Commit 8c03bfcf authored by Jiri Slaby (SUSE)'s avatar Jiri Slaby (SUSE) Committed by Greg Kroah-Hartman
Browse files

tty: n_hdlc: use guard()s 



Use guards in the n_hdlc code. This improves readability, makes error
handling easier, and marks locked portions of code explicit. All that
while being sure the lock is unlocked.

Signed-off-by: default avatarJiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://patch.msgid.link/20251119100140.830761-5-jirislaby@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 3ae99599

drivers/tty/n_hdlc.c

+26 −41
Original line number Diff line number Diff line
@@ -263,21 +263,18 @@ static int n_hdlc_tty_open(struct tty_struct *tty) 
 */

static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty)

{

	unsigned long flags;

	struct n_hdlc_buf *tbuf;

	ssize_t actual;



check_again:



	spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);

	scoped_guard(spinlock_irqsave, &n_hdlc->tx_buf_list.spinlock) {

		if (n_hdlc->tbusy) {

			n_hdlc->woke_up = true;

		spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);

			return;

		}

		n_hdlc->tbusy = true;

		n_hdlc->woke_up = false;

	spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);

	}



	tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);

	while (tbuf) {
@@ -324,9 +321,8 @@ static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty) 
		clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);



	/* Clear the re-entry flag */

	spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);

	scoped_guard(spinlock_irqsave, &n_hdlc->tx_buf_list.spinlock)

		n_hdlc->tbusy = false;

	spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);



	if (n_hdlc->woke_up)

		goto check_again;
@@ -585,7 +581,6 @@ static int n_hdlc_tty_ioctl(struct tty_struct *tty, unsigned int cmd, 
{

	struct n_hdlc *n_hdlc = tty->disc_data;

	int count;

	unsigned long flags;

	struct n_hdlc_buf *buf = NULL;



	pr_debug("%s() called %d\n", __func__, cmd);
@@ -594,26 +589,26 @@ static int n_hdlc_tty_ioctl(struct tty_struct *tty, unsigned int cmd, 
	case FIONREAD:

		/* report count of read data available */

		/* in next available frame (if any) */

		spin_lock_irqsave(&n_hdlc->rx_buf_list.spinlock, flags);

		scoped_guard(spinlock_irqsave, &n_hdlc->rx_buf_list.spinlock) {

			buf = list_first_entry_or_null(&n_hdlc->rx_buf_list.list,

						       struct n_hdlc_buf, list_item);

			if (buf)

				count = buf->count;

			else

				count = 0;

		spin_unlock_irqrestore(&n_hdlc->rx_buf_list.spinlock, flags);

		}

		return put_user(count, (int __user *)arg);



	case TIOCOUTQ:

		/* get the pending tx byte count in the driver */

		count = tty_chars_in_buffer(tty);

		/* add size of next output frame in queue */

		spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);

		scoped_guard(spinlock_irqsave, &n_hdlc->tx_buf_list.spinlock) {

			buf = list_first_entry_or_null(&n_hdlc->tx_buf_list.list,

						       struct n_hdlc_buf, list_item);

			if (buf)

				count += buf->count;

		spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);

		}

		return put_user(count, (int __user *)arg);



	case TCFLSH:
@@ -720,14 +715,10 @@ static struct n_hdlc *n_hdlc_alloc(void) 
static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list,

						struct n_hdlc_buf *buf)

{

	unsigned long flags;



	spin_lock_irqsave(&buf_list->spinlock, flags);

	guard(spinlock_irqsave)(&buf_list->spinlock);



	list_add(&buf->list_item, &buf_list->list);

	buf_list->count++;



	spin_unlock_irqrestore(&buf_list->spinlock, flags);

}



/**
@@ -738,14 +729,10 @@ static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list, 
static void n_hdlc_buf_put(struct n_hdlc_buf_list *buf_list,

			   struct n_hdlc_buf *buf)

{

	unsigned long flags;



	spin_lock_irqsave(&buf_list->spinlock, flags);

	guard(spinlock_irqsave)(&buf_list->spinlock);



	list_add_tail(&buf->list_item, &buf_list->list);

	buf_list->count++;



	spin_unlock_irqrestore(&buf_list->spinlock, flags);

}	/* end of n_hdlc_buf_put() */



/**
@@ -758,10 +745,9 @@ static void n_hdlc_buf_put(struct n_hdlc_buf_list *buf_list, 
 */

static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *buf_list)

{

	unsigned long flags;

	struct n_hdlc_buf *buf;



	spin_lock_irqsave(&buf_list->spinlock, flags);

	guard(spinlock_irqsave)(&buf_list->spinlock);



	buf = list_first_entry_or_null(&buf_list->list,

						struct n_hdlc_buf, list_item);
@@ -770,7 +756,6 @@ static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *buf_list) 
		buf_list->count--;

	}



	spin_unlock_irqrestore(&buf_list->spinlock, flags);

	return buf;

}	/* end of n_hdlc_buf_get() */