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Message-ID: <20251119100140.830761-5-jirislaby@kernel.org>
Date: Wed, 19 Nov 2025 11:01:34 +0100
From: "Jiri Slaby (SUSE)" <jirislaby@...nel.org>
To: gregkh@...uxfoundation.org
Cc: linux-serial@...r.kernel.org,
linux-kernel@...r.kernel.org,
"Jiri Slaby (SUSE)" <jirislaby@...nel.org>
Subject: [PATCH 04/10] 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: Jiri Slaby (SUSE) <jirislaby@...nel.org>
---
drivers/tty/n_hdlc.c | 67 +++++++++++++++++---------------------------
1 file changed, 26 insertions(+), 41 deletions(-)
diff --git a/drivers/tty/n_hdlc.c b/drivers/tty/n_hdlc.c
index 66bb8ce6ec40..3c9dcb0928c6 100644
--- a/drivers/tty/n_hdlc.c
+++ b/drivers/tty/n_hdlc.c
@@ -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);
- if (n_hdlc->tbusy) {
- n_hdlc->woke_up = true;
- spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
- return;
+ scoped_guard(spinlock_irqsave, &n_hdlc->tx_buf_list.spinlock) {
+ if (n_hdlc->tbusy) {
+ n_hdlc->woke_up = true;
+ return;
+ }
+ n_hdlc->tbusy = true;
+ n_hdlc->woke_up = false;
}
- 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);
- n_hdlc->tbusy = false;
- spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
+ scoped_guard(spinlock_irqsave, &n_hdlc->tx_buf_list.spinlock)
+ n_hdlc->tbusy = false;
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);
- 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);
+ 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;
+ }
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);
- 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);
+ 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;
+ }
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() */
--
2.51.1
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