_head_init(&llcp_sock->tx_pending_queue);
 	skb_queue_head_init(&llcp_sock->tx_backlog_queue);