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@kernel.org>
Link: https://patch.msgid.link/20251119100140.830761-5-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/n_hdlc.c b/drivers/tty/n_hdlc.c
index 66bb8ce6ec40c258964723a41eb7228b66acd72b..3c9dcb0928c6fbd967fc699bd3fa1e57408f3275 100644 (file)
--- 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 @@ check_again:
                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() */