Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 983 insertions, 0 deletions

diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
new file mode 100644
index 000000000..697e32122
--- /dev/null
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -0,0 +1,983 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ *  Bluetooth HCI UART driver
+ *
+ *  Copyright (C) 2000-2001  Qualcomm Incorporated
+ *  Copyright (C) 2002-2003  Maxim Krasnyansky <maxk@qualcomm.com>
+ *  Copyright (C) 2004-2005  Marcel Holtmann <marcel@holtmann.org>
+ */
+
+#include <linux/module.h>
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/fcntl.h>
+#include <linux/interrupt.h>
+#include <linux/ptrace.h>
+#include <linux/poll.h>
+
+#include <linux/slab.h>
+#include <linux/tty.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/signal.h>
+#include <linux/ioctl.h>
+#include <linux/skbuff.h>
+#include <linux/firmware.h>
+#include <linux/serdev.h>
+
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+
+#include "btintel.h"
+#include "btbcm.h"
+#include "hci_uart.h"
+
+#define VERSION "2.3"
+
+static const struct hci_uart_proto *hup[HCI_UART_MAX_PROTO];
+
+int hci_uart_register_proto(const struct hci_uart_proto *p)
+{
+	if (p->id >= HCI_UART_MAX_PROTO)
+		return -EINVAL;
+
+	if (hup[p->id])
+		return -EEXIST;
+
+	hup[p->id] = p;
+
+	BT_INFO("HCI UART protocol %s registered", p->name);
+
+	return 0;
+}
+
+int hci_uart_unregister_proto(const struct hci_uart_proto *p)
+{
+	if (p->id >= HCI_UART_MAX_PROTO)
+		return -EINVAL;
+
+	if (!hup[p->id])
+		return -EINVAL;
+
+	hup[p->id] = NULL;
+
+	return 0;
+}
+
+static const struct hci_uart_proto *hci_uart_get_proto(unsigned int id)
+{
+	if (id >= HCI_UART_MAX_PROTO)
+		return NULL;
+
+	return hup[id];
+}
+
+static inline void hci_uart_tx_complete(struct hci_uart *hu, int pkt_type)
+{
+	struct hci_dev *hdev = hu->hdev;
+
+	/* Update HCI stat counters */
+	switch (pkt_type) {
+	case HCI_COMMAND_PKT:
+		hdev->stat.cmd_tx++;
+		break;
+
+	case HCI_ACLDATA_PKT:
+		hdev->stat.acl_tx++;
+		break;
+
+	case HCI_SCODATA_PKT:
+		hdev->stat.sco_tx++;
+		break;
+	}
+}
+
+static inline struct sk_buff *hci_uart_dequeue(struct hci_uart *hu)
+{
+	struct sk_buff *skb = hu->tx_skb;
+
+	if (!skb) {
+		percpu_down_read(&hu->proto_lock);
+
+		if (test_bit(HCI_UART_PROTO_READY, &hu->flags) ||
+		    test_bit(HCI_UART_PROTO_INIT, &hu->flags))
+			skb = hu->proto->dequeue(hu);
+
+		percpu_up_read(&hu->proto_lock);
+	} else {
+		hu->tx_skb = NULL;
+	}
+
+	return skb;
+}
+
+int hci_uart_tx_wakeup(struct hci_uart *hu)
+{
+	/* This may be called in an IRQ context, so we can't sleep. Therefore
+	 * we try to acquire the lock only, and if that fails we assume the
+	 * tty is being closed because that is the only time the write lock is
+	 * acquired. If, however, at some point in the future the write lock
+	 * is also acquired in other situations, then this must be revisited.
+	 */
+	if (!percpu_down_read_trylock(&hu->proto_lock))
+		return 0;
+
+	if (!test_bit(HCI_UART_PROTO_READY, &hu->flags) &&
+	    !test_bit(HCI_UART_PROTO_INIT, &hu->flags))
+		goto no_schedule;
+
+	set_bit(HCI_UART_TX_WAKEUP, &hu->tx_state);
+	if (test_and_set_bit(HCI_UART_SENDING, &hu->tx_state))
+		goto no_schedule;
+
+	BT_DBG("");
+
+	schedule_work(&hu->write_work);
+
+no_schedule:
+	percpu_up_read(&hu->proto_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(hci_uart_tx_wakeup);
+
+static void hci_uart_write_work(struct work_struct *work)
+{
+	struct hci_uart *hu = container_of(work, struct hci_uart, write_work);
+	struct tty_struct *tty = hu->tty;
+	struct hci_dev *hdev = hu->hdev;
+	struct sk_buff *skb;
+
+	/* REVISIT: should we cope with bad skbs or ->write() returning
+	 * and error value ?
+	 */
+
+restart:
+	clear_bit(HCI_UART_TX_WAKEUP, &hu->tx_state);
+
+	while ((skb = hci_uart_dequeue(hu))) {
+		int len;
+
+		set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+		len = tty->ops->write(tty, skb->data, skb->len);
+		if (len < 0 || len > skb->len) {
+			hdev->stat.err_tx++;
+			kfree_skb(skb);
+			continue;
+		}
+
+		hdev->stat.byte_tx += len;
+
+		skb_pull(skb, len);
+		if (skb->len) {
+			hu->tx_skb = skb;
+			break;
+		}
+
+		hci_uart_tx_complete(hu, hci_skb_pkt_type(skb));
+		kfree_skb(skb);
+	}
+
+	clear_bit(HCI_UART_SENDING, &hu->tx_state);
+	if (test_bit(HCI_UART_TX_WAKEUP, &hu->tx_state))
+		goto restart;
+
+	wake_up_bit(&hu->tx_state, HCI_UART_SENDING);
+}
+
+void hci_uart_init_work(struct work_struct *work)
+{
+	struct hci_uart *hu = container_of(work, struct hci_uart, init_ready);
+	int err;
+	struct hci_dev *hdev;
+
+	if (!test_and_clear_bit(HCI_UART_INIT_PENDING, &hu->hdev_flags))
+		return;
+
+	err = hci_register_dev(hu->hdev);
+	if (err < 0) {
+		BT_ERR("Can't register HCI device");
+
+		percpu_down_write(&hu->proto_lock);
+		clear_bit(HCI_UART_PROTO_READY, &hu->flags);
+		percpu_up_write(&hu->proto_lock);
+
+		/* Safely cancel work after clearing flags */
+		cancel_work_sync(&hu->write_work);
+
+		/* Close protocol before freeing hdev */
+		hu->proto->close(hu);
+		hdev = hu->hdev;
+		hu->hdev = NULL;
+		hci_free_dev(hdev);
+		return;
+	}
+
+	set_bit(HCI_UART_REGISTERED, &hu->flags);
+}
+
+int hci_uart_init_ready(struct hci_uart *hu)
+{
+	if (!test_bit(HCI_UART_INIT_PENDING, &hu->hdev_flags))
+		return -EALREADY;
+
+	schedule_work(&hu->init_ready);
+
+	return 0;
+}
+
+int hci_uart_wait_until_sent(struct hci_uart *hu)
+{
+	return wait_on_bit_timeout(&hu->tx_state, HCI_UART_SENDING,
+				   TASK_INTERRUPTIBLE,
+				   msecs_to_jiffies(2000));
+}
+
+/* ------- Interface to HCI layer ------ */
+/* Reset device */
+static int hci_uart_flush(struct hci_dev *hdev)
+{
+	struct hci_uart *hu  = hci_get_drvdata(hdev);
+	struct tty_struct *tty = hu->tty;
+
+	BT_DBG("hdev %p tty %p", hdev, tty);
+
+	disable_work_sync(&hu->write_work);
+
+	if (hu->tx_skb) {
+		kfree_skb(hu->tx_skb); hu->tx_skb = NULL;
+	}
+
+	/* Flush any pending characters in the driver and discipline. */
+	tty_ldisc_flush(tty);
+	tty_driver_flush_buffer(tty);
+
+	percpu_down_read(&hu->proto_lock);
+
+	if (test_bit(HCI_UART_PROTO_READY, &hu->flags))
+		hu->proto->flush(hu);
+
+	percpu_up_read(&hu->proto_lock);
+
+	/* Resume TX. Also reschedule in case work was queued concurrently;
+	 * this may schedule write_work although there's nothing to do.
+	 */
+	enable_work(&hu->write_work);
+	clear_bit(HCI_UART_SENDING, &hu->tx_state);
+	if (test_bit(HCI_UART_TX_WAKEUP, &hu->tx_state))
+		hci_uart_tx_wakeup(hu);
+
+	return 0;
+}
+
+/* Initialize device */
+static int hci_uart_open(struct hci_dev *hdev)
+{
+	BT_DBG("%s %p", hdev->name, hdev);
+
+	/* Undo clearing this from hci_uart_close() */
+	hdev->flush = hci_uart_flush;
+
+	return 0;
+}
+
+/* Close device */
+static int hci_uart_close(struct hci_dev *hdev)
+{
+	BT_DBG("hdev %p", hdev);
+
+	hci_uart_flush(hdev);
+	hdev->flush = NULL;
+	return 0;
+}
+
+/* Send frames from HCI layer */
+static int hci_uart_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	struct hci_uart *hu = hci_get_drvdata(hdev);
+
+	BT_DBG("%s: type %d len %d", hdev->name, hci_skb_pkt_type(skb),
+	       skb->len);
+
+	percpu_down_read(&hu->proto_lock);
+
+	if (!test_bit(HCI_UART_PROTO_READY, &hu->flags) &&
+	    !test_bit(HCI_UART_PROTO_INIT, &hu->flags)) {
+		percpu_up_read(&hu->proto_lock);
+		return -EUNATCH;
+	}
+
+	hu->proto->enqueue(hu, skb);
+	percpu_up_read(&hu->proto_lock);
+
+	hci_uart_tx_wakeup(hu);
+
+	return 0;
+}
+
+/* Check the underlying device or tty has flow control support */
+bool hci_uart_has_flow_control(struct hci_uart *hu)
+{
+	/* serdev nodes check if the needed operations are present */
+	if (hu->serdev)
+		return true;
+
+	if (hu->tty->driver->ops->tiocmget && hu->tty->driver->ops->tiocmset)
+		return true;
+
+	return false;
+}
+
+/* Flow control or un-flow control the device */
+void hci_uart_set_flow_control(struct hci_uart *hu, bool enable)
+{
+	struct tty_struct *tty = hu->tty;
+	struct ktermios ktermios;
+	int status;
+	unsigned int set = 0;
+	unsigned int clear = 0;
+
+	if (hu->serdev) {
+		serdev_device_set_flow_control(hu->serdev, !enable);
+		serdev_device_set_rts(hu->serdev, !enable);
+		return;
+	}
+
+	if (enable) {
+		/* Disable hardware flow control */
+		ktermios = tty->termios;
+		ktermios.c_cflag &= ~CRTSCTS;
+		tty_set_termios(tty, &ktermios);
+		BT_DBG("Disabling hardware flow control: %s",
+		       (tty->termios.c_cflag & CRTSCTS) ? "failed" : "success");
+
+		/* Clear RTS to prevent the device from sending */
+		/* Most UARTs need OUT2 to enable interrupts */
+		status = tty->driver->ops->tiocmget(tty);
+		BT_DBG("Current tiocm 0x%x", status);
+
+		set &= ~(TIOCM_OUT2 | TIOCM_RTS);
+		clear = ~set;
+		set &= TIOCM_DTR | TIOCM_RTS | TIOCM_OUT1 |
+		       TIOCM_OUT2 | TIOCM_LOOP;
+		clear &= TIOCM_DTR | TIOCM_RTS | TIOCM_OUT1 |
+			 TIOCM_OUT2 | TIOCM_LOOP;
+		status = tty->driver->ops->tiocmset(tty, set, clear);
+		BT_DBG("Clearing RTS: %s", status ? "failed" : "success");
+	} else {
+		/* Set RTS to allow the device to send again */
+		status = tty->driver->ops->tiocmget(tty);
+		BT_DBG("Current tiocm 0x%x", status);
+
+		set |= (TIOCM_OUT2 | TIOCM_RTS);
+		clear = ~set;
+		set &= TIOCM_DTR | TIOCM_RTS | TIOCM_OUT1 |
+		       TIOCM_OUT2 | TIOCM_LOOP;
+		clear &= TIOCM_DTR | TIOCM_RTS | TIOCM_OUT1 |
+			 TIOCM_OUT2 | TIOCM_LOOP;
+		status = tty->driver->ops->tiocmset(tty, set, clear);
+		BT_DBG("Setting RTS: %s", status ? "failed" : "success");
+
+		/* Re-enable hardware flow control */
+		ktermios = tty->termios;
+		ktermios.c_cflag |= CRTSCTS;
+		tty_set_termios(tty, &ktermios);
+		BT_DBG("Enabling hardware flow control: %s",
+		       !(tty->termios.c_cflag & CRTSCTS) ? "failed" : "success");
+	}
+}
+
+void hci_uart_set_speeds(struct hci_uart *hu, unsigned int init_speed,
+			 unsigned int oper_speed)
+{
+	hu->init_speed = init_speed;
+	hu->oper_speed = oper_speed;
+}
+
+void hci_uart_set_baudrate(struct hci_uart *hu, unsigned int speed)
+{
+	struct tty_struct *tty = hu->tty;
+	struct ktermios ktermios;
+
+	ktermios = tty->termios;
+	ktermios.c_cflag &= ~CBAUD;
+	tty_termios_encode_baud_rate(&ktermios, speed, speed);
+
+	/* tty_set_termios() return not checked as it is always 0 */
+	tty_set_termios(tty, &ktermios);
+
+	BT_DBG("%s: New tty speeds: %d/%d", hu->hdev->name,
+	       tty->termios.c_ispeed, tty->termios.c_ospeed);
+}
+
+static int hci_uart_setup(struct hci_dev *hdev)
+{
+	struct hci_uart *hu = hci_get_drvdata(hdev);
+	struct hci_rp_read_local_version *ver;
+	struct sk_buff *skb;
+	unsigned int speed;
+	int err;
+
+	/* Init speed if any */
+	if (hu->init_speed)
+		speed = hu->init_speed;
+	else if (hu->proto->init_speed)
+		speed = hu->proto->init_speed;
+	else
+		speed = 0;
+
+	if (speed)
+		hci_uart_set_baudrate(hu, speed);
+
+	/* Operational speed if any */
+	if (hu->oper_speed)
+		speed = hu->oper_speed;
+	else if (hu->proto->oper_speed)
+		speed = hu->proto->oper_speed;
+	else
+		speed = 0;
+
+	if (hu->proto->set_baudrate && speed) {
+		err = hu->proto->set_baudrate(hu, speed);
+		if (!err)
+			hci_uart_set_baudrate(hu, speed);
+	}
+
+	if (hu->proto->setup)
+		return hu->proto->setup(hu);
+
+	if (!test_bit(HCI_UART_VND_DETECT, &hu->hdev_flags))
+		return 0;
+
+	skb = __hci_cmd_sync(hdev, HCI_OP_READ_LOCAL_VERSION, 0, NULL,
+			     HCI_INIT_TIMEOUT);
+	if (IS_ERR(skb)) {
+		BT_ERR("%s: Reading local version information failed (%ld)",
+		       hdev->name, PTR_ERR(skb));
+		return PTR_ERR(skb);
+	}
+
+	if (skb->len != sizeof(*ver)) {
+		BT_ERR("%s: Event length mismatch for version information",
+		       hdev->name);
+		goto done;
+	}
+
+	ver = (struct hci_rp_read_local_version *)skb->data;
+
+	switch (le16_to_cpu(ver->manufacturer)) {
+#ifdef CONFIG_BT_HCIUART_INTEL
+	case 2:
+		hdev->set_bdaddr = btintel_set_bdaddr;
+		btintel_check_bdaddr(hdev);
+		break;
+#endif
+#ifdef CONFIG_BT_HCIUART_BCM
+	case 15:
+		hdev->set_bdaddr = btbcm_set_bdaddr;
+		btbcm_check_bdaddr(hdev);
+		break;
+#endif
+	default:
+		break;
+	}
+
+done:
+	kfree_skb(skb);
+	return 0;
+}
+
+/* ------ LDISC part ------ */
+/* hci_uart_tty_open
+ *
+ *     Called when line discipline changed to HCI_UART.
+ *
+ * Arguments:
+ *     tty    pointer to tty info structure
+ * Return Value:
+ *     0 if success, otherwise error code
+ */
+static int hci_uart_tty_open(struct tty_struct *tty)
+{
+	struct hci_uart *hu;
+
+	BT_DBG("tty %p", tty);
+
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
+	/* Error if the tty has no write op instead of leaving an exploitable
+	 * hole
+	 */
+	if (tty->ops->write == NULL)
+		return -EOPNOTSUPP;
+
+	hu = kzalloc_obj(*hu);
+	if (!hu) {
+		BT_ERR("Can't allocate control structure");
+		return -ENFILE;
+	}
+	if (percpu_init_rwsem(&hu->proto_lock)) {
+		BT_ERR("Can't allocate semaphore structure");
+		kfree(hu);
+		return -ENOMEM;
+	}
+
+	tty->disc_data = hu;
+	hu->tty = tty;
+	tty->receive_room = 65536;
+
+	/* disable alignment support by default */
+	hu->alignment = 1;
+	hu->padding = 0;
+
+	/* Use serial port speed as oper_speed */
+	hu->oper_speed = tty->termios.c_ospeed;
+
+	INIT_WORK(&hu->init_ready, hci_uart_init_work);
+	INIT_WORK(&hu->write_work, hci_uart_write_work);
+
+	/* Flush any pending characters in the driver */
+	tty_driver_flush_buffer(tty);
+
+	return 0;
+}
+
+/* hci_uart_tty_close()
+ *
+ *    Called when the line discipline is changed to something
+ *    else, the tty is closed, or the tty detects a hangup.
+ */
+static void hci_uart_tty_close(struct tty_struct *tty)
+{
+	struct hci_uart *hu = tty->disc_data;
+	struct hci_dev *hdev;
+	bool proto_ready;
+
+	BT_DBG("tty %p", tty);
+
+	/* Detach from the tty */
+	tty->disc_data = NULL;
+
+	if (!hu)
+		return;
+
+	/* Wait for init_ready to finish to prevent registration races */
+	cancel_work_sync(&hu->init_ready);
+
+	proto_ready = test_bit(HCI_UART_PROTO_READY, &hu->flags);
+	if (proto_ready) {
+		percpu_down_write(&hu->proto_lock);
+		clear_bit(HCI_UART_PROTO_READY, &hu->flags);
+		percpu_up_write(&hu->proto_lock);
+	}
+
+	/*
+	 * Unconditionally cancel write_work AFTER clearing PROTO_READY.
+	 * This ensures that concurrent protocol timers cannot requeue
+	 * write_work via hci_uart_tx_wakeup(), permanently preventing
+	 * double-free races and UAFs.
+	 */
+	cancel_work_sync(&hu->write_work);
+
+	hdev = hu->hdev;
+	if (hdev)
+		hci_uart_close(hdev); /* proto->flush is safely skipped */
+
+	if (proto_ready) {
+		if (hdev) {
+			if (test_bit(HCI_UART_REGISTERED, &hu->flags))
+				hci_unregister_dev(hdev);
+		}
+		/* Close protocol before freeing hdev (intrinsically purges queues) */
+		hu->proto->close(hu);
+
+		if (hdev)
+			hci_free_dev(hdev);
+	}
+	clear_bit(HCI_UART_PROTO_SET, &hu->flags);
+
+	percpu_free_rwsem(&hu->proto_lock);
+
+	kfree(hu);
+}
+
+/* hci_uart_tty_wakeup()
+ *
+ *    Callback for transmit wakeup. Called when low level
+ *    device driver can accept more send data.
+ *
+ * Arguments:        tty    pointer to associated tty instance data
+ * Return Value:    None
+ */
+static void hci_uart_tty_wakeup(struct tty_struct *tty)
+{
+	struct hci_uart *hu = tty->disc_data;
+
+	BT_DBG("");
+
+	if (!hu)
+		return;
+
+	clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+
+	if (tty != hu->tty)
+		return;
+
+	if (test_bit(HCI_UART_PROTO_READY, &hu->flags) ||
+	    test_bit(HCI_UART_PROTO_INIT, &hu->flags))
+		hci_uart_tx_wakeup(hu);
+}
+
+/* hci_uart_tty_receive()
+ *
+ *     Called by tty low level driver when receive data is
+ *     available.
+ *
+ * Arguments:  tty          pointer to tty instance data
+ *             data         pointer to received data
+ *             flags        pointer to flags for data
+ *             count        count of received data in bytes
+ *
+ * Return Value:    None
+ */
+static void hci_uart_tty_receive(struct tty_struct *tty, const u8 *data,
+				 const u8 *flags, size_t count)
+{
+	struct hci_uart *hu = tty->disc_data;
+
+	if (!hu || tty != hu->tty)
+		return;
+
+	percpu_down_read(&hu->proto_lock);
+
+	if (!test_bit(HCI_UART_PROTO_READY, &hu->flags) &&
+	    !test_bit(HCI_UART_PROTO_INIT, &hu->flags)) {
+		percpu_up_read(&hu->proto_lock);
+		return;
+	}
+
+	/* It does not need a lock here as it is already protected by a mutex in
+	 * tty caller
+	 */
+	hu->proto->recv(hu, data, count);
+
+	if (hu->hdev)
+		hu->hdev->stat.byte_rx += count;
+
+	percpu_up_read(&hu->proto_lock);
+
+	tty_unthrottle(tty);
+}
+
+static int hci_uart_register_dev(struct hci_uart *hu)
+{
+	struct hci_dev *hdev;
+	int err;
+
+	BT_DBG("");
+
+	/* Initialize and register HCI device */
+	hdev = hci_alloc_dev();
+	if (!hdev) {
+		BT_ERR("Can't allocate HCI device");
+		return -ENOMEM;
+	}
+
+	hu->hdev = hdev;
+
+	hdev->bus = HCI_UART;
+	hci_set_drvdata(hdev, hu);
+
+	/* Only when vendor specific setup callback is provided, consider
+	 * the manufacturer information valid. This avoids filling in the
+	 * value for Ericsson when nothing is specified.
+	 */
+	if (hu->proto->setup)
+		hdev->manufacturer = hu->proto->manufacturer;
+
+	hdev->open  = hci_uart_open;
+	hdev->close = hci_uart_close;
+	hdev->flush = hci_uart_flush;
+	hdev->send  = hci_uart_send_frame;
+	hdev->setup = hci_uart_setup;
+	SET_HCIDEV_DEV(hdev, hu->tty->dev);
+
+	if (test_bit(HCI_UART_RAW_DEVICE, &hu->hdev_flags))
+		hci_set_quirk(hdev, HCI_QUIRK_RAW_DEVICE);
+
+	if (test_bit(HCI_UART_EXT_CONFIG, &hu->hdev_flags))
+		hci_set_quirk(hdev, HCI_QUIRK_EXTERNAL_CONFIG);
+
+	if (!test_bit(HCI_UART_RESET_ON_INIT, &hu->hdev_flags))
+		hci_set_quirk(hdev, HCI_QUIRK_RESET_ON_CLOSE);
+
+	/* Only call open() for the protocol after hdev is fully initialized as
+	 * open() (or a timer/workqueue it starts) may attempt to reference it.
+	 */
+	err = hu->proto->open(hu);
+	if (err) {
+		hu->hdev = NULL;
+		hci_free_dev(hdev);
+		return err;
+	}
+
+	set_bit(HCI_UART_PROTO_INIT, &hu->flags);
+
+	if (test_bit(HCI_UART_INIT_PENDING, &hu->hdev_flags))
+		return 0;
+
+	if (hci_register_dev(hdev) < 0) {
+		BT_ERR("Can't register HCI device");
+		percpu_down_write(&hu->proto_lock);
+		clear_bit(HCI_UART_PROTO_INIT, &hu->flags);
+		percpu_up_write(&hu->proto_lock);
+		/* Cancel work after clearing flags */
+		cancel_work_sync(&hu->write_work);
+
+		/* Close protocol before freeing hdev */
+		hu->proto->close(hu);
+		hu->hdev = NULL;
+		hci_free_dev(hdev);
+		return -ENODEV;
+	}
+
+	set_bit(HCI_UART_REGISTERED, &hu->flags);
+
+	return 0;
+}
+
+static int hci_uart_set_proto(struct hci_uart *hu, int id)
+{
+	const struct hci_uart_proto *p;
+	int err;
+
+	p = hci_uart_get_proto(id);
+	if (!p)
+		return -EPROTONOSUPPORT;
+
+	hu->proto = p;
+
+	err = hci_uart_register_dev(hu);
+	if (err)
+		return err;
+
+
+	set_bit(HCI_UART_PROTO_READY, &hu->flags);
+	clear_bit(HCI_UART_PROTO_INIT, &hu->flags);
+
+	return 0;
+}
+
+static int hci_uart_set_flags(struct hci_uart *hu, unsigned long flags)
+{
+	unsigned long valid_flags = BIT(HCI_UART_RAW_DEVICE) |
+				    BIT(HCI_UART_RESET_ON_INIT) |
+				    BIT(HCI_UART_INIT_PENDING) |
+				    BIT(HCI_UART_EXT_CONFIG) |
+				    BIT(HCI_UART_VND_DETECT);
+
+	if (flags & ~valid_flags)
+		return -EINVAL;
+
+	hu->hdev_flags = flags;
+
+	return 0;
+}
+
+/* hci_uart_tty_ioctl()
+ *
+ *    Process IOCTL system call for the tty device.
+ *
+ * Arguments:
+ *
+ *    tty        pointer to tty instance data
+ *    cmd        IOCTL command code
+ *    arg        argument for IOCTL call (cmd dependent)
+ *
+ * Return Value:    Command dependent
+ */
+static int hci_uart_tty_ioctl(struct tty_struct *tty, unsigned int cmd,
+			      unsigned long arg)
+{
+	struct hci_uart *hu = tty->disc_data;
+	int err = 0;
+
+	BT_DBG("");
+
+	/* Verify the status of the device */
+	if (!hu)
+		return -EBADF;
+
+	switch (cmd) {
+	case HCIUARTSETPROTO:
+		if (!test_and_set_bit(HCI_UART_PROTO_SET, &hu->flags)) {
+			err = hci_uart_set_proto(hu, arg);
+			if (err)
+				clear_bit(HCI_UART_PROTO_SET, &hu->flags);
+		} else
+			err = -EBUSY;
+		break;
+
+	case HCIUARTGETPROTO:
+		if (test_bit(HCI_UART_PROTO_SET, &hu->flags) &&
+		    test_bit(HCI_UART_PROTO_READY, &hu->flags))
+			err = hu->proto->id;
+		else
+			err = -EUNATCH;
+		break;
+
+	case HCIUARTGETDEVICE:
+		if (test_bit(HCI_UART_REGISTERED, &hu->flags))
+			err = hu->hdev->id;
+		else
+			err = -EUNATCH;
+		break;
+
+	case HCIUARTSETFLAGS:
+		if (test_bit(HCI_UART_PROTO_SET, &hu->flags))
+			err = -EBUSY;
+		else
+			err = hci_uart_set_flags(hu, arg);
+		break;
+
+	case HCIUARTGETFLAGS:
+		err = hu->hdev_flags;
+		break;
+
+	default:
+		err = n_tty_ioctl_helper(tty, cmd, arg);
+		break;
+	}
+
+	return err;
+}
+
+/*
+ * We don't provide read/write/poll interface for user space.
+ */
+static ssize_t hci_uart_tty_read(struct tty_struct *tty, struct file *file,
+				 u8 *buf, size_t nr, void **cookie,
+				 unsigned long offset)
+{
+	return 0;
+}
+
+static ssize_t hci_uart_tty_write(struct tty_struct *tty, struct file *file,
+				  const u8 *data, size_t count)
+{
+	return 0;
+}
+
+static struct tty_ldisc_ops hci_uart_ldisc = {
+	.owner		= THIS_MODULE,
+	.num		= N_HCI,
+	.name		= "n_hci",
+	.open		= hci_uart_tty_open,
+	.close		= hci_uart_tty_close,
+	.read		= hci_uart_tty_read,
+	.write		= hci_uart_tty_write,
+	.ioctl		= hci_uart_tty_ioctl,
+	.compat_ioctl	= hci_uart_tty_ioctl,
+	.receive_buf	= hci_uart_tty_receive,
+	.write_wakeup	= hci_uart_tty_wakeup,
+};
+
+static int __init hci_uart_init(void)
+{
+	int err;
+
+	BT_INFO("HCI UART driver ver %s", VERSION);
+
+	/* Register the tty discipline */
+	err = tty_register_ldisc(&hci_uart_ldisc);
+	if (err) {
+		BT_ERR("HCI line discipline registration failed. (%d)", err);
+		return err;
+	}
+
+#ifdef CONFIG_BT_HCIUART_H4
+	h4_init();
+#endif
+#ifdef CONFIG_BT_HCIUART_BCSP
+	bcsp_init();
+#endif
+#ifdef CONFIG_BT_HCIUART_LL
+	ll_init();
+#endif
+#ifdef CONFIG_BT_HCIUART_ATH3K
+	ath_init();
+#endif
+#ifdef CONFIG_BT_HCIUART_3WIRE
+	h5_init();
+#endif
+#ifdef CONFIG_BT_HCIUART_INTEL
+	intel_init();
+#endif
+#ifdef CONFIG_BT_HCIUART_BCM
+	bcm_init();
+#endif
+#ifdef CONFIG_BT_HCIUART_QCA
+	qca_init();
+#endif
+#ifdef CONFIG_BT_HCIUART_AG6XX
+	ag6xx_init();
+#endif
+#ifdef CONFIG_BT_HCIUART_MRVL
+	mrvl_init();
+#endif
+#ifdef CONFIG_BT_HCIUART_AML
+	aml_init();
+#endif
+	return 0;
+}
+
+static void __exit hci_uart_exit(void)
+{
+#ifdef CONFIG_BT_HCIUART_H4
+	h4_deinit();
+#endif
+#ifdef CONFIG_BT_HCIUART_BCSP
+	bcsp_deinit();
+#endif
+#ifdef CONFIG_BT_HCIUART_LL
+	ll_deinit();
+#endif
+#ifdef CONFIG_BT_HCIUART_ATH3K
+	ath_deinit();
+#endif
+#ifdef CONFIG_BT_HCIUART_3WIRE
+	h5_deinit();
+#endif
+#ifdef CONFIG_BT_HCIUART_INTEL
+	intel_deinit();
+#endif
+#ifdef CONFIG_BT_HCIUART_BCM
+	bcm_deinit();
+#endif
+#ifdef CONFIG_BT_HCIUART_QCA
+	qca_deinit();
+#endif
+#ifdef CONFIG_BT_HCIUART_AG6XX
+	ag6xx_deinit();
+#endif
+#ifdef CONFIG_BT_HCIUART_MRVL
+	mrvl_deinit();
+#endif
+#ifdef CONFIG_BT_HCIUART_AML
+	aml_deinit();
+#endif
+	tty_unregister_ldisc(&hci_uart_ldisc);
+}
+
+module_init(hci_uart_init);
+module_exit(hci_uart_exit);
+
+MODULE_AUTHOR("Marcel Holtmann <marcel@holtmann.org>");
+MODULE_DESCRIPTION("Bluetooth HCI UART driver ver " VERSION);
+MODULE_VERSION(VERSION);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_LDISC(N_HCI);