[PATCH net v7 2/3] nfc: nci: uart: quiesce callbacks during teardown

@@ -154,19 +154,24 @@ struct nfcmrvl_private *nfcmrvl_nci_register_dev(enum nfcmrvl_phy phy,
 
 	nci_set_drvdata(priv->ndev, priv);
 
+	/* Ensure that the controller is powered off before exposing it. */
+	nfcmrvl_chip_halt(priv);
+
+	if (priv->if_ops->nci_ready)
+		priv->if_ops->nci_ready(priv);
+
 	rc = nci_register_device(priv->ndev);
 	if (rc) {
 		nfc_err(dev, "nci_register_device failed %d\n", rc);
 		goto error_fw_dnld_deinit;
 	}
 
-	/* Ensure that controller is powered off */
-	nfcmrvl_chip_halt(priv);
-
 	nfc_info(dev, "registered with nci successfully\n");
 	return priv;
 
 error_fw_dnld_deinit:
+	if (priv->if_ops->nci_quiesce)
+		priv->if_ops->nci_quiesce(priv);
 	nfcmrvl_fw_dnld_deinit(priv);
 error_free_dev:
 	nci_free_device(priv->ndev);

@@ -181,6 +186,9 @@ void nfcmrvl_nci_unregister_dev(struct nfcmrvl_private *priv)
 	struct nci_dev *ndev = priv->ndev;
 
 	nci_unregister_device(ndev);
+	if (priv->if_ops->nci_quiesce)
+		priv->if_ops->nci_quiesce(priv);
+
 	if (priv->ndev->nfc_dev->fw_download_in_progress)
 		nfcmrvl_fw_dnld_abort(priv);
 

@@ -241,6 +249,7 @@ void nfcmrvl_chip_halt(struct nfcmrvl_private *priv)
 	if (priv->config.reset_gpio)
 		gpiod_set_value(priv->config.reset_gpio, 1);
 }
+EXPORT_SYMBOL_GPL(nfcmrvl_chip_halt);
 
 int nfcmrvl_parse_dt(struct device_node *node,
 		     struct nfcmrvl_platform_data *pdata)

@@ -112,6 +112,8 @@ struct nfcmrvl_if_ops {
 	int (*nci_open) (struct nfcmrvl_private *priv);
 	int (*nci_close) (struct nfcmrvl_private *priv);
 	int (*nci_send) (struct nfcmrvl_private *priv, struct sk_buff *skb);
+	void (*nci_ready)(struct nfcmrvl_private *priv);
+	void (*nci_quiesce)(struct nfcmrvl_private *priv);
 	void (*nci_update_config)(struct nfcmrvl_private *priv,
 				  const void *param);
 };

@@ -44,6 +44,27 @@ static int nfcmrvl_uart_nci_send(struct nfcmrvl_private *priv,
 	return nu->ops.send(nu, skb);
 }
 
+static void nfcmrvl_uart_nci_ready(struct nfcmrvl_private *priv)
+{
+	struct nci_uart *nu = priv->drv_data;
+
+	priv->support_fw_dnld = true;
+	nu->drv_data = priv;
+	nu->ndev = priv->ndev;
+	nci_uart_set_ready(nu);
+}
+
+static void nfcmrvl_uart_nci_quiesce(struct nfcmrvl_private *priv)
+{
+	struct nci_uart *nu = priv->drv_data;
+
+	nci_uart_rx_stop(nu);
+	nci_uart_tx_stop(nu);
+	nfcmrvl_chip_halt(priv);
+	nu->drv_data = NULL;
+	nu->ndev = NULL;
+}
+
 static void nfcmrvl_uart_nci_update_config(struct nfcmrvl_private *priv,
 					   const void *param)
 {

@@ -58,6 +79,8 @@ static const struct nfcmrvl_if_ops uart_ops = {
 	.nci_open = nfcmrvl_uart_nci_open,
 	.nci_close = nfcmrvl_uart_nci_close,
 	.nci_send = nfcmrvl_uart_nci_send,
+	.nci_ready = nfcmrvl_uart_nci_ready,
+	.nci_quiesce = nfcmrvl_uart_nci_quiesce,
 	.nci_update_config = nfcmrvl_uart_nci_update_config
 };
 

@@ -136,11 +159,6 @@ static int nfcmrvl_nci_uart_open(struct nci_uart *nu)
 	if (IS_ERR(priv))
 		return PTR_ERR(priv);
 
-	priv->support_fw_dnld = true;
-
-	nu->drv_data = priv;
-	nu->ndev = priv->ndev;
-
 	return 0;
 }
 

@@ -436,6 +436,7 @@ struct nci_uart;
 
 struct nci_uart_ops {
 	int (*open)(struct nci_uart *nci_uart);
+	/* Quiesce callbacks before releasing transport-private state. */
 	void (*close)(struct nci_uart *nci_uart);
 	int (*recv)(struct nci_uart *nci_uart, struct sk_buff *skb);
 	int (*send)(struct nci_uart *nci_uart, struct sk_buff *skb);

@@ -452,6 +453,7 @@ struct nci_uart {
 	/* Dynamic data */
 	struct nci_dev		*ndev;
 	spinlock_t		rx_lock;
+	spinlock_t		tx_lock; /* protects tx_state */
 	struct work_struct	write_work;
 	struct tty_struct	*tty;
 	unsigned long		flags;

@@ -466,5 +468,8 @@ struct nci_uart {
 int nci_uart_register(struct nci_uart *nu);
 void nci_uart_unregister(struct nci_uart *nu);
 void nci_uart_set_config(struct nci_uart *nu, int baudrate, int flow_ctrl);
+void nci_uart_set_ready(struct nci_uart *nu);
+void nci_uart_rx_stop(struct nci_uart *nu);
+void nci_uart_tx_stop(struct nci_uart *nu);
 
 #endif /* __NCI_CORE_H */

@@ -34,6 +34,7 @@
 /* TX states  */
 #define NCI_UART_SENDING	1
 #define NCI_UART_TX_WAKEUP	2
+#define NCI_UART_CLOSING	3
 
 /* UART flags */
 #define NCI_UART_DRIVER_SET	0

@@ -64,24 +65,61 @@ static inline int nci_uart_queue_empty(struct nci_uart *nu)
 
 static int nci_uart_tx_wakeup(struct nci_uart *nu)
 {
+	unsigned long flags;
+
+	spin_lock_irqsave(&nu->tx_lock, flags);
+	if (test_bit(NCI_UART_CLOSING, &nu->tx_state) ||
+	    !test_bit_acquire(NCI_UART_READY, &nu->flags))
+		goto unlock;
+
 	if (test_and_set_bit(NCI_UART_SENDING, &nu->tx_state)) {
 		set_bit(NCI_UART_TX_WAKEUP, &nu->tx_state);
-		return 0;
+		goto unlock;
 	}
 
 	schedule_work(&nu->write_work);
 
+unlock:
+	spin_unlock_irqrestore(&nu->tx_lock, flags);
+
 	return 0;
 }
 
+void nci_uart_tx_stop(struct nci_uart *nu)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&nu->tx_lock, flags);
+	set_bit(NCI_UART_CLOSING, &nu->tx_state);
+	spin_unlock_irqrestore(&nu->tx_lock, flags);
+
+	cancel_work_sync(&nu->write_work);
+	clear_bit(TTY_DO_WRITE_WAKEUP, &nu->tty->flags);
+
+	spin_lock_irqsave(&nu->tx_lock, flags);
+	clear_bit(NCI_UART_SENDING, &nu->tx_state);
+	clear_bit(NCI_UART_TX_WAKEUP, &nu->tx_state);
+	spin_unlock_irqrestore(&nu->tx_lock, flags);
+}
+EXPORT_SYMBOL_GPL(nci_uart_tx_stop);
+
 static void nci_uart_write_work(struct work_struct *work)
 {
 	struct nci_uart *nu = container_of(work, struct nci_uart, write_work);
 	struct tty_struct *tty = nu->tty;
 	struct sk_buff *skb;
+	unsigned long flags;
 
 restart:
+	spin_lock_irqsave(&nu->tx_lock, flags);
+	if (test_bit(NCI_UART_CLOSING, &nu->tx_state)) {
+		clear_bit(NCI_UART_SENDING, &nu->tx_state);
+		clear_bit(NCI_UART_TX_WAKEUP, &nu->tx_state);
+		spin_unlock_irqrestore(&nu->tx_lock, flags);
+		return;
+	}
 	clear_bit(NCI_UART_TX_WAKEUP, &nu->tx_state);
+	spin_unlock_irqrestore(&nu->tx_lock, flags);
 
 	if (nu->ops.tx_start)
 		nu->ops.tx_start(nu);

@@ -99,14 +137,55 @@ static void nci_uart_write_work(struct work_struct *work)
 		kfree_skb(skb);
 	}
 
-	if (test_bit(NCI_UART_TX_WAKEUP, &nu->tx_state))
+	spin_lock_irqsave(&nu->tx_lock, flags);
+	if (test_bit(NCI_UART_CLOSING, &nu->tx_state)) {
+		clear_bit(NCI_UART_SENDING, &nu->tx_state);
+		clear_bit(NCI_UART_TX_WAKEUP, &nu->tx_state);
+		spin_unlock_irqrestore(&nu->tx_lock, flags);
+		if (nu->ops.tx_done)
+			nu->ops.tx_done(nu);
+		return;
+	}
+	if (test_and_clear_bit(NCI_UART_TX_WAKEUP, &nu->tx_state)) {
+		spin_unlock_irqrestore(&nu->tx_lock, flags);
 		goto restart;
+	}
+	spin_unlock_irqrestore(&nu->tx_lock, flags);
 
 	if (nu->ops.tx_done && nci_uart_queue_empty(nu))
 		nu->ops.tx_done(nu);
 
+	spin_lock_irqsave(&nu->tx_lock, flags);
+	if (!test_bit(NCI_UART_CLOSING, &nu->tx_state) &&
+	    test_and_clear_bit(NCI_UART_TX_WAKEUP, &nu->tx_state)) {
+		spin_unlock_irqrestore(&nu->tx_lock, flags);
+		goto restart;
+	}
 	clear_bit(NCI_UART_SENDING, &nu->tx_state);
+	clear_bit(NCI_UART_TX_WAKEUP, &nu->tx_state);
+	spin_unlock_irqrestore(&nu->tx_lock, flags);
+}
+
+void nci_uart_set_ready(struct nci_uart *nu)
+{
+	/* Publish transport fields before callbacks observe READY. */
+	smp_mb__before_atomic();
+	set_bit(NCI_UART_READY, &nu->flags);
+
+	if (!nci_uart_queue_empty(nu))
+		nci_uart_tx_wakeup(nu);
 }
+EXPORT_SYMBOL_GPL(nci_uart_set_ready);
+
+void nci_uart_rx_stop(struct nci_uart *nu)
+{
+	spin_lock(&nu->rx_lock);
+	clear_bit(NCI_UART_READY, &nu->flags);
+	kfree_skb(nu->rx_skb);
+	nu->rx_skb = NULL;
+	spin_unlock(&nu->rx_lock);
+}
+EXPORT_SYMBOL_GPL(nci_uart_rx_stop);
 
 static int nci_uart_set_driver(struct nci_uart *nu, unsigned int driver)
 {

@@ -136,21 +215,17 @@ static int nci_uart_set_driver(struct nci_uart *nu, unsigned int driver)
 	if (ret)
 		goto err_module;
 
-	/* Publish transport fields before callbacks observe READY. */
-	smp_mb__before_atomic();
-	set_bit(NCI_UART_READY, &nu->flags);
+	nci_uart_set_ready(nu);
 
 	return 0;
 
 err_module:
-	cancel_work_sync(&nu->write_work);
+	nci_uart_rx_stop(nu);
+	nci_uart_tx_stop(nu);
 	kfree_skb(nu->tx_skb);
 	nu->tx_skb = NULL;
-	kfree_skb(nu->rx_skb);
-	nu->rx_skb = NULL;
 	skb_queue_purge(&nu->tx_q);
-	clear_bit(NCI_UART_SENDING, &nu->tx_state);
-	clear_bit(NCI_UART_TX_WAKEUP, &nu->tx_state);
+	clear_bit(NCI_UART_CLOSING, &nu->tx_state);
 	module_put(nu->owner);
 	nu->owner = NULL;
 	goto err_clear;

@@ -173,6 +248,7 @@ static int nci_uart_tty_alloc(struct tty_struct *tty)
 	nu->tty = tty;
 	skb_queue_head_init(&nu->tx_q);
 	INIT_WORK(&nu->write_work, nci_uart_write_work);
+	spin_lock_init(&nu->tx_lock);
 	spin_lock_init(&nu->rx_lock);
 
 	tty->disc_data = nu;

@@ -213,26 +289,25 @@ static void nci_uart_tty_close(struct tty_struct *tty)
 {
 	struct nci_uart *nu = tty->disc_data;
 
-	/* Detach from the tty */
-	tty->disc_data = NULL;
-
 	if (!nu)
 		return;
 
+	tty->disc_data = NULL;
+
 	if (test_bit(NCI_UART_DRIVER_SET, &nu->flags)) {
-		kfree_skb(nu->tx_skb);
-		kfree_skb(nu->rx_skb);
+		nu->ops.close(nu);
 
+		nci_uart_rx_stop(nu);
+		nci_uart_tx_stop(nu);
+
+		kfree_skb(nu->tx_skb);
 		skb_queue_purge(&nu->tx_q);
 
-		nu->ops.close(nu);
 		module_put(nu->owner);
 	}
 
 	nu->tty = NULL;
 
-	cancel_work_sync(&nu->write_work);
-
 	kfree(nu);
 }
 

@@ -348,6 +423,10 @@ static void nci_uart_tty_receive(struct tty_struct *tty, const u8 *data,
 		return;
 
 	spin_lock(&nu->rx_lock);
+	if (!test_bit(NCI_UART_READY, &nu->flags)) {
+		spin_unlock(&nu->rx_lock);
+		return;
+	}
 	nci_uart_default_recv_buf(nu, data, count);
 	spin_unlock(&nu->rx_lock);