Commit 88d65e22 authored by Jiri Slaby (SUSE)'s avatar Jiri Slaby (SUSE) Committed by Greg Kroah-Hartman
Browse files

tty: tty_port: use guard()s 



Having all the new guards, use them in the tty_port code. This improves
readability, makes error handling easier, and marks locked portions of
code explicit.

Signed-off-by: default avatar"Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250814072456.182853-6-jirislaby@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9f8da7b2

drivers/tty/tty_port.c

+74 −94
Original line number Diff line number Diff line
@@ -63,12 +63,8 @@ static void tty_port_default_lookahead_buf(struct tty_port *port, const u8 *p, 


static void tty_port_default_wakeup(struct tty_port *port)

{

	struct tty_struct *tty = tty_port_tty_get(port);



	if (tty) {

		tty_wakeup(tty);

		tty_kref_put(tty);

	}

	scoped_guard(tty_port_tty, port)

		tty_wakeup(scoped_tty());

}



const struct tty_port_client_operations tty_port_default_client_ops = {
@@ -225,26 +221,27 @@ EXPORT_SYMBOL_GPL(tty_port_unregister_device); 
int tty_port_alloc_xmit_buf(struct tty_port *port)

{

	/* We may sleep in get_zeroed_page() */

	mutex_lock(&port->buf_mutex);

	if (port->xmit_buf == NULL) {

		port->xmit_buf = (u8 *)get_zeroed_page(GFP_KERNEL);

	guard(mutex)(&port->buf_mutex);



	if (port->xmit_buf)

			kfifo_init(&port->xmit_fifo, port->xmit_buf, PAGE_SIZE);

	}

	mutex_unlock(&port->buf_mutex);

		return 0;



	port->xmit_buf = (u8 *)get_zeroed_page(GFP_KERNEL);

	if (port->xmit_buf == NULL)

		return -ENOMEM;



	kfifo_init(&port->xmit_fifo, port->xmit_buf, PAGE_SIZE);



	return 0;

}

EXPORT_SYMBOL(tty_port_alloc_xmit_buf);



void tty_port_free_xmit_buf(struct tty_port *port)

{

	mutex_lock(&port->buf_mutex);

	guard(mutex)(&port->buf_mutex);

	free_page((unsigned long)port->xmit_buf);

	port->xmit_buf = NULL;

	INIT_KFIFO(port->xmit_fifo);

	mutex_unlock(&port->buf_mutex);

}

EXPORT_SYMBOL(tty_port_free_xmit_buf);
@@ -301,13 +298,8 @@ EXPORT_SYMBOL(tty_port_put); 
 */

struct tty_struct *tty_port_tty_get(struct tty_port *port)

{

	unsigned long flags;

	struct tty_struct *tty;



	spin_lock_irqsave(&port->lock, flags);

	tty = tty_kref_get(port->tty);

	spin_unlock_irqrestore(&port->lock, flags);

	return tty;

	guard(spinlock_irqsave)(&port->lock);

	return tty_kref_get(port->tty);

}

EXPORT_SYMBOL(tty_port_tty_get);
@@ -321,12 +313,9 @@ EXPORT_SYMBOL(tty_port_tty_get); 
 */

void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty)

{

	unsigned long flags;



	spin_lock_irqsave(&port->lock, flags);

	guard(spinlock_irqsave)(&port->lock);

	tty_kref_put(port->tty);

	port->tty = tty_kref_get(tty);

	spin_unlock_irqrestore(&port->lock, flags);

}

EXPORT_SYMBOL(tty_port_tty_set);
@@ -342,11 +331,14 @@ EXPORT_SYMBOL(tty_port_tty_set); 
 */

static void tty_port_shutdown(struct tty_port *port, struct tty_struct *tty)

{

	mutex_lock(&port->mutex);

	guard(mutex)(&port->mutex);



	if (port->console)

		goto out;

		return;



	if (!tty_port_initialized(port))

		return;



	if (tty_port_initialized(port)) {

	tty_port_set_initialized(port, false);

	/*

	 * Drop DTR/RTS if HUPCL is set. This causes any attached
@@ -358,9 +350,6 @@ static void tty_port_shutdown(struct tty_port *port, struct tty_struct *tty) 
	if (port->ops->shutdown)

		port->ops->shutdown(port);

}

out:

	mutex_unlock(&port->mutex);

}



/**

 * tty_port_hangup		-	hangup helper
@@ -374,15 +363,15 @@ static void tty_port_shutdown(struct tty_port *port, struct tty_struct *tty) 
void tty_port_hangup(struct tty_port *port)

{

	struct tty_struct *tty;

	unsigned long flags;



	spin_lock_irqsave(&port->lock, flags);

	scoped_guard(spinlock_irqsave, &port->lock) {

		port->count = 0;

		tty = port->tty;

		if (tty)

			set_bit(TTY_IO_ERROR, &tty->flags);

		port->tty = NULL;

	spin_unlock_irqrestore(&port->lock, flags);

	}



	tty_port_set_active(port, false);

	tty_port_shutdown(port, tty);

	tty_kref_put(tty);
@@ -393,15 +382,16 @@ EXPORT_SYMBOL(tty_port_hangup); 


void __tty_port_tty_hangup(struct tty_port *port, bool check_clocal, bool async)

{

	struct tty_struct *tty = tty_port_tty_get(port);

	scoped_guard(tty_port_tty, port) {

		struct tty_struct *tty = scoped_tty();



	if (tty && (!check_clocal || !C_CLOCAL(tty))) {

		if (!check_clocal || !C_CLOCAL(tty)) {

			if (async)

				tty_hangup(tty);

			else

				tty_vhangup(tty);

		}

	tty_kref_put(tty);

	}

}

EXPORT_SYMBOL_GPL(__tty_port_tty_hangup);
@@ -490,7 +480,6 @@ int tty_port_block_til_ready(struct tty_port *port, 
				struct tty_struct *tty, struct file *filp)

{

	int do_clocal = 0, retval;

	unsigned long flags;

	DEFINE_WAIT(wait);



	/* if non-blocking mode is set we can pass directly to open unless
@@ -519,10 +508,10 @@ int tty_port_block_til_ready(struct tty_port *port, 
	retval = 0;



	/* The port lock protects the port counts */

	spin_lock_irqsave(&port->lock, flags);

	scoped_guard(spinlock_irqsave, &port->lock) {

		port->count--;

		port->blocked_open++;

	spin_unlock_irqrestore(&port->lock, flags);

	}



	while (1) {

		/* Indicate we are open */
@@ -561,11 +550,11 @@ int tty_port_block_til_ready(struct tty_port *port, 
	/* Update counts. A parallel hangup will have set count to zero and

	 * we must not mess that up further.

	 */

	spin_lock_irqsave(&port->lock, flags);

	scoped_guard(spinlock_irqsave, &port->lock) {

		if (!tty_hung_up_p(filp))

			port->count++;

		port->blocked_open--;

	spin_unlock_irqrestore(&port->lock, flags);

	}

	if (retval == 0)

		tty_port_set_active(port, true);

	return retval;
@@ -604,12 +593,10 @@ static void tty_port_drain_delay(struct tty_port *port, struct tty_struct *tty) 
int tty_port_close_start(struct tty_port *port,

				struct tty_struct *tty, struct file *filp)

{

	unsigned long flags;



	if (tty_hung_up_p(filp))

		return 0;



	spin_lock_irqsave(&port->lock, flags);

	scoped_guard(spinlock_irqsave, &port->lock) {

		if (tty->count == 1 && port->count != 1) {

			tty_warn(tty, "%s: tty->count = 1 port count = %d\n", __func__,

				 port->count);
@@ -621,11 +608,9 @@ int tty_port_close_start(struct tty_port *port, 
			port->count = 0;

		}



	if (port->count) {

		spin_unlock_irqrestore(&port->lock, flags);

		if (port->count)

			return 0;

	}

	spin_unlock_irqrestore(&port->lock, flags);



	tty->closing = 1;
@@ -744,9 +729,8 @@ EXPORT_SYMBOL_GPL(tty_port_install); 
int tty_port_open(struct tty_port *port, struct tty_struct *tty,

							struct file *filp)

{

	spin_lock_irq(&port->lock);

	scoped_guard(spinlock_irq, &port->lock)

		++port->count;

	spin_unlock_irq(&port->lock);

	tty_port_tty_set(port, tty);



	/*
@@ -755,21 +739,17 @@ int tty_port_open(struct tty_port *port, struct tty_struct *tty, 
	 * port mutex.

	 */



	mutex_lock(&port->mutex);



	if (!tty_port_initialized(port)) {

	scoped_guard(mutex, &port->mutex) {

		if (tty_port_initialized(port))

			break;

		clear_bit(TTY_IO_ERROR, &tty->flags);

		if (port->ops->activate) {

			int retval = port->ops->activate(port, tty);



			if (retval) {

				mutex_unlock(&port->mutex);

			if (retval)

				return retval;

		}

		}

		tty_port_set_initialized(port, true);

	}

	mutex_unlock(&port->mutex);

	return tty_port_block_til_ready(port, tty, filp);

}

EXPORT_SYMBOL(tty_port_open);